Toole and why I like Tone Controls

In another thread I was pointed to a really excellent paper by Dr. Floyd Toole (he doesn't use the Dr. but it is well earned) on getting to neutral.

So I want to go back with a little history. In all of audio reproduction theater sound reproduction is among the most rigidly controlled areas of audio. From the needs of Dolby Surround playback, to introduction of acoustic decay requirements introduced by THX, and more, the attempt to deliver a uniform theater experience has been a subject of serious effort by many, and continues to be so.

That's in sharp contrast to consumer music.

So while this article focuses heavily on theater sound, it also touches on just how difficult it is for even theater sound experts to get to neutral. If they can't do it, imagine how hard it is for music!

And, yes, I'm going to hijack Dr. Toole's paper to plug tone controls. With all the guessing that goes on, not using tone controls, and not having great tone controls to use is folly.  Quote me. I said FOLLY!

Also, personal request, if anyone knows how I can get in touch with him and be a fan boy, please let me know. :) I'd love to hang with him, and it turns out he's a local.
Sorry, credit to @pirad - This really was a great article to see. Thank you.
He posts on a number of forums although, apparently, not here.  Do a little Googling for him.
In all of audio reproduction theater sound reproduction is among the most rigidly controlled areas of audio.
In fact its not controlled at all. This is complete misrepresentation. As usual.
The only thing you could possibly be referring to is THX. Which is a trademark, not a standard. THX is for Tomlinson Holman eXperiment, the result of some research they did into what it would take to reproduce sound at realistic levels.

THX was a great marketing move and became the de-facto standard. The key word being de-facto! There is in fact no standard whatsoever, other than the ones THX set, which only apply to theaters that wish to use the THX logo in their marketing. Which a lot did, and do.

Hey @MillerCarbon

Duuuuuuude, an area in which I have some hands on expertise in is not where you want to jump in without a life vest.

Just saying.  Maybe asking questions politely is a great way to show class and sobriety??
A thread a day keeps the Audiophiles away.
Also @millercarbon

How many different ways can you contradict yourself in a single sentence?? Are you a newspaper astrologist??
I got myself a ringside seat.
Dude, I have an ancient (ca 1963) Macintosh c20 preamp. It has tone controls as well as a built-in parametric equalizer for different recording co. standards (the preamp dates to before RCIA standards, which normalized recording equalization across major music publishers, so it's suitable for 78s, etc.)

Some people will tell you that tone controls degrade clarity, etc. If so, I can't tell. My old Mac is the clearest, most honest preamp I own, and I own numerous more modern choices.

So once again, musical quality, clarity, etc. comes down to manufacturing quality, not features. I understand the "purest signal" argument - if nothing else, a simpler circuit provides less opportunity for screwups - but in reality, tone controls well done are fine, and they're quite helpful, user friendly, and will actually permit you to listen to and appreciate more music, especially badly recorded stuff. 
Hello jeffjoeblob,

     I'm just curious about how you tend to use your tone controls and built-in PEQ, do you have the controls set at specific positions and generally keep them there or do you find yourself adjusting them from song to song or album to album?
Just to add something pertinent
I use in my second system an old Sanyo receiver, circa 1970 something, all silver shiny faceplate, big tuner analog dial and lots of switches and knobs, ooh shiny things......

It has bass and treble and loudness button, hi filter cut and low filter cut.

Do I use them?

Heck yes indeed!

I tend to find myself boosting the bass a little on vinyl and cutting the treble on cds.

So yes I am constantly adjusting, there is no good one setting fits all.

So in theory it should translate to the main rig that there cannot be just one setting ( neutral or wherever the amp designer has voiced the preamp section) that fits all genres and sources.

Part of the reason I use a Jolida bass expander in the analog section of my main rig, now seriously considering best way to implement a complete DSP type of setup down the road.
Some people will tell you that tone controls degrade clarity, etc. If so, I can’t tell.

