A DIY out board tone control???

Frederick Petersen · 11941

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Offline 2wo

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Reply #15 on: June 01, 2013, 12:07:38 PM
I have an Audio Research SP3a. I don't use in my current setup but it has a "contour" control, an adjustable loudness, which was nice for low level listening.

Never found the tone controls very useful. If I needed them all was pretty much lost to begin with.

I like Paul's idea of using a BSC as a loudness control...John       

John S.


Offline Paul Joppa

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Reply #16 on: June 01, 2013, 12:40:30 PM
My reading of the history is that tone controls appeared when tubes got cheap enough that the extra gain was affordable, and were (in the thirties and forties for example) useful because speakers were very far from flat. Even the best home-audio speakers had serious deficits in both bass and treble. Remember, back then "transient smearing" referred to the treble coming out of a bass horn 5-10 milliseconds before the bass, or the bass ringing for a similar time after the signal stopped. The term was "bass overhang" IIRC.

These days it is a reasonable expectation to look for a speaker with a fairly flat response. But between bad recordings and room acoustics (not to mention esoteric speaker designs with oddball response curves) a bit of equalization can come in mighty handy.

There was an important paper that came out, maybe early seventies(?) that suggested "loudness" controls did not accurately reflect human hearing - this was because the ancient Fletcher-Munson curves were updated around then. But that was also when tone controls were disappearing, and I think this improvement never actually made it into commercial production - they just kept on using the old designs. That would be another interesting thing to revive.

Paul Joppa


Offline Frederick Petersen

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Reply #17 on: June 01, 2013, 01:42:33 PM
4KROW (Greg Peyton)
(QUOTE)
I would add that while tone controls are sometimes an invasion into perfection, the real world may suggest otherwise. That is to say, as mentioned above, there are those recordings that need help, either in an addition or subtraction of frequency balance. Also, I don't like to admit it, but my ears hear a little different from one another these  days. Lastly, my room has few issues that could be diminished a bit with a little help. Other times, it is just fine to bypass the tone control altogether.

(QUOTE) 2WO (John Scanlon)

I have an Audio Research SP3a. I don't use in my current setup but it has a "contour" control, an adjustable loudness, which was

nice for low level listening. Never found the tone controls very useful. If I needed them all was pretty much lost to begin with.

I like Paul's idea of using a BSC as a loudness control...John       

(QUOTE) Paul Joppa

My reading of the history is that tone controls appeared when tubes got cheap enough that the extra gain was affordable, and were (in the thirties and forties for example) useful because speakers were very far from flat. Even the best home-audio speakers had serious deficits in both bass and treble. Remember, back then "transient smearing" referred to the treble coming out of a bass horn 5-10 milliseconds before the bass, or the bass ringing for a similar time after the signal stopped. The term was "bass overhang" IIRC.

These days it is a reasonable expectation to look for a speaker with a fairly flat response. But between bad recordings and room acoustics (not to mention esoteric speaker designs with oddball response curves) a bit of equalization can come in mighty handy.

There was an important paper that came out, maybe early seventies(?) that suggested "loudness" controls did not accurately reflect human hearing - this was because the ancient Fletcher-Munson curves were updated around then. But that was also when tone controls were disappearing, and I think this improvement never actually made it into commercial production - they just kept on using the old designs. That would be another interesting thing to revive.
   
(QUOTE) fastfred (Fred Petersen)
  I like the reference to the paper about loudness controls and the improvement which never got to market (thanks Paul)

  I'm hoping that Doc B and the guys will weigh in soon. One last observation from me. To be honest as long as I can improve the sound of those old thin sounding moldie oldies that I have so many of it doesn't matter to me whether the design decided upon is passive or active. I know Doc B & the guys wouldn't bring a below par product to market.

Another reason for a tone control, back in the day if a record sounded bad you just tweeked the tone controls. It's still a valid reason for having them today. I was culling my cd collection last week, by just quickly listening to each cut what amazed me was how poorly recorded some of those cd's were. I pulled out some box sets & recordings I never listen to any more and made myself    about $250 for 6 box sets & 30 CD's 60's & 70's rock mostly. The plan was to use the money to download hi res files of those recordings. Then I remembered the change from vinyl to cd, the the release of the remastered cd's, set aside the audiophile versions, example I have Exile on Mainstreet the latest box set, & found a 2 disc version of Exile, as well as a version with both albums on 1 disc. How many times do I have to buy a recording in a new format to keep up with the Jones's. Thats actually when I had the "aha" moment. I'm not going to repurchase a 1200 cd record collection. I'm going to find a tone control. I'm sick of lining record company pockets.



