Definition of dBs ?
ken_...@my-deja.com
I see it in JVC specs. For instance my camcorder audio output level is
spec'd at -8dBs. But all of the references I can find only refer to
dBu, dBm, or dBV.
Sent via Deja.com http://www.deja.com/
Before you buy.
Brian Tankersley
impressed.
Regards,
Brian T
Peter Garrens wrote:
>
> dB - from alexandera Bell (I think)
> d is deci,B is Bell ie the deci bell
> the Bell is to large a value and for sound and others deci (1*10^-3) is used
>
> It is a logarithmic representation of gain.
>
> Gain = output power / input power
> and to get gain in dB's Gdb = 10logGain
> Where Gain = Po/Pi
>
> for interest:
> there is a Voltage gain also, dB= 10log Vgain^2 = 20logVgain
> ie the square of voltage to convert to a power as p=IV =V^2/R=I^2R, and
> Pout/Pin = (Vo^2/R)/(Vin^2/R) = (Vo/Vin)^2
> hence following the above gain in dB formulae Gdb = 10log(Vo/Vin)^2 and
> using usual log rules, hence Gdb = 20log(Vo/Vi)
>
> So why put gain in dB?
> Because multiplication of two power with out dB you do just that multiply
> them. Calculators were hard to come by back then, and using logarithms (dB)
> allowed the following rules:
>
> for multiplication, you just add the dB
> is lets take 10*10 = 100 (pretend that was hard)
> 10 in db = 10db, hence 10+10 = 20dB
> to verify use anti-log ie 10^(20/10)=100
>
> for division you just subtract.
>
> u - micro typest shorthane for the real micro symbol (greek I think)
> dBV - decibel volts referenced to 1V
> dBmV - decibels refference to the milli-volt
>
> doubling of gain coresponds to about a 3db gain
>
> ie 5*2 = 10
> 10log(5) =6.99
> 10log(10)=10
> 10-6.77 = 3
>
> ie 10*2 = 20
> 10log(20) - 10log(10) = 3db (aprox)
>
> and it just so happens people can hear if a sound is twice the level of the
> previous one ... handy!
>
> <ken_...@my-deja.com> wrote in message news:8ah79p$llr$1...@nnrp1.deja.com...
Jay Rose
|: Can anyone tell me what "dBs" means with regard to audio line level?
|: I see it in JVC specs. For instance my camcorder audio output level is
|: spec'd at -8dBs. But all of the references I can find only refer to
|: dBu, dBm, or dBV.
Elegant explanations of dB aside, I think the guy was referring to dBs as
opposed to dBu or dBm. I've never heard of that standard, and I'm not sure
what the 's' would indicate as a reference. Decibels referred to slate? to
softness? to shh?
--
Jay Rose <<jay at dplay dotcom>>
Clio/Emmy-winning Sound Designer
Want to learn audio for video? http://www.dplay.com/book
Peter Garrens
> Can anyone tell me what "dBs" means with regard to audio line level?
> I see it in JVC specs. For instance my camcorder audio output level is
> spec'd at -8dBs. But all of the references I can find only refer to
> dBu, dBm, or dBV.
>
>
Peter Garrens
computer technology" and an NZCE electrical and a bachelor of engineering
does for you
"Brian Tankersley" <gbt...@home.com> wrote in message
news:38CC2F5D...@home.com...
> Peter, if you didn't just copy and paste that from someplace, I'm
> impressed.
>
> Regards,
> Brian T
>
>
>
> Peter Garrens wrote:
> >
Tom MacIntyre
<gar...@ihug.co.nz> wrote:
>dB - from alexandera Bell (I think)
>d is deci,B is Bell ie the deci bell
>the Bell is to large a value and for sound and others deci (1*10^-3) is used
deci is 10^-1, isn't it? He asked about dBs.
^
Tom
Peter Garrens
1/10 = 10^-1 as pointed out by tom
thanks
"Tom MacIntyre" <tmac...@ns.sympatico.ca> wrote in message
news:38cc3610...@news.wolf...
Dan Popp
the other usual designations. A video tech showed me a spec on Sony gear
that was, in fact dBS, in which the "S" (he said) stood for Sony. In other
words, this is a proprietary standard. You'll have to try to get an
explanation from Sony or JVC if you think the effort is worthwhile!
Yours,
Dan Popp
Colors Audio
USA
.
Ben Bradley
>
>|: Can anyone tell me what "dBs" means with regard to audio line level?
>|: I see it in JVC specs. For instance my camcorder audio output level is
>|: spec'd at -8dBs. But all of the references I can find only refer to
>|: dBu, dBm, or dBV.
>
>Elegant explanations of dB aside, I think the guy was referring to dBs as
>opposed to dBu or dBm. I've never heard of that standard, and I'm not sure
>what the 's' would indicate as a reference. Decibels referred to slate? to
>softness? to shh?
It (dBs) could even be a plural, as in -1 dee-bee or -8 dee-bee's.
But this still doesn't tell what this '-8' is referenced to. I suppose
the original poster will have to ask JVC.
-----
http://listen.to/benbradley New guitar pics!
Yes, ben_nospa...@mindspring.com is my correct email address.
Robert
Every tech and engineer should know that - its not such a big deal.
But the guy asked about dbS not just db theory. I know dbm and dbv but
I never heard of dbs... I'll ask around.
Stephen DeVore, Seattle, WA
novice's way of saying dBs-plural. (I know people who say
dee bees instead of just dB.) In fact, until your comment,
that's exactly how I first interpreted his reference to dBs!
:)
halleluYah, Stephen
Robert <FlintSof...@nospam.org> wrote in message
news:38cc62d8...@nntp.hip.cam.org...
Stephen DeVore, Seattle, WA
In layman's terms, how many dB doubles the SPL, power, or
gain, etc.?
DEAR PETER:
Your post says 3dB! (I.E., Peter Garrens's post.)
EVERYONE:
However, I have seen and heard:
* 6dB (audio courses, the most common reference to doubling
I've heard)
* 10dB (a Radio Shack publication)
and even
* 3dB (as you indicated).
Obviously the most useful uses of knowing would be for
hands-on engineers who don't do the math!
So when we are looking at:
* Console VU meters;
* Meters in audio editors AND mixers!;
* Meters on tape decks of all kinds, including Cassettes,
DATs, and all;
* A Radio Shack dB (SPL) meter;
* Reading books that talk about dB;
* Reading info. about doubling in volume;
* anything else you can think of!
HOW MANY dB DOUBLES THE VOLUME, POWER, GAIN, LEVEL,
(WHATEVER) ETC.?
I have asked this question of a number of people with varying
results. And since "dB" is kind of generic with many
different kinds of dB and uses, I got different answers.
This is important to the layman, for if 6dB of SPL doubles
the volume (does it?), but some sort of level meter somewhere
registers only a 3dB change (where?) someone gets confused!
So, can someone unconfuse us, with a simple chart of dB
types, their doubling levels, and day-to-day practical uses?
Thanks!
Stephen
halleluYah!
George Gleason
chuckles for all
George
Graham Hinton
"Stephen DeVore, Seattle, WA" <nonep...@hotmail.com> wrote:
>EVERYONE:
>In layman's terms, how many dB doubles the SPL, power, or
>gain, etc.?
10log(2) = 3.01029995664 (rounded to 3)
Period.
>* 6dB (audio courses, the most common reference to doubling
>I've heard)
This is a doubling of *voltage* (or current) and as power = V^2/R the power
is quadrupled.
>* 10dB (a Radio Shack publication)
>and even
What do you expect from Radio Shack? ;-)
>* 3dB (as you indicated).
This is a doubling of power and decibels are defined as a *power ratio*
>Obviously the most useful uses of knowing would be for
>hands-on engineers who don't do the math!
There is no such thing as an engineer that does not do maths. That is the
difference between a *real* engineer and a technician or amateur
enthusiast.
>So when we are looking at:
>* Console VU meters;
The *proper* VU meter is very specific. It is a *moving iron* meter and the
size and scale are defined, it measures directly connected to the signal.
