Review and Measurements of Purifi 1ET400A Amplifier

[March Audio]

Since audiophonics have a different design, the pin 1 problem is not a an issue?

Difficult to say from that picture, no idea how they have wired it. Only thing to mention is that having RCA sockets on the amp is not the ideal way to wire a balanced input amp (presuming their buffers are balanced).

Its specifically commented on in Hypex documentation. Ground currents (noise) will still flow in the low signal wire if the RCA is on the amp.

Not sure what the copper tape is all about.

 

[Julf]

Since audiophonics have a different design, the pin 1 problem is not a an issue?

Unbalanced inputs? Sure, that is one way to get rid of the issue.

 

[spacebar]

@March Audio thanks. I remember you mentioned the rca thing in your purifi mono thread.

 

[Ykar]

Only thing to mention is that having RCA sockets on the amp is not the ideal way to wire a balanced input amp (presuming their buffers are balanced).

I guess this is assuming the the RCA socket and RCA low signal conductor are connected together right ?
On the Audiophonics, none of the signal conductors, RCA or XLR, not even pin 1 are connected to the earthed chassis, at least on the one I own (2 x nc250mp). I feed it with RME DAC and it is perfectly noise free using either RCA or XLR.
I've been looking at that pin 1 question and tried to measure noise at amp output but didn't see any difference with pin 1 to chassis or floating. Noise is significant only if I don't connect XLR shield to measurement device shield (DIY).

 

[Pultzar]

Is anybody selling a 4 channel Purifi based amp? I'm thinking 4 modules and 2 power supplies per chassis. I saw one on Nord's website but now it is gone.

 

[spacebar]

Is anybody selling a 4 channel Purifi based amp? I'm thinking 4 modules and 2 power supplies per chassis. I saw one on Nord's website but now it is gone.

Like this? https://www.audiophonics.fr/en/power-amplifier/audiophonics-hpa-q400et-amplificateur-4-voies-class-d-purifi-4x400w-4-ohm-p-14452.html

 

[Pultzar]

Like this? https://www.audiophonics.fr/en/power-amplifier/audiophonics-hpa-q400et-amplificateur-4-voies-class-d-purifi-4x400w-4-ohm-p-14452.html

Yup, that's the ticket! How does construction look from the eagle eyes here? Too bad it isn't a rack mount.

 

[Labjr]

Yup, that's the ticket! How does construction look from the eagle eyes here? Too bad it isn't a rack mount.

Looks nice to me. As long as the assembly, case and hardware look good. not much else to critique but the the input/buffer board? I guess that's made in house?

 

[TabCam]

Yup, that's the ticket! How does construction look from the eagle eyes here? Too bad it isn't a rack mount.

If you read up a little in the last pages, they mention a lot of pin1 problems. I did not experience any problems with it when connecting either via RCA, unbalanced XLR or balanced XLR.

 

[March Audio]

I guess this is assuming the the RCA socket and RCA low signal conductor are connected together right ?
On the Audiophonics, none of the signal conductors, RCA or XLR, not even pin 1 are connected to the earthed chassis, at least on the one I own (2 x nc250mp). I feed it with RME DAC and it is perfectly noise free using either RCA or XLR.
I've been looking at that pin 1 question and tried to measure noise at amp output but didn't see any difference with pin 1 to chassis or floating. Noise is significant only if I don't connect XLR shield to measurement device shield (DIY).

The RCA shield and low signal conductor are the same thing. They will be connected to the amps balanced low input.

If the xlr shield is not connected to chassis its wired incorrectly.

 

[spacebar]

I couldn’t get this pin 1 thing out of my head, and find it very interesting. I believe this is the module. Balanced to unbalanced converter. The module has only 2 cables out, and no third cable for earth. Would it be better with a third cable from the xlr to earth instead of using a noise resistor? Any thoughts on this module @March Audio ?

https://www.audiophonics.fr/en/diy-...nbalanced-converter-xlr-rca-pair-p-14305.html

 

[March Audio]

I couldn’t get this pin 1 thing out of my head, and find it very interesting. I believe this is the module. Balanced to unbalanced converter. The module has only 2 cables out, and no third cable for earth. Would it be better with a third cable from the xlr to earth instead of using a noise resistor? Any thoughts on this module @March Audio ?

https://www.audiophonics.fr/en/diy-...nbalanced-converter-xlr-rca-pair-p-14305.html

It's not that board, you can see its different in the other picture.

You would not want to use the board you have shown. It's a balanced to single ended converter. The OP amp used is pretty mediocre in performance.

 

[spacebar]

Ah, I see that now. My bad.

 

[Ykar]

That board ?

 

[spacebar]

That board ?

View attachment 60297

I believe so. Thanks

Edit: I think it’s a similar board.

 

[Ykar]

This is the way I understand the board and input connexions :

 

[Ykar]

Here are current wiring + possible other options, which one is best ?

 

[spacebar]

Maybe @March Audio can help you @Ykar

 

[Ykar]

Ok I think get it now. March audio is striclty following Hypex guidance on their Pin 1 white paper. I still can't tell about IOM, Apollon or Nord.

 

[spacebar]

If you look closely you can see where pin 1 goes. I think he uses a rf filter board too, I have not seen anyone else do that. Correct me if I’m wrong March Audio.