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Tone controls, the ear and the audiophile - curse or saviour?

Macjager

New member
Alan
Some days I feel that I am sitting in a university class, striving to get a joint degree in common sense/audiophilia (even if there is such a thing as audiophillia...).

The question I have relates to the "addition" of tone controls after the fact, ie . I have a pre-amplifier and a separate amp, neither of which have said adjustment ( in fact I have a very expensive pre-amp connected to a $300 "Big Joe" amps, having relegated my stupidly expensive tube amps to the back room for occasional listening). Does it make sense to add a device (whatever that may be) that can introduce some type of frequency controls, be it digital or analogue?

For example some of my digital computer applications have frequency controls, that can be adjusted, either by selecting the type of music I am listening to, or manually adjusting the sliders, though usually I just leave it as a flat response. I also recall that there used to be the analogue versions of said controller, which these days are very hard to come by and are considered as inserting unwanted sound interference (coloration that the amp designer does not want affecting his design...marketing nonsense...)

So, do we go looking for said device, allowing us some more personal control over the sound generated in our surroundings, or do we depend on the "expertise" of the amplifier designer?

Cheers

George

I listen through 7ES-3s sitting on Skylan stands and am very happy with them!
 

A.S.

Administrator
Staff member
The question I have relates to the "addition" of tone controls after the fact... Does it make sense to add a device (whatever that may be) that can introduce some type of frequency controls, be it digital or analogue? ...
So, do we go looking for said device, allowing us some more personal control over the sound generated in our surroundings, or do we depend on the "expertise" of the amplifier designer?...
Now this is a question that falls neatly into a speaker designer's arena, since loudspeaker design is all about 'shading' energy between one frequency band and another, and completely unlike the audiophile amplifier designer's brief where he will go to lengths to (hopefully) ensure that there is a completely flat response across the audio band. By 'flat' we mean that the energy (or voltage or loudness or frequency response: really all the same thing) will have no emphasis or leanness in one band of the frequency spectrum (the audio band) compared with any other. At least, that is what I would hope a serious audiophile amplifier designer would set as his working goal.

A speaker designer has to consider the frequency response (= loudness v. particular frequency bands across the entire audio band) not as measured by a voltmeter in a laboratory under steady state conditions, as you would an amplifier, but after those volts are converted into sound by the speaker and then blasted into 3D space by that loudspeaker radiating (uncontrollably?) in all directions with the room absorbing quite differently in particular audio bands at different angles relative to the speaker. For example, if there is a deep well-filled bookcase 90º to the side of the speaker the subjective balance of that speaker will surely be different to having a glass wall at that point in the room relative to the speaker. Thus the speaker designer has to consider the room environment as part 'of' the speaker listening experience: the amplifier designer needn't care a jot about the speaker or the room; he can live in blissful ignorance and disinterest about anything downstream of his glorious amplifier creation, anything outside his laboratory. He needn't even listen to music. He needn't even connect a speaker at all to his amp - he could work from the lab technical measurement alone. You'll appreciate then that the amp and speaker designer are living in completely different worlds, and sadly, as we will see, the amplifier designer's incessant mantra that the amp's tone controls will somehow ruin his precious sound (and that they have no place in an audiophile amp) is as example of his complete detachment from the reality of real speakers in real rooms playing real music listened to by real people who just want the best possible - most realistic - sound at home.

I state my position again - and this paraphrases what QUAD's Peter Walker said - it is logical to provide the listener of some means - acoustic, mechanical or electrical - of adjusting the perceived sonics of the recording/speakers/room/personal taste to give that home listener a fighting chance of recreating the concert hall experience. Since most home listeners living in the real world are unable/unwilling to apply mechanical (acoustic) treatment to their living space for cosmetic or cost reasons, then it is the duty of the amplifier and/or speaker designer to provide that means of adjustment for best possible sound. And the easiest way to empower the listener with the tools he needs is to build into the electronic chain (say, the amplifier) some "tone controls". Yes, some simple boost/cut frequency correction could be (and have been) built into the speaker's passive crossover, but the very simple topography of the passive crossover means that such tone adjustment controls would be very crude in their effectiveness, have a broad-brush application over wide audio bands and would most likely be of only a cut nature in the middle frequencies and of a boost in the upper frequencies, and at high cost. Tone control shaping circuitry in the amplifier should be extremely effective: as narrow or as wide a bandwidth range as needed, and with as much boost or cut in those bands as you would ever want. And all for just a few dollars. The amp is the natural choice for where to place any tone controls. Precisely what Peter Walker said half a century ago.

