There is no doubt that most commercially available recordings have been subjected to electronic equalization (EQ) at one or more stages of the recording/production process. However, for more than a generation, audiophiles were highly averse to applying any such electronic EQ in the home listening room. Any equipment which had serious pretentions to being "high end" at least had to have defeat switched on the tone controls, and mostly such controls were entirely banished.
But since the dawn of the current millennium, at the "What's Best" level of audiophilia, as well as among home theater devotees, there has been a slow increase in recognition that the availability of electronic EQ in the home music system can be helpful--at least sometimes and for correcting some problems. Some have jumped in with both feet and unreservedly trust DSP-based speaker equalization, DSP-created crossovers, and DSP room correction to bring them closer to audio heaven than is possible with "old fashioned" analog electronics with minimally complex signal paths. Others are not so sure.
The Goal of Equalization
Assuming you want to use some form of electronic equalization, how do you learn how to use that equalization to improve the sound of your system? Now, anyone, even a child, can fool around with a software program, or twiddle knobs and sliders on an "old fashioned" analog equalizer and change the sound of an audio system in a few seconds.
It is less trivial to be able to reliably make electronic equalization changes which you think "sound better" to you. Oh, it may be fairly easy to make one bit of program material sound better. It may only take a few minutes for a novice. But change to a different track or different type of music and you may find yourself less sure.
Some folks go to the extreme of developing a number of customized "target curves" and labeling each track to indicate which equalization approach sounds best with that track. Some folks actually apply their favorite-of-the-moment equalization for that piece of music and save an equalized version as a file in their computerized music software library; the wiser of these folks don't discard the unequalized version.
The problem with this "sounds better to you" approach is that it is not transportable. Not transportable from system to system, listener to listener, track to track, mood to mood, or sometimes not even from moment to moment. Change something--anything--about the system, the set up, the room, or the listener and all your careful choices may go out the window. For some careful listeners who are actually more interested in at least sometimes being able to just listen to music rather than fiddle with adjusting the equalization, this is enough to cause them to give up on trying to apply electronic EQ to their home listening.
Others, seeing this peril, settle on single or very few target equalization curves which they or some trusted expert in their lives have developed and more or less just "set it and forget it." When I use electronic EQ at all, I tend to fall into this category.
Still, the question remains as to how do you know when you are making progress? Some folks think they just know when a music system is more life-like. They claim to have the sound of an orchestra playing in their head. Audio designers Bob Carver (Carver, Sunfire) and Arnie Nudell (Infinity, Genesis) have claimed this about themselves. For such folks, accurate musical reproduction is like some judges talk about pornography: they know it when they see/hear it.
Then there are those who just know the way they like their music to sound and they apply equalization of a fairly heavy-handed nature to make sure that most everything they play will have that sonic flavor--say, for example, lots of bass and lots of high frequency "air." There are potentially as many flavors of "sounds good to me" as there are people setting up electronically equalized home audio systems.
Then there are those who want "flat response" from their systems and are willing to live with the unvarnished, naked truth about any program material, even if they have to grit their teeth to bear it. They seek "the truth" about the recording and are willing to listen through any unpleasantness to hear that truth. They also seek maximum differentiation in the sound of various recordings, believing that the more the sound of recordings vary, the more truthful their system must be in reproducing exactly what is on the recording.
Another type of EQ user is the one who wants the sound of music, tonally speaking, to mimic to the greatest possible extent, what one would hear at a live unamplified concert in a good hall. I tend to fall more into this category than any of the others, I think. One way to be able to move your system sound toward such a goal is to attend a lot of such concerts so that you have a decent aural memory of what various instruments really sound like. That's me.
How I Learned to EQ
I have had more experience with a variety of EQ systems than most audiophiles, I think. I also have more experience using EQ to help match a known sound than most audiophiles. In a past life, for about a decade I worked with and eventually became the head of a volunteer technical production crew of a large church I attended, recording and amplifying voice and acoustic music in the sanctuary using fairly high quality equipment worth more than $250,000.
If you are amplifying familiar voices, as I was, you have an absolute reference point in that room. You know how the voice should sound in that room talking to the person close up. All you have to do is make that voice louder so it sounds from 50 or 100 feet away like it does when you are only a couple of feet from the person as the person talks to you without amplification in the same room. You sit at the mixer and play with the controls until you get it sounding about right. You soon learn what various controls do and what needs to be done to get accurate sound.
