My monitor/subwoofer system

[MadFloyd]

Thanks for sharing your thoughts, Al, particularly in light of your recent visit to Tasos'. Also enjoyed reading how you think your sound has changed over the past while (with break-in, etc.).

One of these days I have to get up there and hear it again.

 

[ack]

Al, as I mentioned yesterday, you struck gold with your new system! Looking forward to listening to it again soon

 

[Al M.]

Thanks, Madfloyd and Ack, I look forward to your next visits.

As for striking gold with my new system, Ack, thanks for the compliment. I guess the price/performance ratio is not too shabby ...

 

[morricab]

Keep in mind that I have yet to see a single tube amplifier with as good a squarewave response as typical great solid state, and it's quite a common issue with tubes. That attribute alone doesn't obviously make SS better than tubes, but it is definitely a differentiating factor. On the other hand, I have also seen "soft" solid state squarewaves, which attempt to mimic that attribute of tube sound. Regarding, Isodamp, it will be interesting to see if they do anything to your amps and subs, at least when it comes to inherent higher-order vibrations in the subs than what we felt with our hands.

What does a square wave have to do with sound quality? I will answer: nothing. The only reason most tube amps have a somewhat rounded square wave is that they are bandwidth limited by the output transformer to about 30Khz...sometimes a bit higher. There are OTLs that can easily go to 100Khz or higher and should have a nearly perfect squarewave...as if it mattered. An SS amp that has a "soft" squarewave is just one that is also somewhat bandwidth limited (not a bad idea actually when you think about RFI that is ubiquitous in our world) and has nothing to do with mimicing a tube amp.

 

[ack]

What does a square wave have to do with sound quality? I will answer: nothing.

I say quality of transients. And yes, I would expect OTLs to fare better here, having wider bandwidth

 

[Pb Blimp]

What does a square wave have to do with sound quality? I will answer: nothing. The only reason most tube amps have a somewhat rounded square wave is that they are bandwidth limited by the output transformer to about 30Khz...sometimes a bit higher. There are OTLs that can easily go to 100Khz or higher and should have a nearly perfect squarewave...as if it mattered. An SS amp that has a "soft" squarewave is just one that is also somewhat bandwidth limited (not a bad idea actually when you think about RFI that is ubiquitous in our world) and has nothing to do with mimicing a tube amp.

So the rise time I love about my Soulutions compared to tubes is all my imagination? Well that's good to know.

 

[Ron Resnick]

What does a square wave have to do with sound quality? I will answer: nothing. . . .

+1

 

[Al M.]

What does a square wave have to do with sound quality? I will answer: nothing. The only reason most tube amps have a somewhat rounded square wave is that they are bandwidth limited by the output transformer to about 30Khz...sometimes a bit higher. There are OTLs that can easily go to 100Khz or higher and should have a nearly perfect squarewave...as if it mattered. An SS amp that has a "soft" squarewave is just one that is also somewhat bandwidth limited (not a bad idea actually when you think about RFI that is ubiquitous in our world) and has nothing to do with mimicing a tube amp.

Very good point, Brad. Thanks for bringing this up!

Bandwidth limitation of course explains it. We have the same in digital. People complain why Redbook CD digital cannot reproduce square waves, but instead of being a 'problem' with the technology, it is naturally due to the intended bandwidth limitation which just follows the bandwidth limitation of human hearing *). Amir once explained it very well in this post, using the example of a sawtooth wave rather than a square wave, but it's the same principle:

http://www.whatsbestforum.com/showt...ral-resolution&p=334892&viewfull=1#post334892

And of course, because of this, the square wave reproduction has nothing to do with transients. I hear no more transient speed in Ack's system with Spectral SS amps than I hear in mine, as I reported on the previous thread page. In both systems the transients are excellent.

(Again, like every system, mine has shortcomings as well, but transient speed is not one of them -- at least as far as I hear it.)

________________

*) I might add, that most microphones are also very much bandwidth limited above 20 kHz -- or even above 15 kHz at a time in the 1950s and 1960s that delivered us so many great 'audiophile' recordings

 

[Pb Blimp]

Very good point, Brad. Thanks for bringing this up!