Make sense so far? Let me know and then we can move on to look at what 'tone controls' do and why.
 

Macjager

New member
I use tone adjusters

I use tone adjusters

Very clear, thank you. Let's look at tone controls!

As a side note, I have a Toshiba receiver from 1976-77 that still works perfectly, and has tone controls for bass, treble and a loudness switch. I found that I would adjust it often, and seemed to prefer the loudness switch in the on position, for that added oomph that it provided.

Cheers

George
 

A.S.

Administrator
Staff member
OK, before we get much deeper, please have a look at the first attached picture. There is so much commonality in photography and its light spectrum and sound and its audio spectrum. Look at the neutral greys, whites, blues and especially reds in that image. How do they look on your monitor? The reds look greatly overblown (over-saturated) to me. They ruin the overall balance of the scene. If we visualise that picture as a sound-scene, a musical performance where the colours are instruments, those over-saturated reds may be the equivalent of the over-blown bass end of the audio spectrum which is so typical of home listening, simply due to the room having inadequate absorption in the low frequencies. Getting an overall neutral picture image or sound image is why lighting technicians and acousticians earn their money: they design environments that add as little as possible to the scene being photographed or sound recorded.

When we see a colour is prominent or deficient in an image, or a part of the audio spectrum likewise sounds prominent or weak, we have just observed that specific colours or sounds are louder or softer than they should be. We then describe the image or the recording as 'unnatural', 'unrealistic', 'too bright', 'harsh' and so on. These words are simply a shorthand non-technical way of saying that the energy in certain regions of the light or sound spectra is more than we would expect were we at the live venue. Or to put it in simple words 'the reds are too loud - they shout at you' or the 'bass end of the spectrum is too rich - it adds a warmth to every type of music that is played'. See how we can easily switch between our optical sensitivity to colour and our sonic sensitivity to sound? The language is almost identical because the issues are too: of an excess or leanness of energy in certain bands. And in my picture of the over-saturated reds, were we to put a volt meter on the camera image sensor's red channel output we would see that there was a higher voltage there than for the green and blue channels. And the sound equivalent is that, if we measure the frequency response of the typical speaker in the typical room and connect the microphone to the same volt meter, when the frequency range under measurement is at the low end of the audio scale, the microphone would generate a higher voltage in response to the more prominent sound waves in the typical room.

If we can accept that our eyes and ears are sensitive to the 'loudness' of colours or sounds then we are really on the road. We observe the tools the professional and serious amateur photographer uses every day, without hesitation, as part of his job, to reduce the loudness (or sometimes to boost the loudness) of colours in his image. And we know that in the sound world, we also have loudness adjusting tools available to use. We really shouldn't reject those tools - they are our friends. The photographer's magic correction tool box is called Photoshop (or equivalent). The listener's toolbox is called 'tone controls'. They just do the same thing - selectively adjust loudness. Nothing more, nothing less. The audio tone controls do not change the pitch of the recording; they do introduce distortion; they do not alter the stereo width; they do not degrade the dynamic range; they don't have any of these unwanted side effects. They just change the loudness of certain user-selected frequency bands which, if those bands correlate with the sonic character of musical instruments, may make them more or less audible.

Now compare with picture B - where I have reduced the loudness of the red end of the light spectrum and the image now looks correctly balanced. I have merely adjusted the images red colour (= bass tone) control. Nothing else has changed, but our perception is now that B is a much more natural and life like image. It's the same as using tone controls (or mechanical damping) to improve the sound of my listening room. Why wouldn't I want to do that if my goal is naturalness? Why on earth would I reject out of hand the very tone control tools devised 50 years ago that allow me to make those adjustments? Why would a photographer point-blank refuse to use Photoshop?

More later.... (sorry, just as I returned to this, a WW2 Spitfire started a looping the loop flying display just a mile from home, a lady pilot ... Thanos would have enjoyed!)

This train of thought continues directly here, post #10
 
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Pluto

New member
Baxandall, and parametrics (as used by a sound pro in-studio)

Baxandall, and parametrics (as used by a sound pro in-studio)

{MODERATOR'S COMMENT: This is a fine contribution from a top-flight sound professional who uses this tone adjustment equipment daily. It may be I may too complex at this stage of the walk-through for non-professionals. Fear not! You can return to it much later!}
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I may well be jumping ahead too far but let's go. What do people mean by the phrase "tone controls"? Whether you know it or not, it's likely that you are thinking of some variant of the basic Baxandall configuration which originated in 1953. This is what you get...