Offline Armaegis

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Reply #18 on: June 01, 2013, 05:31:27 PM
Whoa... another Winnipegger...

/back on topic



Offline Doc B.

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Reply #19 on: June 02, 2013, 06:07:05 AM
At this point in the conversation I will mention that it could be some time before we can get to this. Off the top of my head there is the Reduction manual to finish and those kits to get shipping, Mainline to finish and get shipping, The DAC to finish, the experiments with an active step up to finish, The AC motor controller and several other things we are working on. So if it seems at some point that nothing is moving on this idea understand that it's probably just because we always have many projects going at once.

Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.


Offline johnsonad

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Reply #20 on: June 02, 2013, 07:52:09 AM
Don't forget the SR45 v2!  Two years and counting :)

Aaron Johnson


Offline pboser

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Reply #21 on: June 02, 2013, 10:52:24 AM
I've never used them, but I know that many feel that the tone controls on the Quad preamps are very useful for helping with different recordings.  They have a tilt control, which sounds intuitively right to me for correcting some recordings.  This page has an interesting discussion of the tone controls: http://kenrockwell.com/audio/quad/34-preamplifier.htm (disclaimer - I don't know the author or anything about him.)
I've never used a Quad preamp, but I do have an Apt Holman, which also has unusual and less-intrusive-than-normal tone controls.  The same guy has a page on this preamp too: http://kenrockwell.com/audio/apt/holman-preamplifier.htm
Food for thought for tone control designers.
Pete

Peter Boser


Offline adamct

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Reply #22 on: June 03, 2013, 06:18:32 AM
Take anything Ken Rockwell says with a grain of salt. He is often deliberately provocative, and he isn't shy about spouting opinions, including on things he isn't terribly knowledgable about (he reviews all kinds of stuff). It isn't that he doesn't know anything, and he sometimes has a valid point when he is being provocative, but you just need to bring your own knowledge and experience to bear when evaluating what he says. Again, he's not a bad guy, but I never start out assuming he is right.

Regards,
Adam



Offline caffeinator

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Reply #23 on: June 03, 2013, 06:42:16 AM
AC Motor Controller?  Sounds like you've got a veritable Skunk Works going over there!  Awesome :)



Offline Doc B.

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Reply #24 on: June 03, 2013, 07:52:33 AM
AC Motor Controller?  Sounds like you've got a veritable Skunk Works going over there!  Awesome :)

Yeah, next project is an AC flying saucer controller.

Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.


Offline 2wo

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Reply #25 on: June 03, 2013, 12:54:17 PM
I'll beta test for you, I already have my tin foil hat ;D...John

John S.


Offline Henry's Cat

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Reply #26 on: June 11, 2013, 10:50:05 AM
The tone controls on the Quad 22 pre-amp. are subtle but really do make a difference.  I'm a fan of both tone and loudness controls, they have their uses when used in moderation.

A few years ago I designed and built my own loudness control using two poles of an Electroswitch 4-pole 23-way switch from Parts Connexion.  The inspiration for this project was in an article from Audio Engineering, August 1951, page 15 by William O. Brooks.  I use it as the volume control for a line-level preamp. feeding a couple of 76 triodes.   I've found that loudness controls really do restore the 'body' to music when listening at low levels.

If anyone's interested I could post more information on this site. 



Offline xcortes

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Reply #27 on: June 11, 2013, 11:46:24 AM
I just moved the independent volume controls to the top of my amps to be able to adjust "by ear" and "on the fly". My crossover points are 100, 500 and 7khz. It is a fun new toy.

Xavier Cortes


Offline Paul Birkeland

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Reply #28 on: June 11, 2013, 02:01:42 PM
I'll just mention that a passive EQ with a gain stage to restore the lost level is very similar in operation to a phono preamp with passive equalization.  (I'm just mentioning this since arguments were made that this is a violation of some type of unspoken audiophile code)

-PB

Paul "PB" Birkeland

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Offline pboser

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Reply #29 on: June 12, 2013, 02:39:04 PM
The tone controls on the Quad 22 pre-amp. are subtle but really do make a difference.  I'm a fan of both tone and loudness controls, they have their uses when used in moderation.

A few years ago I designed and built my own loudness control using two poles of an Electroswitch 4-pole 23-way switch from Parts Connexion.  The inspiration for this project was in an article from Audio Engineering, August 1951, page 15 by William O. Brooks.  I use it as the volume control for a line-level preamp. feeding a couple of 76 triodes.   I've found that loudness controls really do restore the 'body' to music when listening at low levels.

If anyone's interested I could post more information on this site. 

Yes please!

Peter Boser