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PS Audio M700 Monoblock Amplifier Review

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Racheski

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I am not an engineer or mathematician, so I have to ask: was this all about calculating something in a way that Amir doesn't care to calculate for already considered reasons?
AFAIK Yes.
Also, is the argument over a (dynamic range) threshold that engineering-wise has been surpassed by pretty much any state-of-the-art amplifier?
The premise is that "real world dynamic range" is a better method to evaluate amps vs Amir's.
To try to think about how this relates to the thread, are we simply trying to not hurt the feelings of an amplifier that uses someone else's modules when considering the field at play today?
Amplifiers don't have feelings, until a discussion involves the amp you own ;)
 

PeteL

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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.
Look, maybe you are right,and the test is valid and there is something that I don't get, but then, the maths NEED to work if it don't there are flaws in the tests. I see possible flaws but i'd need a bit more time to come up with something credible, I would not as an engineer come up with theories that I have not verified, but for the sake of argument, Now I will go ahead and give the benefit of the doubt for this methodology, if you agree that on the video we saw from Harbeth, If he had performed the test, he would have come up with the same result, 600W peak power per channels is what is needed for these speakers in this room for the level he was at. If the experiment you mention is "deceptively simple" Well this one is even more simple and valid. You have an amp with unlimited power, you measure how it draws, can't get simpler than that. Now when confronted with evidence, and filmed evidence at that, you prefered to come with the argument that the measuring equipment was flawed. That right there diminish your credibility off the bat. Now I'll dig a bit deeper, but you seem to understand the diy audio test well, I can give you that. How does it work when you set the volume of your power limited amp "as loud as you'd want" but what you are listening to is already clipped?
 

March Audio

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You maintain wrong. 96 dB momentary peaks for music would mean 76 dB average. No way you would go deaf or even have your neighbor complain. There are cars out there where at speed have higher average noise level and we don't see people going deaf in them.

This whole argument comes from misreading of OSHA safety standards which are for noise and continuous basis, not momentary peaks in music. Here are the OSHA standard:

View attachment 77342

As indicated, you can have 95 dB SPL for whopping 4 hours per day and still be safe!

You can go up to 110 dB and still be OK for half hour.

So no, that is a myth. You don't go deaf at 96 dB SPL peak. Average will be at 76 which is not even in the above table.
Not quite correct, sorry for being pedantic :)

There is a subtle distinction between a system with 96dB dynamic rage and one reaching a peak SPL level of 96dB. Its not the same thing dependant on room noise levels.

Part of a previous role I had was a noise officer here in Oz. Noise exposure is as noted calculated from level and time. What people measure at home with a simple SPL meter (I still have my Rat Shack one somewhere along with my Bruel and Kjaar) is not exposure.

The peaks do add into the equation as the measurement is integrated over time, so it will depend on the nature of the music as to what your actual exposure is.

Too much noise: a definition
In the model WHS Regulations the exposure standard for noise involves two measures:

  • LAeq,8h of 85 dB(A)
  • LC,peak of 140 dB(C).
LAeq,8h of 85 dB(A) means that over an eight-hour shift a worker can’t be exposed to more than 85 decibels. Whether this is exceeded depends on the level of noise involved and how long a worker is exposed to it.

LCpeak of 140 dB(C) means a worker can’t be exposed to a noise level above 140 decibels. Peak noise levels greater than this usually occur with impact or explosive noise such as sledge-hammering or a gun shot. Any exposure above this peak can create almost instant damage to hearing.

  • These limits should protect most but not all people. The risks from workplace noise must be eliminated or minimised so far as is reasonably practicable.
Ideally, you should keep noise levels below:

  • 50 decibels if your work requires high concentration or effortless conversation
  • 70 decibels if your work is routine, fast-paced and demands attentiveness or if it is important to carry on conversations.

https://www.commerce.wa.gov.au/sites/default/files/atoms/files/noise_ready_reckoner.pdf


I think most countries have adopted very similar standards around the limit of LAeq,8h of 85 dB(A).

