100 Watt receiver, 300 watt speakers
Mara
I just bought 12" Cerwin-Vegas yesterday, and was reading through the
owner's manual when I came across the section on underpowering. The
receiver I have is rated at 100 watts, but the speakers are 300 watts.
Is this too much of a discrepancy? Am I going to damage my speakers or
the receiver? How much of a difference in wattage is safe? I'd hate
to go out and buy a new receiver out of paranoia if it's not really
necessary!
Thanks very much,
Mara
Sent via Deja.com
http://www.deja.com/
Scott Dorsey
>
>I just bought 12" Cerwin-Vegas yesterday, and was reading through the
>owner's manual when I came across the section on underpowering. The
>receiver I have is rated at 100 watts, but the speakers are 300 watts.
>Is this too much of a discrepancy? Am I going to damage my speakers or
>the receiver? How much of a difference in wattage is safe? I'd hate
>to go out and buy a new receiver out of paranoia if it's not really
>necessary!
Basically, the speaker power ratings come out of some marketing guy's
butt. They could be "maximum power" or "minimum power" or "nominal power."
If the speaker says "300 watts minimum power" that's a sign that you
might want a larger amp. If it says "300 watts maximum" then you probably
don't.
Either way, as long as you don't run the system until it clips, you're
fine. The question, though, is how loud you can run it before it clips,
and if you're going to have some bozo at a party operating it who is too
deaf to notice that it's well into clipping, and who will promptly blow
your tweeters from overdriving the amp.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
Harry Lavo
some bozo with access to the amp outside of my presence. I now throw a
"bozo-free" zone around all my equipment.
Harry
"Scott Dorsey" <klu...@panix.com> wrote in message
news:94g0ov$ob$1...@panix3.panix.com...
Bill Whitlock
> Basically, the speaker power ratings come out of some marketing guy's
> butt.
I just love it when the truth is stated so simply and eloquently! LOL !!
Bill Whitlock
good...@my-deja.com
rms, program, and peak
and whether it's per channel or bridged(both channels combined)
also you need to know if your speakers are 8 ohms or 4 ohms or 2 ohms
if you put two 8 ohm speakers on the amp in parallel on the same
channel then the load on the amp will be 4 ohms for that channel
and so on. a smaller ohm load on the amp will cause it to put more
current through to the speaker which means that there is more watts
going to the speaker and the amp will run hotter and may not last
as long.
for example an amp thats rated at 100 watts rms into an 8 ohm load
will be able to put out more than 100 watts but is rated to put out
100 watts to that 8 ohm speaker continuously and not have a problem.
the same amp may have a rating of 250 watts rms into a 4 ohm load
if the same amp is rated for 200 watts program into 8 ohms, then it
will be able to supply that 8 ohm speaker for short periods with 200
watts but won't be able to sustain it indefinetly.
the same amp may have a rating of 450 watts program into 4 ohms
if the same amp is rated at 300 watts peak into 8 ohms, then it will
be able to give that 8 ohm speaker one very brief blast of 300 watts
without distortion.
the same amp may have a rating of 675 watts peak into 4 ohms
if the speaker has a rating of 300 watts peak then don't use an amp
that is capable of more than 300 watts peak although the manufacturers
usually are conservative and the speaker (especially pro audio types)
are built to handle abuse.
now if you are using an amp that is too small (you have to run the
volume knob up all the way to get the sound), then you won't have
head room and you won't get that good punch from the woofers when
needed. the speaker manufacturers warn against undersized amps
because of distortion, which is harmful to speakers.
so
you need to find out whether your 300 watt speakers are
300 watts rms or 300 watts peak or 300 watts program
then you need to find out the same for the receiver
a 100 watt per channel receiver is not all that much power
In article <94fvjs$cp8$1...@nnrp1.deja.com>,
Mara <andy...@my-deja.com> wrote:
FIVE
> <!doctype html public "-//w3c//dtd html 4.0 transitional//en">
> <html>
> Scott, your answer is basically correct, but I suspect the woman who posted
> this question doesn't understand what "power" or "clipping" is in the first
> place, and doesn't have the least idea what your answer means.
> <p>I wish I had the time to give a clear, simple answer, but like Voltaire,
> I'm in a rush. Maybe tonight or tomorrow.
> <br> </html>
>
>
Basically a speaker is made up of a coil and a fixed magnet. The coil
(voice coil) is fixed to the cone of the speaker. When a signal or ac
sine wave is applied to the speaker, the coil becomes a magnet reacting
with or against the fixed magnet and causing the speaker cone to move.
