speaker phasing

[captainvi...@gmail.com]

I'm making some additions to my stereo system and I'll try to explain this as concise as possible. I have two additional speakers which I'd like to connect to the receiver in the living room. The room is about 15 X 22 feet. The existing two speakers are situated against an inside wall facing the windows. They are properly phased and sound very good. One of these existing speakers (left side speaker A system), is very slightly caddy corner so that it projects into the room. I would like to connect the additional left side counterpart on the opposite window wall so that it's speaker, (proposed speaker B system) is doing the same thing from the corner it's in. The new right speaker from proposed system B will essentially facing it's counterpart from speaker A system,separated by about 15 feet. What I'm trying to accomplish is more sound filling the room from more directions and hopefully simulating a sort of pseudo "surround" type of effect. But I'm not sure about how this is going to work out. Perhaps this is a mistake, so I thought I'd ask.

If all four speakers are facing one another and are in phase, and by this I mean before connecting to the receiver confirming that a small battery makes all four cones move in the same direction, connected like this what happens when the two lefts for instance are outputting the same signal. With the cones facing each other, will the projected sound buck and effectively try to cancel? Or should both cones in proposed B system be in phase as a pair but out of phase with respect to A system? Or should I forget the whole thing and just stick with my two existing A speakers? I hope I've explained this well. Thanks for any advice. Lenny

[dave]

Experiment, but start with all 4 in phase. "Stereo everywhere" is when
every chair is between a pair of speakers and was very popular in the
pre-SQ 1970s.

[William Sommerwerck]

This is a common source of confusion. "Same direction" means "outward or
inward", /not/ same direction viewed from overhead. The same signal should
produce compression or rarefaction from all speakers.

Other than a sore back from moving your speakers, it costs nothing to
experiment. As dave says, start with them in phase, then play around.

[Phil Allison]

"William Sommerwerck"

>
> This is a common source of confusion. "Same direction" means "outward or
> inward", /not/ same direction viewed from overhead. The same signal should
> produce compression or rarefaction from all speakers.

** Correct.

Phasing similar speakers is all about making the low frequency output from
each *reinforce* the others rather than cancel.

Compared to the wavelengths of low frequency sound, woofers are a point (
hence omnidirectional ) source of sound pressure - so it is irrelevant
which way the cone faces.

Ideally, a listener should be seated at the same distance from each speaker
so all time ( of arrival ) delays are identical and do NOT create phase
changes.


... Phil

[dave]

There is no such thing as correct time of arrival type of phase
coherence in modern electronic media. Everything is close-miked and
smeared together with "pan pots" and any spatial sensation is created
with DSP. In real life, the stereo "sweet spot" has room for one person
at a time.

Put your speakers where they make sense to you. The floor reinforces the
bass. The wall reinforces the bass. Too much bass get spkr off floor and
away from wall, for more bass put speaker in corner. Usually you want
the tweets at ear level, unless they are harsh.

[Phil Allison]

"dave the dickhead"

> Phil Allison wrote:
>>
>> "William Sommerwerck"
>>>
>>> This is a common source of confusion. "Same direction" means "outward or
>>> inward", /not/ same direction viewed from overhead. The same signal
>>> should
>>> produce compression or rarefaction from all speakers.
>>
>>
>> ** Correct.
>>
>> Phasing similar speakers is all about making the low frequency output
>> from
>> each *reinforce* the others rather than cancel.
>>
>> Compared to the wavelengths of low frequency sound, woofers are a point (
>> hence omnidirectional ) source of sound pressure - so it is irrelevant
>> which way the cone faces.
>>
>> Ideally, a listener should be seated at the same distance from each
>> speaker
>> so all time ( of arrival ) delays are identical and do NOT create phase
>> changes.
>>
>>
>> ... Phil
>>
>
> There is no such thing as correct time of arrival type of phase coherence
> in modern electronic media.

** WTF is meant by "modern electronic media " ??

Got nothing to do with my comments, what ever this idiot says.

> Everything is close-miked and smeared together with "pan pots"

** Pan pots do not "smear" .

> and any spatial sensation is created with DSP.

** Laughably stupid and wrong.

> In real life, the stereo "sweet spot" has room for one person at a time.

** Correct.

Due to the criteria I just mentioned.

[dave]

Do you work with roustabouts or what? Modern electronic media like Pop
Tunes and Rock tracks. I don't want to say CDs or downloads or whatever.
I have worked behind the scenes and if you bring up time alignment
outside the context of an electronic crossover for loudspeakers you get
blank stares. Yes Pan Pots suck, almost as bad as graphic equalizers.
The sound stage can only be preserved by recording live with no more
than 1 directional microphone per channel, and both microphones as close
to each other as possible. Then the sound stage is accurately preserved.
Any other approach will degrade phase, time or whatever you like to call
it. I learned this in the rigging at Jones Hall, recording the Symphony
on Nagras.

