New P482 Stereo Power Amplifier

james dyson said:
Hey Alan
On ASR there was a question regarding the validity of your corrected SINAD figure. The poster said it wasn't valid because the noise floor increases with increasing power output. Therefore just taking the shorted input noise figure doesn't account for the increased noise at higher power output. Whats your response to that?
Click to expand...
Hi @james dyson

Thanks for your question. If I understand the question correctly, the poster makes a valid point. An amplifiers noise floor does indeed increase at higher output levels compared to low or no signal output.

However, at the test point in question that of ASRs favourite 5 watts into 4 ohms :) , the noise increase on the P482 is barely visible. We are talking 0.1 to 0.2 dB. This is easily in the area of measurement repeatability/error.

So at this test point, it is a far more accurate method to measure THD+N than not taking the signal generator inherent noise into account (circa 3dB error).

If I get time I will publish some measurements of how the noise floor changes with output level.

Hope that helps.

Alan
 
I received the New P482 Stereo Power Amplifier
And It works awesome.

Without any colouration, quiet, and It played The assault/entering sequence at the beginning of the movie Sicario (2015) silky smooth. Which has rush of low frequencies and high dynamic range quite challenging to drive.

It may take some time, but I'll post the objective review after I do some test including really interesting measurements. I'm very excited to be able to use the newest Purifi amplifier on the market so quickly.
 
Alan March said:
Hi @james dyson

Thanks for your question. If I understand the question correctly, the poster makes a valid point. An amplifiers noise floor does indeed increase at higher output levels compared to low or no signal output.

However, at the test point in question that of ASRs favourite 5 watts into 4 ohms :) , the noise increase on the P482 is barely visible. We are talking 0.1 to 0.2 dB. This is easily in the area of measurement repeatability/error.

So at this test point, it is a far more accurate method to measure THD+N than not taking the signal generator inherent noise into account (circa 3dB error).

If I get time I will publish some measurements of how the noise floor changes with output level.

Hope that helps.

Alan
Click to expand...
Hey Alan,

I was wondering if you have had some free time to publish some of those measurements of how the P482's noise floor changes with the output level?

It would be really great to see whilst I await delivery :)
 
Alan March said:
Hi @james dyson

Thanks for your question. If I understand the question correctly, the poster makes a valid point. An amplifiers noise floor does indeed increase at higher output levels compared to low or no signal output.

However, at the test point in question that of ASRs favourite 5 watts into 4 ohms :) , the noise increase on the P482 is barely visible. We are talking 0.1 to 0.2 dB. This is easily in the area of measurement repeatability/error.

So at this test point, it is a far more accurate method to measure THD+N than not taking the signal generator inherent noise into account (circa 3dB error).

If I get time I will publish some measurements of how the noise floor changes with output level.

Hope that helps.

Alan
Click to expand...
Hey @Alan March

I'm curious to see those measurements of how the noise floor changes with the output level on the P482, you had mentioned it about a month or so ago :)
 
Hey @Alan March

I was wondering if you would know the reason as to why Purifi has released a revision to the 1ET6525SA module, there is the 1ET6525SA01B & 1ET6525SA01C, seems strange to implement some component changes upon release, the 1ET6525SA01B is pictured in Purifi's 1ET6525SA datasheet below,
Purifi 1ET6525SA01B.png

I believe you have the 1ET6525SA01C which I assume is the latest revision of the module on your P482, P282, P481 product pages as pictured below,
Purifi 1ET6525SA01C.png
 
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