It does not show fast peaks. Many similar looking meters are *moving coil*
and may or may not be the correct size and are driven by electronics to
simulate the ballistics the original moving iron type. Some are better than
others. Some have peak detectors.
>* Meters in audio editors AND mixers!;
These could be anything. It is a common trick in digital audio to just
display the linear values as a bargraph because it is easy to do and hardly
anybody bothers to check. There is rarely a calibrated scale. To do the
job properly an rms calculation has to be done on every sample of the
signal and only dedicated meter units would do that.
Never trust *any* metering system until you have put a few test tones
through it.
>* Meters on tape decks of all kinds, including Cassettes,
>DATs, and all;
Most are bargraphs now. Digital machines show dBFS i.e. compared to Full
Scale digital signal and there are different SMPTE and EBU standards for
how that relates to any analogue I/O to give some headroom. e.g. an EBU
calibrated meter reads -11dbFS when the line level is +4dBm, so if you play
a normalised FS digital signal the output will be +15dBm!
The meters on recorders and consoles display the internal working levels,
not the external signal levels. Apart from Mackie who don't understand the
need to conform to established industry standards.
>* A Radio Shack dB (SPL) meter;
See above.
Radio Shack and Mackie are the low end of the industry, they make products
that look like the real thing for people that cannot tell the difference.
>* Reading books that talk about dB;
It depends on the subject of the book. dB-s are used for representing power
ratios in many types of engineering, especially where the power varies over
a wide range of several decades.
In audio engineering where the human hearing range is about 140dB we need a
unit to help us comprehend all the ratios within that range and the dB fits
the bill neatly. It corresponds quite well to the way we perceive sound
too.
>* Reading info. about doubling in volume;
"Volume" is not an exact scientific quantity. Different people can perceive
different amounts of volume change, most would agree with changes more than
3 or 4 dB, but below that in may not always be percieved as a volume
change. Most people would agree that a change of 0.5dB is different, but
not necessarily a loudness difference. It depends on the type of sound
material, the way the comparison is presented and their experience. Try it
- you'll be surprised.
>I have asked this question of a number of people with varying
>results. And since "dB" is kind of generic with many
>different kinds of dB and uses, I got different answers.
There is only one correct answer, all the rest are incomplete.
There is only one definition of a dB, the only variation is the reference
point.
>So, can someone unconfuse us, with a simple chart of dB
>types, their doubling levels, and day-to-day practical uses?
Once you understand that the dB is just a unitless ratio and can be used
for many purposes it should be obvious.
For audio voltages:
6db = x 2
10db = x sqrt(10) = x 3.16227766017
12dB = x 4
18dB = x 8
20dB = x 10
40dB = x 100
60dB = x 1000
120dB = x 1,000,000
Those are ratios. For audio voltage levels:
+26dBm = about the highest level found with common power rails
+4dBm = studio line level for 0VU internal
-10dBm = "hifi" / consumer 0VU line level
-50dBm = tape hiss (approx)
-95dBm = noise level of single op amp stage (approx)
(For the last two some are better than others)
Beware of the way some quantities are specified, e.g. a microphone
amplifier may have a noise output of -80dBm when used at +50dB gain and
would be then be rated as -130db EIN = Equivalent Input Noise. This is a
derived measurement and seems impressive, but I'd rather know the true
worst case performance figure because that is what is feeding into a mix.
Also noise measurements may be "weighted" by putting them through a filter
to remove some frequencies in an attempt to simulate the human hearing
response and show the annoyance value. This should always be stated, but
some spec sheets omit this to make the products look better than they
really are.
There is another confusing use of decibels used to describe frequency
responses and filter slopes - dB/octave. Note that as both the dB and the
octave are logs of ratios saying that something is 6dB/oct response just
means that the gain is proportional to frequency.
John Woodgate
>Can anyone tell me what "dBs" means with regard to audio line level?
>I see it in JVC specs. For instance my camcorder audio output level is
>spec'd at -8dBs. But all of the references I can find only refer to
>dBu, dBm, or dBV.
that answered every question except the one you asked!
While people have attached virtually every possible letter to the 'dB'
symbol, from 'dBA' to 'dBz' (would you believe 'dBq0ps', and that's an
officially respectable one?). I suspect that 'dBs' here is a
marketroid's symbol for 'decibelS'. The output level is probably -8dB(V)
(the correct way of writing 'decibels reference 1 volt', according to
IEC600027-3). Conversion to 0.4 volts is left as an exercise for the
reader. (Oh, damn!)
--
Regards, John Woodgate, OOO - Own Opinions Only. Phone +44 (0)1268 747839
Fax +44 (0)1268 777124. http://www.jmwa.demon.co.uk
I wanted to make a fully-automated nuclear-powered trawler,
but it went into spontaneous fishing.
John Woodgate
inimitably wrote:
>well that's what a "new Zealand certificate in engineering - electronic and
>computer technology" and an NZCE electrical and a bachelor of engineering
>does for you
You mean, posting one side of A4 that doesn't actually answer the
question? (;-)
We have engineering graduates like that in UK also. They usually go into
management and do very well.
John Woodgate
<FlintSof...@nospam.org> inimitably wrote:
>
>Every tech and engineer should know that - its not such a big deal.
>But the guy asked about dbS not just db theory. I know dbm and dbv but
>I never heard of dbs... I'll ask around.
>
10 Brownie points to that man!
Stephen DeVore, Seattle, WA
Wow.
I plan to feed it to my math engineer to look at! Your
answers, believe it or not, still left lingering questions of
the most basic sort. (I guess it's back to college. Please
read ALL the following before answering ANY. Thanks.)
Simple: How many dB is 2x as loud? (That is, How many dB
SPL?)
Will the dB SPL-change be the as the VU meter's dB change?
When you said "doubling of *voltage* (or current)," since
Voltage and Current are not the same, I assume you meant
"doubling of either Voltage (V) OR Current/Amps (A),
depending on which is being referred to." Correct?
You said "The *proper* VU meter is very specific." OK, but
are the dB on that meter intended by the manufacturer to
represent Voltage or SPL (loosely called loudness)?
You also said "doubling of [V or A (depending on which is
being measured)] ... = ... the power is quadrupled." Does
"power" in the equation P = V^2/R refer to Amperage? (Now
I'm looking ignorant.) What type of "power" do you mean? If
you mean SPL, then...
IF the VU meter represents Voltage (in dB) -- if I understood
you -- THEN the SPL ("power") will quadruple for every
doubling of that Voltage. And if the VU's dB does refer to
Voltage (I asked above if that was so), then every 3dB change
on the VU meter (and on the faders) represents a doubling of
the Voltage and therefore a quadrupling of the SPL?? 4x the
"loudness," loosely speaking??? I'm not terribly experienced
at the Console, but I don't recall a 3dB change on the VU
meter or fader being even remotely 4x as loud, maybe 1/2 as
loud! So, I must have something mixed up.
Basically, what this all comes down to for me personally is:
1) How many dB SPL is 2x as loud (SPL)? AND
2) How many dB will that be on a VU meter (console or tape)
or a bar graph meter (whether on a mixer, DAT machine,
software program, cassette deck, or whatever)?
AND since you mentioned that Mackie does not conform to
industry standards -- and as my upcoming mixing may actually
be done with the Digital 8 bus (d8b), HUI, or the Mackie 8 or
4 bus mixers (industry "standards" for entry- and mid-level
priced mixers) -- will your answer for the questions I just
asked be relatively the same for these Mackie machines?
That's great! I appreciate the knowledge and time! Thanks
again!
halleluYah, Stephen
Graham Hinton <g...@hinton.demon.co.uk> wrote in message
news:B4F29F31...@0.0.0.0...
Stephen DeVore, Seattle, WA
(found in a different spot) at "5:35 AM" on 3/13, I'm more
confused than ever. (Note his usage of "power." It seems
that you and he are saying the opposite; but I'm just
confused; so you better look for yourself!) Maybe you and he
can duke it out with the winner being the more easily
understood. Since I'm the ignorant one who has to understand
it, I can play referee. <s>
If I understand you, 3dB higher SPL is REALLY 2x as loud, but
it takes 10dB higher SPL for many to PERCEIVE it as 2x as
loud??
