New P482 Stereo Power Amplifier

@Alan March It appears that Purifi are almost ready to list the 1ET6525SA officially on their website, it appears the 8/4 Ohm power rating specs have been slightly revised to 250W 8 Ohm/450W 4 Ohm from 230W 8 Ohm/480W 4 Ohm, perhaps you can verify with them to see it may in fact be a misprint as to avoid another potential model number snafu 😉

Oniiz86 wrote:
@Alan March It appears that Purifi are almost ready to list the 1ET6525SA officially on their website, it appears the 8/4 Ohm power rating specs have been slightly revised to 250W 8 Ohm/450W 4 Ohm from 230W 8 Ohm/480W 4 Ohm, perhaps you can verify with them to see it may in fact be a misprint as to avoid another potential model number snafu 😉
192

Hi

We are happy with the data from our tests. Remember, as discussed above, power output does depend upon the behaviour of the power supply. Plus of course the limiting behaviour of the module protection system.

A production batch of modules have been shipped form Purifi, so sales can go live with the P482 (and new P282) next week.

Hey Alan,

It appears Purifi now explicitly mention to utilise a "Thermal Interface Material" (Thermal Grease or Pad) in the 1ET6525SA datasheet to optimise heat dissipation, this isn't something previously documented for their other modules like the predecessor 1ET400A, I thought the aluminium enclosure was wholly sufficient for Purifi modules & the new 1ET6525SA has Idle Losses of only 1.6W which makes it the coolest & most efficient on the market 🙂

Our enclosure provides perfectly adequate cooling. We can run full power sine waves which you should remember are not representative of real world use. Music has a high crest factor which leads to much lower RMS power levels than sine waves and therefore much lower heat dissipation.

However, some manufacturers have smaller less heat dissipative cases which may require careful heat management and optimisation.

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?

james dyson wrote:
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?

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 wrote:
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

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 wrote:
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

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,

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,

No idea. I'm sure it went through multiple revisions during development.

Oniiz86 wrote:
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 🙂

Soon! I'm on my way now!

Alan, what makes the difference between the P482 and P282 stereo amps, since they both use the same 1ET6525 modules?

Magic!

Funny!:sneaky: ... but me thinks you lowered the supply rails from the standard 65v to between 40v - 50v :).