[Excellence]

What do you think the effects of the tact equipment would be on a high end amp? Would it make expensive tubes sound less tubey with it's correction, or would it make different amps sound very simillar after correction?


Interesting question.


It's been said by a very intelligent (seriously) poster here that the Tact equipment should not be able to discern the difference between one high end amp and another.


What kind of amplifier differences do you think the tact would miss? frequency, amplitude, phase, arrival time? Or the magic unmeasurable 5th variable. Perhaps it just won't do a good job with the first 4.

 

[audioguy]

Recommendation: (a version of what you have heard before -- several times). After you get the rest of your system together, "TRY" a Tact and decide for your self. If there is a dealer in you area, I'm sure they will loan you one and if not, I KNOW that Tact will.


In direct answer to your question, it will NOT affect the amp other than by changing the signal it will see (both time and amplitude). It will, then, greatly affect what you hear and only you can decide if you like it.

 

[Michael Grant]

There's no way I can say this from direct experience, but it seems to me that there's no way that a TacT system is going to make a tube amp sound like a solid-state. The tube "sound" is caused by a different distortion profile than solid-state amps have, and that distortion will not be corrected with TacT gear (or any other equalization or room correction system you might consider). So the result should be a flatter frequency response, largely corrected in amplitude and phase/delay, but with the tube sound intact.


But audioguy said it best, don't listen to speculation, just give it a shot.

 

[Raul GS]

Quote:

Originally posted by Michael Grant There's no way I can say this from direct experience, but it seems to me that there's no way that a TacT system is going to make a tube amp sound like a solid-state. The tube "sound" is caused by a different distortion profile than solid-state amps have, and that distortion will not be corrected with TacT gear (or any other equalization or room correction system you might consider).

Actually, I'm not sure I concur with you michael. To my understanding the Tact uses a microphone to measure and interactions between the speaker and the room and then tries to compensate for any frequency anomalies. Now, if we are using a tube amp whose frequency is being altered by its high output impedance and thus help create a tube sound, the Tact could interpret this as a frequency anomaly and try to compensate (unless of course the frequency anomaly is actually synergistic with the room and speakers, then instead it would compensate for the SS amp). So, if I'm correct on how the Tact works, then it should affect an amp whose euphonic quality deviates from a "linear" frequency response.


Cheers,

Raul

 

[Kal Rubinson]

Quote:

Originally posted by Excellence Would it make expensive tubes sound less tubey with it's correction, or would it make different amps sound very simillar after correction?

Tube amps still sound like tube amps even with the Tact.


Kal

 

[KeithR]

As you are building a new room, not sure why you are looking to Tact right now.

 

[Raul GS]

Quote:

Originally posted by Kal Rubinson Tube amps still sound like tube amps even with the Tact. Kal

Kal,


In and of itself, this statement is rather glib. First off, not all tube amps sound the same. In fact, some of the newer top of the line tube amps are indistinguishable from a top SS amp in a blind test. So to state "tube amp will still sound like a tube amp" obscures rather than clarifies the question. Now with regards to the Tact, no one can assume it will not make a single ended tube Cary amp sound like 200 w/c Krell. But, in the case where it is adjusting a rather nonlinear frequency response of a particular tube amp, it will in that context change its sound to approximate more the sound of a linear SS amp (which of course is also being modified to addressed the speaker-room relationship). So yes, a tube amp with the stereotype "tube" sound will still reflect many of those qualities even after being altered by a tool like the Tact (since the Tact cannot address certain inherent limitations of said amp), but the use of a Tact should make both amps sound more similar than prior to its use (i.e. the frequency aberrations separating the two are minimized).


R.

 

[Michael Grant]

Quote:

RaulGS: So, if I'm correct on how the Tact works, then it should affect an amp whose euphonic quality deviates from a "linear" frequency response.

No, this is not correct. The only type of correction that the TacT is capable of applying is linear in nature: frequency response flattening and phase/time alignment. It is incapable of performing any sort of distortion correction. So any nonlinear distortion characteristics present in the signal chain, due to the amp, speakers, etc., will remain unaltered with the TacT in place.