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This was revolutionary in its day because it allowed the use of two potentiometers (variable resistors) to control bass and treble response independently of each other, and 99.9% of analogue equipment that has bass and treble controls today, contains a circuit that Peter Baxandall would recognise, but for which he earned no royalties.

I'm sure we will get around to the reasons that modern self-styled "audiophile" equipment contains no tone controls; in my view part of the reason for this is that the configuration outlined above isn't actually all that useful in the context of a system of reasonably flat response. Allow me to introduce you to one of my best friends in audio, the parametric equalizer.

The circuit isn't quite as simple as Baxandall's, but it's quite straightforward by modern standards. Each parametric equalizer ("PEQ" for short) consists of three controls - frequency, Q and gain.

The first of these defines the centre frequency of the curve and may, in theory, be anywhere in the audio range - which is 10 octaves wide, give or take. That's an awfully big range to put onto one control so "frequency" will usually be divided into smaller, more manageable chunks, typically 4 octaves wide with some overlap between them.

"Gain" defines the amount of boost or cut applied to the selected frequency, and "Q" is the effective width of the curve, typically from about .3 to 10. If you wan't to know how Q is defined, see Wikipedia or a similar reference but for our purposes, thinking of it as the width of the curve is adequate. Here are some curves to illustrate the effect of Q and gain, all centred at a frequency of 400Hz.

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When you buy a commercial box called a "Parametric Equalizer", you typically get three of four modules, each with three controls with overlap between the frequencies as described above.

Something like this can be a far more useful tone control system than anything that can be achieved with Baxandall circuits, but I now hand it over to you, Harbeth forum members, to discuss the possibilities!
 
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Macjager

New member
Parametrics

Parametrics

Now, before my cranium explodes out the left side due to the intense pressure of assimilating this information, riddle me this: most parametric equalizers have a lot of sliders, (the ones that i have looked at thus far on the 'net) thus allowing you to adjust them up and down. In this case then, am I correct in assuming that the movement of a slider will affect that particular frequency it will affect Q and gain?...or am I missing something, as your description and mine don't seem to be quite in sync.

George

{Moderator's comment: Q and gain are not necessarily coupled. They can be varied independently (in the better class of parametrics). Alan will doubtless step through this slowly later ....}
 
M

muypogi

Guest
Tone controls are a godsend

Tone controls are a godsend

If you're " very happy " I would suggest you leave well alone.
Agree, but after having my Luxman Class A integrated with it's built-in loudness + tone controls, I must say I also agree with Alan that controls that allow you to adjust per your listening requirements are a godsend. That's assuming of course that the tone controls are properly implemented. Not all amps nowadays have these. I've owned a NAD 320bee and some vintage amps, and by far the best implementation of tone + loudness controls have been with my current Luxman.

For late night listening or listening at the office, loudness being on improves on the sound as the lower end frequencies become fuller at low volumes. In situations where I cannot crank up the volume, loudness saves the day.

I also find that slight tweaks on the tone controls work well to "fix" some recordings. However, if you feel the need to reach for the extreme settings (too much treble or too much bass) then the problem possibly lies somewhere else. Too much bass, and I think you may need a sub or some bigger speakers to get your bass fix. Too much treble adjustment, and you may just have a dull recording or you may need speakers with more treble detail.
 

Pluto

New member
Graphic equaliasers v. parametric equalisers

Graphic equaliasers v. parametric equalisers

riddle me this: most parametric equalizers have a lot of sliders
Sorry if I have dived in too deeply here - the device (I think) you are describing is not a parametric EQ at all but rather, what is more generally known as a graphic equaliser. Lots of sliders.

The graphic equaliser (colloquially referred to as a "graphic") consists of a lot of fixed frequency, fixed Q gain adjustments. The theory is that you adjust the sliders to create the overall desired response curve. Obviously, the more sliders there are, the more precise the curve that you can draw. The best conventional graphics will offer about 30 controls, spaced at intervals ⅓ octave apart. Precision greater than this (40, 50 sliders) is usually considered unnecessary. Cheaper units tend to offer intervals of ⅔ octave, 10 or 15 sliders).

So what are the key differences between a "graphic" and a "parametric"? The former offers a large number of controls at a fixed Q (bandwidth). The latter offers fewer frequencies (actually not strictly true - it offers as many frequencies as you choose to pay for modules) but each of those frequencies may be tuned to total accuracy and any desired Q setting.