Bandwidth limitation of course explains it. We have the same in digital. People complain why Redbook CD digital cannot reproduce square waves, but instead of being a 'problem' with the technology, it is naturally due to the intended bandwidth limitation which just follows the bandwidth limitation of human hearing *). Amir once explained it very well in this post, using the example of a sawtooth wave rather than a square wave, but it's the same principle:

http://www.whatsbestforum.com/showt...ral-resolution&p=334892&viewfull=1#post334892

And of course, because of this, the square wave reproduction has nothing to do with transients. I hear no more transient speed in Ack's system with Spectral SS amps than I hear in mine, as I reported on the previous thread page. In both systems the transients are excellent.

(Again, like every system, mine has shortcomings as well, but transient speed is not one of them -- at least as far as I hear it.)

________________

*) I might add, that most microphones are also very much bandwidth limited above 20 kHz -- or even above 15 kHz at a time in the 1950s and 1960s that delivered us so many great 'audiophile' recordings

The transient speed you perceive (hear) on any particular system is a function of not just the amps rated (generic) rise time capability but the specific match of that amplifier to the impedance and phase angle curve of the speaker it happens to be mated with at the time. Making general claims about transients without understanding the most important determining variable is tricky.

The question here, IMO, as to how or whether an amp's wave form effects sound is not about "sound quality" from a tonal or timbre perspective, it is about wave propagation per time (T) which definitionally is a function of the degree to which the wave is square with a true square wave (which is physically unattainable) being where delta T between V+ and V- is zero (i.e., where transients are maximized).

 

[morricab]

So the rise time I love about my Soulutions compared to tubes is all my imagination? Well that's good to know.

What you hear or don't has nothing to do with "rise time". "Speed" perception has little to do with this as well.

 

[morricab]

I say quality of transients. And yes, I would expect OTLs to fare better here, having wider bandwidth

This tells you nothing about the quality of transients because you cannot see the distortion lying in those squarewaves at high frequencies...that and perhaps phase shift (with some amps) is have an impact on the quality of the transients...not if the squarewave looks perfect or rounded, which again just indicates bandwidth limiting. Distortion is what affects quality of transients, not reaching 2Mhz bandwidth.

 

[morricab]

The transient speed you perceive (hear) on any particular system is a function of not just the amps rated (generic) rise time capability but the specific match of that amplifier to the impedance and phase angle curve of the speaker it happens to be mated with at the time. Making general claims about transients without understanding the most important determining variable is tricky.

The question here, IMO, as to how or whether an amp's wave form effects sound is not about "sound quality" from a tonal or timbre perspective, it is about wave propagation per time (T) which definitionally is a function of the degree to which the wave is square with a true square wave (which is physically unattainable) being where delta T between V+ and V- is zero (i.e., where transients are maximized).

Since nearly all amplifiers will get to at least 20Khz without significant slew rate limiting I don't see how this is really a factor in sound quality, unless there is significant phase shift in the highs, then it is more about noise and distortion being generated in the audible frequency range and especially where we are most sensitive from an auditory perspective. Perception of transient correctness (not just "speed" or leading edge) has a lot to do with phase/time coherence and a more coherent system in time will usually lead to more correct transients relative to the whole sound envelope. Afterall, the sound is not just the leading edge or transient, there is also a body and decay of that sound (unless of course it is purely electronic). That leading edge can be exaggerated though by noise and distortion creating a false "attack" OR it can be emphasized by the relative absence of the rest of the sound envelope. Most of the technical sounding gear falls, IMO, into one of these two groups. This leads to a perception of "speed" but also what is described as an "analytical" sound, which is nearly never heard with live, unamplified instruments or even a good amplified concert. People get obsessesed with hearing "detail" to the exclusion of the rest of the sound envelope and want to claim this is correct but a short listen to a live instrument should dispel this notion...yet it persists.

To me, it is like having the sharpness and contrast on the TV turned to max. It becomes unnaturally sharp and contrasted...something never seen in real life.

