PS Audio M700 Monoblock Amplifier Review

[Alexanderc]

Might be only ideal and not necessary, but I see again this table....

1. 
   >116dB Superior. Performance exceeds human hearing threshold.
2. █ 115dB-106dB Excellent. Performance is capable of higher resolution output.
3. █ 105dB-96dB Proper. Performance fully covers 16-bit (CD) resolution.
4. █ 95dB-86dB Mediocre. Performance does not meet 16-bit (CD) resolution.
5. █ <85dB Low. Avoid if you take any interest in audio performance.

...and as you can see, not achieving 96 dB is something to be avoided, not something to be happy with because the nothing will happen.

So, my previous question ramains still unanswered so far...

What are the differences between hearing my CDs through AHB2 [113 SINAD], and Behringer A800 [SINAD 77]....please?

What is the source of this list? I know I’ve seen it before but can’t remember where. Also, it is referring to DACs right, not amplifiers?

 

[PeteL]

I have used -20 db test signals when I've done something like this. It doesn't matter however, if you used -12 the end result would point to the same power level. You aren't thinking through the Pano test. Whether 100 watts is enough depends on the speaker. Not everyone listens at 80 plus db spl average levels.

I haven't said, for ANY recordings, for ANY speakers, and for EVERYONE, yes it depends, my point is that you are LIMITED with a 100W (8 ohm) amp, and there are many real life, not extreme situations where the recording dynamic range will be affected. Many people tough listent to more 80 dB spl, and a spl value is ALWAYS an "average" level. It is a rms measurment.

 

[CDMC]

Then again this is one of a few threads that have gone this way recently and I'm at a loss to see why.

A few have. As a group, our forum may have hit the point where there have been enough when a low poster counts trolling, we react assume anyone who does so is a troll. It might be a good idea for the moderators and Amir to consider how to address these derailments in reviews. Taking the posts that derail and moving them to a new thread where they can sort themselves out may help.

 

[CDMC]

These are truly huge SPLs even if just momentary. I’m sure many of us with large floorstanding speakers have gone significantly over 110dB in moments of enthusiasm but 125dB is pretty insane! I suspect you’re right though I’ve been to one or two concerts (unamplified) with 20+ trumpets, and a similar number of trombones, clarinets etc and on several occasions my ears were ringing.
Apropos nothing at all do you own an audiology business.

I was rather shocked recently when I was playing with my new Revels and had them turned up from my normal reference (78db each at -20dbfs) to find when I checked the peak SPL with REW, I was hitting 111db (108 a speaker) on peaks. This is much louder than my my Maggies would ever hit, but presumably due to the Revel’s lower distortion didn’t seem as loud. Calculating this, I was drawing 400 watts per speaker momentarily on the peaks, 2db from my amplifier clipping.

 

[CDMC]

You can call it what you want, but if you have peaks 20 dB above the rms level, you'll have spikes of power 100X what it is used continuously. when he sets the tone "relative to digital clipping" this tone should reflect that, if not Pano's didn't set the tone properly. Also if you see a speaker that gives a sensitivity of say 90 dB spl 1W 1m it doesn't mean you use only 1W continuously, obviously,it is for 1k, for a wideband signal, it is more, speakers doesn't have even impedance across the band, and most people obviously listen at more than a meter. Regardless on how you choose to do the maths, a 100W amp cannot give you a fairly dynamic recording unclipped/uncompressed/unlimited if you like to listen to 80+ dB SPL or so.

And this is the real crux of the issue. Going from a 90 db speaker to 84 db changes the needed power by 4x for the same level. Going from a 9 foot listening distance to 18 feet has a similar effect. It becomes very room, speaker, and listener dependent.

 

[maltux]

..... after reading the past 12 pages; I forgot what this review was about. .
I used the ICEPower 200 ASC & 200AC and a Ghent audio case. I paid $320 for the parts total. I am a power amplifier manufacturer (joke ).
Thanks for the initial review. I would have used Hypex modules but I am on a strict budget. PM is a great salesman; another PT Barnum.

Cheers!

 

[LTig]

That's Alan Shaw of Harbeth and the video is a surprise to me. I started my interest in power demands when sharing with Harbeth at CES shows. I was back then arguing for more power not less. It was with Harbeth at shows that I was measuring with an Oscilloscope and recording numbers. Alan Shaw argued vehemently for modest powers being sufficient. I was looking to justify the 250 watt partnering.

I never saw power such as this video is showing, and of course the one uncertainty here is the amplifier power meter, how do we know what the accuracy of those is or how they calculate actual power. Is it for example a volt/amp measurement? If so then very high power levels could be recorded by an amplifier that was rated at say 200 w into 8Ohms but which had large current reserves.