You can then apply the same technique to amplifying musical instruments in that room: listen live up close to a solo instrument or group--everything from a solo flute, violin, or harpsichord, to a piano to full orchestra or various vocal groups or full choir, and then get as close a match to that sound through the PA (public address) speaker as you can. This was possible since the instrumentalists and vocalists always were practicing when I was setting up mikes and other equipment close by on stage.
Dips are harder to hear in all frequency ranges than peaks and are therefore less worth worrying about. I should mention, however, that a decent PA mixer operator will try very hard not to have a dip in the midrange if speech is involved since any dip there will drastically reduce intelligibility and presence of the voice, making it sound hollow and distant as well. The type of EQ which may work wonders in terms of desirably "backing off" the sound of a full orchestra in your listening room sounds amateurish with live amplification of a speaking voice in an auditorium.
Equalizers I Have Known at Home
I do not pretend to know all there is to know about the merits of electronic equalization or about the merits of the various systems for implementing such equalization at home. For one thing, I have not (yet) used Acourate, which many EQ devotees believe to be the best such system currently available in terms of sonic results. But I believe that most who use it would also admit that Acourate has a very steep learning curve and is best used in the context of a hard-drive-based music system, which mine is not (yet).
I applied what I learned "on the job" to my home music system. The first two equalizers I owned were the Cello Palette Preamplifier and the Z-Systems rdp-1. These were generally acknowledged as two of the most transparent (in terms of not doing anything to the sound other than the intended EQ) such devices of that time and are still so regarded. The Cello used an analog six-band graphic EQ scheme developed by Mark Levinson (the man's) guru, Dick Burwen. Last I checked, the Z-Systems is still listed in Stereophile's Recommended Components and was a parametric digital preamp/equalizer. I wrote my comparative thoughts about the Cello and the Z-Systems in Audio Review back in 1999.
I could have stopped with the Z, but as audiophiles are wont to do, with system changes I eventually began to hear (or imagine I heard) a certain digital sterility, edge, and brightness to the Z-Systems sound. Even so, I was still convinced of the merits of home EQ. Thus, about the time I got my Harbeth M40s in 2004, I moved to an all-analog parametric EQ device, the Rives PARC. Sonically, I never heard anything wrong with the Rives, but it was not very flexible and was limited to correcting at most three bands of frequencies below 350 Hz, leaving me with no way to control the peaky highs of, say, old Mercury Living Presence recordings.
Thus, I eventually moved on to a professional equalizer of 30-band 1/3-octave digital graphic design, the Rane DEQ-60L. It was very flexible (all those bands, adjustable by channel) and was very easy to use (mechanical sliders with little interaction among adjacent sliders). Unfortunately, I heard sonic problems which I attributed to its A/D - D/A path (or imagined I heard--other owners hear no such problems with this unit) and quickly got rid of it.
I traded it for the all-analog Audient ASP231 31-band 1/3-octave graphic equalizer. This had all the flexibility of the Rane and all the sonic purity of the Rives, but unfortunately was a pain in the butt to adjust since it had LOTS of interaction among adjacent bands of adjustment. I soon tired of the hassle.
Having read many favorable comments about the TacT RCS units, I conquered my fear of computer-assisted equalization and purchased a TacT RCS 2.2XP AAA, which I still own. I shouldn't have worried about the computer-assisted part; I found the program, while buggy, to be reasonably easy to use.
Among the good points about the TacT is that the corrections it applies really can help with system balance, and thereby help solidify imaging and staging. Thus, despite the heavy-duty digital processing to which all music is subject, the subjective staging and imaging are about equal overall to a decent analog preamp like the Bryston BP-26 I also had when I bought the TacT, plus the best mechanical set up you can muster. I'd give the Bryston the edge in terms of stage depth, size, and ambient feel, but the TacT was not far behind in those respects and had the edge in terms of unwavering instrumental placement.
The TacT also allows full digital electronic crossover adjustments between stereo subwoofers and main speakers with a wide range of slopes from first to 18th order. In addition to minute correction of response to conform to a target curve of your choice or design, the TacT also offers 12 bands per channel of parametric EQ, as well as an interesting Ambiophonics-mimicking function.