I thought the whole dB thing in relation to SPL was based
originally on perceptions of people regarding sound. Maybe
I'm remembering RMS or something. I've got to get some
sleep. Maybe then the numbers will make more sense to me.
Thanks again!
halleluYah, Stephen
Nigel Orr <news@river-view_dot_freeserve.co.uk> wrote in
message news:wkityr6qf6.fsf@river-view_dot_freeserve.co.uk...
> "Stephen DeVore, Seattle, WA" <nonep...@hotmail.com>
writes:
>
> > EVERYONE:
> > In layman's terms, how many dB doubles the SPL, power, or
> > gain, etc.?
>
> 3dB is a doubling of power, which is an increase of sqrt(2)
in
> voltage (Power is proportional to square of voltage)
> 6dB is 4x increase in power, which results from 2x voltage
>
> In psychoacoustic terms, 1-3dB is generally accepted as the
minimum
> step for a just noticable difference in controlled
experiments,
> 10dB is 'perceived' as doubling of loudness.
>
> So, confusingly, 10x the power only _sounds_ twice as loud.
>
> In an open environment (no reflections etc), sound pressure
level
> from a sound source will decrease by 6dB for each doubling
of distance.
>
> Hope that helps,
>
> Nigel
>
Stephen DeVore, Seattle, WA
Nigel Orr's reply (located elsewhere: same Subject, but find
it in the "Definition of dBs" tree) seemed to state the
opposite of something you said, but then I'm confused, so
maybe you could read it and see. And if so, you can play it
out, with me as simplicity referee!
Let me know!
Now I have to go to bed! After rest, maybe I can understand
this better. Thank you!
halleluYah! Stephen
Stephen DeVore, Seattle, WA
Mike Rivers
> It (dBs) could even be a plural, as in -1 dee-bee or -8 dee-bee's.
> But this still doesn't tell what this '-8' is referenced to. I suppose
> the original poster will have to ask JVC.
Both things that I thought about - the rarely used and incorrect in
this context plural of dB (this is a spec sheet of non-English origin)
and some standard of the manufacturer's choice (dB relative to
"something") have been suggested here.
dB* means different things in different contexts, and is pretty well
accepted as jargon in those fields.
dBm is always a power measurement. 0 dBm = 1 milliwatt
- In broadcast and telephony the standard load and source impedance
for power measurements is 600 ohms
- In RF, the standard load impedance is 50 ohms.
- The voltage across each of those two load impedances will be
different for the same 1 milliwatt of power, but a milliwatt is still a
milliwatt.
In audio, we use the voltage across a 600 ohm load at a power of 1
milliwatt (0.775 V - the square root of 600 x 0.001) as a voltage
reference, but 0.775 V is still 0.775 V whether measured across a 600
ohm resistor, a loudspeaker, a light bulb, or a high impedance audio
input. We use dBu to indicate this reference voltage. While not
documented anywhere that I've been able to find, the "u" might stand
for "unspecified power level or impedance". 0 dBu = 0.775 V
regardless of where you're measuring that voltage.
Since some people would rather work with round numbers, the term dBV
was coined to help those abacus-challanged. It's just like dBu only
the reference is 1.0 V.
Any other dB reference (with the exception of dBv, which is what some
European countries call dBu - indicating that it's a voltage
measurement, not a power measurement) is either a typo or something
that the manufacturer made up because he knows the equipment
specification won't look very good when one of the standard terms is
used.
--
I'm really Mike Rivers (mri...@d-and-d.com)
s...@randomc.com
>In article <qY1z4.331$wJ3....@news.uswest.net>,
>"Stephen DeVore, Seattle, WA" <nonep...@hotmail.com> wrote:
>>* 3dB (as you indicated).
>This is a doubling of power and decibels are defined as a *power ratio*
The question is, does it sound twice as loud? Not really. That's one of the
natural facts about decibels and exponents. We experience power - light,
sound, etc. on decibel and exponent scales. I engineer light, and its the
same thing there.
>>Obviously the most useful uses of knowing would be for
>>hands-on engineers who don't do the math!
>There is no such thing as an engineer that does not do maths. That is the
>difference between a *real* engineer and a technician or amateur
>enthusiast.
I'm an engineer and I don't do math anymore - don't need to. A "real"
engineer is truly lazy and only does math when absolutely necessary. The test
of experience and understanding as an engineer is how far you can go before
you have to get out the calculator!
Steve
Mark McQuilken
>
> You mean, posting one side of A4 that doesn't actually answer the
> question? (;-)
>
> We have engineering graduates like that in UK also. They usually go into
> management and do very well.
> Regards, John Woodgate, OOO - Own Opinions Only. Phone +44 (0)1268 747839
LOL, John! Ditto for the US...
__
Mark McQuilken
FMR Audio
www.fmraudio.com
(800)343-9976 - US Only
(512)280-6557 Voice
(512)280-8627 Fax
John Woodgate
>EVERYONE:
>In layman's terms, how many dB doubles the SPL, power, or
>gain, etc.?
>
>Your post says 3dB! (I.E., Peter Garrens's post.)
>
>
>EVERYONE:
>
>However, I have seen and heard:
>I've heard)
6 dB is double voltage, current or sound pressure (among other things)
>* 10dB (a Radio Shack publication)
10 dB is (approximately) double subjective loudness.
>and even
>* 3dB (as you indicated).
3 dB is double power (or double money, since 'Money is Power').
--
Regards, John Woodgate, OOO - Own Opinions Only. Phone +44 (0)1268 747839
John Woodgate
inimitably wrote:
>The *proper* VU meter is very specific. It is a *moving iron* meter and the
>size and scale are defined, it measures directly connected to the signal.
>It does not show fast peaks.
I think you need to provide evidence that the original ANSI standard
calls for a moving-iron meter. IEC60268-17 calls for a 'full-wave
rectifier', which would not be required for a moving iron meter.
Scott Dorsey
John Woodgate <j...@jmwa.demon.co.uk> wrote:
><B4F29F31...@0.0.0.0>, Graham Hinton <g...@hinton.demon.co.uk>
>inimitably wrote:
>>size and scale are defined, it measures directly connected to the signal.
>>It does not show fast peaks.
>
>calls for a moving-iron meter. IEC60268-17 calls for a 'full-wave
>rectifier', which would not be required for a moving iron meter.
Well, that IEC standard is based on an ANSI standard which is based on
an ASA standard which is based on a WE standard. I know that the WE
standard mandates copper-oxide rectifiers and very tightly specified
ballistics, with a D'Arsonval movement.
However, that's not to say that there isn't a still earlier standard
that I don't know about.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
John Woodgate
No. 3dB higher sound pressure level is just 1.414 times the original
sound pressure. 6 dB higher is double the pressure. Loudness is a purely
subjective thing.
> but
>it takes 10dB higher SPL for many to PERCEIVE it as 2x as
>loud??
>
>I thought the whole dB thing in relation to SPL was based
>originally on perceptions of people regarding sound.
So it was. But the only way to find out what sounds 'twice as loud' to
human beings is to ask a lot of human beings and take the average. Of
course, the real experiments are a lot more sophisticated than that, but
that is the principle.
John Woodgate
inimitably wrote:
>In article <WCUw2yAIcQz4EwC$@jmwa.demon.co.uk>,
>John Woodgate <j...@jmwa.demon.co.uk> wrote:
>><B4F29F31...@0.0.0.0>, Graham Hinton <g...@hinton.demon.co.uk>
>>inimitably wrote:
>>>size and scale are defined, it measures directly connected to the signal.
>>>It does not show fast peaks.
>>
>>calls for a moving-iron meter. IEC60268-17 calls for a 'full-wave
>>rectifier', which would not be required for a moving iron meter.
>
>Well, that IEC standard is based on an ANSI standard
Except that US experts didn't participate in its preparation.