I think the meters were correct because the second piece played (string quartet) showed around 15W peaks and 28W peak maximum, at a quite high SPL. So it is clear that the type of music also plays a significant role to find out how much power an individual may need. Here the difference was a factor of more than 20!

 

[PeteL]

And this is the real crux of the issue. Going from a 90 db speaker to 84 db changes the needed power by 4x for the same level. Going from a 9 foot listening distance to 18 feet has a similar effect. It becomes very room, speaker, and listener dependent.

Yes, I didn't really understood why the foray into the CD's dynamic range and ambient noise levels where of relevence of the argument for more power. For a discussion about gain structure of a audio delivery system, yes, but for Watts per channels needed, the dynamic range of the recording matters, along with the parameters you rightfully bring, not the dynamic range of the cd.

 

[F1308]

Probably that the Behringer gives you a VU-meter (?) to look at while you listen.

Don't tell me you listen to music with your eyes wide open !!!!

 

[amirm]

Yes, I didn't really understood why the foray into the CD's dynamic range and ambient noise levels where of relevence of the argument for more power. For a discussion about gain structure of a audio delivery system, yes, but for Watts per channels needed, the dynamic range of the recording matters, along with the parameters you rightfully bring, not the dynamic range of the cd.

The analysis I did is how it is done. With 20 million albums out there, we can not survey them all and determine what the extremes are. So we make a theoretical analysis that is all encompassing.

You start with the dynamic range of the CD. Without dither, it is 96 dB. To have that channel not impacted by additional noise, whatever your system does has to have a noise floor way below -96 dB. As a rule, if your system is -10 dB quieter, it will cost you half a dB. In that regard, for your system to not reduce the dynamic range of CD, you need it to have a SNR/dynamic range of 96+10 = 106 dB. Using that, your CD dynamic range will then become 95.5.

In my comments, I derate that good bit and just settle for 96 dB. That will reduce the CD's dynamic range to 93 dB.

This is the worst case situation of course. The beauty of it though is that you don't have to qualify it with "it depends on content."

Note that the follow on to this is to use the hearing dynamic range of about 115 dB. This by definition then says that you can hear CD's noise floor even in a perfect system (if you didn't use noise shaping). This requires peak playback level above 96 dB at listening position though. But again, it makes for easy analysis.

These are the things that inform me as I comment about performance specs. They are absolute rules for transparency. What happens to you in a noisy car, with compressed content, is another matter.

 

[F1308]

What is the source of this list? I know I’ve seen it before but can’t remember where. Also, it is referring to DACs right, not amplifiers?

Well, I guess it is something to be kept along the chain, from beginning to end.
What point is there in having a DAC with SINAD 140 if your amplifier gives SINAD 50 ?

 

[Racheski]

What is the source of this list? I know I’ve seen it before but can’t remember where. Also, it is referring to DACs right, not amplifiers?

@pozz posted this at some point when discussing the DAC histogram.

 

[PeteL]

The analysis I did is how it is done. With 20 million albums out there, we can not survey them all and determine what the extremes are. So we make a theoretical analysis that is all encompassing.

You start with the dynamic range of the CD. Without dither, it is 96 dB. To have that channel not impacted by additional noise, whatever your system does has to have a noise floor way below -96 dB. As a rule, if your system is -10 dB quieter, it will cost you half a dB. In that regard, for your system to not reduce the dynamic range of CD, you need it to have a SNR/dynamic range of 96+10 = 106 dB. Using that, your CD dynamic range will then become 95.5.

In my comments, I derate that good bit and just settle for 96 dB. That will reduce the CD's dynamic range to 93 dB.

This is the worst case situation of course. The beauty of it though is that you don't have to qualify it with "it depends on content."

Note that the follow on to this is to use the hearing dynamic range of about 115 dB. This by definition then says that you can hear CD's noise floor even in a perfect system (if you didn't use noise shaping). This requires peak playback level above 96 dB at listening position though. But again, it makes for easy analysis.

These are the things that inform me as I comment about performance specs. They are absolute rules for transparency. What happens to you in a noisy car, with compressed content, is another matter.