The TacT's computer display is very informative and running response measurements, while a bit tricky to get best results, are relatively straightforward. You can guild the sonic lily with a better measuring microphone, feeding it pure power, damping the chassis, playing with the delay applied to the main speakers, and (by all user accounts--I don't use them) with after-market part swap outs from Maui Mods.
But there are some flies in the TacT ointment:
The usual caveats about these being my current impressions subject to drastic revision later and not being transferrable to other users or systems apply. But I HAVE been around the EQ block a few times now and I think I've garnered a few nuggets which can help others down the path:
1. First and definitely foremost: electronic EQ at home works best when it has the least to correct. Exhaust all mechanical and set up tricks first before applying electronic EQ. I cannot stress this enough. Mechanical set up has no chance of introducing any kind of electronic distortion. EQ is not a cure all. It will not help or cure room reflections at mid and high frequencies. It cannot fill in severe dips in frequency response without stressing amps and speakers and generally lousing up the sound in the room no matter what your measurements say. EQ cannot correct for inherent distortion in speaker drivers or material colorations in the drivers.
2. Electronic EQ works best at bass and lower midrange frequencies, meaning below 500 Hz or so. Some would say below 300 Hz and I won't argue. At such frequencies, what you see on your frequency response measurement graph is what you audibly get, moreso at least than higher up. Higher up, electronic EQ is more problematic because it predominantly EQs only the direct sound from the speakers, not the room sound which is part of what you hear but progressively not part of what the microphone measures as frequency increases. It is better to control the room sound--sound bouncing off room surfaces--with passive acoustic absorbers (foam or fiberglass, typically).
Even when just applied to the bass, I would say that, in most cases, if you try to EQ your system so as to achieve a ruler flat bass response, even when extended to below 20 Hz, the result will sound a bit thin. You may find that the addition of anything from .5 to 3 dB or even more extra measured bass is necessary for proper subjective bass weight. You can do this either by adjusting your target curve to be "up" a bit at all frequencies below, say 200 Hz, or by not fully knocking down measured peaks in bass response, but only reducing them by about 70% of their peak value. A 10 dB peak could be reduced to a 3 dB peak, for example.
3. You should NEVER attempt to fill in significant (more than 2 or 3 dB) dips in frequency response in the bass or elsewhere via electronic EQ. It sounds bad and strains both amp and speaker.
4. Given the way commercial recordings are recorded and produced, with most speakers and most music, if you are attempting to mimic the sound of live unamplified music in a concert hall (and probably even if you are just adjusting the sound to "sound better" to you) you will end up with a target curve which generally slopes down in level by 4 to 10 dB from bottom bass to highest treble. The preloaded target curves which come with the TacT are almost all of such a shape. Almost all individually constructed target curves end up with such a shape. How much of a drop from bass to treble will sound correct to you depends on your individual taste, your set of reference recordings, your sonic goal, your speakers, and your room. In very general terms, the narrower the high frequency dispersion of your speakers, the less drop you will likely want to apply to the measured on-axis treble response. You may also find that inserting a bit of a dip in the response between 2 and 6 kHz (while anathema to live sound reinforcement) will be helpful with many speakers on much recorded material.
5. Since EQ works better in cutting back on bass response peaks than in filling in dips, you should buy your speakers wisely. Buy speakers that seem, if anything, overly generous in many rooms in bass response. You do not want to buy speakers which have "tight" bass in most dealer demos. By buying generous-bass speakers, you can be more certain that when you get them home and EQ them, you will basically only have to cut back on bass response, not fill in dips. Cutting back on bass with electronic EQ helps both speakers and amps to loaf along even at high levels, lowering distortion of both electronic and mechanical nature.
6. Never try to extend the ultimate low-bass rolloff with electronic EQ. That is the same as, or worse than, attempting to fill in dips in response. This strains amps and speakers and increases distortion in the bass and further up. If you want low bass, buy more capable speakers and/or add subwoofers.
7. I have found that it is better to buy speakers whose UNEQUALIZED midrange and highs sound great to you at dealers and in a home trial than to buy something you will need to EQ in that range. As mentioned above, equalizing above the bass gets problematic because the measurements frequently don't well reflect the subjective sound in the listening room.