For instance, if you have a troubling room resonance, using a parametric it is theoretically possible to match the precise frequency, Q and amount of that resonance with its compliment, thereby compensating for the problem. Using a graphic, the process is more visually intuitive but the accuracy is ultimately limited to the best approximation that your graphic equaliser can achieve with its fixed frequencies and fixed filter shapes.

So that sums up the difference - the parametric device is less intuitive but more precise. The graphic, with its sliders, offers a superb visual representation of the overall response curve but you are restricted to the filter characteristics given to you by the designer of the unit.

I'm sure Alan will now proceed to explain the basic nature of equalisation (a fancy word for "tone controls") and the sonic reasons for artificially enhancing some frequency bands over others. When that is done, these two postings describing the tools for achieving these effects will, I'm certain, make a lot more sense.
 

A.S.

Administrator
Staff member
Tone controls # 2: the audio colour spectrum ...

Tone controls # 2: the audio colour spectrum ...

Directly continued from post #5 in this thread ....

Before we can proceed much further I think we need to be able to interpret a 'frequency response plot' or graph or chart. Then we can make sense of the shape and characteristics of tone controls when we see their characteristics plotted onto a graph.

Sound is invisible and very hard to visualise. We can hear its character and power but we can never see directly. So the first step is to emphasis that we can (and should) always try work with terminology that gives us an equivalence of effect but in a more intuitive way. We can use the light spectrum to give us an entirely adequate analogy of the sound spectrum. So, please take a look at the attached standard frequency response chart (literally a printed blank sheet torn-off a roll of pre-printed paper) which in the days of the pen chart recorder was the standard way of plotting sound loundness versus frequency. I've modified it.

Along the horizontal axis we see the familiar 20Hz to 20kHz (actually the chart extends to 40kHz) sound bandwidth which is considered to contain all the frequencies detectable to the perfect (youthful) human ear. The Y axis, the vertical axis, is ruled in repeating blocks of fine lines - each one representing one decibel - with a major fatter line every 10dB. Each on of those five, 10dB vertical cycles is as good as any other in describing a 10dB change in nature, and this chart is capable of showing a frequency range from 20-20kHz and a loudness (aka dynamic) range of 50dB. Normally, just for neatness, we'd position the pen arm arbitrarily somewhere in the middle of the graph and not use the whole of the graph paper sine every 10dB block is interchangeable with every other cycle. Important note: unlike a business graphic chart, there is no 'zero' line. When we are working with dBs we are working with relative measurements so we can pick any vertical line as our reference, and then draw whatever we want to show as a variation above or below that reference line. So frequency response plots are nothing more or less than graphs showing the variation of loudness (actually, usually voltage or sound pressure level) relative to an arbitrary but fixed reference that we pick at the start of the measurement. In the good old days of the pen chart recorder, once we'd loaded the paper roll onto the motor unit, we'd twiddle the ink pen arm until the nib was aligned neatly somewhere vertically along the chart's dB scale, and then start the motor and make the trace. I used to prefer to line-up along the thicker 30dB line (just above the middle of the chart height) just for neatness.

Now, we can't visualize sound but we are all familiar with the colours of the rainbow. So let's overlay the rainbow optical spectrum onto the graph, aligning it so that the redest red is on 20Hz and the most violet violet is adjacent to 20kHz. This is just my interpretation of sound v. light: there is no formal association between these! You are free to invent your own representation which would be equally valid. You could even reverse it so that 20Hz is violet and 20kHz is red. The reason I picked this particular spread with red at the low end of the spectrum is because we often associate adjectives like 'warm' and 'rich' with low frequency sounds and conversely, we use words like 'piercing' and 'sharp' for issues towards the top end of the sound spectrum. If you've seen a flashing blue light on an emergency vehicle you'll know how sharp it is and how it immediately grabs your attention - even in daylight. As for the other colours such as green, well that just falls as it falls in the spectrum. OK so far?

No we have this relationship between sound and light across the audio band we can use the power of picture tone controls (which is what Photoshop is all about) to take manipulate images and to demonstrate the vertical scale of our chart.

To be continued ....
 
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A.S.