Now you are correct that the distortion in the amps, speakers, listenening environment, and microphone may have an impact on the correction process itself---so it may prevent you from getting a perfect correction. But actually there are a variety of reasons you're not going to get a perfectly flat corrected response anyway. And again, once the microphone is disconnected and the correction is locked in, the impact on the sound is linear (in the signal processing sense).
Quote:

RaulGS: But, in the case where it is adjusting a rather nonlinear frequency response of a particular tube amp, it will in that context change its sound to approximate more the sound of a linear SS amp (which of course is also being modified to addressed the speaker-room relationship).

I have to say that this statement seems to reflect a misunderstanding of signal processing. In particular, the term "nonlinear frequency response" is oxymoronic---frequency response is strictly a linear phenomenon. The bottom line is that Kal is right: a tube amp will still sound like a tube amp. Its distortion signature will still be present.
Quote:

KeithR: As you are building a new room, not sure why you are looking to Tact right now.

It seems to me that it would be the perfect time to consider it. Room treatments alone aren't necessarily going to give you a flat, time-aligned response at the listening position---though they will of course solve the gross problems and make it easier for a correction system like the TacT to dial you in the rest of the way.


I'm looking forward to the opportunity to doing both (professional room design and electronic correction) in my next HT room (18 months or more away, but hey, I see it on the horizon )

 

[Kal Rubinson]

Quote:

Originally posted by Raul GS In and of itself, this statement is rather glib. First off, not all tube amps sound the same. In fact, some of the newer top of the line tube amps are indistinguishable from a top SS amp in a blind test. So to state "tube amp will still sound like a tube amp" obscures rather than clarifies the question.

Intentionally glib. In my experience with SF tube preamps/amps and BlueCircle tube preamps, none of them lost their characteristic identities with the TacT.

Quote:

Originally posted by Raul GS Now with regards to the Tact, no one can assume it will not make a single ended tube Cary amp sound like 200 w/c Krell. But, in the case where it is adjusting a rather nonlinear frequency response of a particular tube amp,

Never used a Cary or, afaik, any amp with a markedly nonlinear FR. Why would I? ;-)


Kal

 

[KeithR]

Michael-- my idea was more to get room designed, then bring in Tact if necessary.

 

[Michael Grant]

Oh, I see---sorry for the misunderstanding. But I didn't detect any sort of urgency in his post, either---I figured he was just speculating.

 

[Michael Grant]

Quote:

Kal: markedly nonlinear FR

OK, there's that term again, "nonlinear FR." I must have missed a memo somewhere. What exactly are people trying to communicate when they say this? IDo you mean a non-flat FR? If so, maybe that should be specified instead. After all, an amp whose frequency response has a linear shape---but steadily falls between 20Hz and 20kHz---isn't at all desirable either. Then again, Bag-End uses an "integrator" response, which is not flat but linear in shape, to extend its subwoofer range down to subsonic frequencies.


I say this because in the signal processing sense, frequency repsonse is a measure of the linear performance of an amp or other device: that is, its performance in the operating region where nonlinear (e.g., harmonic) distortion is minimized or ignored. No matter what the shape of the response is, it is linear by definition. The term "linear" in this context does not refer to shape, but to a more technical property that insures that frequencies are preserved and that gain is independent of amplitude.

 

[Mark Seaton]

Quote:

Originally posted by Raul GS Kal, In and of itself, this statement is rather glib.

Raul-


Do note that while it may seem a bit glib, Kal does own a Tact unit, and has most likely had a variety of tube and solid state amplifiers through the system.

 

[Andy Lammer]

Why limit the speculation to only amps ?

Why would the TacT not make all CDPs, DACs, pre-amps, speakers, cables, power cords, anti-vibration devices, etc, sound the same ?


I like Michael's response above in that there is more to audio "correction" the FR & Time correction. Each device will contribute some amount of distortion with a certain sonic signature.