[Phil Allison]

"dave"

> Phil Allison wrote:
>> "dave the dickhead"
>>> Phil Allison wrote:
>>>>
>>>> "William Sommerwerck"
>>>>>
>>>>> This is a common source of confusion. "Same direction" means "outward
>>>>> or
>>>>> inward", /not/ same direction viewed from overhead. The same signal
>>>>> should
>>>>> produce compression or rarefaction from all speakers.
>>>>
>>>>
>>>> ** Correct.
>>>>
>>>> Phasing similar speakers is all about making the low frequency output
>>>> from
>>>> each *reinforce* the others rather than cancel.
>>>>
>>>> Compared to the wavelengths of low frequency sound, woofers are a point
>>>> (
>>>> hence omnidirectional ) source of sound pressure - so it is irrelevant
>>>> which way the cone faces.
>>>>
>>>> Ideally, a listener should be seated at the same distance from each
>>>> speaker so all time ( of arrival ) delays are identical and do NOT
>>>> create phase
>>>> changes.
>>>>
>>>>
>>>
>>>

>>> There is no such thing as correct time of arrival type of phase
>>> coherence
>>> in modern electronic media.
>>
>> ** WTF is meant by "modern electronic media " ??
>>
>> Got nothing to do with my comments, what ever this idiot says.
>>
>>
>>> Everything is close-miked and smeared together with "pan pots"
>>
>> ** Pan pots do not "smear" .
>>
>>
>>> and any spatial sensation is created with DSP.
>>
>> ** Laughably stupid and wrong.
>>
>>
>>> In real life, the stereo "sweet spot" has room for one person at a time.
>>
>>
>> ** Correct.
>>
>> Due to the criteria I just mentioned.
>>
>> " Ideally, a listener should be seated at the same distance from each
>> speaker so all time ( of arrival ) delays are identical and do NOT create
>> phase
>> changes."
>>
>

> Do you work with roustabouts or what? Modern electronic media like Pop
> Tunes and Rock tracks.

** So any popular music recording made in the last 50 years.

> Yes Pan Pots suck, almost as bad as graphic equalizers.

** But do not smear - you fucking nutter.


> The sound stage can only be preserved by recording live ..

** Your hobby horse - not mine.



.... Phil

[David Platt]

In article <f08512ea-4819-4ec0...@googlegroups.com>,

In the situation you've suggested - if the two left-channel speakers
are in phase, then their outputs will reinforce. You'll be doing
something like moving the location of the left output to a point
located half-way between the two left-channel speakers. Ditto on the
right side. This may or may not give you an effect you like... it may
"open up" the sound, but at the cost of creating a less-realistic
"sound stage" stereo image between the left front and right front
speakers.

You might want to experiment with a "phase difference" approach for
your rear speakers... something akin to the old Dynaquad system. The
simplest way to do this, is to wire the "-" inputs of the two
rear-channel speakers together (and not back to the amp). Run the "+"
inputs of the left rear and right rear speakers to the "+" terminals
of the left and right amplifer outputs, respectively. You may wish to
include a rheostat or pad somewhere in this wiring, so you can reduce
the (relative) sound level from the rear speakers.

In this setup, the parts of the musical signal which are in phase and
at the same volume, will be played only from the front speakers, and
will appear to be "dead center". As an instrument or singer moves to
the left or right, and the amplitude or phase of their music is
different between the two channels, the rear speakers will begin to
play it (in addition to one or both of the front speakers). Sounds
which are very different in phase between the two channels
(e.g. reflected "hall ambience" sounds) will be played most strongly
from the rear speakers.

This is a simple and inexpensive setup to create, and it can sound
surprisingly good. Compared to the "two left and two right" layout
you suggested, it tends to leave you with a more realistic left/right
stereo image.

If I recall correctly, the original Dynaquad setup works a bit
differently. It requires four identical speakers (the above system
works OK with two pairs that can be different from one
another)... left, right, rear, and center... and the wiring is a bit
more complex. Similar idea, though.

[dave]

On 11/29/2013 03:41 PM, Phil Allison wrote:
>
> "dave"

>> Yes Pan Pots suck, almost as bad as graphic equalizers.
>
> ** But do not smear - you fucking nutter.
>

I appear to have trod upon sacred ground of some sorts. So sorry.

[Phil Allison]

"dave dickhead"

>
>> "dave"
>
>>> Yes Pan Pots suck, almost as bad as graphic equalizers.
>>
>> ** But do not smear - you fucking nutter.
>>
>
> I appear to have trod upon sacred ground of some sorts. So sorry.
>

** Your the one preaching strange religion - fuckwit.

[Gareth Magennis]

wrote in message
news:f08512ea-4819-4ec0...@googlegroups.com...

Back in the early 90's I was Sound Engineer in the Ministry of Sound Club,
London. The main system was 6 stacks of a large PA system, all facing
towards the centre of the oblong dance floor.
One stack in each corner, and a stack half way down both long sides of the
oblong.