I have found that this is very preamp specific, plus now that we are in the digital world, I do my tone controls before my DAC. I feel like I’m cheating.
I tend to find myself boosting the bass a little on vinyl and cutting the treble on cds.

Speaking of which, we've all heard how bad early CD's were. From Talking Heads to U2, some of it was crap. The bass sounds like a sheet drying on a clothesline. Adjusting for the sensibilities of the times is also a real thing.
Erik, cracking me up, have no idea what a sheet drying on a clothesline sounds like.  But love the way they turn out.
I respect Toole quite a bit. He was great in Becket.
What's a clothesline?
They can be used as either speaker cables or interconnects.  But be sure to watch for the correct directionality.  
Cello Palette, look it up Eric. Ask me how I know. My 1965 MX110 has well implemented tone and other controls that I use in my vintage system.  
Hey @tomic601

I don't need to look up the Palette, I remember it. I'll never see one in real life, but I remember. :)


Erik, cracking me up, have no idea what a sheet drying on a clothesline sounds like. But love the way they turn out.

Haha. :) Just like a flag flapping in the wind. :)
They can be used as either speaker cables or interconnects. But be sure to watch for the correct directionality.
And  here I have been using zip cord all this time!
Now I know why my system needs tone controls!
The Cello Palette is an incredible piece but prices are out of this world too.
$5000 for used if you can find one but what a preamp!
Sorry, to clarify before some one starts making their speaker cables from actual clothes lines....
I meant that the sound that you hear from sheets flapping on a clothes line is what early CD bass sounds like. Floppy, lifeless, like there's nothing behind it.
Thomlinson Holman gave a engineering sales group of which I was a fortunate one..the best presentation ever. In my opinion better than that of Snell, Dahlquist and even Pass all who had been in front of us before. He told us all about the Apt Holman gear and then went into 9.2 before we were barely into 5.1..Lucas did a smart thing when he grabbed that Tom guy up. Tom
One early CD with Golden Gate cable tight bass is Peter Gabriel - Security

disclaimer : you are going to need about 1 KW to do real justice to this

EC : I can probably arrange a Palette demo at the annual gathering of the Directionally Correct Inert Gas Die Society gathering, wine will be served. 
@tomic601 - Before I go listening again, are you sure you aren't listening to the remaster??
Does anyone hear have any actual experience with anything other than reading and gurtitating and  jiving many white papers. This goes the same for all the jive bass threads. Besides me who has ever experienced the obvious location of mixed mono bass to the left or right of center. It is easy to hear the location of bass below 80hz even at 40 hz you just need to have ears and body mass that's just not filled with gas. Phase correct stereo bass makes the sound stage correct not mono bass every where. Use your own senses and listen just dont read lines of others experience your own. Tom
I went to read the article, clicked the link and was greeted with the dreaded "404 Not Found" error.

Not Found

The requested URL /tmpFiles/elib/20200201/17839.pdf was not found on this server.

Apache/2.2.15 (CentOS) Server at Port 80
(maybe a flood of Audiogon redirects :)
Just tried it, seems to work.
Does anyone hear have any actual experience with anything other than reading and gurtitating and jiving many white papers.


Um, yes.

I’m ignoring the entire rest of your post since it is clearly off topic. Good news is that Audiogon has told me they have plenty of room for new threads, so feel free to start your own.

This thread is about how hard it is to get tonal balance right of any recording. Bass was not brought up.

Your all about bass any where you land.
None of it is phase correct or of your own experience. Tom
Your all about bass any where you land.

That’s your own bias my friend. It’s not in this thread.

None of it is phase correct

Which I’ve not brought up, Toole has not brought up in this article, and only a very few people believe is an issue, and that’s what I meant. Being phase correct or not is a subject I have little interest in, and you can happily take that to your own thread.

or of your own experience. Tom

Tom I have no idea what you are trying to say but it doesn’t seem to be on topic, and honestly you are attempting to bring up an issue so obliquely I can’t possibly answer you. Maybe you’d feel like you can fully explain yourself by starting a thread of your own? If you have been drinking early today maybe you want to leave this topic alone for a little while and come back when you feel you can better express yourself to those who can’t read your mind?