Administrator
Staff member
Tone Controls #3 - the perfect execution of the tone control concept

Tone Controls #3 - the perfect execution of the tone control concept

I haven't had any feedback as to whether this subject is of interest or not so I hesitate to probe any deeper. However, it seems that the genius of the late Peter Walker of QUAD has done much of the work for me in developing the fantastic QUAD tilt control. I'm not saying that the QUAD vintage 80s preamp is the ultimate in fidelity. It may or may not be: I don't actually care. I've found the 34/44 tone control to be absolutely ideal for getting the best out of any speaker in any difficult listening room at home. As I have said many times, all amplifiers designed to make good music at home in untreated acoustics ideally need some sort of tone control to get the best possible sound out of the environment. Without tone controls, the user is really missing-out on optimising the best possible speaker/room interface. Although I have no personal experience of the later QUAD 99 (I've never actually seen one) the 99 downloadable user guide states on page 11: 'The bass control has one position of lift and one of cut. This can be used to rectify deficiencies in a recording or to compensate for poor room acoustics e.g. where speakers are placed too close to a corner etc..'. That real-world appreciation of how speakers actually behave in the typical living room endears me greatly to the brand. We'll look specifically at the QUAD bass control in another port; this time I want to concentrate on the QUAD-type tilt control*.

Now, a few post back, Pluto, a sound engineer, kindly gave us a frequency response plot for the boost and cut versus frequency for a typical 'Baxandall' tone control. The Baxandall circuit we can say with reasonable confidence is used in every amplifier except QUAD. QUAD don't use a bass and treble control: they use a tilt control. That's a significantly different animal, and if Harbeth were ever to make an amplifier, it would feature a tilt control with characteristics similar to those of the QUAD tilt control. Fig 1 and 2 show the front of the Quad 34 from which we can see two tone adjuster controls: the bass lift/step control and a tilt control. There are no conventional bass and treble controls. It's another tribute to the QUAD team that the physical rotation of the paddles gives you a perfect indication of what measurable and sonic effect you will experience. These control are highly intuitive. If we look at the tilt paddle we see a really clever thing: depending upon how we turn the paddle we can have either less bass and more top or more bass and less top pivoting about a centre frequency. This single overall tilt control has a functionality which is totally different to a conventional bass and treble control.

A conventional bass and treble arrangement with two independent control allows us to have any crazy combination of bass and treble simultaneously because there are two knobs. We could go mad and turn the bass and the treble fully up or both fully down. We can really destroy the neutrality of sound by the random and injudicious use of the conventional tone controls. But with the tilt control, all we are doing is applying a gently upwards or downwards bias to the overall sound shape. What Peter Walker appreciated was that, relative to (acoustics issues are always relative to something) a central frequency where the ear is known to be sensitive (around 1kHz) what was wanted was a little shading of the overall balance giving a slight preference (or mild emphasis) to these frequencies above 1kHz and simultaneously as slight de-emphasis to those below, or vice versa. The reason the effect was simultaneous is because in the real world what audiophiles find in a typical listening room is, for example, that there is 'too much bass', the 'bottom end is muddy', 'the room is boomy' or conversely, the room is 'too bright', the top end is 'too sharp', the upper frequencies are 'brittle'. We never seem to experience a combination of these unwelcome low and high frequency problems together do we. When did you hear someone complain of a room which was simultaneously 'too rich and too brittle' - most likely the opposite would be found: the room would be simultaneously 'too rich' and 'rather dull in the treble'. That's how real rooms behave with real speakers. So this tilting idea of applying a little gentle shaping is really appropriate.

QUAD are reported saying, "The results obtained from any programme source depend on the aggregate effect of the listening room and the recording environment together with the (tone) corrections applied by the recording engineer, and the equipment of the reproducing chain and … it is extremely unlikely that the arbitrary combination of these variables when listening at home will will yield the closest approach to the original sound... The TILT control can improve the subjective quality of musical reproduction, while adding no colouration, just a simply slight increase or decrease in overall warmth or brightness." So that's the rationale.

I've measured the shelving up/down characteristics of the QUAD 34 - attached. Remember! If you follow the coloured traces depicting the dB boost/cut action versus frequency you'll see that you cannot have a random combination of bass and treble boost or cut. Bass and treble are linked so that if you pick maximum boost in the bass (blue curve) you will automatically have maximum cut in the treble (also blue). This is unlike a conventional two knob bass and treble control with complete isolation between the controls.

Now we can overlay the characteristic curves of the tilt control onto my previous rainbow plot with it's familiar 50dB range [this revised graph is to follow]. I've carefully adjusted the measurements to overlay perfectly on the paper chart and now we can see the truth: the QUAD control has an extremely benign action of only about ± 3dB in either the bass or treble ranges. And also, as we'll see in the next post, the boosting or cutting flattens out - unlike Pluto's conventional bass/treble curve which continues up or down to infinity.

