[AJinFLA]

The Mills just sound cleaner.  Build yourself a test fixture that has a really, really good DPDT switch in it (you know - silver plated coin silver contacts) that you can use forever.  Put a Mills and a boat on the legs running to a tweeter.  You will hear the distortion as additional edge on transients like cymbal crashes, etc.  I know that this is Mr. Empirical talking to Mr. Theoretical, but it really is an interesting experiment.  Kind of like "Watch Mr. Lizard".   

Well I could do all that Dave...but I'm afraid it wouldn't get us any closer to explaining why Brian heard drier sound varying resistors, in his sensing circuit...in his subwoofer.
Plus, again, I already use Mills (and Mundorf) for reasons previously stated.

Here is one of the long standing op amp links.  FWIW the most highly regarded opamps for audio at present are ones with distortion (THD + noise_ of around 0.00008% or below:
http://tangentsoft.net/audio/opamps.html
http://www.ti.com/product/opa2134
http://www.ti.com/lit/ds/symlink/lm4562.pdf
Dave

Can't recall where I saw the one I referenced, but go over to the tubes circle and tell them ultra-low THD is preferred...and results in fuller, "wetter" sound  .

cheers,

AJ

[AJinFLA]

Yup, or else you might end up like StigErik on DIYaudio with 8 21" in OB to get results.  Or Monte Kay with his nutty OB arrays of how many Dayton Refs per side?  No sense modulating the heck out of 150-200Hz with 1" P-P 40Hz, right? 

Greg

If-when I come over we'll do some SPL tests

[rythmik]

  No sense modulating the heck out of 150-200Hz with 1" P-P 40Hz, right? 

Greg

what you described is called Doppler distortion and I did a bit more google search and Elliot (ESP) call it phase distorton which I think is more appropriate.

[jtwrace]

Plus, again, I already use Mills (and Mundorf) for reasons previously stated.

I think I missed this. Can you post the link? 

[Davey]

Yup, or else you might end up like StigErik on DIYaudio with 8 21" in OB to get results.  Or Monte Kay with his nutty OB arrays of how many Dayton Refs per side?  No sense modulating the heck out of 150-200Hz with 1" P-P 40Hz, right? 

Greg

I think you've missed the point.  The reason for using so many "Dayton Refs per side" is so you WON'T be operating them at 1" peak-to-peak.  Thus lowering non-linear distortion. 

I would surmise that 95% of the time the cones are not visibly moving, and that Monte's bass system leaves anything we're talking about here in the dust....both in quality and quantity.  (And it doesn't even use servo amps/drivers.)

You can call it "nutty" if you want. 

Cheers,

Dave.

[DBO]

Reading through this interesting discussion, I got real curious about 20Hz output of my open 2-way speakers system which uses two AE TD15LOs per side.

I can only measure with handheld Realistic SPL meter, C weighted, slow response, at the listening seat 3 meters (9') from speakers in 35 sqm (375 sq feet) room. I get some 92 to 93 dB at 20 Hz while cone movement seems to be just about on borders of linear movement which is declared +/- 9 mm for these drivers. All of these are completely eyesight estimates from looking at the back of the cone from the side.

If I leave attenuator control at the same position, few of the following values are these, of course cone movement reduces very quickly;

20 Hz – 92 dB +/- 9mm
25 Hz – 95 dB +/- 7mm
31 Hz – 99 dB +/- 5 mm
40 Hz – 98 dB +/- 2 mm
50 Hz – 100 dB +/- 1 mm

These are all with my usual EQ scheme applied.

So far I only found one music selection which got me to what I saw as maximum linear cone movement and at what I feel was a concert level volume. So I would like to have some reserve for such, but most of the time cone movement is not visible at all even for fairly loud stuff. I consider average of 90 dBA quite loud, 95 loudest that I want to listen anything and only for short periods, 100 dB or so is only for peaks in well recorded acoustic music. I guess transient peaks are actually louder than that, but SPL meter needle cannot follow them.

[dBe]

Well I could do all that Dave...but I'm afraid it wouldn't get us any closer to explaining why Brian heard drier sound varying resistors, in his sensing circuit...in his subwoofer.
Plus, again, I already use Mills (and Mundorf) for reasons previously stated.

Can't recall where I saw the one I referenced, but go over to the tubes circle and tell them ultra-low THD is preferred...and results in fuller, "wetter" sound  .

cheers,

AJ

I'm kind of like you in the enjoy the music mode.  We could spend all of our time measuring things and little time enjoying the message.

Tubes and solid state really are apples and oranges.  For music production, recording and mastering, I always use(d) the proper tool for the job.  Can't beat an old LA2A or 1176 tube compressor, but a Grace, or Avalon mic pre is the deal.  A lot of the new digital clones sound great, but not like the real thing.  That fuller, wetter sound comes from tubes, not algorithms... certainly not from .0000000000000000000001%-ish distortion.  I"m a second order guy 

What do you pair your Soundfields with for low bass?  They are great sounding speakers and go low well on their own.  Do you use any augmentation?