I spent a long time trying all combinations of phase, assigning left and
right to various stacks, and soon came to the conclusion that running 6
stacks this way in a large room pretty much produced such a chaotic/random
sound, and that almost nothing I did produced an overall improvement, if you
walked around the room and thus got an "average" assessment of the sound of
the PA & room combined.
It all sounded really good, actually, especially when the club was full and
hot.


If you have a single preferred listening position, e.g. a comfy chair, then
this might not apply so much to your situation, but even if it did, i would
guess that moving your head a few centimetres would drastically alter the
sound you observed, as the results from your 4 speakers are so random and
dependent on listening position.


Here's an old photo - you can see 2 of the corner stacks either side of the
podium, and one centre stack down one side of the long oblong.
http://www.ibiza-spotlight.com/image/night/club_reviews/2011/dance_music_history_ministry_of_sound/ministry_of_sound_london.jpg

(Stacks were 2 x 18" Y bins subs, 2 x 15" bass, 2 x 12" flared mids, 1 x
huge horn compression driver, 1 array of bullet tweeters)

It sounded awesome, and any phase cancellations were totally ignored by a
brain if it was pretty much constantly moving through the space covered by
the speakers, as yours might when moving around your home.



Gareth.

[dave]

https://www.soundonsound.com/sos/1997_articles/feb97/stereomiking.html

[michelle...@gmail.com]

On Friday, November 29, 2013 8:51:32 AM UTC-5, captainvi...@gmail.com wrote:
> I'm making some additions to my stereo system and I'll try to explain this as concise as possible. I have two additional speakers which I'd like to connect to the receiver in the living room. The room is about 15 X 22 feet. The existing two speakers are situated against an inside wall facing the windows. They are properly phased and sound very good. One of these existing speakers (left side speaker A system), is very slightly caddy corner so that it projects into the room. I would like to connect the additional left side counterpart on the opposite window wall so that it's speaker, (proposed speaker B system) is doing the same thing from the corner it's in. The new right speaker from proposed system B will essentially facing it's counterpart from speaker A system,separated by about 15 feet. What I'm trying to accomplish is more sound filling the room from more directions and hopefully simulating a sort of pseudo "surround" type of effect. But I'm not sure about how this is going to work out. Perhaps this is a mistake, so I thought I'd ask.
>
>
>
> If all four speakers are facing one another and are in phase, and by this I mean before connecting to the receiver confirming that a small battery makes all four cones move in the same direction, connected like this what happens when the two lefts for instance are outputting the same signal. With the cones facing each other, will the projected sound buck and effectively try to cancel? Or should both cones in proposed B system be in phase as a pair but out of phase with respect to A system? Or should I forget the whole thing and just stick with my two existing A speakers? I hope I've explained this well. Thanks for any advice. Lenny

Well I tried a few different scenarios and eventually I ended up with all four speakers in phase connected to both A and B front outputs. It would have been really nice if I could have used the rear speaker circuit of the receiver as it was intended, but unfortunately that was not possible.

I never mentioned that the receiver is an old Sansui QRX5500. That was a top of the line 4 channel SQ unit circa 1975. Sadly neither the four channel or the SQ circuit no longer is functioning, and after spending a gret deal of time trying to repair this several years ago I finally abandoned the project.

This unit, although a quality piece of equipment was built like your typical brick shit house, with circuit boards, harnesses, switch banks, etc. "layered" on top of one another. It makes signal tracing, not to mention parts replacement an absolute nightmare. But it does work well on two channel mode so that's how I use it.

I have to say the sound quality assessment of this project was really difficult. As was mentioned by others in the discussion, depending upon where you stand in the room certainly influences the way this sounds. The fact is that every arrangement seemed to sound fairly good. However lacking the proper equipment to scientifically do this, (and if I had wanted to get that technical anyway), the final decision was at best a good guess.

I did notice that with the final setup, that is everything in phase, left and right rears facing fronts from across the room the bass seemed especially strong. In fact standing in the kitchen, two rooms away, I could feel Iron butterfly pounding in my chest. I've never heard sound like this from my system before so I must have done something right.

In fact I was thinking about how good some of my old records were actually sounding. I haven't listened to many of these in quite some time and I noticed that I could hardly hear any scratches. Wow, ttis Stanton cartridge with the elliptical stylus tracking at 1.25 grams must be really something. Then I remembered the results of my last hearing test, which pretty much showed that essentially everything is down almost 40DB above eight KHZ, which essentially translates to "deaf as a doorknob", and I realized that yes they're still scratched. The difference is, I just can't hear it anymore.

Now if I could only upgrade that, so that music could once again sound like I remember it....Thanks to everyone for your advice and suggestions. Lenny

[Pat]

On Sat, 30 Nov 2013 07:00:29 +1100, "Phil Allison" <phi...@tpg.com.au>
wrote:

>Phasing similar speakers is all about making the low frequency output from
>each *reinforce* the others rather than cancel.
>
>Compared to the wavelengths of low frequency sound, woofers are a point (
>hence omnidirectional ) source of sound pressure - so it is irrelevant
>which way the cone faces.
>
>

>... Phil
>
>
Hi Phil,
I was away for a while, so this thread is new to me today. Your
comments above make sense, but bring up a question I have had for many
years. I own a pair of ESS AMT Monitor speakers that I purchased new
back in the 80's. Each has a pair of 12" woofers - one active (ie, a
normal speaker) and the other passive. I would think that when the
active one is compressing the air in the cabinet, the passive one
would be pushed out thereby appearing to be out of phase to a
listener. That doesn't appear to be the case because these speaker
have a great low end sound. Can you explain why they work? (I am
just picking you because you seem to know something about the subject,
but others are welcome to explain my misunderstanding as well.)