You just repeat the obvious in every thread you start..nothing is ever original just something you read nothing of your own. 



You just repeat the obvious in every thread you start..nothing is ever original just something you read nothing of your own.

I'm so glad you agree with everything I've posted.  Would you prefer a T-shirt with my face on it, or a signed picture??



No Eric, I have the original issue CD and an incredibly vivid memory of Biamping the BIG ADS 2030 with 4 Hafler power amps ( because we could ! )....
Thanks @tomic601 I'll take a listen ...

erik, I am certainly not the one to argue as I use the best tone controls ever made, full spectrum room control. I can adjust the frequency response any way I want and see the actual results on the computer that controls the system by impulse test. It gets even better. I have dynamic loudness compensation. The system will follow the appropriate loudness curve depending on the actual volume so no matter what the volume the music sounds exactly the same. Various curves are stored in memory to cover specific problems. As an example I have a curve with a notch filter centered on 3000 Hz. I use it for sibilant voices and such. The unit is a Tact 2.2X. Tact went out of business. Trinnov and Anthem make units that are good but do not quite make it to the level of the TACT. I could never live without it. Fortunately the Tact is very well made but if it died I would probably go with the Trinnnov Amethyst.    
mijostyn: "The system will follow the appropriate loudness curve depending on the actual volume so no matter what the volume the music sounds exactly the same. Various curves are stored in memory to cover specific problems."

Hello mijostyn,

     As I stated earlier in this thread, it’s my experience that good quality class D amps (Currently very noticeably present on my pair of class D DSonic M3-600-M monoblocks), do this naturally with all source content. I use a Levinson 326S ss balanced preamp with no tone controls.
     I have no idea how technically this happens but I’m suspecting it’s been incorporated into the comparator circuitry of the class D power modules, that are constantly comparing the inputted signal to the outputted post amplified signals to make sure they match, then making any necessary adjustments to the signals prior to releasing them to the speakers. It seems to me that this would be the logical circuitry to insert some sort of automatic, algorithm based loudness control.
     I’ve noticed this very unusual but obvious characteristic on all of the good quality class D amps I’ve owned or listened to thus far. I’m not stating this as factual, rather as a possible explanation for what I know I perceive.  I haven’t heard any other class D amp users discuss this trait but I’d still be very interested in asking Bruno Putzeys and other class D amp power module designers about this phenomenon.


I have dynamic loudness compensation. The system will follow the appropriate loudness curve depending on the actual volume so no matter what the volume the music sounds exactly the same.

Very nice! Reminds me of the Yamaha/Denon loudness dials.  Loved those too.
  As I stated earlier in this thread, it’s my experience that good quality class D amps (Currently very noticeably present on my pair of class D DSonic M3-600-M monoblocks), do this naturally with all source content. I use a Levinson 326S ss balanced preamp with no tone controls.

I'm generally pro Class D, but while I haven't heard this particular effect be unique to Class D, I will say that the amps, regardless of class, I like tend to have more extension in the treble and bass.