Taken together, we can see that not only is the QUAD control really rather special in its aptness for room correction in just the one control, but that it has a very subtle correction range unlike the conventional controls. Yet the circuit is no more complex or costly to implement. In my long-term view that all amplifiers really would benefit the user with some sort of room-compensating tone controls fitted as standard. Whether the QUAD sound is for you (and I know nothing about post 80s QUADs) I'll leave for you to decide. But it could be that if you have a challenging room in which no speaker sounds right, a gentle use of the tone controls, sensitively applied, may well solve your sonic problems.

I'd next like to look at how the typical room messes-up the low end of the loudspeaker.

* The circuit used by QUAD to implement the tilt control is almost certainly public domain. A I recall, it was an implementation of the Ambler circuit which appeared in Wireless World in March 1970, some years before the QUAD 34. Note the comments on page 1 of the usefulness of tone controls in adjusting the recording and of how the operation of conventional bass & treble controls becomes more extreme the more they are turned up or down. The QUAD implementation took the Ambler concept for very benign adjustment and added, in effect, speaker/room correction with the secondary bass tilt /step control, on the left of the QUAD panel.

>
 
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Will

New member
Design in secret

Design in secret

I wish Harbeth would pick up the amplifier project again and release an amp with Quad-like tone controls. But this time do it in secrecy and release it when ready instead of having everyone throw in their $0.02
 

Macjager

New member
This knowledge database ...

This knowledge database ...

Alan

This information is invaluable! Once I had read Pluto's comments, I started searching for parametric and graphic equalizers (now that I know the difference), and came upon some really "market driven" (mindless) comments about why one should not bother with an equalizer, but rather change your cables and interconnects!! Needless to say, I left those sites more quickly than I arrived (I have played around with various wires/cables and things, and frankly, there is no difference to my ear...others who believe will never be convinced otherwise...imagine how many digital recordings one can buy instead of spending $1500!! on a cable).

This knowledge database is definitely a resource that many should seek out to get a clear understanding of how sound can be modified, and why the modification, as described, will increase the listeners pleasure. I already have a 100% increase in my knowledge, and would love to gain further information, as this will allow me to more accurately define if and what type of "sound modifying" equipment should be considered for my system and my room.

As I move every few years due to my work, each new room has new "challenges", and having the ability to adjust the output would be appreciated. Plus, hey, its fun to play around with this hobby!

cheers

George
 

denjo

New member
Cables and interconnects v. tone

Cables and interconnects v. tone

The challenge of tone controls is in deciding how to judiciously use the controls to get the 'correct' sound! Also, is there not a tendency to be obsessed with the controls, to fiddle with it depending on the recording, etc? I'm sure those suffering from OCD would not find this a godsend!

And those not suffering from OCD, might find themselves gravitating in that direction. In a way, not having tone controls will make life a lot simpler since there will be nothing much to adjust except speaker placement. In a way, audiophiles who use cables and interconnects to tweak and tune the system ate probably doing what you are achieving with your tone controls!
 

A.S.

Administrator
Staff member
Sound pressure drives everything in audio evaluation

Sound pressure drives everything in audio evaluation

(A) I started searching for parametric and graphic equalizers (now that I know the difference), and came upon some really "market driven" (mindless) comments about why one should not bother with an equalizer, but rather change your cables and interconnects!! Needless to say, I left those sites more quickly than I arrived (I have played around with various wires/cables and things, and frankly, there is no difference to my ear.
(B) In a way, audiophiles who use cables and interconnects to tweak and tune the system ate probably doing what you are achieving with your tone controls!
Now, these two quotes are fascinating for they lay out clearly both (mutually incompatible) views about "tone adjustment" in an audio system. So what do we make of them?

First, we have to take a view on one absolutely central matter. Posting this one day after the CERN people announce, with conviction, that working at the very edge of measurement technology they have identified the Higgs boson particle after a fifty year search, we have to ask ourselves about audio measurements. The way the ear works is extremely well documented and thoroughly understood, and has been for decades. What all research shows is that the ear is a pressure sensitive device, or to put that another way, the ear is sensitive to loudness versus frequency (and angle of incidence). The core of every single post I make here, and of every single example, is that of illuminating how a difference in loudness - a completely measurable parameter even with rather crude equipment - critically influences our subjective opinion about sound.

If you grasp nothing else from this entire Harbeth User Group, please make it this one fact:

... if there is no difference in loudness (aka energy) between sonic event X and Y at the ear we cannot differentiate any subjective sound quality or character difference between X and Y. There has to be an energy difference between X and Y for there to be a physically detectable difference between X and Y, not a spurious phantom mental difference.