> which is based on
>an ASA standard which is based on a WE standard. I know that the WE
>standard mandates copper-oxide rectifiers
Since they are less common than hen's teeth these days, the IEC standard
doesn't specify the type of semiconductor.
> and very tightly specified
>ballistics,
Quite right.
> with a D'Arsonval movement.
That's a moving-coil movement, for non-French people. (;-)
>
>However, that's not to say that there isn't a still earlier standard
>that I don't know about.
When we were writing IEC60268-17, no-one mentioned one.
John Woodgate
wrote:
>Any other dB reference (with the exception of dBv, which is what some
>European countries call dBu
That is completely mythical. No-one, anywhere, uses 'dbv' to mean that,
as far as we could find when we write the AES document on the subject.
In fact, that 'u' is almost certainly derived from what is now the IEC
symbol for voltage - U, originally mostly used in Germany, which was in
Europe the last time I was there.
David Satz
> >European countries call dBu
>
> That is completely mythical. No-one, anywhere, uses 'dbv' to mean that,
> as far as we could find when we write the AES document on the subject.
> In fact, that 'u' is almost certainly derived from what is now the IEC
> symbol for voltage - U, originally mostly used in Germany, which was in
> Europe the last time I was there.
The (possibly mythical) story I learned is that the u in dBu stood
for "unloaded"--that 0 dBu and 0 dBm both occur at 0.775 V,
but that a dBm measurement must be made into 600 Ohms
while dBu would be appropriate for voltage measurements
made across a bridging, rather than a matching, load.
And Germany is still in Europe--it's Austria that seems to be in
some doubt at the moment.
--best regards
tim
just 'smoke em out' ? Opens that short circuit pretty fast ! No
ohms laws required !
* Sent from RemarQ http://www.remarq.com The Internet's Discussion Network *
The fastest and easiest way to search and participate in Usenet - Free!
Stephen DeVore, Seattle, WA
--
halleluYah! Stephen DeVore, Seattle, WA
John Woodgate <j...@jmwa.demon.co.uk> wrote in message
news:RnrhPhA2...@jmwa.demon.co.uk...
> <7q8z4.37$Xs4....@news.uswest.net>, Stephen DeVore,
Seattle, WA
> <nonep...@hotmail.com> inimitably wrote:
> >If I understand you, 3dB higher SPL is REALLY 2x as loud,
>
> No. 3dB higher sound pressure level is just 1.414 times the
original
> sound pressure. 6 dB higher is double the pressure.
Loudness is a purely
> subjective thing.
>
> > but
> >it takes 10dB higher SPL for many to PERCEIVE it as 2x as
> >loud??
> >
> >I thought the whole dB thing in relation to SPL was based
> >originally on perceptions of people regarding sound.
>
> So it was. But the only way to find out what sounds 'twice
as loud' to
> human beings is to ask a lot of human beings and take the
average. Of
> course, the real experiments are a lot more sophisticated
than that, but
> that is the principle.
Stephen DeVore, Seattle, WA
--
halleluYah! Stephen DeVore, Seattle, WA
Nigel Orr <news@river-view_dot_freeserve.co.uk> wrote in
message news:wkaek27qn4.fsf@river-view_dot_freeserve.co.uk...
> "Stephen DeVore, Seattle, WA" <nonep...@hotmail.com>
writes:
>
> I don't _think_ Graham's reply disagreed with mine at all,
but
> one or both of us may have confused you with some part of
it.
> Which part didn't seem to agree?
>
> > Simple: How many dB is 2x as loud? (That is, How many
dB
> > SPL?)
>
> Generally it's taken as 10dB. It is a psychological and
> psychoacoustic effect though, so it does depend on the
listener,
> and probably various other things like room acoustics and
type
> of sound.
>
> > Will the dB SPL-change be the as the VU meter's dB
change?
>
> Basically, yes... different types of meters have different
> response times, for different purposes (eg peaks or overall
> level), but with the same meter, and the same source, if
> the meter reads 10dB louder, the SPL should be 10dB higher.
>
> > When you said "doubling of *voltage* (or current)," since
> > Voltage and Current are not the same, I assume you meant
> > "doubling of either Voltage (V) OR Current/Amps (A),
> > depending on which is being referred to." Correct?
>
> They're not the same, but if resistance is fixed, doubling
> voltage will also double current.
>
> You can calculate power as VxI (volts times current),
R*(I^2)
> or (V^2)/R, in all cases power is proportional to the
> square of voltage or current, if resistance is fixed.
>
> > are the dB on that meter intended by the manufacturer to
> > represent Voltage or SPL (loosely called loudness)?
>
> dB scales on meters are always referred to a particular
unit.
> That might be volts, milliwatts, or even amps. BUT an
> increase of 6 dB will always be 4x the power, 2x the
voltage,
> 2x the current (as Graham said, it's not exactly 6dB, but
> close enough!)
>
> > Does
> > "power" in the equation P = V^2/R refer to Amperage?
(Now
> > I'm looking ignorant.)
>
> I'm afraid you are, in electronics terms anyway. Don't
worry
> about that though. You might be best to get some books on
> electronics to get you started if you really want to
understand
> more about it- usenet discussions aren't always the most
> efficient way to learn :-)
>
> Easiest way to think of it might be a commonly used analogy
> of water- think of a tank, a pipe leading down from it, and
> a water wheel at the end of the pipe.
>
> Voltage is like the pressure due to the height of the tank,
> current (or 'amperage' if you want to use a
not-really-a-word)
> is like the flow rate along the pipe, and power is how
quickly
> the waterwheel can do a certain amount of work, or how
quickly
> it can lift a given load. Resistance is a bit like the
> cross-sectional area of the pipe.
>
> Increase water pressure, with the same pipe, and flow rate
> will increase too. Power will be the product of
> water pressure and water flow. Because water pressure is
> related to water flow, power could also be calculated using
> water pressure squared and the pipe resistance.
>
> > IF the VU meter represents Voltage (in dB) -- if I
understood
> > you -- THEN the SPL ("power") will quadruple for every
> > doubling of that Voltage.
>
> Power will _always_ quadruple for doubling of voltage
(assuming
> resistance doesn't change, which is a reasonable starting
point!)
>
> > And if the VU's dB does refer to
> > Voltage (I asked above if that was so), then every 3dB
change
> > on the VU meter (and on the faders) represents a doubling
of
> > the Voltage and therefore a quadrupling of the SPL??
>
> No. Decibels are a power measurement, always, even if they
are
> measured from a voltage reference. That can be confusing,
I
> agree. 0dBV is 1V (voltage), +6dBV is 2V, 0dBW is 1 Watt
(power),
> +6dBW is 4W. Read that last sentence a few times... 3dB is
> always twice the power, 6dB is always 4x the power. 10dB
is
> always 10x the power. -3dB is always half the power, -6dB
> is always a quarter of the power, -10dB is always 1/10th of
> the power.
>
> > but I don't recall a 3dB change on the VU
> > meter or fader being even remotely 4x as loud, maybe 1/2
as
> > loud!
>
> 3dB is usually a just noticable difference.
>
> > 1) How many dB SPL is 2x as loud (SPL)? AND
>
> Roughly 10dB
>
> > 2) How many dB will that be on a VU meter (console or
tape)
>
> Roughly 10dB on any meter.
>
> Nigel
Stephen DeVore, Seattle, WA
--
halleluYah! Stephen DeVore, Seattle, WA
<s...@randomc.com> wrote in message
news:8aj7dm$ejq$1...@zrtph05m.us.nortel.com...
> In article <B4F29F31...@0.0.0.0>,
g...@hinton.demon.co.uk (Graham Hinton) wrote:
> >In article <qY1z4.331$wJ3....@news.uswest.net>,
> >"Stephen DeVore, Seattle, WA" <nonep...@hotmail.com>
wrote:
>
> >>* 3dB (as you indicated).
>
> >This is a doubling of power and decibels are defined as a
*power ratio*
>
> The question is, does it sound twice as loud? Not really.