Perhaps low output impedance that extends to the tweeter helps this?
Tim, it would be nice but doing it requires complicated programming of several DSPs running in concert and in control of the entire frequency range at 1/2 Hz intervals in a 48 bit system. You need to have the native frequency response of the system to start which means you have to do impulse testing with a microphone. Then you create filters that make the system's frequency response perfectly flat and this is the canvas you work from now overlying the inverse of the Fletcher - Munson curves and programming the computer to hop from one to the other at the right volume. 
Now if the front end of the Class D amp were digital the appropriate electronics could be added. I think the company that is most likely to do this at a reasonable price would be Anthem. They have room control built in to some of their units so the basic computing power may be there.
Trinnov has it all except the programming for Dynamic Loudness. You can link your PC to the Trinnov and program target curves into memory so you could create inverse F-M curves and switch to them manually but the programming to do it automatically is not there yet.
Erik, yes, just way more sophisticated. You have to see the computer programming in action. The problem with the Tact system is that it is complicated and consumers had a lot of trouble using it correctly. Tact decided to go direct marketing which was a big mistake. They did not have a trained dealer network to help them out and eventually it all just crashed. The current crop of manufacturers learned from this and have simplified their systems but they also removed a lot of the functionality that made the Tact system so effective like the dynamic loudness and the most amazing bass management which has yet to be matched by anything I have seen. I can change high and low pass filters independently 1 Hz at a time and choose any slope for either filter independently from 6 dB to 80 dB per octave. I can do all this on the fly with my laptop on my lap. The computer also has total control over time and phasing between all the individual drivers and sets the delays automatically when the system is impulse tested. The improvement in sound quality is such that I now digitize my phono amp through a Benchmark ADC. May sound like heresy but there is no turning back. 
In my experience the best tone control is no tone control.

Ideally, the best tone control you can have is a properly calibrated room and system. If this is your situation, you'll have as close to an ideal response curve as is practical. No tone control necessary. Though, with some terrible recordings you may wish you had one. Unfortunately, that's our problem, and the recording engineer's fault. I've learned to live with that, but I understand the desire to make a bad recording sound good...
When I first started out, I used to think flat response curve was my goal, and couldn't figure out why it looked great on the screen and sounded like crap in the room. I didn't trust my hearing, as I hadn't yet learned to listen, and I hadn't learned to respect the 50/50 balance between measurements and listening as I do now. After 13 years of calibrating I'm 100% sure that a dead flat response curve is not even close to the holy grail. No room here to discuss what is ideal, but using DSP, EQ or tone controls to get as close to a flat response curve as possible is almost always a fool's errand.

I've been called in to "fix" many systems that were calibrated using Trinnov, Audyssey, and manufacturer's proprietary auto EQ systems including Krell and JL Audio. None of those systems approach the quality of sound you get from properly, physically, calibrating your system - the room's acoustically acceptable, the speakers and listening position are properly coupled to the room, all participants in the system are respecting and working synergistically with physics. Step 1. Always!

After that, DSP, EQ, and tone controls can be used like a pinch of salt - not a fistful or a backhoe full of salt - to knock the tops off the most egregious problems. That's it! No more! And no more than 5dB of attenuation...preferably no more than 2dB. If your setup requires that you mash the tone control or max out the DSP it's time to set everything at "0" and start over. Parametric EQ is best, with a "Q" of 0.7 being ideal, and only nudge what needs to be nudged. If you have a 20dB hump in your response curve at 32Hz, don't EQ it! Find out what the hell is causing that nightmare and fix it. It's likely a loose sheet of drywall or a floor resonance.

The more tone control or EQ you use the more mangled the phase becomes, and although it's hard to pickup on a meter, your ears and brain know that something's not right. This is a problem in the time domain which affects frequency. That's when your brain starts running its' natural hardware and software, trying to reconcile what it hears with what it knows that should sound like. Our own internal EQ. And that's when listener fatigue starts to kick in, and you may find that after 30 minutes or so you can't wipe that look off your face, you know the look that you get when you bite into a lemon. Not the look that most of us are after...

Go easy, and fix the problems at their source. Then, light on the tone control if necessary. And if you absolutely must, have a tone setting (+bass/-treble) for that rare occasion when you're listening to an 80's CD of Mike and the Mechanics. Good luck!
Not so audiophilenm, at least in the digital world. I was just like you until about 2000. I just played the music at whatever volume it sounded best but there are several factors that even the smartest audio person can not control for. If I measure any system, even set up by a master the frequency response measurements will look like the rocky mountains. The usual response is, "I didn't know it was that bad." Second, the two channels are never identical. I have seen them vary as much as 10 dB in spots. You can't know how this screws up your imaging until you hear a corrected system. Third is you have no way of managing you individual speakers in time. The sound from various divers is getting to you at different times at different phase angles. This is most critical for subwoofers but also can greatly effect imaging. I have never corrected someone's system (and these are died in the wool audiophiles) and had them think it made their systems sound worse. Their usual response is "I did not know it was that bad." So, until you have measured your own system and had a look at what it is doing then corrected it both in the time and frequency realms, you have no idea what your system can sound like. You are determining what the prevailing winds are by licking your finger and sticking it up in the air. 