With the TacT I almost invariably found that with the speakers which sounded best to me in the mids and highs, the best sounding target curve from 500 Hz on up was a target that just followed as exactly as possible the measured response of the speakers. The ability of the V1.0 TacT software to turn off the EQ above a chosen frequency is helpful; you can thus use it for only bass EQ if you like. Believe me, when the mids and highs sound as good as they do on Harbeth M40s or M40.1s, you do not want, much less need, to equalize them, at least with most material.
As an aside, I believe that it is getting harder rather than easier these days to find speakers with natural mid and high frequency balance when judged by concert hall standards. The tendency in recent years has been toward a brighter and more forward balance than is natural. You can see this in measured response tests in Stereophile, for example, within speakers of a given brand as years go by. While speaker drivers have improved greatly over the years in terms of lowering distortion and improving power handling capability, the designed-in overall frequency balance has, if anything, deteriorated significantly. I know of no currently available speakers, for example, which in an ordinary listening room with little or no special acoustical treatment and when positioned out of the way flat against a wall can match the mid-hall naturalness of vintage Acoustic Research speakers such as the AR-3a and AR-5 manufactured around 1970. Harbeths can sound better than the ARs due to their superior modern drivers, but they need "audiophile" set up to do so, with careful out-in-the room placement and/or EQ to tame the warm bass and room treatment to absorb off-axis room reflections in the mids and highs.
8. Broadband correction sounds better than micro-correction, at least above the bass, and on most days I'd say even in the bass. Thus, something like a 1/3-octave graphic EQ or adjustable parametric will actually sound better than the type of micro-correction of which the TacT is capable when applying its target curve. Thus, for example, the TacT results sound better when just applying the 12 parametric bands of EQ than when using the target curve function. One-third-octave bands relate to how our ears average sound levels and thus have plenty of resolution to give optimal results.
9. The best EQ devices should have a great deal of flexibility. You don't want to be locked in to some single (or even a few) automatically chosen EQ curves. The automatic ones usually sound too bright and not full enough in the bass. This means that products like RoomPerfect and Audyssey are out, as far as I'm concerned, unless in the particular implementation, they can be combined with some type of graphic or parametric EQ, as in some AVRs and pre-pros. An electronic EQ device which is limited to just working on the subwoofer's output is not flexible enough. If the subwoofer is being used properly, its output will be rolled off above 80 Hz or even lower, while bass room modes may need correcting up to 300 Hz or so.
10. Some of what you may think you need EQ for is just the product of poor quality digital front end components. Most digital playback still sucks. Once I got my PS Audio Perfect Wave Transport and DAC, I found that much of the annoyance I was trying to correct for with EQ simply vanished. Sure, some recordings made with peaky old mikes still sound too bright, but the brightness is not accompanied by any nasty edge and is much easier to just accept and listen around. Bass firmed up and a degree of relaxation became apparent that just removed many barriers between me and the music. Definitely, YMMV, but, for me, the change wrought by this digital front end change was more important to musical enjoyment than any EQ I've ever used.
11. Not strictly EQ related, but relevant: Even if you have subwoofers, you usually will want to confine their response to the low bass. Yes, you can get good results by mating mini-speakers to subwoofers with a typical THX 80 Hz 4th-order high/low pass crossover, but you will probably get yet better results by using more bass-capable main speakers and rolling your subs out at 40 to 60 Hz. Many speakers, and the Harbeth M40 and M40.1 are among them, sound best when allowed to play down to their natural roll off point and sound less like themselves when rolled off above that point. As a common example, many Quad speaker enthusiasts are tempted to roll off the Quads well above 100 Hz and pass off to the subs at such a high frequency in order to get more SPL capability from the system since Quads will play plenty loud in the midrange, but not the bass. But they find that you trade off some of the Quads' sonic virtues for the increased SPL. What bass a fine main speaker has will often sound better than a subwoofer reproducing that midbass range.
But since the dawn of the current millennium, at the "What's Best" level of audiophilia, as well as among home theater devotees, there has been a slow increase in recognition that the availability of electronic EQ in the home music system can be helpful--at least sometimes and for correcting some problems. Some have jumped in with both feet and unreservedly trust DSP-based speaker equalization, DSP-created crossovers, and DSP room correction to bring them closer to audio heaven than is possible with "old fashioned" analog electronics with minimally complex signal paths. Others are not so sure.