Put simply, we have no way of detecting sound other than movement of the fluid in our cochlea responding to the sound wave entering the ear canal. We can't see sound, can't touch it, can't smell it, can't taste it: the only way we know that a sound is present in the environment around us is because of the secondary effect of that sound wave wobbling fluid in the inner ear, causing tiny hair cells to waft to and fro and generate an electrical signal sent onward to the brain. We know much about the properties of fluids and we know that a certain energy input is necessary to create motion in fluids. Therefore, to hear a difference between event X and Y the pressure wave (at any given frequency) has to have the potential energy to cause those hair cells to move in a changed way. If events X and Y have precisely the same energy v. frequency then they will be scientifically indistinguishable even though the casual listener may prefer, for his own internal mental reasons, one over the other.

This thread is about electrical tone controls. We know that they work because we can measure (even with simple equipment) that in the boost or lift position more energy is applied to the audio signal at certain predictable frequencies and in the cut or minus position, less energy is applied. That energy eventually reaches our cochlea and is interpreted in the brain, which 'feels' the difference in the motion of the hair cells and, based on our internal look-up table, de-constructs that electro-chemical event into an appraisal of the character of the sounds.

Now the crux of the matter: suppose we cannot measure any energy difference in the lab at all between, say, cable C and cable D. Can we truly expect to hear a characteristic sonic difference between them? And if we do, recognising that the ear solely response to pressure-energy-frequency differences and that in this example, there is none, what as yet undiscovered physical mechanism do you propose within the ear/brain should be credited with this super-acuity that requires no difference in energy input? The pressure-wave encoding mechanism (from sound to electricity) in the ear is perfectly illustrated here (needs QuickTime plug-in). Note that as with any chemical-mechanical-electrical dynamic system there are losses. Only a proportion of the soundwave makes it through the tiny bones to the oval window, to vibrate the hair cells and hence to be detected in the brain. These losses are significant and as we know, are much effected by age and abuse. The incoming energy difference has to exceed a certain threshold just to overcome the friction and other losses and be detectable at all - which sets the resolution threshold for human hearing which is far, far poorer than even modest audio electronics is capable of.

If you want to influence the sound balance of an audio system, there has to be a sound pressure change detectable at the ear, at some frequency or other. Electrical tone controls provide a convenient method of making that pressure change. Audio equipment or accessories that do not have a measurable effect on sound pressure do not fit into the model of how the ear/brain works and cannot truly, objectively and repeatedly influence sound quality.
 

Macjager

New member
Tuning through electronics

Tuning through electronics

So, the only way to make an adjustment to sound (as the listening space exists at the moment), is through the use of either built in tone controls (as in the QUAD) or through a Parametric (PEQ) or Graphic EQ (GEQ) (analogue or digital). The next question from my point is how telling is the difference between a PEQ and a GEQ. The basic reason is cost, a PEQ is much more expensive than a GEQ. Based on what Pluto has noted, you can make many more changes to the sound with a PEQ; will those changes make a difference to what I hear (very subjective question I think, however...)?

I also has dawned on me, but correct me if I am wrong, that music, as processed by the amplifier (because the designer has not designed it to have a flat response) will be different between songs. If a sound engineer has chosen to increase certain blue frequencies (using the colour analogy) , and your listening room accentuates those frequencies, thus making that song "harsh" or too blue then nothing short of either a PEQ and/or GEQ can change it...if my amp is designed towards the blue frequency then an engineered song that pushes blue will hurt my ears, fatigue them or just make the music sound poor...

And if cables actually do make a change to the sound (and I vehemently do not believe in cables making a sound), for example they tame the reds {Bass}, they are a one trick pony, and no amount of voodoo dancing and sacrificing chickens will help the sound...

Thus, drawing me to the simple (perhaps simplistic) conclusion that, short of having my listening space redone with all sorts of sound baffles etc, then only a PEQ or GEQ can help me adjust the music to my room...

cheers

George

PS I have a Masters Degree in History...this stuff is just slightly less complicated than Higgs-Boson...
 

A.S.

Administrator
Staff member
A rule of thumb ....

A rule of thumb ....

So, the only way to make an adjustment to sound (as the listening space exists at the moment), is through the use of either built in tone controls (as in the QUAD) or through a Parametric (PEQ) or Graphic EQ (GEQ) (analogue or digital). ...
No. Don't forget about the other options .... physically changing the room by adding/removing surface treatment to make it more or less absorptive and changing to other speakers and/or repositioning the speakers. These options have to be evaluated before diving deeply into electronic eq..