That's one of the
> natural facts about decibels and exponents. We experience
power - light,
> sound, etc. on decibel and exponent scales. I engineer
light, and its the
> same thing there.
>
> >>Obviously the most useful uses of knowing would be for
> >>hands-on engineers who don't do the math!
>
> >There is no such thing as an engineer that does not do
maths. That is the
> >difference between a *real* engineer and a technician or
amateur
> >enthusiast.
>
Stephen DeVore, Seattle, WA
--
halleluYah! Stephen DeVore, Seattle, WA
John Woodgate <j...@jmwa.demon.co.uk> wrote in message
news:byDzKvAX...@jmwa.demon.co.uk...
> <qY1z4.331$wJ3....@news.uswest.net>, Stephen DeVore,
Seattle, WA
> <nonep...@hotmail.com> inimitably wrote:
> >EVERYONE:
> >In layman's terms, how many dB doubles the SPL, power, or
> >gain, etc.?
> >
> >DEAR PETER:
> >Your post says 3dB! (I.E., Peter Garrens's post.)
> >
> >
> >EVERYONE:
> >
> >However, I have seen and heard:
> >* 6dB (audio courses, the most common reference to
doubling
> >I've heard)
>
> 6 dB is double voltage, current or sound pressure (among
other things)
>
> >* 10dB (a Radio Shack publication)
>
> 10 dB is (approximately) double subjective loudness.
>
> >and even
> >* 3dB (as you indicated).
>
> 3 dB is double power (or double money, since 'Money is
Power').
Stephen DeVore, Seattle, WA
--
halleluYah! Stephen DeVore, Seattle, WA
Robert <FlintSof...@nospam.org> wrote in message
news:38cd9a6b...@nntp.hip.cam.org...
>
> HEY can I throw a wrench in here? VU is not really db....
VU as I
> understand it is a meter with xxx ohms Z ( I forget, maybe
7000 or
> something) and certain ballistic properties, reading out
close to db
> but not exactly...
>
> db=20log(e1/e2)
>
> db=10log(p1/p2)
>
> I think this is because voltage is a planer quantity and
power is a
> vector sum - or a squared quantity... Oh hell just gime me
another
> Bud...
>
> >On Mon, 13 Mar 2000 00:50:47 -0800, "Stephen DeVore,
Seattle, WA" <nonep...@hotmail.com> wrote:
>
> >EVERYONE:
> >In layman's terms, how many dB doubles the SPL, power, or
> >gain, etc.?
> >
> >DEAR PETER:
> >Your post says 3dB! (I.E., Peter Garrens's post.)
> >
> >
> >EVERYONE:
> >
> >However, I have seen and heard:
> >* 6dB (audio courses, the most common reference to
doubling
> >I've heard)
> >* 10dB (a Radio Shack publication)
> >and even
> >* 3dB (as you indicated).
> >
> >Obviously the most useful uses of knowing would be for
> >hands-on engineers who don't do the math!
> >
> >So when we are looking at:
> >* Console VU meters;
> >* Meters in audio editors AND mixers!;
> >* Meters on tape decks of all kinds, including Cassettes,
> >DATs, and all;
> >* A Radio Shack dB (SPL) meter;
> >* Reading books that talk about dB;
> >* Reading info. about doubling in volume;
> >* anything else you can think of!
> >HOW MANY dB DOUBLES THE VOLUME, POWER, GAIN, LEVEL,
> >(WHATEVER) ETC.?
> >
> >I have asked this question of a number of people with
varying
> >results. And since "dB" is kind of generic with many
> >different kinds of dB and uses, I got different answers.
> >
> >This is important to the layman, for if 6dB of SPL doubles
> >the volume (does it?), but some sort of level meter
somewhere
> >registers only a 3dB change (where?) someone gets
confused!
> >
> >So, can someone unconfuse us, with a simple chart of dB
> >types, their doubling levels, and day-to-day practical
uses?
> >
> >Thanks!
> >
> >Stephen
> >
> >halleluYah!
> >
> >
> >
> >
> >
>
Stephen DeVore, Seattle, WA
--
halleluYah! Stephen DeVore, Seattle, WA
Ray Palmer <rpa...@primus.com.au> wrote in message
news:38CDAB04...@primus.com.au...
> Stephen,
>
> Have a look at:
>
http://www.music.mcgill.ca/~martin/textbook/electronics/03.ht
ml
> It may be very helpful.
>
> Maybe this'll help too:
>
> In 'electrical' terms,
> if you're comparing power, then double = 10log(2) = 3.01dB
(rounded to
> 3dB).
> But power is proportional to sqrt(P), so with voltage,
6.02dB (rounded
> to 6dB) is double.
>
> In 'audio' terms, you may be looking at voltage, power, or
sound
> pressure level (i.e. the closest real term to perceived
loudness).
> Typically voltage is in dBu or dBV (they're different, see
the webpage),
> power is in dBm, and sound pressure is in dBspl (or usually
just dB).
> Sound pressure is analogous with voltage, i.e. 6dBspl is
double. Sound
> pressure is what they are referring to when they say "a jet
engine is
> 120dB, a jackhammer is 110db" etc.
David Shorter
John Woodgate wrote:
> You mean, posting one side of A4 that doesn't actually answer the
> question? (;-)
>
> We have engineering graduates like that in UK also. They usually go into
> management and do very well.
Luckily New Zealand is a small country, so not many of them have managed to
infiltrate their way into the audio industry. OTOH they are becoming increasingly
common in the electrical engineering industry, which is one reason I have jumped
ship to the audio industry fulltime.
--
Regards,
David Shorter
DazzReal Sound Labs
Auckland, New Zealand
Robert
The way I heard it was:
"Where's Albert Einstein?"
"Gone fishin..."
Robert
HEY can I throw a wrench in here? VU is not really db.... VU as I
understand it is a meter with xxx ohms Z ( I forget, maybe 7000 or
something) and certain ballistic properties, reading out close to db
but not exactly...
db=20log(e1/e2)
db=10log(p1/p2)
I think this is because voltage is a planer quantity and power is a
vector sum - or a squared quantity... Oh hell just gime me another
Bud...
Ray Palmer
Have a look at:
http://www.music.mcgill.ca/~martin/textbook/electronics/03.html
It may be very helpful.
Maybe this'll help too:
In 'electrical' terms,
if you're comparing power, then double = 10log(2) = 3.01dB (rounded to
3dB).
But power is proportional to sqrt(P), so with voltage, 6.02dB (rounded
to 6dB) is double.
In 'audio' terms, you may be looking at voltage, power, or sound
pressure level (i.e. the closest real term to perceived loudness).
Typically voltage is in dBu or dBV (they're different, see the webpage),
power is in dBm, and sound pressure is in dBspl (or usually just dB).
Sound pressure is analogous with voltage, i.e. 6dBspl is double. Sound
pressure is what they are referring to when they say "a jet engine is
120dB, a jackhammer is 110db" etc.
John Woodgate
<FlintSof...@nospam.org> inimitably wrote:
>HEY can I throw a wrench in here? VU is not really db.... VU as I
>understand it is a meter with xxx ohms Z ( I forget, maybe 7000 or
>something) and certain ballistic properties, reading out close to db
>but not exactly...
It's not really a question of 'not exactly' by intention. Because of
different intrinsic current values, the rectifiers' characteristics are
not exactly identical, and temperature affects them. So, to avoid any
complications resulting from claiming that the vu-indicator scale is a
scale of decibels, the original ANSI standard, and IEC60268-17, make no
such claim. Bt it is a good aim at one, for constant signals.
There is another aspect. Because of the non-instantaneous response of
the movement, the indication does not exactly follow the envelope of a
varying signal, and the difference depends on the exact signal.
--
Regards, John Woodgate, OOO - Own Opinions Only. Phone +44 (0)1268 747839
Fax +44 (0)1268 777124. http://www.jmwa.demon.co.uk
mcesar
wrote:
>dB - from alexandera Bell (I think)
>d is deci,B is Bell ie the deci bell
>the Bell is to large a value and for sound and others deci (1*10^-3) is used
...