I understand all that Amirm and this reasoning is flawless, but altough there is a relation, there is no direct relation between an amp dynamic range and the number of Watts it can push. An headphone amplifier can reproduce the full cd's dynamic range, I know I digress, it's a devil's advocate demonstration by the absurd, but, you reviewed the Yamaha wxa-50 here and found a signal to noise ratio of (close to) 96 dB at full power (50 watts) that spec alone gives you absolute transparency only in very limited conditions, you still don't have a current reserve to drive difficult loads without clipping. By saying that I totally agree that it is a great measure of performance, just that it is not the answer to the Question: Why do we need more than a few watts. Your Crest factor argument is the solid one, it's related to the music content. Along with the understanding of the Fletcher Munson curves from the article you pointed to, and the understanding of Speaker efficiency and the exponential nature of power draw.

Edit: ah I see, this debate started by 2 different questions, why you need 96 dB AND How much peak power you measure.

 

[Blumlein 88]

I haven't said, for ANY recordings, for ANY speakers, and for EVERYONE, yes it depends, my point is that you are LIMITED with a 100W (8 ohm) amp, and there are many real life, not extreme situations where the recording dynamic range will be affected. Many people tough listent to more 80 dB spl, and a spl value is ALWAYS an "average" level. It is a rms measurment.

Again, not sure where the disagreement is. This sort of test lets each person get a ballpark figure of how they listen and with what gear they use. Some will find 100 watts plenty, some won't. This sort of test will give you an idea even if you aren't very technically astute.

My video rig is using speakers that are 92 db/2.83v/1 meter. 100 watts gets you about 112 db SPL at one meter. Results in about 105 db SPL at the listening position in general. I have a capable 250 wpc at 8 ohms amp on it. Especially when subs take the lower 80 hz (it is a floorstanding full range speaker) these are probably just fine with a good 100 watt amp on them.

My other rig uses Soundlab ESL's. A kilowatt is not an excess. 100 watts will work though for polite levels only.

 

[GaryMnz]

You can call it what you want, but if you have peaks 20 dB above the rms level, you'll have spikes of power 100X what it is used continuously. when he sets the tone "relative to digital clipping" this tone should reflect that, if not Pano's didn't set the tone properly. Also if you see a speaker that gives a sensitivity of say 90 dB spl 1W 1m it doesn't mean you use only 1W continuously, obviously,it is for 1k, for a wideband signal, it is more, speakers doesn't have even impedance across the band, and most people obviously listen at more than a meter. Regardless on how you choose to do the maths, a 100W amp cannot give you a fairly dynamic recording unclipped/uncompressed/unlimited if you like to listen to 80+ dB SPL or so.

Again someone who doesn't understand the methodology.

He starts from the perspective of the recording. It cannot contain anything useful above digital clip, right?

So he then creates a test signal some dB below that. Just so it won't be too loud when you play it back.

You then play music you would normally listen to, at the loudest level you would normally use.

Then you play the test signal and measure the voltage.

From the data you can definitively say how much amplifier power you need to satisfy your listening in your system.

Those high peaks you talk about are incorporated and allowed for, but will not exceed the defined number of dB above the test tone. Why? Because you can't have recorded signal beyond peak digital, it would just be hard clipped, and the engineer won't have put it in the recording.

Very simple, deceptively clever.

 

[samysound]

He mentioned early on and linked to a DIY audio forum thread on the test he was proposing. Plenty of measurements done there. If you looked at it there is no need for him to do some measures here all over again. He could provide a few if he wished. I too am a bit mystified as to the response of what he has brought up. Seems straightforward as a different take on how much dynamic range we really need. Would have thought it a fertile topic for some back and forth respectful discussion. Not the wagons drawn into a circle showdown atmosphere it has become. I didn't see it as disrespectful, controversial or in another manner trying to cause discord.

Then again this is one of a few threads that have gone this way recently and I'm at a loss to see why.

Reading the original GaryMnz post in this thread, it comes across as mostly rude and challenging without sharing any data to make their point . If the intent was to instigate healthy discussion, I dont think this is the way to go about it. Original post below:

"I'd like to address two things.

1/ You say you like to see 96db sinad minimum so that it can handle the entire dynamic range of CD at least.

So tell me. Under what circumstances in the real world are you able to reproduce 96db dynamic range? What is your listening room noise floor? What is the peak capable or tolerable sound pressure level in your listening room?

Instead please estimate what real world dynamic range your listening environment can support.

2/ This declared need for high power levels for typical loudspeakers. Please play some music on your own system at your normal loudish listening level (ie what would be the acceptable max under normal conditions for you) put a scope across the speaker terminals, and measure the peak voltage you see.

Convert this peak to an rms voltage and calculate the equivalent power into a nominal 8 ohm load (as the amplifier spec assumes).

Tell us that power. "

 

[GaryMnz]

Yeah, two good questions don't you think?