When you are dealing with destruction of a speaker, it is caused by one
of 2 items. Physical limitations or distortion. With the physical
limitations, you basically have so much power that the thrusting of the
speaker litterally tears itself apart. 99% of the time this is never the
case. The other 1% of the time, the blown speaker is caused by
distortion. When you have a pure signal, it resembles a wave in the
ocean with rounded tops and gradual rises. When the sound starts to
distort, the sine wave becomes flat at the top. This flat area is no
longer an alternating wave form and is actually a Direct current wave
form. The pure ac wave does no harm to the speaker, however, the dc wave
form causes the electromagnetic coil to act similar to the filiment of a
light bulb. It gets hot to the point of burning out and then the speaker
ceases to operate. With this said, most speakers are destroyed because
of distortion, not power. A good clean power source will most likely
never destroy a speaker. I wouldn't ever be afraid to run too much power
to a speaker but would be afraid to run too less.
(With not enough power, you tend to keep turning the volume knob to get
more sound, and the amp can not put out more power so it distorts and
blows the speaker or weakens the voice coil till it one day breaks)
Speaker manufactures who give speakers high power ratings, almost always
sacrifices musicality. To make a speaker able to withstand raw power,
you have to make it physically stronger. In making it stronger, it
reacts slower and therefore less efficient. High end speakers almost
always are rated lower in power ratings. The manufacture doesn't want
you to over drive the speaker to physical destruction and therefore will
rate it lower that actual to prevent you from doing that. A speaker
manufacture who wants to be known as the loudest, baddest, mo fo, will
more often rate their speakers higher than realistic.
Generally a good amp will rate it's power in R.M.S. power. Peak power
ratings are lies, or near lies.
A good clean amp for all purpose use would be the notorious ADCOM 555
amps. They have 250 RMS watts into 8 ohm loads and are bridgeable and 1
ohm stable. THey can be found on the used market under $500. I would
say they represent the best value in amps.
I liked mine so much, I sold my Mark Levinson 338, my #38 preamp and
Proceed amps. I still use the Adcom due to it doing all I need an amp to
do for the least amount of money.
Bill Whitlock
"FIVE" <Nik...@aol.com> wrote in message
news:MPG.14d6ba1e9...@news.cavtel.net... (in part):
> Generally a good amp will rate it's power in R.M.S. power. Peak power
> ratings are lies, or near lies.
There's no such thing as RMS power either. I know the term is WIDELY used,
but it is mathematical nonsense. What people usually REALLY mean when they
use it is continuous power! Marketing people trying to change physics ....
again.
Bill Whitlock
Jensen Transformers, Inc.
Mara
William Sommerwerck <will...@nwlink.com> wrote:
>Scott, your answer is basically correct, but I suspect the woman who
>posted this question doesn't understand what "power" or "clipping" is
>in the first place, and doesn't have the least idea what your answer
>means.
You are absolutely correct. I am your typical ignorant consumer who,
up until Saturday, thought that you just bought speakers, brought them
home, and hooked them up. I further displayed my ignorance by posting
to the wrong newsgroup in my haste to find an answer, and for that I
apologize. I know on my other newsgroup there's nothing more despised
than a clueless newbie who asks idiotic questions, and I've just gone
and done exactly that.
I do thank you all for your patience and your answers (even if I
couldn't decipher them!) and I thank you even more for not flaming me!
FIVE
MARA, I apologise for the group
FIVE
bill.w...@verizon.net says...
> Xref: cyclone-pass-sjo.usenetserver.com rec.audio.pro:294607
What are you talking about by saying there is no such thing as RMS power?
Maybe you say that because you don't understand it. RMS can be used
synonomously with continuous although RMS gives a more defined
description.
With a signal that is amplified, you are dealing with AC sine waves. AC
and sine waves by definition can not be considered "CONTINUOUS". This
signal is compared to the near equivalent DC value which would be
CONTINUOUS. Being that the AC value has peaks greater than a continuous
DC value would, you must determin the RMS value to give it a rating that
is measurable. In amplifiers, we don't want DC, we want AC. WE use RMS
because it represents the equivalent value of what a DC value would
measure.
Since AC is not continuous, we must therefore find it's average.
This average is called RMS.
RMS stands for root mean squared. To find the RMS value, first square
the function, find its average (or mean) then take the square root of the
average.
With power amplifiers, it is technically correct to use RMS or PEAK, when
refering to power as we are amplifying AC not DC.
Continuous is the word that is misused, often to make those who don't
understand, grasp the concept. Even the guys at Jensen Transformers use
it.
If you don't know, ask!
Bill Whitlock
DO understand the subject.