I think this is not what ken_lund is asking for. I think he's asking
for the reference level for dBs (note the trailing "s"). As dBm, dBu, dBW
are dB above or below 1 miliwatt, 1 microvolt & 1 watt respectively. dBs are
dB obove or below what?
Greetings.
s...@randomc.com
>On Mon, 13 Mar 2000 12:35:43 +1300, "Peter Garrens" <gar...@ihug.co.nz>
>wrote:
>>dB - from alexandera Bell (I think)
>>d is deci,B is Bell ie the deci bell
>>the Bell is to large a value and for sound and others deci (1*10^-3) is used
>I think this is not what ken_lund is asking for. I think he's asking
>for the reference level for dBs (note the trailing "s"). As dBm, dBu, dBW
>are dB above or below 1 miliwatt, 1 microvolt & 1 watt respectively. dBs are
>dB obove or below what?
A plain old dB is technically unitless - its only a reference point. "3 dB
down" means that the sound, whatever units you are using, is 3 dB down in
level from some reference point. A lot of times when we talk about dBs, we
really are referring to dBm and so on. I use dB meters in my field all the
time - photonics.
Steve
> Greetings.
Graham Hinton
s...@randomc.com wrote:
>The question is, does it sound twice as loud? Not really. That's one of the
>natural facts about decibels and exponents. We experience power - light,
>sound, etc. on decibel and exponent scales. I engineer light, and its the
>same thing there.
How we experience all these quantities is completely subjective, we can
only agree on using objective terms to describe them. Even when we use
measurable quantities our responses are both non-linear and adaptive.
Decibels are a convenient way of fitting a wide range phenomena into a
smaller range of numbers - like percentages.
>>>Obviously the most useful uses of knowing would be for
>>>hands-on engineers who don't do the math!
>
>>There is no such thing as an engineer that does not do maths. That is the
>>difference between a *real* engineer and a technician or amateur
>>enthusiast.
>
>I'm an engineer and I don't do math anymore - don't need to. A "real"
>engineer is truly lazy and only does math when absolutely necessary.
That sounds more like the definition of a bad or stupid engineer and is
nothing to boast about ;-)
This attitude is the root cause of a lot of problems. I don't know why is
seen to be "cool" to pretend not to be able to do maths, but being able and
not is a far worse form of ignorance than being merely numerically
illerate.
Ultimately it is self defeating, if you can't or won't do the maths you
will simply never be able to properly understand what it is all about.
>The test
>of experience and understanding as an engineer is how far you can go before
>you have to get out the calculator!
Calculators are for doing arithmetic, not mathematics. Mathematics is the
process of abstracting and modelling an idea and using it as a tool to
predict results. That is why it is a non-optional part of engineering.
Graham Hinton
klu...@netcom.com (Scott Dorsey) wrote:
>In article <WCUw2yAIcQz4EwC$@jmwa.demon.co.uk>,
>John Woodgate <j...@jmwa.demon.co.uk> wrote:
>><B4F29F31...@0.0.0.0>, Graham Hinton <g...@hinton.demon.co.uk>
>>inimitably wrote:
>>>The *proper* VU meter is very specific. It is a *moving iron* meter and the
>>>size and scale are defined, it measures directly connected to the signal.
>>>It does not show fast peaks.
>>
>>I think you need to provide evidence that the original ANSI standard
>>calls for a moving-iron meter. IEC60268-17 calls for a 'full-wave
>>rectifier', which would not be required for a moving iron meter.
>
>Well, that IEC standard is based on an ANSI standard which is based on
>an ASA standard which is based on a WE standard. I know that the WE
>standard mandates copper-oxide rectifiers and very tightly specified
>ballistics, with a D'Arsonval movement.
>
>However, that's not to say that there isn't a still earlier standard
>that I don't know about.
Standards come later, somebody has to do some real work first :).
The first VU meters were moving iron, they were simple as deflection is
proportional to the ac, connected straight across a line and "felt right".
Moving coil meters are cheaper to make, but are deflected by a dc current
so the subsequent standards tried to define the action and ballistics that
people had got used to.
There seems to be some confusion on this thread about how VU meters measure
dBs. They are just a simple meter, apply a voltage across the teminals and
the needle moves. The scale is marked in dBs, but it is non-linear. It is
only a "lookup table".
The BBC tried to design an "improved" meter called the PPM, Peak Programme
Meter, to show peaks better and the markings on that are a differing number
of dBs, less in the middle i.e. more sensitive. Although useful they never
replaced VU meters.
All monitoring meters and faders scales have non-linear dB scales to make
them more useful in their working range.
Graham Hinton
"Stephen DeVore, Seattle, WA" <nonep...@hotmail.com> wrote:
>I plan to feed it to my math engineer to look at! Your
>answers, believe it or not, still left lingering questions of
>the most basic sort. (I guess it's back to college. Please
>read ALL the following before answering ANY. Thanks.)
Yes, sorry, it is back to school, but we are only talking about basic
physics for 14 year olds. Day 1, class1.
Understanding the basic principles of Ohm's Law and physical dimensions is
fundamental to this subject and if you avoid it you will not get past the
next hurdle.
Also don't forget that the laws of physics work the same for everybody. All
this information is verifiable.
>Simple: How many dB is 2x as loud? (That is, How many dB
>SPL?)
>
>Will the dB SPL-change be the as the VU meter's dB change?
I think this is the bit that is confusing you. dBs can only compare similar
forms of power. In sound equipment the meters are showing a comparison to a
standard reference (assuming they have been calibrated) and that is
straightforward because we already have the "sound" as an electrical
signal. To measure the sound power in the air a transducer (microphone) has
to be used and these are not necessarily linear nor is the response of the
human hearing system.
The Weber-Fechner Law states that the sensation of loudness is proportional
to the logarithm of the intensity of the stimulus (pressure), but it is
also changes with the frequency and content of the sound, see Fletcher
Munson curves. An SPL meter will be calibrated for a 1kHz sinewave.
I don't know what anybody means when they say something is "twice as loud"
and I suspect nor do they ;-). The figures quoted come from tests conducted
on subjects who were being asked this question. Of course they said
*something*, but that does not mean that they ever thought in those terms
before being asked. This is known as "harvesting" a result.
Actually I find it hard enough to judge the weight of something being
double something else, eg 2kgm of feathers against 1kgm brass, even though
that is easily measured. I could tell you that, say, a bass drum was being
played louder than a flute, but when it comes to being precisely double I
don't think so. OTOH, I could say it was *about* 10dB different, but only
because I've got used to looking at meters not the other way round.
>When you said "doubling of *voltage* (or current)," since
>Voltage and Current are not the same, I assume you meant
>"doubling of either Voltage (V) OR Current/Amps (A),
>depending on which is being referred to." Correct?
No. If you double the voltage the current doubles too (for a pure
resistance) so the product, the power, is four times.
Ohm's Law: V = I * R
(Electrical) Power = V * I = V^2 / R (substituting for I)
= I^2 * R (substituting for V)
These are equivalent and inseperable. It does not matter which way we
choose to look at it, it has to come to the same result. So Power is
proportional to the square of the voltage or the square of the current and
that is why the square is taken outside the log function to make it 20
instead of 10.
>You said "The *proper* VU meter is very specific." OK, but
>are the dB on that meter intended by the manufacturer to
>represent Voltage or SPL (loosely called loudness)?
Strictly speaking the power on a 600ohm line, equivalent to a voltage
across the meter terminals.
>You also said "doubling of [V or A (depending on which is
>being measured)] ... = ... the power is quadrupled." Does
>"power" in the equation P = V^2/R refer to Amperage? (Now
>I'm looking ignorant.) What type of "power" do you mean? If
>you mean SPL, then...
Power is measured in Watts, Amps are a current unit.
Power has the dimensions of [M] [L]^2 [T]^-3
There is not any other type of power, just different forms like electrical,
heat, acoustic. Microphones and loudspeakers convert one form into another,
but neither is 100% efficient or linear, some gets converted to heat.