Thanks,
Pat

[William Sommerwerck]

"Pat" wrote in message news:26b1a99mu9p512up8...@4ax.com...

I was away for a while, so this thread is new to me today. Your
comments above make sense, but bring up a question I have had for many
years. I own a pair of ESS AMT Monitor speakers that I purchased new
back in the 80's. Each has a pair of 12" woofers - one active (ie, a
normal speaker) and the other passive. I would think that when the
active one is compressing the air in the cabinet, the passive one
would be pushed out thereby appearing to be out of phase to a
listener. That doesn't appear to be the case because these speaker
have a great low end sound. Can you explain why they work? (I am
just picking you because you seem to know something about the subject,
but others are welcome to explain my misunderstanding as well.)

The passive radiator is not a radiator in the conventional. It "looks like" a
a volume of air with the same mass. In other words, it's used to create a
ducted-port speaker without the tube. (I think this is the correct
explanation.)

[David Platt]

In article <26b1a99mu9p512up8...@4ax.com>,

Pat <p...@nospam.us> wrote:

>I was away for a while, so this thread is new to me today. Your
>comments above make sense, but bring up a question I have had for many
>years. I own a pair of ESS AMT Monitor speakers that I purchased new
>back in the 80's. Each has a pair of 12" woofers - one active (ie, a
>normal speaker) and the other passive. I would think that when the
>active one is compressing the air in the cabinet, the passive one
>would be pushed out thereby appearing to be out of phase to a
>listener. That doesn't appear to be the case because these speaker
>have a great low end sound. Can you explain why they work? (I am
>just picking you because you seem to know something about the subject,
>but others are welcome to explain my misunderstanding as well.)

You have to analyze these "passive radiator" systems as resonant
systems to see how they work.

At very low frequencies (below their cutoff) they do work in the way
you think... the driver and passive-radiator outputs are out of phase
(by angles approaching 180 degrees as you approach DC) and cancel out,
and the acoustic output of the system drops off sharply.

At higher frequencies, the phase offset between the two diaphragms is
different. The driver moves, and compresses the air inside the
cabinet; the air presses on the passive radiator and accelerates it,
and the passive radiator moves. Each of these "presses on" and
"accelerates" steps takes time, and introduces some time delay and
thus some phase delay... and this phase delay adds up, and has the
effect of cancelling out part or all of the 180 degrees of phase shift
between the two drivers.

So, at higher frequencies (above cutoff, but still down in the bass),
the acoustic output of the driver and passive radiator are either in
phase, or close to it... and their outputs reinforce.

The same thing occurs in a common "bass reflex" or "ported" speaker
cabinet. At very low frequencies, the output of the port/vent is
out of phase with that of the driver and there's no useful output from
the system, while at higher frequencies, phase delay in the "back of
the driver, through the air in the cabinet and port, to the port
output" brings the driver and port outputs into phase, and they
reinforce and you get stronger bass.

Both ported, and passive-radiator systems (and sealed "acoustic
suspension" as well) can be modeled as electrical circuits. The
compliance / springiness of the air and the driver surrounds "looks
like" a capacitor, the mass/momentum of the driver and radiator and
air "looks like" an inductor, and frictional and other losses "look
like" a resistor. A speaker system ends up "looking like" an LCR
high-pass filter, and the math for designing and tuning such filters
can be applied to the physics of the speaker driver(s) and enclosure.

The development of this sort of electrical-equivalent modeling some
decades ago was quite an innovation, and it's what enabled the
development of predictable commercial ported speaker enclosures (as
opposed to those which were worked out by trial and error, "by guess
and by God", and tuned through listening tests until they sounded good
to their creators).

[Pat]

David, Thanks to both you and William for your responses. I hadn't
realized the complexity of the system. (Simple to look at in its
physical form but requiring a complex model to analyse it at the
frequencies involved).

Pat

[Phil Allison]

"Pat"
> "Phil Allison"

>
>
>>Phasing similar speakers is all about making the low frequency output from
>>each *reinforce* the others rather than cancel.
>>
>>Compared to the wavelengths of low frequency sound, woofers are a point (
>>hence omnidirectional ) source of sound pressure - so it is irrelevant
>>which way the cone faces.
>>
>>

> I was away for a while, so this thread is new to me today. Your
> comments above make sense, but bring up a question I have had for many
> years. I own a pair of ESS AMT Monitor speakers that I purchased new
> back in the 80's. Each has a pair of 12" woofers - one active (ie, a
> normal speaker) and the other passive. I would think that when the
> active one is compressing the air in the cabinet, the passive one
> would be pushed out thereby appearing to be out of phase to a
> listener. That doesn't appear to be the case because these speaker
> have a great low end sound. Can you explain why they work? (I am
> just picking you because you seem to know something about the subject,
> but others are welcome to explain my misunderstanding as well.)