Also, have you measured a system at varying playback levels ?

In my experimentations with a Velo DD-18, an increase in the volume knob will show varying measured results in the bass regions. Also, distortion will/can increase when a system is driven harder, and each component will react to stress differently from another.


I owned an original TacT RCS 2.0 a few years ago, and currently have the latest RCS 2.0S at home waiting for some play-time from me.


- Andy

 

[Michael Grant]

Quote:

Each device will contribute some amount of distortion with a certain sonic signature.

Including, certainly, the TacT unit itself! One hopes, of course, that those distortions are minimal---at the very least, more than compensated for by the linear corrections it provides.

 

[Bigus]

As I briefly alluded to in the other thread, tact correction is capable of addressing linear response problems (well, and FIR time domain issues... is that correction also linear by definition?). As Michael stated, that means for the purposes of this discussion that the tact is an EQ that adjusts the frequency response.


If an amplifier has a response that is non-flat over the range of the tact correction, to a large enough magnitude that the tact system identifies it as an error, then that amp is simply not designed well. So while the tact might have an audible impact on for example an esoteric tube amp, that is more an indication that the amp is question is a POS (at least when used with conventional speakers expecting electrical damping) rather than any indication that the tact is able to make otherwise well designed amps sound 'more identical' than they already are.

 

[Raul GS]

Quote:

Originally posted by Michael Grant OK, there's that term again, "nonlinear FR." I must have missed a memo somewhere. What exactly are people trying to communicate when they say this? ...The term "linear" in this context does not refer to shape, but to a more technical property that insures that frequencies are preserved and that gain is independent of amplitude.

You are correct Michael, my mistake since I introduced into the discussion knowing it was not the correct term. Obviously I meant flat freq. response.

Quote:

Originally posted by Kal Never used a Cary or, afaik, any amp with a markedly nonlinear FR. Why would I? ;-)

Good point, my bad. The comment without context just seemed to include tubes with euphonic qualities.

Quote:

Originally posted by Bigus So while the tact might have an audible impact on for example an esoteric tube amp, that is more an indication that the amp is question is a POS (at least when used with conventional speakers expecting electrical damping) rather than any indication that the tact is able to make otherwise well designed amps sound 'more identical' than they already are.

While I agree that the Tact does not necessarily "make otherwise well designed amps sound 'more identical' than they already are" my point was merely that an amp that has been voiced to deviate from a flat frequency response would likely now sound closer to an amp with a flat frequency response. That being said, I would not necessarily agree with your point that the euphonic amp is necessarily a POS. Some people derive an emotional response from this type of voicing and enjoy them a great deal. Do I think it is the right amp for me? No. Do I think that it is necessary to charge $$$ for such voiced amp? No since it can be accomplished by other more reasonable means (in _my opinion_). But I cannot deny that I have heard euphonic amps that have be a pleasure to listen (e.g. the Lectron amp and some CJ amps and preamps).


Regards,

Raul

 

[Kal Rubinson]

Quote:

Originally posted by Michael Grant OK, there's that term again, "nonlinear FR."

I know, I know. I just lifted it from the post I was responding to. One of your betes noires, I guess.


Kal

 

[Raul GS]

Quote:

Originally posted by Kal Rubinson Intentionally glib. In my experience with SF tube preamps/amps and BlueCircle tube preamps, none of them lost their characteristic identities with the TacT. Kal

Kal,


Do you think it is possible for a preamp/amp to be affected by an electronic device, such that it makes it sound more similar to another preamp/amp, while still maintaining the sonic characteristics that you preferred?


Regards,

Raul

 

[Michael Grant]

Glad to clear up the nonlinear thing. Because I saw two of you use it I really did think that there was a convention in audio circles that differed from my signal processing experience.


All I am saying is that the "sound" of an amp (or any other device) isn't all contained in its frequency and phase responses. It is also to a certain extent a function of nonlinear effects, and the TacT will do nothing to eliminate them.