The rule of thumb must be 'solve mechanical/acoustic problems mechanically/acoustically as a primary fix. Only if that is not doable, resort to electronics as a second choice.'

For example, if a F1 car engine designer discovered a concerning vibration during prototype trials, would he identify and resolve the mechanical source of the vibration, or would he ignore the mechanical cause and program the onboard computer to try and cancel the effect electronically by opposing motion? He'd be very foolish to use the computer as part of an automatic solution (a feedback loop) because if for whatever reason the feedback failed, the engine could shake itself to destruction.

Good design means solving the problem at source and directly. So the primary solution for poor sound at home or in the studio is and will remain, mechanical damping - absorbers affixed to otherwise reflective walls etc..
 

Macjager

New member
The room?

The room?

I think I may have gone into my own feedback loop...if I should focus on room treatment, speaker placement/replacement before I get into eq, then why do you believe that there should be tone controls on pre-amplifiers or receivers (I am making the assumption that eq can take the place of absent tone controls...)?
Cheers

George
 

A.S.

Administrator
Staff member
The reality of home listening

The reality of home listening

... then why do you believe that there should be tone controls on pre-amplifiers or receivers (I am making the assumption that eq can take the place of absent tone controls...)? George
I refer you back to my post #3 here .... and to quote myself ...

I state my position again - and this paraphrases what QUAD's Peter Walker said - it is logical to provide the listener of some means - acoustic, mechanical or electrical - of adjusting the perceived sonics of the recording/speakers/room/personal taste to give that home listener a fighting chance of recreating the concert hall experience. Since most home listeners living in the real world are unable/unwilling to apply mechanical (acoustic) treatment to their living space for cosmetic or cost reasons, then it is the duty of the amplifier and/or speaker designer to provide that means of adjustment for best possible sound. And the easiest way to empower the listener with the tools he needs is to build into the electronic chain (say, the amplifier) some "tone controls".
To be blunt about this then: to even remotely experience at home what you would in the concert hall, you have to suppress those characteristics in the home listening environment that colour the sound (we've covered that extensively here - echoes are the main problem). Then when we've damped them down below audibility we need to adjust the tonal warmth and brightness (the white-light, all-colour spectra) of the home room so that it is not significantly tipped towards the red end (bass tones) or the blue end (high frequency tones).

Knobbling echoes is not what tone controls can help with. The tone controls merely re-balance the overall sound to make it more life-like because, it's surely obvious, it's a logical and physical impossibility to accurately reproduce the acoustic of the Royal Albert Hall in your untreated listening room. Your room's sonic characteristics will dominate the acoustic of the recording simply because your walls are so much closer to the speakers than the walls of the RAH to the microphones, so the reflections off those home walls arrive at your ears (practically) at the same instant the direct sound from the speakers arrive at your ears. For all practical purposes then, in the real world listening at home, your hifi speakers are radiating sound as if they are in intimately contact with the adjacent walls of your room. The speaker cabinets might as well be superglued to the walls, (NoMoreNails?) since the sound direct from the drive units and that reflected off the walls is fused together as one sound in your brain as one indivisible entity. No human can tease-out the direct and reflected sound over these very short domestic distances - they are melded together in the brain, not the ear.

It follows then that absorptive characteristics of the adjacent walls hugely influences the perceived sound at the stereo hot spot. If those walls are heavily absorptive (book cases, heavy drapes, acoustic traps) there will be less of that reflected energy arriving at your ear. That's a good thing in the lower frequencies, since it dries out any muddiness in the bass, the red end of the spectrum. But - a big but - that may leave the room sounding rather dead and lifeless because those very same absorbers unfortunately don't just dry-out the bass, they soak up the top too and that may leave us with a nice dry tight bass, and a lifeless, airless, dead presence and treble range. Hey presto! Use the tone controls to introduce a little more energy in the high frequency region and we are back to a natural sound again.

The day tone controls ceased to be fashionable for whatever crazy reason, is the day high fidelity music at home became a never ending and insoluble struggle for the average music lover.
 

denjo

New member
What to do without tone controls?

What to do without tone controls?

...The day tone controls ceased to be fashionable for whatever crazy reason, is the day high fidelity music at home became a never ending and insoluble struggle for the average music lover.
Alan

For owners of amplifiers (and preamplifiers) without a tone control, what would you suggest you do to have more control of the ability to recreate actual musical event?
 
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