If you compare VU and SPL meter readings they will show quite similar
changes, but not precisely so.
If you consider "power" as a semantic quantity rather that a precise
scientific one you are going to get into difficulty.
>IF the VU meter represents Voltage (in dB) -- if I understood
>you -- THEN the SPL ("power") will quadruple for every
>doubling of that Voltage. And if the VU's dB does refer to
>Voltage (I asked above if that was so), then every 3dB change
>on the VU meter (and on the faders) represents a doubling of
>the Voltage and therefore a quadrupling of the SPL?? 4x the
>"loudness," loosely speaking???
No. The VU meter is already doing that calculation and you are reading the
result (in dBs) from its scale. Note that the graduations are not equal. If
you had a Voltmeter connected across terminals of the VU meter then you
would see the difference, but as it is you don't actually see what the
volts are.
>Basically, what this all comes down to for me personally is:
>
>1) How many dB SPL is 2x as loud (SPL)? AND
The text books say 10dB, but first you have to know what "twice as loud"
means.
>2) How many dB will that be on a VU meter (console or tape)
>or a bar graph meter (whether on a mixer, DAT machine,
>software program, cassette deck, or whatever)?
About the same number as a change, but not absolute.
> AND since you mentioned that Mackie does not conform to
>industry standards -- and as my upcoming mixing may actually
>be done with the Digital 8 bus (d8b), HUI, or the Mackie 8 or
>4 bus mixers (industry "standards" for entry- and mid-level
>priced mixers) -- will your answer for the questions I just
>asked be relatively the same for these Mackie machines?
Relatively yes.
Mackie's cheapskate metering does not allow for the level change in the
input and output amplifiers, nor balancing compensation. Note the small
print of "0dB=0dBU" on the panel.
It will not match the meter readings of other correctly calibrated
equipment so the cheap fix is sticking a piece of tape over the scale to
"recalibrate" it :).
Dbowey
will simply never be able to properly understand what it is all about."
-------
What you say is largely true, but all too often I run into people who firmly
believe that the math used to model a process (such as amplitude modulation) is
THE answer when all it really does is explain a workable math solution.
Stephen DeVore, Seattle, WA
--
halleluYah! Stephen DeVore, Seattle, WA
Nigel Orr <news@river-view_dot_freeserve.co.uk> wrote in
message news:wk4sa97usp.fsf@river-view_dot_freeserve.co.uk...
> "Stephen DeVore, Seattle, WA" <nonep...@hotmail.com>
writes:
>
> > If I understand you, 3dB higher SPL is REALLY 2x as loud,
but
>
> No, 3dB higher SPL means it takes twice the electrical
power, 'loud'
> is only how things are perceived by the human ear.
>
> > it takes 10dB higher SPL for many to PERCEIVE it as 2x as
> > loud??
>
> Yes.
>
> > I thought the whole dB thing in relation to SPL was based
> > originally on perceptions of people regarding sound.
>
> Partly. 0dB SPL (20uPa of pressure) is generally taken as
the
> quietest audible sound (in other fields, such as underwater
acoustics
> (my day job), the '0dB' pressure reference is 1uPa).
However that is
> just the reference, every 3dB step is only a doubling of
power, no
> psychoacoustics at all.
>
> > I've got to get some
> > sleep. Maybe then the numbers will make more sense to
me.
>
> Maybe :)
>
> Nigel
>
>
>
>
>
>
>
>
>
Stephen DeVore, Seattle, WA
--
halleluYah! Stephen DeVore, Seattle, WA
Graham Hinton <g...@hinton.demon.co.uk> wrote in message
news:B4F455BA...@0.0.0.0...
Stephen DeVore, Seattle, WA
--
halleluYah! Stephen DeVore, Seattle, WA
Graham Hinton <g...@hinton.demon.co.uk> wrote in message
news:B4F455B9...@0.0.0.0...
> Ultimately it is self defeating, if you can't or won't do
the maths you
> will simply never be able to properly understand what it is
all about.
>
>
Stephen DeVore, Seattle, WA
--
halleluYah! Stephen DeVore, Seattle, WA
John Woodgate <j...@jmwa.demon.co.uk> wrote in message
news:4V7LDBA2...@jmwa.demon.co.uk...
mcesar
<nonep...@hotmail.com> wrote:
>Thanks Ray Palmer (Web link).
Why have you send 714 lines of snipable text in 10 messages in order
to thank people? I`m tired about downloading messages, not intended for me,
wasting time and bandwidth. Two possible lines of action:
1.- Wait for thread end and then send a single
message acknowledging all people that helped you.
2.- Use email.
Greetings.
Harvey Gerst
>"Stephen DeVore, Seattle, WA" <nonep...@hotmail.com> wrote:
>
>>EVERYONE:
>>In layman's terms, how many dB doubles the SPL, power, or
>>gain, etc.?
>>* 10dB (a Radio Shack publication)
>>and even
>What do you expect from Radio Shack? ;-)
Hey Graham, watch it!! I think he's refering to a manual for the little RS
stereo VU meter box that I wrote back in 1978. In it I was saying that just
doubling the size of the amp doesn't sound twice as loud, it's just a "little
louder". What most people consider "twice as loud" usually requires an
increase of about 10 dB (a 10x increase in wattage).
Harvey Gerst
Indian Trail Recording Studio
http://www.ITRstudio.com/
Graham Hinton
<573E736257DF75B5.735EE0E0...@lp.airnews.net>,
Harvey Gerst <har...@ITRstudio.com> wrote:
>g...@hinton.demon.co.uk (Graham Hinton) wrote:
>>What do you expect from Radio Shack? ;-)
>
>Hey Graham, watch it!! I think he's refering to a manual for the little RS
>stereo VU meter box that I wrote back in 1978.
Sorry, just my reaction to seeing Radio Shack being quoted as a reference
on what is supposed to be a professional NG :)
In the UK Tandy is synonymous with Tacky.
>In it I was saying that just
>doubling the size of the amp doesn't sound twice as loud, it's just a "little
>louder". What most people consider "twice as loud" usually requires an
>increase of about 10 dB (a 10x increase in wattage).
That is what keeps getting quoted and I have already commented on that.
Since then I've been looking up some papers and it appears that this "fact"
seems to stem from Sabine's tests on the Sense of Loudness in 1910. These
tests were conducted with a small number of people (too small to be
scientifically accurate) using organ pipes adjusted for "equal loudness"
and then playing them in multiples. This obviously did not allow for the
random phases of the pipes and the wave behaviour in the room.
This seems to be a case of repeating something enough times until it
becomes true.
Fletcher's experiments published in 'Speech and Hearing in Communication'
in 1953 are better science and correspond more with what I was saying.
In the whole development of music we still only have a vague ppp to fff to
describe loudness. With other sensations it is quite easy to judge what
double is e.g. you can take two equal length sticks and put them together
and the human eye is very good at perceiving the angle subtended whatever
the distance. Similarly the ear is good at pitch perception especially for
an octave interval, but loudness is like colour in that the concept of
"double" does not seem appropriate. "Double" requires an fixed linear scale
for reference and loudness does not have this for pitch or absolute level
before we even start taking into account exposure to previous loud sounds.
I think this colour analogy is a good one. We can measure the wavelength of
light, but we still only see a rainbow. We do not talk about red being
double violet although it nearly is.
Arny Krüger
I went back to DN and read all your contributions to your thread.
Unless I missed something, I didn't find any place where you
assigned a certain number or even range of dB's to the peception of
"twice as loud".
You've done a nice job of throwing dirt on "conventional wisdom"
which Harvey presented, but I don't see a clear (or even vague)
alternative.
> In the whole development of music we still only have a vague ppp
to fff to
> describe loudness.
OK, so even vague can be put into a range of numbers.
> With other sensations it is quite easy to judge what
> double is e.g. you can take two equal length sticks and put them
together
> and the human eye is very good at perceiving the angle subtended
whatever
> the distance. Similarly the ear is good at pitch perception
especially for
> an octave interval, but loudness is like colour in that the
concept of
> "double" does not seem appropriate. "Double" requires an fixed
linear scale
> for reference and loudness does not have this for pitch or
absolute level
> before we even start taking into account exposure to previous loud
sounds.