The Goal of Equalization
Assuming you want to use some form of electronic equalization, how do you learn how to use that equalization to improve the sound of your system? Now, anyone, even a child, can fool around with a software program, or twiddle knobs and sliders on an "old fashioned" analog equalizer and change the sound of an audio system in a few seconds.
It is less trivial to be able to reliably make electronic equalization changes which you think "sound better" to you. Oh, it may be fairly easy to make one bit of program material sound better. It may only take a few minutes for a novice. But change to a different track or different type of music and you may find yourself less sure.
Some folks go to the extreme of developing a number of customized "target curves" and labeling each track to indicate which equalization approach sounds best with that track. Some folks actually apply their favorite-of-the-moment equalization for that piece of music and save an equalized version as a file in their computerized music software library; the wiser of these folks don't discard the unequalized version.
The problem with this "sounds better to you" approach is that it is not transportable. Not transportable from system to system, listener to listener, track to track, mood to mood, or sometimes not even from moment to moment. Change something--anything--about the system, the set up, the room, or the listener and all your careful choices may go out the window. For some careful listeners who are actually more interested in at least sometimes being able to just listen to music rather than fiddle with adjusting the equalization, this is enough to cause them to give up on trying to apply electronic EQ to their home listening.
Others, seeing this peril, settle on single or very few target equalization curves which they or some trusted expert in their lives have developed and more or less just "set it and forget it." When I use electronic EQ at all, I tend to fall into this category.
Still, the question remains as to how do you know when you are making progress? Some folks think they just know when a music system is more life-like. They claim to have the sound of an orchestra playing in their head. Audio designers Bob Carver (Carver, Sunfire) and Arnie Nudell (Infinity, Genesis) have claimed this about themselves. For such folks, accurate musical reproduction is like some judges talk about pornography: they know it when they see/hear it.
Then there are those who just know the way they like their music to sound and they apply equalization of a fairly heavy-handed nature to make sure that most everything they play will have that sonic flavor--say, for example, lots of bass and lots of high frequency "air." There are potentially as many flavors of "sounds good to me" as there are people setting up electronically equalized home audio systems.
Then there are those who want "flat response" from their systems and are willing to live with the unvarnished, naked truth about any program material, even if they have to grit their teeth to bear it. They seek "the truth" about the recording and are willing to listen through any unpleasantness to hear that truth. They also seek maximum differentiation in the sound of various recordings, believing that the more the sound of recordings vary, the more truthful their system must be in reproducing exactly what is on the recording.
Another type of EQ user is the one who wants the sound of music, tonally speaking, to mimic to the greatest possible extent, what one would hear at a live unamplified concert in a good hall. I tend to fall more into this category than any of the others, I think. One way to be able to move your system sound toward such a goal is to attend a lot of such concerts so that you have a decent aural memory of what various instruments really sound like. That's me.
How I Learned to EQ
I have had more experience with a variety of EQ systems than most audiophiles, I think. I also have more experience using EQ to help match a known sound than most audiophiles. In a past life, for about a decade I worked with and eventually became the head of a volunteer technical production crew of a large church I attended, recording and amplifying voice and acoustic music in the sanctuary using fairly high quality equipment worth more than $250,000.
If you are amplifying familiar voices, as I was, you have an absolute reference point in that room. You know how the voice should sound in that room talking to the person close up. All you have to do is make that voice louder so it sounds from 50 or 100 feet away like it does when you are only a couple of feet from the person as the person talks to you without amplification in the same room. You sit at the mixer and play with the controls until you get it sounding about right. You soon learn what various controls do and what needs to be done to get accurate sound.
You can then apply the same technique to amplifying musical instruments in that room: listen live up close to a solo instrument or group--everything from a solo flute, violin, or harpsichord, to a piano to full orchestra or various vocal groups or full choir, and then get as close a match to that sound through the PA (public address) speaker as you can. This was possible since the instrumentalists and vocalists always were practicing when I was setting up mikes and other equipment close by on stage.
Dips are harder to hear in all frequency ranges than peaks and are therefore less worth worrying about. I should mention, however, that a decent PA mixer operator will try very hard not to have a dip in the midrange if speech is involved since any dip there will drastically reduce intelligibility and presence of the voice, making it sound hollow and distant as well. The type of EQ which may work wonders in terms of desirably "backing off" the sound of a full orchestra in your listening room sounds amateurish with live amplification of a speaking voice in an auditorium.