 

[morricab]

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Like those Reflectors...interesting that Ref 3a went away from offsetting the tweeter to recessing the tweeter in a waveguide...any idea why or what benefit it brings? My Master Control MMCs were Be tweetered and that elevated their level as well. They had very chunky double wall cabinets, of which the Reflector is the latest evolution. They were great monitors. I also heard the older Corian cabinet (not full Corian model but the composite one) Royal Virtuoso...that was a really good sounding monitor as well. Not surprised you are loving these Reflectors. What do you think is causing the forward sound? A friend had Octave monos (MRE130s with SBB) and he had a forward sound as well (with THiel CS3.7s and Cabasse Baltic Evo satellites).

 

[morricab]

For reference, here's the squarewave response from the older Octave RE 290 amp, from https://www.stereophile.com/content/octave-audio-re-290-power-amplifier-measurements, where the rise delay is only 0.02 milliseconds long (20 microseconds), and whatever it is in the 320, it is still audible to me. I would be curious to see what Stereophile measures, if it ever gets to review the 320. Perhaps I was hearing a combined delay between the amps and speakers ?!??

I think you mean rise time, not rise delay. From what I see the rise time from the bottom of the squarewave to the top is < 0.02 ms. Each bar on the x-axis is 0.025 ms and the rise is significantly shorter than the width of one of those bars. It looks more like about 10 microseconds to me. You will never hear this between this amp and your amp and has nothing to do with any perceived "rounding" you heard at Al's.

 

[Al M.]

Like those Reflectors...interesting that Ref 3a went away from offsetting the tweeter to recessing the tweeter in a waveguide...any idea why or what benefit it brings? My Master Control MMCs were Be tweetered and that elevated their level as well. They had very chunky double wall cabinets, of which the Reflector is the latest evolution. They were great monitors. I also heard the older Corian cabinet (not full Corian model but the composite one) Royal Virtuoso...that was a really good sounding monitor as well. Not surprised you are loving these Reflectors. What do you think is causing the forward sound? A friend had Octave monos (MRE130s with SBB) and he had a forward sound as well (with THiel CS3.7s and Cabasse Baltic Evo satellites).

Toe-in with the new tweeter arrangement still does affect the sound quite a bit, but less in terms of high-frequency amount, and more in sound presentation -- more direct or a bit more indirect.

With these speakers, the more forward sound in my system is mostly due to the listening position. At the same distance as Peter A. sits from his Magico Q3, at 9.8 feet ear to tweeter, my system sounds more or less as forward or distant as his, depending on the recording to be reproduced. The Q3 are certainly not known for being forward sounding. For most music I prefer my usual 9.0 feet distance, which gives me the more upfront perspective that I personally like. In all cases, if I sit 8.4 feet away (equilateral triangle, ear to tweeter, tweeter to tweeter), my usual distance of 9.0 feet, or 9.8 feet away, there is great spatial depth -- recordings with deep spatial layering from front to back (e.g., many orchestral recordings) are reproduced as such. Of course, the generous distance from the front wall, 7 feet to tweeter, helps with that as it did with my previous speakers.

As for the Octave amp, it sounds 'normal' with my speakers, like other amps that I have heard in my system in comparison (but it's clearly the highest quality 'normal' ). There is no accentuated forwardness from the amp itself, as also suggested by above observations. I'd have to go back to other amps to confirm, but I don't remember anything that would have caught my ear. With the Thiel CS3.7s in your friends' system there might have been an issue of impedance matching which might have caused aberrations in frequency response, with the Cabasse Baltic Evo satellites I don't know what could have caused the forward sound, if it's not the speakers themselves.