** Using a "passive radiator" is just a variation of the ported enclosure -
it allows a small box to be tuned to a lower frequency and with a larger
radiating surface area than is possible with a conventional port.

Drawbacks are increased cost and non-linearity in the radiator's suspension.

The radiator and the driven cone operate essentially in phase over the
octave above radiator resonance.


.... Phil

[Pat]

On Fri, 6 Dec 2013 09:16:21 +1100, "Phil Allison" <phi...@tpg.com.au>
wrote:

>

ESS also had a version where the passive radiator was on the rear. (I
think it was AMT 1's vs. my AMT Monitors). I had previously wondered
how the rear facing passive in the AMT 1 and the front facing passive
in the ATM Monitors both could work well. Now, I think I understand.

Thanks,
Pat

[dave]

On 12/06/2013 07:32 AM, Pat wrote:
> On Fri, 6 Dec 2013 09:16:21 +1100, "Phil Allison" <phi...@tpg.com.au>

>>
>>

> ESS also had a version where the passive radiator was on the rear. (I
> think it was AMT 1's vs. my AMT Monitors). I had previously wondered
> how the rear facing passive in the AMT 1 and the front facing passive
> in the ATM Monitors both could work well. Now, I think I understand.
>
> Thanks,
> Pat

Why not just put balloons inside a sealed box? Or maybe a hydraulic
shock absorber.,..,

[William Sommerwerck]

"dave" wrote in message
news:I7CdndBnRJT7nD_P...@earthlink.com...

> Why not just put balloons inside a sealed box? Or maybe a hydraulic shock

> absorber...

It's been done. William Michael Watson Dayton-Wright built conventional
dynamic speakers with bags of SF6 in the woofer box. He got clean bass to
below 16Hz from a small cabinet.

[dave]

We learned 16 Hz is perceived more as a train of pulses and less like a
sinusoidal tone; it is right on the border of flatulence.


These are the jokes, folks. No tirades if you can suppress the urge.

[William Sommerwerck]

"dave" wrote in message
news:_IudnaaUYK9ntD_P...@earthlink.com...

> We learned 16 Hz is perceived more as a train of pulses and
> less like a sinusoidal tone; it is right on the border of flatulence.

When I put 16Hz through the Watson woofers in my concrete-slab apartment...
//nothing// audible came out of the woofers. But everything in the room
rattled.

[dave]

Like when we have mild earthquakes.

[Phil Allison]

"William Sommerwerck"

> It's been done. William Michael Watson Dayton-Wright built conventional
> dynamic speakers with bags of SF6 in the woofer box.

** For what advantage ?

The speed of sound is about half in SF6 but that is no help in a sealed box
where resonance depends only on the stiffness of the volume of gas trapped
behind the woofer.

The smaller the volume or the larger the woofer, the stiffer it becomes.

> He got clean bass to below 16Hz from a small cabinet.

** Really ?



.... Phi

[William Sommerwerck]

"Phil Allison" wrote in message news:bgf6ev...@mid.individual.net...

"William Sommerwerck"

> It's been done. William Michael Watson Dayton-Wright built conventional
> dynamic speakers with bags of SF6 in the woofer box.

** For what advantage ?
> The speed of sound is about half in SF6 but that is no help in a sealed
> box where resonance depends only on the stiffness of the volume of
> gas trapped behind the woofer.
> The smaller the volume or the larger the woofer, the stiffer it becomes.

The lower speed of sound makes the bag appear to have a larger acoustic volume
than the air it replaces.

> He got clean bass to below 16Hz from a small cabinet.

** Really?

Really. The bass cabinet was about 20" by 20" by 12". At 16Hz, there was no
/audible/ output from the speaker, but everything loose in the room was
rattling.

The spec sheet for these speakers included a harmonic distortion curve. If I
recall correctly, the speaker had something like 5% harmonic distortion at
20Hz at 90dB output. (Don't hold me to the exact numbers, but the distortion
was very low.)

He also claimed that aluminum wool was a better damping material than
Fibreglas, fiberfill, or foam. He said the linearity of the driver's movement
depended in part on the thermal linearity of the damping material, and that
aluminum wool did a better job. I didn't fully understand this, so don't jump
on me.

Ever heard his SF6-filled electrostatics? We sold a pair to a man with a
large, dead basement. With each speaker powered by bridged Crown M300 amps,
the system could play at ear-splitting levels with no strain.

[gregz]

I heard the ess once, in a Vegas disco, of all places. Just a fill in
speaker.

On a port or passive, most of the output is from the port or passive, so
they don't cancel. This is around th tuned frequency. Woofer movement
becomes minimal. If you drove it with an oscillator you could probably find
this out.