Equalizers I Have Known at Home
I do not pretend to know all there is to know about the merits of electronic equalization or about the merits of the various systems for implementing such equalization at home. For one thing, I have not (yet) used Acourate, which many EQ devotees believe to be the best such system currently available in terms of sonic results. But I believe that most who use it would also admit that Acourate has a very steep learning curve and is best used in the context of a hard-drive-based music system, which mine is not (yet).
I applied what I learned "on the job" to my home music system. The first two equalizers I owned were the Cello Palette Preamplifier and the Z-Systems rdp-1. These were generally acknowledged as two of the most transparent (in terms of not doing anything to the sound other than the intended EQ) such devices of that time and are still so regarded. The Cello used an analog six-band graphic EQ scheme developed by Mark Levinson (the man's) guru, Dick Burwen. Last I checked, the Z-Systems is still listed in Stereophile's Recommended Components and was a parametric digital preamp/equalizer. I wrote my comparative thoughts about the Cello and the Z-Systems in Audio Review back in 1999.
I could have stopped with the Z, but as audiophiles are wont to do, with system changes I eventually began to hear (or imagine I heard) a certain digital sterility, edge, and brightness to the Z-Systems sound. Even so, I was still convinced of the merits of home EQ. Thus, about the time I got my Harbeth M40s in 2004, I moved to an all-analog parametric EQ device, the Rives PARC. Sonically, I never heard anything wrong with the Rives, but it was not very flexible and was limited to correcting at most three bands of frequencies below 350 Hz, leaving me with no way to control the peaky highs of, say, old Mercury Living Presence recordings.
Thus, I eventually moved on to a professional equalizer of 30-band 1/3-octave digital graphic design, the Rane DEQ-60L. It was very flexible (all those bands, adjustable by channel) and was very easy to use (mechanical sliders with little interaction among adjacent sliders). Unfortunately, I heard sonic problems which I attributed to its A/D - D/A path (or imagined I heard--other owners hear no such problems with this unit) and quickly got rid of it.
I traded it for the all-analog Audient ASP231 31-band 1/3-octave graphic equalizer. This had all the flexibility of the Rane and all the sonic purity of the Rives, but unfortunately was a pain in the butt to adjust since it had LOTS of interaction among adjacent bands of adjustment. I soon tired of the hassle.
Having read many favorable comments about the TacT RCS units, I conquered my fear of computer-assisted equalization and purchased a TacT RCS 2.2XP AAA, which I still own. I shouldn't have worried about the computer-assisted part; I found the program, while buggy, to be reasonably easy to use.
Among the good points about the TacT is that the corrections it applies really can help with system balance, and thereby help solidify imaging and staging. Thus, despite the heavy-duty digital processing to which all music is subject, the subjective staging and imaging are about equal overall to a decent analog preamp like the Bryston BP-26 I also had when I bought the TacT, plus the best mechanical set up you can muster. I'd give the Bryston the edge in terms of stage depth, size, and ambient feel, but the TacT was not far behind in those respects and had the edge in terms of unwavering instrumental placement.
The TacT also allows full digital electronic crossover adjustments between stereo subwoofers and main speakers with a wide range of slopes from first to 18th order. In addition to minute correction of response to conform to a target curve of your choice or design, the TacT also offers 12 bands per channel of parametric EQ, as well as an interesting Ambiophonics-mimicking function.
The TacT's computer display is very informative and running response measurements, while a bit tricky to get best results, are relatively straightforward. You can guild the sonic lily with a better measuring microphone, feeding it pure power, damping the chassis, playing with the delay applied to the main speakers, and (by all user accounts--I don't use them) with after-market part swap outs from Maui Mods.
But there are some flies in the TacT ointment:
- The subwoofer/main crossover adds a bit of glaze and brightness to the sound, especially when used with slopes greater than 4th order (24 dB/octave).
- The software, as I mentioned, is buggy, and has been so from the start. This has actually gotten worse with the latest V1.0 beta software. That's a shame since the V1.0 software does sound a bit better. For example, I cannot get the beta software to simultaneously correct my subwoofers and correct the main speakers above 10 kHz. Others have no such problem, but have other problems I don't seem to have.