 

[Pb Blimp]

Since nearly all amplifiers will get to at least 20Khz without significant slew rate limiting I don't see how this is really a factor in sound quality, unless there is significant phase shift in the highs, then it is more about noise and distortion being generated in the audible frequency range and especially where we are most sensitive from an auditory perspective. Perception of transient correctness (not just "speed" or leading edge) has a lot to do with phase/time coherence and a more coherent system in time will usually lead to more correct transients relative to the whole sound envelope. Afterall, the sound is not just the leading edge or transient, there is also a body and decay of that sound (unless of course it is purely electronic). That leading edge can be exaggerated though by noise and distortion creating a false "attack" OR it can be emphasized by the relative absence of the rest of the sound envelope. Most of the technical sounding gear falls, IMO, into one of these two groups. This leads to a perception of "speed" but also what is described as an "analytical" sound, which is nearly never heard with live, unamplified instruments or even a good amplified concert. People get obsessesed with hearing "detail" to the exclusion of the rest of the sound envelope and want to claim this is correct but a short listen to a live instrument should dispel this notion...yet it persists.

To me, it is like having the sharpness and contrast on the TV turned to max. It becomes unnaturally sharp and contrasted...something never seen in real life.

Ya I find this response somewhat pedestrian and not really to point.

Effectively--

I say: Rise time matters. (A statement I obviously consider true.)

You say: Rise time doesn't matter because most of the time it's already adequate and, more importantly, other things can matter more. (A statement that while technically true completely neglects my point.)

I was referring not to situation where rise time doesn't matter. Rather, I was referring to systems that do not suffer from phase and distortion problems but rather where rise time deltas can be discerned. By claiming this doesn't exist and then changing the conversation to the traditional arguments that mask the shortcomings of amps with lesser slew rates does not address the point. To be clear and to the point, is it your opinion that in a phase optimized system with nil distortion all the effort by designers to improve rise time versus the competition is of no consequence?

This is, IMO, similar to the "second order distortion" arguement from SET guys. They have there "go to" arguments to address the inherent shortcomings with their particular topology....high distortion, lower rise time, limited bandwidth etc. Some of these are sound positions, some are straw men. Don't get me wrong, I love to listen to SETs with all of the luscious, euphonic character of their more modest rise times and second order distortion. It is romantic, engaging, etc., etc, but that is not something I want all the time. And, IMO, contrary to your comment what I hear in my system sounds more like live music, but hey maybe I have a hearing problem.

 

[morricab]

Ya I find this response somewhat pedestrian and not really to point.

Effectively--

I say: Rise time matters. (A statement I obviously consider true.)

You say: Rise time doesn't matter because most of the time it's already adequate and, more importantly, other things can matter more. (A statement that while technically true completely neglects my point.)

I was referring not to situation where rise time doesn't matter. Rather, I was referring to systems that do not suffer from phase and distortion problems but rather where rise time deltas can be discerned. By claiming this doesn't exist and then changing the conversation to the traditional arguments that mask the shortcomings of amps with lesser slew rates does not address the point. To be clear and to the point, is it your opinion that in a phase optimized system with nil distortion all the effort by designers to improve rise time versus the competition is of no consequence?

This is, IMO, similar to the "second order distortion" arguement from SET guys. They have there "go to" arguments to address the inherent shortcomings with their particular topology....high distortion, lower rise time, limited bandwidth etc. Some of these are sound positions, some are straw men. Don't get me wrong, I love to listen to SETs with all of the luscious, euphonic character of their more modest rise times and second order distortion. It is romantic, engaging, etc., etc, but that is not something I want all the time. And, IMO, contrary to your comment what I hear in my system sounds more like live music, but hey maybe I have a hearing problem.

"To be clear and to the point, is it your opinion that in a phase optimized system with nil distortion all the effort by designers to improve rise time versus the competition is of no consequence? "

No, I do not think even a phase optimized system will not show anything that can be obviously laid at the feet of rise time (otherwise known as slew rate) once above the level required for actual music.

Now, please direct me to the nearest phase optimized system that we can supposedly discern the deltas between slew rates of different amplifiers... Can I assume you mean your system? I didn't realize the Raidho D3.1 was phase and time coherent. Their description mentions nothing of the sort. Please tell me how slew rates of amps that will differ by microseconds can be discerned through speakers that will delay the signal at different frequencies by up to milliseconds. So, even IF you could hear slew rate differences in amps when all the amps tested have adequate bandwidth and slew rate that would be drowned out by the majority of loudspeakers that will smear the transients by a significant amount.