So with current standards here in Oz the table would be:

8 hrs 85dB(A)
4 hrs 88dB(A)
2 hrs 91
1 hr 94
30mins 97
15 mins 100
7.5 mins 103
3.75 mins 106
1.37 mins 109
 
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RayDunzl

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What people measure at home with a simple SPL meter (I still have my Rat Shack one somewhere along with my Bruel and Kjaar) is not exposure.


REW includes an array of SPL measures in the logger.

Twelve mnutes of right-wing-wacko TV:

1597025420431.png


For definitions of the "L" values:

http://www.acoustic-glossary.co.uk/definitions-l.htm
 
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March Audio

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Here is a video showing the exposure level LAeq V the peak level LAFP whilst playing some Daft Punk. (LAFP is the level A weighted with "fast" integration period 125ms)

We see by the end of the song its 88dB v 97dB so only 9dB difference.


So on this basis I could listen for 4 hours at this level.

So take care of your hearing, once its gone, its gone!
 
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restorer-john

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So take care of your hearing, once its gone, its gone!

So, do your insanely high powered amplifiers come with a warning? ;)

Like: "This amplifier is capable of ball-tearingly high sound pressure levels into almost any loudspeaker. Exposure at high SPLs should be limited to protect your ears. I want repeat customers, not deaf ones!"
 

March Audio

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So, do your insanely high powered amplifiers come with a warning? ;)

Like: "This amplifier is capable of ball-tearingly high sound pressure levels into almost any loudspeaker. Exposure at high SPLs should be limited to protect your ears. I want repeat customers, not deaf ones!"
:)

Actually I have had a couple of requests recently regarding making amps with the Hypex NC2K module which can manage 2.5kW into 4 ohms. I have had to politely ask "are you really sure you want or need that" :)
 

Doodski

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:)

Actually I have had a couple of requests recently regarding making amps with the Hypex NC2K module which can manage 2.5kW into 4 ohms. I have had to politely ask "are you really sure you want or need that":)
Geeech... Power de jour. Would that require 120VAC or 240VAC for the mains?
HYpex.jpg
 
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RayDunzl

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Well obviously domestic 110V systems have their limitations

That's my safety.

If I get too crazy the 15A breaker pops in the garage.

Way under "full power", too.
 

RayDunzl

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With your Krell amps is that a 10 amp breaker or a 15 amp?

The amplifier claim:

1597039598447.png


Idle is actually about 100W.

Times two, monoblocks.

The breaker for the branch circuit is 120V/15A in the garage, at least 80 wire feet distant, probably more, as that is the straight shot frome the outlet, and I don't have a clue as to the branch wiring.

Everything in this room comes off that breaker.

Everything in the rack comes off one outlet.

The PC stuff is on the same branch but a different outlet.

The kitchen flourescent lights are even on the same branch.

I bought the materials to run a new 20A line a couple of years ago, but never installed it, don't need it.

Just don't play loud and turn on the kitchen lights and vacuum at the same time.

I mostly use the little JBLs now for general audio, the big rig reserved for real music. and special movies.

---

There's the 15A breaker in the garage, 15A breakers on the input and output of the Equitech, and breakers on the Krells acting as power switches. I can't see their rating, but I might presume 15A --- 1700W @ 120V = 14.6A

1597040514733.png
 
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Doodski

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The amplifier claim:

View attachment 77392

Idle is actually about 100W.

Times two, monoblocks.

The breaker for the branch circuit is 15A in the garage.

Everything in this room comes off that breaker.

Everything in the rack comes off one outlet.

The PC stuff is on the same branch but a different outlet.

The kitchen flourescent lights are even on the same branch.

I bought the materials to run a new 20A line a couple of years ago, but never installed it, don't need it.

Just don't play loud and turn on the kitchen lights and vacuum at the same time.

I mostly use the little JBLs now for general audio, the big rig reserved for real music. and special movies.
.. and no arc welding with the Krells. :D
 

Thomas savage

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Well this threads a write-off , no one's created a new thread and now's there's hundreds of off topic posts across many pages .

im closing the thread as there's no other way to stop you all and no one wants to talk about this amp , feel free to make a dedicated one for this off topic discussion you spammed the thread with. As your all going round in mind numbing repetitive circles I doubt it makes much difference if I move this off topic or you just carry in going round and round in a new thread.

cheers
 
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