- The Ambiophonics software, although entertaining and initially enthralling, is highly colored in terms of frequency response. You cannot simultaneously apply EQ and use the Ambiophonics processing, resulting in bass and treble heavy sound when the Ambiophonics processing is used.
- The frequency response after TacT correction, measured with other measurement software, is not nearly as conformed to the target curve as the TacT's own computations or measurements show.
- Check out on-line comments about TacT's recent level of customer support if you are thinking about buying a TacT unit.
The usual caveats about these being my current impressions subject to drastic revision later and not being transferrable to other users or systems apply. But I HAVE been around the EQ block a few times now and I think I've garnered a few nuggets which can help others down the path:
1. First and definitely foremost: electronic EQ at home works best when it has the least to correct. Exhaust all mechanical and set up tricks first before applying electronic EQ. I cannot stress this enough. Mechanical set up has no chance of introducing any kind of electronic distortion. EQ is not a cure all. It will not help or cure room reflections at mid and high frequencies. It cannot fill in severe dips in frequency response without stressing amps and speakers and generally lousing up the sound in the room no matter what your measurements say. EQ cannot correct for inherent distortion in speaker drivers or material colorations in the drivers.
2. Electronic EQ works best at bass and lower midrange frequencies, meaning below 500 Hz or so. Some would say below 300 Hz and I won't argue. At such frequencies, what you see on your frequency response measurement graph is what you audibly get, moreso at least than higher up. Higher up, electronic EQ is more problematic because it predominantly EQs only the direct sound from the speakers, not the room sound which is part of what you hear but progressively not part of what the microphone measures as frequency increases. It is better to control the room sound--sound bouncing off room surfaces--with passive acoustic absorbers (foam or fiberglass, typically).
Even when just applied to the bass, I would say that, in most cases, if you try to EQ your system so as to achieve a ruler flat bass response, even when extended to below 20 Hz, the result will sound a bit thin. You may find that the addition of anything from .5 to 3 dB or even more extra measured bass is necessary for proper subjective bass weight. You can do this either by adjusting your target curve to be "up" a bit at all frequencies below, say 200 Hz, or by not fully knocking down measured peaks in bass response, but only reducing them by about 70% of their peak value. A 10 dB peak could be reduced to a 3 dB peak, for example.
3. You should NEVER attempt to fill in significant (more than 2 or 3 dB) dips in frequency response in the bass or elsewhere via electronic EQ. It sounds bad and strains both amp and speaker.
4. Given the way commercial recordings are recorded and produced, with most speakers and most music, if you are attempting to mimic the sound of live unamplified music in a concert hall (and probably even if you are just adjusting the sound to "sound better" to you) you will end up with a target curve which generally slopes down in level by 4 to 10 dB from bottom bass to highest treble. The preloaded target curves which come with the TacT are almost all of such a shape. Almost all individually constructed target curves end up with such a shape. How much of a drop from bass to treble will sound correct to you depends on your individual taste, your set of reference recordings, your sonic goal, your speakers, and your room. In very general terms, the narrower the high frequency dispersion of your speakers, the less drop you will likely want to apply to the measured on-axis treble response. You may also find that inserting a bit of a dip in the response between 2 and 6 kHz (while anathema to live sound reinforcement) will be helpful with many speakers on much recorded material.
5. Since EQ works better in cutting back on bass response peaks than in filling in dips, you should buy your speakers wisely. Buy speakers that seem, if anything, overly generous in many rooms in bass response. You do not want to buy speakers which have "tight" bass in most dealer demos. By buying generous-bass speakers, you can be more certain that when you get them home and EQ them, you will basically only have to cut back on bass response, not fill in dips. Cutting back on bass with electronic EQ helps both speakers and amps to loaf along even at high levels, lowering distortion of both electronic and mechanical nature.
6. Never try to extend the ultimate low-bass rolloff with electronic EQ. That is the same as, or worse than, attempting to fill in dips in response. This strains amps and speakers and increases distortion in the bass and further up. If you want low bass, buy more capable speakers and/or add subwoofers.
7. I have found that it is better to buy speakers whose UNEQUALIZED midrange and highs sound great to you at dealers and in a home trial than to buy something you will need to EQ in that range. As mentioned above, equalizing above the bass gets problematic because the measurements frequently don't well reflect the subjective sound in the listening room.