All AC (not just sine waves) and DC voltages and currents have RMS (Root of
the Mean Square) values and these values are useful precisely because they
result in equal power (heating value) in resistive loads. For example, 120
volts RMS of AC will create the same power as 120 volts of DC into the same
resistive load. The computation process of squaring, averaging, and
square-rooting automatically takes into account the fact that
*instantaneous* power is proportional to the square of *instantaneous*
voltage or current values. Therefore, watts are either "peak/instantaneous"
or they are "average/continuous," but not RMS - the RMS operation has
already been performed on voltage or current used in computation.
A good math-oriented treatment of this subject, "RMS Watt, or Not" by
Lawrence Woolf, appeared in Electronics World, December 1998, pp 1043-1045.
Check it out ...
Bill Whitlock
"FIVE" <Nik...@aol.com> wrote in message
news:MPG.14d7ea625...@news.cavtel.net... (in part):
EarlK
RMS is meaningful in VOLTAGE or CURRENT measurements, as it gives an
"equivalent DC voltage" for POWER MEASUREMENT purposes. Read that a few
times before going on.
RMS POWER is meaningless. Root of the mean of the squares. Now, squaring all
the instantaneous power measurements (well, a bunch of them, approaching the
infinite), averaging them, then taking the root of that average would give
us a figure, but it wouldn't be useful. We do that with voltage or current.
Not power. Period.
RMS is equated with sine waves in the brains of a lot of audio folks,
because electronics training uses a sine when explaining the RMS method. So
people think RMS means sine. Not necessarily. "RMS power" measurements imply
that a sine was used for measuring power because of this association (and it
was, actually). Using a sine gives a nice steady signal, though it doesn't
correlate well with audio signals for power measurements. It also gives a
higher figure than any program material power measurement would, for the
same amplifier. Higher figure. Audio people love numbers. Big numbers.
Marketing people know that.
The engineers know the story, but they don't really care, and they'd lose.
The marketing people get "RMS Power" put on the box, and in the spec sheets.
The engineers just grin. And audio people look a little silly.
Folks should think about this for a while before jumping back and carrying
on about it. The first sentence should be read again and again. They'll be
glad they did.
Regards from Virginia Beach,
EarlK
ea...@livenet.net
-------------------------------------------------------------
"FIVE" <Nik...@aol.com> wrote in message
news:MPG.14d7ea625...@news.cavtel.net...
William Sommerwerck
otherwise, my remarks about her not understanding the answer were NOT intended
at a slap at her ignorance. Rather, I was implying that a full answer requires
more information than can be given in a paragraph or two, especially for
someone who has no knowledge of electronics.
If the woman who posted this will send me her phone number, I will call her at
MY expense and explain what she needs to know. (I simply don't have time to
write it up. It takes quite a bit of explanation.)
I'm sorry if there was any misunderstanding over what I meant.
Steve Jackson
Think, and know to whom you are speaking before opening your mouth (or typing
on your keyboard). I think Bill knows just a little bit about what he is
talking considering that he is a top-notch analog designer and president of
Jensen Transformers. Doh!!!
Regards,
Steve J.
William Sommerwerck
Mr. Whitlock is correct. RMS applies only to voltage or current. Squaring either
and dividing/multiplying by the load resistance gives the average (heating-effect)
power.
You can definitely compute RMS power, but it has no practical meaning or use.
By the way, there's an apostrophe in D'oh!.
FIVE
> Although I'm not the head of any big transformer company, I just wanted to add that
> Mr. Whitlock is correct. RMS applies only to voltage or current. Squaring either
> and dividing/multiplying by the load resistance gives the average (heating-effect)
> power.
>
> You can definitely compute RMS power, but it has no practical meaning or use.
>
> By the way, there's an apostrophe in D'oh!.
>
I understand what Mr Whitlock was saying, and technically it is correct.
His ass hole way of saying it was what I understood less. My using RMS
and POWER was only a non-essential use of one of the words.
By your saying that you can compute RMS power, goes back to what I was
saying.
By your saying that, you would be wrong as well. The idea is that by the
time it is actually "POWER" it is no longer rms as that applies only to
the AC portion of a voltage effectiveness. Wrong as it may be in
gramatical expression, RMS is widely used due to amplifiers being AC
amplifiers.
The expression and meaning of my words were the same and the resultant
use of a word only made the text redundant. It didn't change the
effective meaning of the text. Some people are so anal! Get a life I
say to them.
Dave Plowman
FIVE <Ni...@FiveMinutesofFame.com> wrote:
> Wrong as it may be in gramatical expression, RMS is widely used due to
> amplifiers being AC amplifiers.