Greg

[gregz]

I used to rattle things in my old basement. It resonated around 30 hz, but
16 hz will shake things. With 30 hz in the basement, you had to be in the
right spots to hear or not hear 30 hz.

Greg

[Phil Allison]

"William Sommerwanker"
>
> "Phil Allison"

>> It's been done. William Michael Watson Dayton-Wright built conventional
>> dynamic speakers with bags of SF6 in the woofer box.
>
> ** For what advantage ?
>>
>> The speed of sound is about half in SF6 but that is no help in a sealed
>> box where resonance depends only on the stiffness of the volume of
>> gas trapped behind the woofer.
>>
>> The smaller the volume or the larger the woofer, the stiffer it becomes.
>
> The lower speed of sound makes the bag appear to have a larger acoustic
> volume than the air it replaces.

** You have simply ignored question, which is the stiffness of a fixed
volume of gas.

Take a look at Boyle's Law ( PV = k )

> Really. The bass cabinet was about 20" by 20" by 12".

** That is not a "small cabinet" at circa 50 litres internal volume.

Had an 15 inch woofer fitted - did it ?

> At 16Hz, there was no /audible/ output from the speaker, but everything
> loose in the room was rattling.

** Standing waves are a real bitch........

> Ever heard his SF6-filled electrostatics?

** Now that was done for an entirely different reason.



.... Phil

[William Sommerwerck]

I'm giving a respectful response, despite being called Sommerwanker. Shall I
start calling you Anuson?

>>> It's been done. William Michael Watson Dayton-Wright built
>>> conventional dynamic speakers with bags of SF6 in the woofer box.

>> ** For what advantage ?

>> The speed of sound is about half in SF6 but that is no help in a sealed
>> box where resonance depends only on the stiffness of the volume of
>> gas trapped behind the woofer.
>> The smaller the volume or the larger the woofer, the stiffer it becomes.

> The lower speed of sound makes the bag appear to have a larger acoustic
> volume than the air it replaces.

** You have simply ignored the question, which is the stiffness of a fixed

volume of gas.

Take a look at Boyle's Law (PV = k)

As Michael Flanders put it... "The greater the pressure, the larger the volume
of hot air."

I found the spec sheet. He describes the SF6 as performing a linearizing
function. He says nothing about increasing the cabinet's "apparent" volume.
I'll call a friend who designs speakers and have him put me right -- if such
needs be done.

>>>>> http://www.dayton-wright.com/WATSON-10_.html

> Really. The bass cabinet was about 20" by 20" by 12".

** That is not a "small cabinet" at circa 50 litres internal volume.

I consider it "small", as it was the bottom structure of a floor-standing
speaker. That's not a large enclosure for a speaker that gets to 20Hz and
lower with low distortion.


> Had an 15 inch woofer fitted -- did it ?

Nope. Two oddball 10" drivers -- with pie plates glued to them! See the photo.

> At 16Hz, there was no /audible/ output from the speaker, but everything
> loose in the room was rattling.

** Standing waves are a real bitch...

Oh, I walked around to see if I could hear any subsonic output. There was
none. Assuming you believe the spec sheet, note the ridiculously low LF
distortion.

[William Sommerwerck]

I just found the following quote:

"Only the woofer/subwoofer were not bipolar. These relied in the use of SF6
(sulfur hexafluoride) gas (which is inert), to increase the virtual volume of
the enclosure. As SF6 is an 'ideal gas', it operates as an 'isothermal'
spring, thus avoiding the problems with 'acoustic-suspension' loudspeakers
that operated partially as an isothermal and partially as an adiabatic system.
Some designers seemed to lave little knowledge of Boyles Law or the Laws of
Thermodynamics.

"In effect, the use of SF6, increases the virtual volume of the enclosure by a
factor of 27! As can be appreciated, this both lowers the distortion as well
as permitting a lower resonant frequency of the woofer."

It's here...

http://www.dayton-wright.com/WATSONLABS_.html

I should point out that the bass cabinet is not completely filled with SF6. If
I recall correctly, the gas bags were separated with foam sheets.

[Phil Allison]

"William Sommerwerck"

>
>>>> It's been done. William Michael Watson Dayton-Wright built
>>>> conventional dynamic speakers with bags of SF6 in the woofer box.
>
>>> ** For what advantage ?
>
>>> The speed of sound is about half in SF6 but that is no help in a sealed
>>> box where resonance depends only on the stiffness of the volume of
>>> gas trapped behind the woofer.
>>
>>> The smaller the volume or the larger the woofer, the stiffer it becomes.
>
>> The lower speed of sound makes the bag appear to have a larger acoustic
>> volume than the air it replaces.
>
> ** You have simply ignored the question, which is the stiffness of a fixed
> volume of gas.
>
> Take a look at Boyle's Law (PV = k)
>
> As Michael Flanders put it...

** You have ignored the question AGAIN !!!!!

> I found the spec sheet. He describes the SF6 as performing a linearizing
> function.