With the TacT I almost invariably found that with the speakers which sounded best to me in the mids and highs, the best sounding target curve from 500 Hz on up was a target that just followed as exactly as possible the measured response of the speakers. The ability of the V1.0 TacT software to turn off the EQ above a chosen frequency is helpful; you can thus use it for only bass EQ if you like. Believe me, when the mids and highs sound as good as they do on Harbeth M40s or M40.1s, you do not want, much less need, to equalize them, at least with most material.
As an aside, I believe that it is getting harder rather than easier these days to find speakers with natural mid and high frequency balance when judged by concert hall standards. The tendency in recent years has been toward a brighter and more forward balance than is natural. You can see this in measured response tests in Stereophile, for example, within speakers of a given brand as years go by. While speaker drivers have improved greatly over the years in terms of lowering distortion and improving power handling capability, the designed-in overall frequency balance has, if anything, deteriorated significantly. I know of no currently available speakers, for example, which in an ordinary listening room with little or no special acoustical treatment and when positioned out of the way flat against a wall can match the mid-hall naturalness of vintage Acoustic Research speakers such as the AR-3a and AR-5 manufactured around 1970. Harbeths can sound better than the ARs due to their superior modern drivers, but they need "audiophile" set up to do so, with careful out-in-the room placement and/or EQ to tame the warm bass and room treatment to absorb off-axis room reflections in the mids and highs.
8. Broadband correction sounds better than micro-correction, at least above the bass, and on most days I'd say even in the bass. Thus, something like a 1/3-octave graphic EQ or adjustable parametric will actually sound better than the type of micro-correction of which the TacT is capable when applying its target curve. Thus, for example, the TacT results sound better when just applying the 12 parametric bands of EQ than when using the target curve function. One-third-octave bands relate to how our ears average sound levels and thus have plenty of resolution to give optimal results.
9. The best EQ devices should have a great deal of flexibility. You don't want to be locked in to some single (or even a few) automatically chosen EQ curves. The automatic ones usually sound too bright and not full enough in the bass. This means that products like RoomPerfect and Audyssey are out, as far as I'm concerned, unless in the particular implementation, they can be combined with some type of graphic or parametric EQ, as in some AVRs and pre-pros. An electronic EQ device which is limited to just working on the subwoofer's output is not flexible enough. If the subwoofer is being used properly, its output will be rolled off above 80 Hz or even lower, while bass room modes may need correcting up to 300 Hz or so.
10. Some of what you may think you need EQ for is just the product of poor quality digital front end components. Most digital playback still sucks. Once I got my PS Audio Perfect Wave Transport and DAC, I found that much of the annoyance I was trying to correct for with EQ simply vanished. Sure, some recordings made with peaky old mikes still sound too bright, but the brightness is not accompanied by any nasty edge and is much easier to just accept and listen around. Bass firmed up and a degree of relaxation became apparent that just removed many barriers between me and the music. Definitely, YMMV, but, for me, the change wrought by this digital front end change was more important to musical enjoyment than any EQ I've ever used.
11. Not strictly EQ related, but relevant: Even if you have subwoofers, you usually will want to confine their response to the low bass. Yes, you can get good results by mating mini-speakers to subwoofers with a typical THX 80 Hz 4th-order high/low pass crossover, but you will probably get yet better results by using more bass-capable main speakers and rolling your subs out at 40 to 60 Hz. Many speakers, and the Harbeth M40 and M40.1 are among them, sound best when allowed to play down to their natural roll off point and sound less like themselves when rolled off above that point. As a common example, many Quad speaker enthusiasts are tempted to roll off the Quads well above 100 Hz and pass off to the subs at such a high frequency in order to get more SPL capability from the system since Quads will play plenty loud in the midrange, but not the bass. But they find that you trade off some of the Quads' sonic virtues for the increased SPL. What bass a fine main speaker has will often sound better than a subwoofer reproducing that midbass range.
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I just couldn't resist the urge to throw that in there because cable length is another audiophile dictum that has cemented itself, even if it means putting a rack loaded with thick aluminum faceplates right between the speakers just to keep the signals as pristine as possible. Even folks that don't believe cables sound different follow this! Just to be clear I'm not knocking anyone with racks up front. Just those that have the luxury of relocating their rack but refuse to for the reason already stated.