I would maintain that very few of us run a system that offers up 96dB dynamic range on the music we listen to. We would lose our hearing fairly quickly if we did, and our neighbours would regularly call the noise police.

On the amplifier power question... Well I think we've been oversold by the marketers on this. Do the Diyaudio test and prepare to be surprised.

And of course my two questions are linked because dynamic range in playback is tied to amplifier power capability.

 

[Blumlein 88]

Reading the original GaryMnz post in this thread, it comes across as mostly rude and challenging without sharing any data to make their point . If the intent was to instigate healthy discussion, I dont think this is the way to go about it. Original post below:

"I'd like to address two things.

1/ You say you like to see 96db sinad minimum so that it can handle the entire dynamic range of CD at least.

So tell me. Under what circumstances in the real world are you able to reproduce 96db dynamic range? What is your listening room noise floor? What is the peak capable or tolerable sound pressure level in your listening room?

Instead please estimate what real world dynamic range your listening environment can support.

2/ This declared need for high power levels for typical loudspeakers. Please play some music on your own system at your normal loudish listening level (ie what would be the acceptable max under normal conditions for you) put a scope across the speaker terminals, and measure the peak voltage you see.

Convert this peak to an rms voltage and calculate the equivalent power into a nominal 8 ohm load (as the amplifier spec assumes).

Tell us that power. "

I would take it as a friendly challenge. There are such things. Mainly he is asking for people do to the little test, and share the results. Then we'd have a basis of comparing and discussing what that means. People doing a shared activity whether remotely or in person is often a very good basis for understanding each other and learning from each other.

I lean toward GaryMNZ on sometimes people don't need the power they think. I lean toward Amir on the idea of wide dynamic range. I explained somewhat why. Because our hearing breaks down sound into bands, and in our most sensitive range of frequencies (3-5 khz) even a room with a 40 db spl aggregate noise floor can have a noise floor in that 3-5 khz range which is down close to zero spl. Our hearing could hear the difference in those ranges or at least theoretically could.

 

[Racheski]

Again, not sure where the disagreement is. This sort of test lets each person get a ballpark figure of how they listen and with what gear they use. Some will find 100 watts plenty, some won't. This sort of test will give you an idea even if you aren't very technically astute.

My video rig is using speakers that are 92 db/2.83v/1 meter. 100 watts gets you about 112 db SPL at one meter. Results in about 105 db SPL at the listening position in general. I have a capable 250 wpc at 8 ohms amp on it. Especially when subs take the lower 80 hz (it is a floorstanding full range speaker) these are probably just fine with a good 100 watt amp on them.

My other rig uses Soundlab ESL's. A kilowatt is not an excess. 100 watts will work though for polite levels only.

As @amirm has mentioned over and over again recently, context matters. The question "Under what circumstances in the real world are you able to reproduce 96db dynamic range?" was first posted as a direct challenge to Amir's review methodology. You would have to be insane not to think this.
Naturally, it immediately received pushback from other members and from Amir. If the poster had created a separate thread, which has been recommended to him repeatedly including by a moderator btw, discussing the estimation of "real world dynamic range" using the process described in the DIY forum, there would have been an entirely different outcome. Until a separate thread is created, I can only see this question in the context of a direct challenge to Amir's review methodology, so there will continue to be a very high level of skepticism.

 

[Blumlein 88]

As @amirm has mentioned over and over again recently, context matters. The question "Under what circumstances in the real world are you able to reproduce 96db dynamic range?" was first posted as a direct challenge to Amir's review methodology. You would have to be insane not to think this.
Naturally, it immediately received pushback from other members and from Amir. If the poster had created a separate thread, which has been recommended to him repeatedly including by a moderator btw, discussing the estimation of "real world dynamic range" using the process described in the DIY forum, there would have been an entirely different outcome. Until a separate thread is created, I can only see this question in the context of a direct challenge to Amir's review methodology, so there will continue to be a very high level of skepticism.

Well Thomas agreed to move it if someone gathered up a list of posts. I'll say I was too lazy to do it myself.

If you have a noise floor of 40 db spl, then 96 db on top of that would suggest 136 db SPL capable playback. I think that is too simplified, and Amir has pointed to his article based upon Dolby testing and other results as to why that isn't the correct way to view it. I agree on that being overly simplified. But if one took instrumented measures and didn't elaborate that is what you'd think. And you could say the way Amir does his testing would leave someone with that impression. One could go into many nuances of the question. My first beef is with lumping noise in with THD. But I'll stop there. I understand why Amir tests like he does, and I'm okay with it.

The power question can be almost divorced from dynamic range or linked somewhat to it. Depends upon context and purposes.