** Pure marketing hype.

>> Really. The bass cabinet was about 20" by 20" by 12".
>
> ** That is not a "small cabinet" at circa 50 litres internal volume.
>
> I consider it "small",

** Yawnnnnnnnnnnnnnnnnn....

It is not small - a 10 litre box is small.

And Boyle's law makes all the claims re SF6 all wrong.



.... Phil

[Phil Allison]

"William Sommerwerck"

>I just found the following quote:

** I found it two days ago and roared laughing.

It is the greatest pile of * bullshit * I have ever seen about woofers.

> "Only the woofer/subwoofer were not bipolar. These relied in the use of
> SF6 (sulfur hexafluoride) gas (which is inert), to increase the virtual
> volume of the enclosure. As SF6 is an 'ideal gas', it operates as an
> 'isothermal' spring, thus avoiding the problems with 'acoustic-suspension'
> loudspeakers that operated partially as an isothermal and partially as an
> adiabatic system. Some designers seemed to lave little knowledge of Boyles
> Law or the Laws of Thermodynamics.
>
> "In effect, the use of SF6, increases the virtual volume of the enclosure
> by a factor of 27! As can be appreciated, this both lowers the distortion
> as well as permitting a lower resonant frequency of the woofer."
>
> It's here...
>
> http://www.dayton-wright.com/WATSONLABS_.html

** Marketing hype - not engineering fact.

The very next line is soooo telling:

" But to use this, a larger cone mass is needed and the suspension has to be
much more compliant."

Cos it contradicts the rest of the hype.

If SF6 worked as claimed, standard woofers would be all that was needed.

It doesn't.



.... Phil

[William Sommerwerck]

Unfortunately, Mr Anuson, I owned these speakers and can vouch for their
performance.

Mr Anuson, name a brand and model of woofer, of the volume given, that can get
down to 16Hz with such low distortion. I'm waiting...

It's impossible to have any kind of a discussion -- you know everything.
You're polite when people agree with you, and a vicious -- I can't think of
anything bad enough -- when they don't.

[William Sommerwerck]

Here's the answer to your question about Boyle's Law (which you will ignore,
of course)...

PV = k assumes a constant temperature. If the temperature changes, then PV
changes. The relationship is no longer linear, and as the air trapped in the
cabinet is supposedly providing a significant part of the restoring force, the
cone's displacement will not be as linear. (Duh... Get it?)

This is what WDW is talking about when he says "As SF6 is an 'ideal gas', it

operates as an 'isothermal' spring, thus avoiding the problems with
'acoustic-suspension' loudspeakers that operated partially as an isothermal
and partially as an adiabatic system. Some designers seemed to lave little
knowledge of Boyles Law or the Laws of Thermodynamics."

There is no such thing as an ideal gas, so WDW is wrong on this particular
point. However, if SF6 is significantly closer to being an isothermal gas than
air is, * then what he says makes sense. QED.

Gotcha! Finally got ya!

You may now jump up and down, Rumplestiltskin, until you break through the
floor.

* I can't find anything on this at the moment. But I'm looking.

[Maynard A. Philbrook Jr.]

In article <l81tsp$u0v$1...@dont-email.me>, grizzle...@comcast.net
says...

>
> Here's the answer to your question about Boyle's Law (which you will ignore,
> of course)...
>
> PV = k assumes a constant temperature. If the temperature changes, then PV
> changes. The relationship is no longer linear, and as the air trapped in the
> cabinet is supposedly providing a significant part of the restoring force, the
> cone's displacement will not be as linear. (Duh... Get it?)
>
> This is what WDW is talking about when he says "As SF6 is an 'ideal gas', it
> operates as an 'isothermal' spring, thus avoiding the problems with
> 'acoustic-suspension' loudspeakers that operated partially as an isothermal
> and partially as an adiabatic system. Some designers seemed to lave little
> knowledge of Boyles Law or the Laws of Thermodynamics."
>
> There is no such thing as an ideal gas, so WDW is wrong on this particular
> point. However, if SF6 is significantly closer to being an isothermal gas than
> air is, * then what he says makes sense. QED.
>
> Gotcha! Finally got ya!

But But But but!!!!!

:)
Jamie

[William Sommerwerck]

"Maynard A. Philbrook Jr." wrote in message
news:MPG.2d0e5cef2...@news.eternal-september.org...

In article <l81tsp$u0v$1...@dont-email.me>, grizzle...@comcast.net
says...

>> Gotcha! Finally got ya!

> But But But but!!!!!
> :)

Indeed. Hoist with his own petard.

The best part is that the point was reasonable, so I had to do some research.
In the process, I learned something.

[Phil Allison]

"William Sommerwanker"

>
> Here's the answer to your question about Boyle's Law (which you will
> ignore, of course)...
>
> PV = k assumes a constant temperature.

** PV= k shows that it does not matter what the gas is - the same volume
changes produce the same pressure changes.

So the stiffness of an enclosed volume of gas is the same for all gasses.

The resonance frequency of a woofer will be unaffected by it.