I agree that tone controls can make good sense and suit the needs or desires of many people.   And also I think the fear many audiophiles have of contaminating the purity of their signal are likely overblown.  Personally I’d never decry anyone’s choice to use tone controls or and EQ.

That said, I had a “transparent” digital eq in my rack for years and years (RDP-1).   I found that I essential found I never felt the need for it.  Once my speakers are dialed in nicely I tend to enjoy pretty much everything played through them.  Also, my CJ tube amps may be acting as a subtle tone control for my speakers.  If so, it’s a set-and-forget tone that I seem to like across the board :)

Further, I don’t really like the idea of fiddling with EQ per track.  That’s a more fidgety approach to music listening than I want to engage in.  Simply accepting the sound as it is leads me to focus on the music more.  (Though when I DO want to play with the sound I tend to do it via acoustics, whether it’s pulling a curtain on the side wall for a more or less spacious lively sound, putting a pillow behind my head or the like).

But that’s just an account of the approach I take.  Someone else may be the opposite where if, for instance, they find a track too shrill or lacking bass it would detract from their musical enjoyment so they activate tone controls.
Simple Path makes sense, EXCEPT, lack of controls leaves you with no control when adjustments would increase enjoyment.

Controls, done right, do nothing until desired/engaged. Optional Tone Control Bypass are liked by many.


I see this as distinct/related/interactive parts

1. TONE controls

2. BALANCE Control

3. IMAGING Refinement (assuming decent imaging to begin with).

4. LOUDNESS: AUTOMATIC Low Volume Contour.

1. TONE Control.

1a. Generally, I prefer listening to what artist/engineer put out. If I don’t like it, I am not likely to listen again. However, they certainly can be beneficial.

1b. Tone Controls, in some situations, can ’fix’ asymmetrical/difficult listening spaces, finding a general adjustment for the system.

1c. In the past, other systems, I’ve tried for ’perfection’ with advanced equalizers, pro microphones, ... it was a trap, back to basics please.

2. BALANCE. System’s Balanced, Great.

2a. After that, I find for some tracks, tweaking balance a little can make a large improvement. Adjusting Imaging ’opens up’ all the instruments. It could be/occasionally is the engineering; your side wall; a system imbalance; a slightly weak tube ...

2b. Remote Balance is the easiest to make very slight and quick adjustment from the listening position.

2c. PHONO/TT setup (skip to 3 if no phono)

Anti-skate is critical for balance/imaging/groove/stylus wear.

Get it right, re-check it occassionally. (re-check tracking force occassionally also). I just learned a lot due to an arm with only one 2.5g weight.

1. TT dial/hanging weight/rod with notches often are not perfect, or even close!

2. Stylus shape varies the effect of inward skate.

3. Smooth disk method works very well.

4. Stylus with brush effects both downward force, AND inward/anti-skate. Using the smooth disk, leaving the brush DOWN while adjusting anti-skate proved successful.

5. I use my protractor/overhang/null point disc, it has enough smooth area

6. I saw a video of someone using a blank CD. However, small diameter, be ready to catch the arm before it goes off the outside edge onto .....

7. Listening. This disc is my final confirmation/tweak.

Side 2, tracks 2 and 3: Three distinct guitars, and equal audience noise.

It is a very good example of 2a. above, how a slight tweak can make a large difference.

Eurythmics, Any: Annie Lennox/Dave’s Symetrical effects; Cassandra Wilson, Blue Light Till Dawn; Fontella Bass, New Look. Your favorite. Voices engineered to be dead center. (as long as they are not moving around the stage, i.e. live performances). Get them center, then, look a bit to the left: can you imagine them over there? Look a bit right, can you imagine ... tweak, dead on!