IIRC, it sort of came into use by the press to differentiate between the
often optimistic 'peak power' ratings that some claimed. But I'd be
surprised to see it quoted in a manufacturer's specification. If it were,
I'd buy something else.;-)
--
* The early bird gets the worm, but the second mouse gets the cheese *
Dave Plowman dave....@argonet.co.uk London SW 12
RIP Acorn
William Sommerwerck
the late '60s and early '70s. It's always been wrong, and always will be wrong.
It's unfortunate that engineers are reluctant to insist that the advertising
department use the correct term. Of course, maybe they don't know "RMS power"
is wrong. After all, there are only a dozen or so people in the entire world
who understand the difference between analog and digital.
Dave Plowman wrote:
Ben Bradley
>No, the term "RMS power" was used for years before the power-inflation wars of
>the late '60s and early '70s. It's always been wrong, and always will be wrong.
>
>It's unfortunate that engineers are reluctant to insist that the advertising
>department use the correct term.
I don't think engineers are reluctant at all on this. The
advertising department doesn't listen to the engineers because the
advertising department's budget doesn't come from the engineers.
>Of course, maybe they don't know "RMS power"
>is wrong.
What did that bumper sticker say about two decades ago, "I know
Watt's wrong"? :)
>After all, there are only a dozen or so people in the entire world
>who understand the difference between analog and digital.
We're trying to educate the rest of you, but since we don't pay
your salaries most people won't listen and don't care.
Most people don't know the difference between internal combustion
engines and hamsters in squirrelcages.
Is it ignorance or is it apathy? Who knows? Who cares?
-----
http://listen.to/benbradley
ben_nospa...@mindspring.com { no Secret Decoder Ring needed! }
Captain Analogue
good...@my-deja.com wrote:
> for example an amp thats rated at 100 watts rms into an 8 ohm load
> will be able to put out more than 100 watts but is rated to put out
> 100 watts to that 8 ohm speaker continuously and not have a problem.
> the same amp may have a rating of 250 watts rms into a 4 ohm load
>
Pardon me, but even in theory (that mythical land where everything
works flawlessly) an amp which delivers 100W into an 8ohm load can
deliver 200W into 4 ohms, not 250W. Most amps don't actually have the
ability to deliver enough current to double their power for half the
impedance, but none will ever exceed twice the power for half the load
impedance.
Otherwise, a good post.
--
MUSIC happens in the analogue domain.
Jim Gilliland
>
> I understand what Mr Whitlock was saying, and technically it is correct.
> His ass hole way of saying it was what I understood less.
I found Bill's statement to be succinct, clear, and informative.
Jim Gilliland
>
> In rec.audio.pro, William Sommerwerck <will...@nwlink.com> wrote:
>
> >It's unfortunate that engineers are reluctant to insist that the advertising
> >department use the correct term.
>
> I don't think engineers are reluctant at all on this. The
> advertising department doesn't listen to the engineers because the
> advertising department's budget doesn't come from the engineers.
>
> >Of course, maybe they don't know "RMS power" is wrong.
The advertising department doesn't listen to the engineers because the
job of the ad is not "to communicate accurate information", the job of
the ad is to "sell the product".
90% of the ad's audience doesn't know the difference between "peak"
power and continuous power. For nearly all of those who DO know the
difference, the terms "RMS power" and "continuous power" are
synonymous. The miniscule fraction of people who know which term is
technically correct is so small that the advertisers are completely
unconcerned about them - and rightly so.
From an advertiser's perspective, the term "RMS power" is preferable to
the term "continuous power". "RMS" is a term that is obviously
scientific, mathematical. Most readers don't even know what it stands
for, but they recognize it as conveying some sort of legitimacy to the
number that accompanies it. The term "continuous", on the other hand,
is far too commonplace to have that connotation.
Mara
William Sommerwerck <will...@nwlink.com> wrote:
>I want the woman who posted this to understand that, though it might
>look otherwise, my remarks about her not understanding the answer were
>NOT intended at a slap at her ignorance.
Yeah, this is an old thread by now, but I haven't had an opportunity to
respond before this.
I just wanted the group to know that I did not take offense at anything
that was said. Honestly. Even if your remarks were aimed deliberately
high, it was no more than I deserved for posting to the wrong group.
In any case, after having a cryptographer advise me via e-mail, we
figured out that my receiver was, in fact, only 40 watts. Much too
light. However, he did say that if it were a 100-watt receiver and the
speakers were 8 ohms, I should be set for life. So just to be safe, I
went out and got a new receiver. Damned thing has a 490 page manual -
and that's just the guide to the remote.
Anyway, I wanted to thank everyone who helped me, or attempted to help
me, both on this forum and via e-mail. You'll never know the relief
and gratitude this commoner has, finally owning a decent system and
knowing I'm not going to unwittingly destroy it!
Peace,