I would be interested in the justification (not from manufacturers) for why having an ultra high slew rate (ie. very fast rise time) is inherently superior. I am open to scientific studies that demonstrate this effect.

The measurement oriented gear designers and owners don't seem to understand that distortion is a funny thing because it's perception is VERY non-linear...non-linear with regard to harmonic order and non-linear with regard to SPL. This means that even ultra low distortion amps will likely have audible artifacts. There is quite a bit of literature regarding measurements and psychoacoustics...they tend to support the revival of SETs. Where SETs fall down is that in lower price classes compromises are made in output iron and this could be where you are hearing something that might be overly ripe sounding.

The ultra slew rate concept has been around since the late 70s and yet the trend, with a couple of notable exceptions, has been away from ultra bandwidth, ultra low THD and ultra slew rate...because those things are not really very important for sound quality.

 

[Pb Blimp]

"To be clear and to the point, is it your opinion that in a phase optimized system with nil distortion all the effort by designers to improve rise time versus the competition is of no consequence? "

No, I do not think even a phase optimized system will not show anything that can be obviously laid at the feet of rise time (otherwise known as slew rate) once above the level required for actual music.

Now, please direct me to the nearest phase optimized system that we can supposedly discern the deltas between slew rates of different amplifiers... Can I assume you mean your system? I didn't realize the Raidho D3.1 was phase and time coherent. Their description mentions nothing of the sort. Please tell me how slew rates of amps that will differ by microseconds can be discerned through speakers that will delay the signal at different frequencies by up to milliseconds. So, even IF you could hear slew rate differences in amps when all the amps tested have adequate bandwidth and slew rate that would be drowned out by the majority of loudspeakers that will smear the transients by a significant amount.

I would be interested in the justification (not from manufacturers) for why having an ultra high slew rate (ie. very fast rise time) is inherently superior. I am open to scientific studies that demonstrate this effect.

The measurement oriented gear designers and owners don't seem to understand that distortion is a funny thing because it's perception is VERY non-linear...non-linear with regard to harmonic order and non-linear with regard to SPL. This means that even ultra low distortion amps will likely have audible artifacts. There is quite a bit of literature regarding measurements and psychoacoustics...they tend to support the revival of SETs. Where SETs fall down is that in lower price classes compromises are made in output iron and this could be where you are hearing something that might be overly ripe sounding.

The ultra slew rate concept has been around since the late 70s and yet the trend, with a couple of notable exceptions, has been away from ultra bandwidth, ultra low THD and ultra slew rate...because those things are not really very important for sound quality.

So I guess from your response the answer to my question in the first bold above is "no". Well, hopefully you can at least agree that your view is not held by some of the world's top amp designers, but you are of course entitled to your beliefs. As an aside, regarding my second bold above, I think you are very confused in this comment. The trend away from high slew rate, ultra low distortion amps is most certainly NOT because those things are not "very important to sound quality," but, rather, because of the deleterious effects of using lots of negative feedback in the audible frequency band in design of the amps to which you you refer.

Look at how Cyrill uses negative feedback in his Soulution designs. (First few paragraphs in review below.) All of the "analytical" stereotyping you refer to in your descriptions is replaced by a sweet, extremely resolving sound when design and execution are right. Using a flawed approach trying to achieve better performance from speed and resolution does not mean speed and resolution are not beneficial to SQ. This logic is completely lost on me.

http://www.theabsolutesound.com/articles/soulution-711-stereo-amplifier-701-monoblock-amplifier-and-725-full-function-preamplifier/

 

[Al M.]

Gentlemen,

at this point I would like to make the friendly request to take this very interesting discussion about slew rate and transients out of my system thread, where it has already occupied a lot of space.

I know, that's the way internet discussions sometimes go, and I blame nobody. So far I had few problems with the discussion, in fact I enjoyed it, and I have learned new things. Yet I think my system thread is now in danger of getting derailed. Perhaps one of you can start a new thread titled "Amplifier slew rates and musical realism" or the like. I would enjoy a continuation of the discussion in such a manner.

Thank you all for your consideration.

 

[Pb Blimp]

Al,

Very sorry for that; my bad.