Kinda' OT for this thread, but I thought I would sneak in the question.

Dave

[studiotech]

I think you've missed the point.  The reason for using so many "Dayton Refs per side" is so you WON'T be operating them at 1" peak-to-peak.  Thus lowering non-linear distortion. 

Dave.

Sure I get that perfectly well, but just the fact that one may have to go to such herculean measures, makes my decision a little easier to let that last octave or 2 go to a boxed woofer.  My system already takes up enough space, I do not need two additional refrigerators in here.

Greg

[JohnR]

Yeah, and StigErik doesn't get much lower than 20hz.  That's why whenever someone says they are getting low bass with their OB system, I never believe them.

You wouldn't be the only person not to know what low bass sounds like. Why do you want to get lower than 20 Hz?

[jtwrace]

You wouldn't be the only person not to know what low bass sounds like. Why do you want to get lower than 20 Hz?

I'm flat to 12 Hz.   

[JohnR]

I'm flat to 12 Hz.   

Er... and?

[JohnR]

Sure I get that perfectly well, but just the fact that one may have to go to such herculean measures, makes my decision a little easier to let that last octave or 2 go to a boxed woofer.  My system already takes up enough space, I do not need two additional refrigerators in here.

I don't think it's necessary to go quite as far as 8 x 21s... although anyone's definition of "necessary" may be different I need to dig out my SPL meter and see where my 4 x 10s are getting me... just for the sake of scientific advancement

[AJinFLA]

I think I missed this. Can you post the link?

Page 12 right under your post, since I can't figure how to do a direct link

[jtwrace]

Page 12 right under your post, since I can't figure how to do a direct link

http://www.audiocircle.com/index.php?topic=111452.msg1159757#msg1159757

[AJinFLA]

I'm kind of like you in the enjoy the music mode.  We could spend all of our time measuring things and little time enjoying the message.

Oh I'm blasting Marcus Roberts doing Gershwin as I type right now.

Tubes and solid state really are apples and oranges.  For music production, recording and mastering, I always use(d) the proper tool for the job.  Can't beat an old LA2A or 1176 tube compressor, but a Grace, or Avalon mic pre is the deal.  A lot of the new digital clones sound great, but not like the real thing.  That fuller, wetter sound comes from tubes, not algorithms... certainly not from .0000000000000000000001%-ish distortion.  I"m a second order guy 

..and that was largely one of my contentions, that is often lack of distortion that leads to dryish sound. Hence my "inverse"...umm.."theory"  .

What do you pair your Soundfields with for low bass?  They are great sounding speakers and go low well on their own.  Do you use any augmentation?

I assume you mean the M1s, so - rarely, but at RMAF I used a third M1 cab as a smoothing sub...and got +/-3db across all 8 seats. I usually do demos without any, but advise for smoothing, +one sub usually does the trick in most rooms.
I don't use them at home, as I have the 1812s as my main rig, which is what I was measuring above. Don't know about the whole "eyeballing" Xmax thing, I drove them until I could sense some distress, which I'm sure was past Xmax and closer to Xmech (36mm p-p).
Would strongly urge caution for folks not experienced with such endeavors, who don't want to replace often expensive drivers.

cheers,

AJ

[Rclark]

You wouldn't be the only person not to know what low bass sounds like. Why do you want to get lower than 20 Hz?

What do you mean I don't know what low bass sounds like? Or should I say, feels like. Definitely been there. FWIW I do own music that goes that low, but it isn't Lawrence Welk.

Movies do as well. When I go into a house from this apartment I have two monstrous XBL^2 15's waiting in the wings for that duty. Unused.

[JohnR]

What do you mean I don't know what low bass sounds like? Or should I say, feels like. Definitely been there. FWIW I do own music that goes that low, but it isn't Lawrence Welk.

Have you tried putting any of it through an FFT to see what's really on it? Give it a try, it can be quite illuminating. Audacity is free.

[dBe]

Have you tried putting any of it through an FFT to see what's really on it? Give it a try, it can be quite illuminating. Audacity is free.

Pretty amazing what people consider low bass.  Me - Don Dorsey's 16Hz tone at the end of Telarc's recording of Toccata and Fugue in D Minor on the Bachbusters disc...

http://www.amazon.com/Bachbusters-Johann-Sebastian-Bach/dp/B000003CTU

Looooooow, baby.     That one will load a room.

Dave

[Rclark]

Let's just say it's nothing you gents would ever listen to. 

[HAL]

The RR Pomps and Pipes CD has lots of low frequency if you like pipe organs.

This is Weinberger's Schwanda the bagpiper cut analyzed with Audacity.  Main peak just at 20Hz. 




The large pipe organ in Atlantic City, NJ has a 64 foot stop that has an 8 Hz fundamental.  It is no longer functional, but hope they one day they refurbish it. There is a recording of it.  My understanding is that the organ has a 600HP drive motor.  You just feel that one!