Review and Measurements of Purifi 1ET400A Amplifier

[JustJones]

This is the VTV with the stock Ncore buffer.
View attachment 59628

 

[March Audio]

This is the VTV with the stock Ncore buffer.
View attachment 59628

Your xlr screen is also incorrectly wired.

 

[JustJones]

Your xlr screen is also incorrectly wired.

Pins wired wrong? I think it's in upside down

 

[March Audio]

Pins wired wrong? I think it's in upside down

No its not that. The screen shouldn't go directly to pin one, it should go to chassis elsewhere.

Do a search on " xlr pin1 problem"

It's also not clear if pin one does go to chassis from the photo. It should.

First and foremost, have you checked your earth connection?

 

[JustJones]

No I haven't checked earth connection. Pin 1 wire just goes to the square connector on the buffer board.

 

[JimB]

It appears to be counting on the filter body contact from snapping into the back panel.

 

[March Audio]

It appears to be counting on the filter body contact from snapping into the back panel.

Which isn't reliable hence the push on connector tab.

 

[orangejello]

Please Note my vested interest here but these are genuine observations

No earth connection. The mains wiring doesn't confirm to class 2 standards so it is required for safety. Add it in yourself for your own safety.
Speaker post soldering quality.
XLR screen incorrectly wired.
General wiring routing and hygiene. Yes it matters. Tight twisting required to minimise switching radiation and pickup.

Any comments on the orientation of the power supply to the amp modules? Is any shielding necessary? How about heat sinks? Does the power supply need them?

 

[March Audio]

No I haven't checked earth connection. Pin 1 wire just goes to the square connector on the buffer board.

It's a simple fix for you to do yourself but it should never be sold like that. It's potentially dangerous. The manufacturer clearly doesn't have adequate electrical safety knowledge. From the observations above lacking electronics knowledge too.

 

[March Audio]

Any comments on the orientation of the power supply to the amp modules? Is any shielding necessary? How about heat sinks? Does the power supply need them?

I think "sub optimal" covers it Those inductors right next to the amp module.

Shielding won't help, the switching signals are floating around and conducted and radiated through that wiring anyway.

The psu bolted to the chassis should be adequate heatsinking.

 

[JustJones]

When I look up xlr pin 1 problem I found this. Looks like audio ground is different than digital ground like a computer https://electronics.stackexchange.c...nd-mesh-ground-and-contradictory-grouding-pra

 

[PaulD]

When I look up xlr pin 1 problem I found this. Looks like audio ground is different than digital ground like a computer https://electronics.stackexchange.c...nd-mesh-ground-and-contradictory-grouding-pra

Try this: http://pin1problem.com I always found the Rane paper most useful.

 

[March Audio]

https://www.ranecommercial.com/legacy/note165.html
https://www.prosoundweb.com/the-pin-1-problem-revisited/

 

[JustJones]

Thank you, so pin 1 wire should just go to the chassis as a ground not to the board.

 

[Cujobob]

I contacted the owner of VTV and his response is this:

“Yes there is no pin one problem. The chassis is ground led to earth and the modules audio signal is not. That is what Hypex directs.”

(I mistakenly did not specify Purifi in my email contact, but he ensured me in a follow up that it works the same)

I also purchased a Purifi amplifier from him with stock Hypex board, I haven’t received it yet.

 

[JustJones]

I contacted the owner of VTV and his response is this:

“Yes there is no pin one problem. The chassis is ground led to earth and the modules audio signal is not. That is what Hypex directs.”

(I mistakenly did not specify Purifi in my email contact, but he ensured me in a follow up that it works the same)

I also purchased a Purifi amplifier from him with stock Hypex board, I haven’t received it yet.

OK, now I'm even more confused.

 

[SIY]

OK, now I'm even more confused.

Mission accomplished.

 

[SIY]

I contacted the owner of VTV and his response is this:

“Yes there is no pin one problem. The chassis is ground led to earth and the modules audio signal is not. That is what Hypex directs.”

(I mistakenly did not specify Purifi in my email contact, but he ensured me in a follow up that it works the same)

I also purchased a Purifi amplifier from him with stock Hypex board, I haven’t received it yet.

Please ask, "Where exactly is Pin 1 tied to the chassis?" That will be a harder question to evade.

 

[Cujobob]

Please ask, "Where exactly is Pin 1 tied to the chassis?" That will be a harder question to evade.

I sent another email his way. He responds very quickly, I’ll give him that. It’s fairly late so I may not get a response tonight.

After seeing the internals, I’m a little bummed. If it is ground correctly, is the lack of twisted wiring and proximity of the boards to PSU enough to worry the amplifier will not function as intended?

Edit: his response is that pin 1 is not tied to the chassis.

 

[Labjr]

OK, now I'm even more confused.

Pin #1 goes to chassis GND and that's it.