Review and Measurements of Purifi 1ET400A Amplifier

[rajapruk]

If possible, please overlay IMD and THD per frequency with nc400.

 

[amirm]

If possible, please overlay IMD and THD per frequency with nc400.

I don't have a good IMD measurement for Hypex NC400. At that time, I was testing *input* level to the amp versus IMD which is not good because different amps have different gains. With that important caveat, here it is:

 

[amirm]

If possible, please overlay IMD and THD per frequency with nc400.

And here is the THD+N versus level versus input level for Hypex NC400 relative to Purifi 1ET400A:

We definitely have a cleaner amplifier here, as good as the NC400 was.

 

[rajapruk]

Do you test output impedance?
What is difference here to nc400 and AHB2?

 

[amirm]

Do you test output impedance?

I hate running that test.....

 

[digitalfrost]

Here you go:
View attachment 28951

It would be nice to have a hard on/off switch to avoid the high idle current of the switching power supply. But otherwise, efficiency at power is 90% or so and gets there in a hurry.

The X axis is what, watts?

 

[tktran303]

So the first 14dB of amplification was perfect in the nCore400.

In this refined product Bruno perfected the final 8dB of amplication.

Bravo

 

[amirm]

The X axis is what, watts?

It is except that the Purifi was run with two channels running, the AHB2 was with one (compensated in the formula that computes efficiency).

 

[amirm]

Here is the output impedance versus frequency. Note that the scale is in milliohm (1/1000 of an ohm):

The spec is 65 micro-ohm at 1 kHz (0.065 milliohm). Likely they measure right at amplifier terminals. Mine are through the case wiring, and into my 3 to 4 feet of wire, connectors, etc. So the amp basically has zero impedance and what is seen is the wiring impedance. No rise with frequency which is very good for a class-d amp.

 

[Soniclife]

Here is the output impedance versus frequency. Note that the scale is in milliohm (1/1000 of an ohm):

View attachment 28956

The spec is 65 micro-ohm at 1 kHz (0.065 milliohm). Likely they measure right at amplifier terminals. Mine are through the case wiring, and into my 3 to 4 feet of wire, connectors, etc. So the amp basically has zero impedance and what is seen is the wiring impedance. No rise with frequency which is very good for a class-d amp.

Excellent, I was hoping it was very good and nothing for anyone to ever worry about, it's rather better than that.

If these are sensibly priced they are going to be in a lot in amps very soon, so it's good to get as comprehensive a set of measurements as possible.

 

[HammerSandwich]

I'm looking to learn, so links to standards, schematics etc. would be much appreciated.

Considering this is the Purifi thread, read The G Word, written by some Bruno P guy.

 

[somebodyelse]

Considering this is the Purifi thread, read The G Word, written by some Bruno P guy.

I'll re-read and hope to understand more fully this time...

 

[Massimo]

Looking forward to seeing how any of the NC1200 based amps stack up. Hopefully we’ll see one on the test bench soon.

 

[orangejello]

Hey Amir! I just want to thank you for giving us so much of your effort and integrity in producing this data.

 

[maty]

1ET400A + input buffer <- CMRR?

 

[maty]

The old DIY alternative.

Hypex NC400

[PDF] https://www.diyaudio.com/archive/bl...01-ncore-based-power-amplifier-nc400_04xx.pdf

CMRR (all frequencies) 55 dB

PSRR (either rail, f < 1 kHz) Min: 75 dB - Typ 80 dB

 

[maty]

Hypex NC500

[PDF] https://www.hypex.nl/documenten/download/854

CMRR Min: 50 dB - Typ: 65 dB

PSRR (either rail, f < 1 kHz) Min: 75 dB - Typ 85 dB

 

[amirm]

@maty, let's keep this thread focused on Purifi.

 

[maty]

Purifi 1ET400A is the evolution of those two modules, the DIY and the OEM. It is logical to make the comparison to know what they have improved.

And I was not the first to compare with NC400.

 

[tktran303]

I really don’t understand why you bother comparing CMRR or PSRR.

The data is clear to see that new module is better than the old.
The designer of both is the Bruno Putzeys.