This suggests that the perception of 'twice as loud" would depend on
the original loudness. The human ear shows evidence of being
nonlinear at higher levels even on a logrithmic scale. OK, so is
there a hint of a scale of "doubled loudness" as a function of
initial loudness?
> I think this colour analogy is a good one. We can measure the
wavelength of
> light, but we still only see a rainbow. We do not talk about red
being
> double violet although it nearly is.
Is the answer that there is no answer and none is possible?
Harvey Gerst
>Harvey Gerst <har...@ITRstudio.com> wrote:
>
>>g...@hinton.demon.co.uk (Graham Hinton) wrote:
>>>What do you expect from Radio Shack? ;-)
>>
>>Hey Graham, watch it!! I think he's refering to a manual for the little RS
>>stereo VU meter box that I wrote back in 1978.
>
>Sorry, just my reaction to seeing Radio Shack being quoted as a reference
>on what is supposed to be a professional NG :)
>In the UK Tandy is synonymous with Tacky.
Hmmm Graham, you seem to paint with a pretty broad brush. For example, the
old RS 33-1080 1/2" condensor mic was actually manuactured by Sony for RS and,
with the addition of a 12 volt battery in place of the 1-1/2 volt battery, was
a very good mic. Their better headphones are made by Koss and are very good
values.
>>In it I was saying that just
>>doubling the size of the amp doesn't sound twice as loud, it's just a "little
>>louder". What most people consider "twice as loud" usually requires an
>>increase of about 10 dB (a 10x increase in wattage).
>That is what keeps getting quoted and I have already commented on that.
>Since then I've been looking up some papers and it appears that this "fact"
>seems to stem from Sabine's tests on the Sense of Loudness in 1910. These
>tests were conducted with a small number of people (too small to be
>scientifically accurate) using organ pipes adjusted for "equal loudness"
>and then playing them in multiples. This obviously did not allow for the
>random phases of the pipes and the wave behaviour in the room.
>
>This seems to be a case of repeating something enough times until it
>becomes true.
>
>Fletcher's experiments published in 'Speech and Hearing in Communication'
>in 1953 are better science and correspond more with what I was saying.
>
>In the whole development of music we still only have a vague ppp to fff to
>describe loudness. With other sensations it is quite easy to judge what
>double is e.g. you can take two equal length sticks and put them together
>and the human eye is very good at perceiving the angle subtended whatever
>the distance. Similarly the ear is good at pitch perception especially for
>an octave interval, but loudness is like colour in that the concept of
>"double" does not seem appropriate. "Double" requires an fixed linear scale
>for reference and loudness does not have this for pitch or absolute level
>before we even start taking into account exposure to previous loud sounds.
Why can't it be logrithmic? If you want a fixed linear scale, try 10dB=2X.
>I think this colour analogy is a good one. We can measure the wavelength of
>light, but we still only see a rainbow. We do not talk about red being
>double violet although it nearly is.
The basic premise is still true - doubling the power DOES NOT sound twice as
loud to anybody; it just sounds a "little" louder.
sjjoh...@my-deja.com
Stamey).
Yes, that is my final answer.
Sent via Deja.com http://www.deja.com/
Before you buy.
Graham Hinton
"Arny Krüger" <ar...@flash.net> wrote:
>I went back to DN and read all your contributions to your thread.
>Unless I missed something, I didn't find any place where you
>assigned a certain number or even range of dB's to the peception of
>"twice as loud".
No, I didn't. I meant the bit I said about comparing a bass drum with a
flute and how being "twice as loud" does not describe the difference. I
then made a leap looking at the Fletcher Munson curve shapes which I did
not adequately explain.
There are lots of other observations in their work which do not get as much
exposure as the famous equal loudness graphs. I don't know how their tests
were conducted. Most people seem to have a lot of difficulty comparing two
sounds of slightly different levels, say <2dB apart.
>You've done a nice job of throwing dirt on "conventional wisdom"
>which Harvey presented, but I don't see a clear (or even vague)
>alternative.
I'm just questioning text book answers, there does not appear to be any
proof or repeatability.
>> In the whole development of music we still only have a vague ppp
>to fff to
>> describe loudness.
>
>OK, so even vague can be put into a range of numbers.
Isn't that more just in order? There are no absolutes in that range.
I am quite happy in talking in dBs or even the 0-10 markings on a volume
knob because those are fixed frames of reference. I just don't think there
is a natural intuitive volume unit.
>This suggests that the perception of 'twice as loud" would depend on
>the original loudness. The human ear shows evidence of being
>nonlinear at higher levels even on a logrithmic scale. OK, so is
>there a hint of a scale of "doubled loudness" as a function of
>initial loudness?
I can't think of any evidence for this. Personally I just don't feel the
need to describe loudness in this way and I don't notice other people doing
so either.
Don't forget that in Sabine's day they barely had electricity and in
Fletcher's recording gear as consumer items was undreamt of. Now we can all
do these tests at home. Try giving different people a fader and tell them
to make a sound, both tones and programme, "twice as loud" blindfold and
then see how many dBs that is.
Try "half as loud" too. I don't think results will be consistent.
>Is the answer that there is no answer and none is possible?
Probably.
Graham Hinton
<866F1DE421EA1D9C.79A20306...@lp.airnews.net>,
Harvey Gerst <har...@ITRstudio.com> wrote:
>g...@hinton.demon.co.uk (Graham Hinton) wrote:
>
>>Sorry, just my reaction to seeing Radio Shack being quoted as a reference
>>on what is supposed to be a professional NG :)
>>In the UK Tandy is synonymous with Tacky.
>
>Hmmm Graham, you seem to paint with a pretty broad brush.
I've got different brushes for different jobs :).
>For example, the
>old RS 33-1080 1/2" condensor mic was actually manuactured by Sony for RS and,
>with the addition of a 12 volt battery in place of the 1-1/2 volt battery, was
>a very good mic. Their better headphones are made by Koss and are very good
>values.
I think there may be quite a difference between their US and UK operations
despite the same parent company. In the UK they are cheap and nasty and
they don't compare well with all the good audio and electronic
distributors.
>>Similarly the ear is good at pitch perception especially for
>>an octave interval, but loudness is like colour in that the concept of
>>"double" does not seem appropriate. "Double" requires a fixed linear scale
>>for reference and loudness does not have this for pitch or absolute level
>>before we even start taking into account exposure to previous loud sounds.
>
>Why can't it be logrithmic?
Why should it be? Some things are naturally logarithmic, but I don't think
this is one of them.
>If you want a fixed linear scale, try 10dB=2X.
I don't *want* one. There is just no need to make this rule up. It does not
describe what we perceive or give any useful information.
>The basic premise is still true - doubling the power DOES NOT sound twice as
>loud to anybody; it just sounds a "little" louder.
No dispute about that.
bg
right on the head!!!!! All these years of the so called Golden ears ,
hashing out whether it is 3db or 10 db or whatever , not a single one of
them ever thought to question as to how the ear can measure loudness. Simply
put , I can't hear it , its just right , or too freakin loud , right?
Now you need to set those people straight that think something is 3db more
red , and 12db more salty!
Graham Hilton...man of the millenium
Bill Gates ......close second........mu vote is cast
bg
>
>>g...@hinton.demon.co.uk (Graham Hinton) wrote:
>>>What do you expect from Radio Shack? ;-)
>In the whole development of music we still only have a vague ppp to fff to
>describe loudness. With other sensations it is quite easy to judge what
>double is e.g. you can take two equal length sticks and put them together
>and the human eye is very good at perceiving the angle subtended whatever
>the distance. Similarly the ear is good at pitch perception especially for
>an octave interval, but loudness is like colour in that the concept of
>"double" does not seem appropriate. "Double" requires an fixed linear scale
>for reference and loudness does not have this for pitch or absolute level
>before we even start taking into account exposure to previous loud sounds.
>