NOT Hot Sardines. (Great Jazz Band). Singer is OFF Center, leaving room for tap dancer, staying close to Piano. She may be right (saw her live at SOPAC), or left, Donna saw her live at Joe’s Pub, at this performance


3a. Balance as noted above.

3b. Boost favorite instrument, i.e. Jazz Bass; Piano; Sax/Trumpet/...; Voice. At decent volume, just change the engineer’s choices to suit. Just a slight touch, only for that track ...

Essentially Bass Boost at Low Volumes. Good but hard to get right. Only needed if you listen at low volumes, i.e. while reading, or dreaded unwanted visitors arrive ...

4a. Mis-named, thus mis-understood, often improper implementation.
LOW BOOST; LOW VOL+; some name short enough to print on panel face.

4b. It does not know your speaker’s efficiency, so, how can it be automatically correct?

4c. Boosting/retaining bass, i.e. Jazz Bass, Low Piano notes, at low volume listening is much better than losing it.

4d. It should begin and work below your ’normal’ listening level, thus 2 volume controls are needed for proper implementation.

4e. Some old pre-amps/receivers had two volume controls.

First, Loudness Volume Control to un-engaged position. Then main volume for preferred listening volume. Then reduce volume using Loudness Volume Control, thereby progressively engaging LOW Volume Boost.

4f. Lacking that rare feature, you need to achieve the same arrangement with a pre-amp with LOUDNESS engaged when you want it.

First get a volume ’mix’ with Loudness OFF.

You need to find when your preamp’s loudness contour begins when ON. Then set pre-amp just above that, and use your amps volume to get your preferred volume, and volume increase, and back to ’normal’ when done listening.

Then, use the preamp to reduce volume, thus beginning the progressive bass boost. Also back to normal when done listening.

If you have two cartridges with different outputs, use the amp’s volume.

Loudness OFF. Amp half way up. Preamp half way up. Raise preamp, then lower preamp, until you hear bass weaken. Raise a bit, that’s where you want Loudness Boost to begin. Loudness ON: lower pre-amp volume: bass remains, not apparently boosted.

Amp volume control for louder, Preamp volume control for reduced, below normal volume listening.

Hello elliotbnewcombjr,

     Let me get this straight, you make all of the adjustments you detailed on your last post every time you decide to enjoy some music?  
     You certainly don't make all of these fine tuning adjustments on every musical track you play, right?  I would think many tracks would be finished playing by the time you made all the fine tuning adjustments you describe.
     Do you play each track twice, once to fine tune all your settings and once again to enjoy the actual music?
     Have you ever considered the possibility that you enjoy making adjustments and fine tuning the controls more than you enjoy the music?

Further, I don’t really like the idea of fiddling with EQ per track.  That’s a more fidgety approach to music listening than I want to engage in

@prof - Absolutely true for me as well.

 Once my speakers are dialed in nicely I tend to enjoy pretty much everything played through them.

I tend to agree that neutral speakers have a much easier time playing anything you want through them, but I eventually found mine were a little too laid back, so I added a little bass, and at night if I'm wide awake I'll turn on the loudness so I can hear it all.


I have 2 "tone control" options: Adjusting the levels of my subs (easy to do with the "chicken head" knobs I put on them) which I do rarely, and a Schiit Loki 4 band EQ also used rarely and when switched to bypass it disappears utterly. Neither has any discernible audible downside.
I only switch to a different curves for recordings with problems. This is usually for cutting female voices or strings. I'll switch to the curve with the 3K notch filter which smooths things out nicely. Other wise I only get into it when there is a significant change in the system like new amps or re- positioning the speakers or a change in the room like a new sofa. Otherwise it is set it and forget it. 
It would be the rare, truly exceptional system and room that would not benefit from correction not to mention other things you can do in the digital domain like subwoofer cross overs and dynamic loudness compensation.