> If the temperature changes,

** Yawnnnnnnnnnnnn.....


Dunno who is the bigger LIAR.

You or the fuckwit you are mindlessly quoting.



.... Phil

[William Sommerwerck]

"Phil Allison" wrote in message news:bgk6rm...@mid.individual.net...

"William Sommerwanker"

> Here's the answer to your question about Boyle's Law (which you will ignore,
> of course)...

> PV = k assumes a constant temperature.

** PV= k shows that it does not matter what the gas is - the same volume
changes produce the same pressure changes.

Uh... No it doesn't. k is temperature-dependent. Sorry about that,. but all
you have to do is look it up.
If a gas isn't perfect, then compressing (or rarefying it) changes its
temperature. This causes the pressure to change more than that caused by the
volume change. The result is a non-linear restoring force.

> So the stiffness of an enclosed volume of gas is the same for all gasses.
> The resonance frequency of a woofer will be unaffected by it.

That's not what we're talking about, Mr Anuson.

> Dunno who is the bigger LIAR.
> You or the fuckwit you are mindlessly quoting.

I'm quoting physics books.

[Phil Allison]

"William Sommerwanker"
>
>> Here's the answer to your question about Boyle's Law (which you will
>> ignore, of course)...
>
>> PV = k assumes a constant temperature.
>
> ** PV= k shows that it does not matter what the gas is - the same
> volume
> changes produce the same pressure changes.
>
> Uh... No it doesn't.

** Yes it does.


> k is temperature-dependent.

** Irrelevant when there are simply no temperature changes going on.

>> So the stiffness of an enclosed volume of gas is the same for all gasses.
>> The resonance frequency of a woofer will be unaffected by it.
>
> That's not what we're talking about,

** Yes it is.

You bullshitting, tenth wit asshole.




.... Phil

[William Sommerwerck]

"Phil Allison" wrote in message news:bgkj0m...@mid.individual.net...

> k is temperature-dependent.

** Irrelevant when there are simply no temperature changes going on.

They can occur when you compress (or rarefy) the gas. What do you think the
terms "adiabatic" and "isothermal" refer to?

[Phil Allison]

"William Sommerwanker"
>
>> Here's the answer to your question about Boyle's Law (which you will
>> ignore, of course)...
>
>> PV = k assumes a constant temperature.
>
> ** PV= k shows that it does not matter what the gas is - the same
> volume
> changes produce the same pressure changes.
>
> Uh... No it doesn't.

** Yes it does.

> k is temperature-dependent.

** Irrelevant when there are simply no temperature changes going on.

>> So the stiffness of an enclosed volume of gas is the same for all gasses.
>> The resonance frequency of a woofer will be unaffected by it.
>
> That's not what we're talking about,


** Yes it is.

You bullshitting, tenth wit asshole.

You simply have no case - so fuck off.



.... Phil

[William Sommerwerck]

Consider the following statements:

"For a fixed amount of an ideal gas kept at a fixed temperature, pressure and
volume are inversely proportional."

Right? Now this one...

"Boyle's law is used to predict the result of introducing a change, in volume
and pressure only, to the initial state of a fixed quantity of gas. The before
and after volumes and pressures of the fixed amount of gas, where the before
and after temperatures are the same (heating or cooling will be required to
meet this condition), are related by the equation P1V1 = P2V2."

See the disclaimer? Compressing/expanding a non-ideal gas heats/cools it.
Assuming that both air and SF6 are non-ideal, this produces a non-linear
restoring force. SF6 is supposedly closer to ideal, so it should provide lower
distortion in a "true" acoustic-suspension system, where the gas provides a
big percentage of the restoring force.

You'd better give up, because I'm going to keep posting this until you do.

[Phil Allison]

[Phil Hobbs]

On 12/09/2013 06:02 PM, Phil Allison wrote:
> "William Sommerwanker"
>>
>>> Here's the answer to your question about Boyle's Law (which you will
>>> ignore, of course)...
>>
>>> PV = k assumes a constant temperature.
>>
>> ** PV= k shows that it does not matter what the gas is - the same
>> volume changes produce the same pressure changes.
>>
>> Uh... No it doesn't.
>
> ** Yes it does.
>
>
>> k is temperature-dependent.
>
> ** Irrelevant when there are simply no temperature changes going on.
>
>
>>> So the stiffness of an enclosed volume of gas is the same for all gasses.
>>> The resonance frequency of a woofer will be unaffected by it.
>>

You're quite right that the compressibility of the gas *at constant
temperature* is very nearly independent of the composition, by the ideal
gas law. However, acoustic waves aren't isothermal, they're nearly
adiabatic (i.e. heat doesn't have time enough to diffuse very far in one
acoustic cycle). In an adiabatic process, the compressibility depends
fairly strongly on the number of degrees of freedom of the gas molecule.

There's a quite reasonable discussion at
<http://en.wikipedia.org/wiki/Adiabatic_process#Ideal_gas_.28reversible_process.29>

SF6 has lots and lots of degrees of freedom.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net