Review and Measurements of Purifi 1ET400A Amplifier

[TabCam]

Just listened to the Audiophonics Purifi amplifier cold out of the box. First impressions with Usher Mini Dancer 2 DMD mkII is that they easily best an Anthem I225 or any other amplifier I have heard on the Ushers. Nice example in clean bass is well known James Blake song "Limits to your love". There is more detail and phases in the generator parts of the song. The bass seems to have more impact at lower volume levels.

Will check on the opamp tomorrow but have no doubt it is good enough to be a keeper. The only inconvenient thing is left/right input placement, which is at the extreme left/right edges. Had to switch from a single stereo interconnect to two mono interconnects.

 

[TabCam]

Is someone aware of a vendor planning a 5 channels Purifi amp for HC usage ?
The current models are just 4 channels. So I would need one 4 channels + 1 stereo, which is 2 boxes instead of one, and more expensive than just 5 channels.
By putting amp board in height like in the NAD M27, you can put 7 channels.
One SMPS3kA400 would be enough for 5 channels.

Are you aware of a case vendor selling HC cases for 5 channels ?

I was thinking of making a three channel amplifier. I know both Apollon Audio and Nord Acoustics do custom order so, while not cheap, you easily get a 5 channel version from them.

 

[Matias]

I was thinking of making a three channel amplifier. I know both Apollon Audio and Nord Acoustics do custom order so, while not cheap, you easily get a 5 channel version from them.

Their prices depend if you ask for their large opamps and buffer or just the regular sized opamps buffer and a chip opamps. The latter should be quite competitive.

 

[Audiophonics]

Don't know. FYI the jumpers are adjacent to an LED (fault indicator?). Re gain options, this is what their website says. What's printed on their PCB is different, perhaps they did an ECO after the boards were made:

• Gain of + 7.2dB, for a total of 20dB (default) - Maximum power reached with a signal of ~ 4.2V RMS
• Gain of + 12.5dB, for a total of 25.3dB - Maximum power reached with a signal of ~ 2.2V RMS
• Bypass: in this case the signal passes directly from the inputs to the modules, allowing the lowest possible gain of 12.8dB. This mode can be interesting when using a powerful preamplifier, capable of driving a load of 2 to 4kOhm and reaching a voltage of ~ 10V RMS

The led is the "AMP ON" output of the module. It indicate that module didn't detected any error and is running.

The PCB is 4 layers so it will not be easy to trace wires.
The Jumper totally bypass the OPA. Direct input to the amplifier module.

The SILK is different from the gain we finally set because we initially set this gain for NC500 OEM, and decided to optimise the gain for each module.
So ET400A can run with a lower gain. 7.2/12.5 instead of 9.5/15.5

 

[TomJ]

Bypass... mode can be interesting when using a powerful preamplifier..."

Thank you for the additional information! In your product testing, how does the amp sound in bypass mode compared to either or both of the gain modes?

 

[rodtor]

Thank you for the additional information! In your product testing, how does the amp sound in bypass mode compared to either or both of the gain modes?

Note that when Amir tested the sample that purifi sent him, SINAD improved by 4 db with the bypass option. Whether this would be audible is another matter. Still, a nice feature of the Audiophonics product that Nord's similarly- priced version lacks.

 

[TabCam]

I opened up the Audiophonics Purifi amp and had to unscrew 18? screws to gain access to the jumpers. They are a little unclear as each channel has two jumpers with the indication buffer so if you bypass them do you need to both set them to 1-2??

The AMPON LED's are quite bright but still difficult to see from a closed box. The outer ring of the power button is lighted as well but seems to indicate power available and not amps turned on.

Have not tried the 12V trigger yet but the amp seems to turn on and off without any loudspeaker pops or clicks except for a small relais like click from inside the amplifier.

 

[rodtor]

I opened up the Audiophonics Purifi amp and had to unscrew 18? screws to gain access to the jumpers. They are a little unclear as each channel has two jumpers with the indication buffer so if you bypass them do you need to both set them to 1-2??

The AMPON LED's are quite bright but still difficult to see from a closed box. The outer ring of the power button is lighted as well but seems to indicate power available and not amps turned on.

Have not tried the 12V trigger yet but the amp seems to turn on and off without any loudspeaker pops or clicks except for a small relais like click from inside the amplifier.

Sounds like a good question. Have you written Audiophonics directly to enquire? It would be interesting to know how responsive they are.

 

[TimoJ]

Hello
below the photos of my Purifi amp, it is cheaper than the Audiophonics and does not require a lot of work ...

Maybe you should post those to the DIY thread:
https://www.audiosciencereview.com/forum/index.php?threads/diy-purifi-amp-builds.10478/

 

[TabCam]

Sounds like a good question. Have you written Audiophonics directly to enquire? It would be interesting to know how responsive they are.

Have asked that and a few more questions on their website. Normally they respond within a day. Will see as these are not normal times.

 

[Audiophonics]

They are a little unclear as each channel has two jumpers with the indication buffer so if you bypass them do you need to both set them to 1-2??

Have not tried the 12V trigger yet but the amp seems to turn on and off without any loudspeaker pops or clicks except for a small relais like click from inside the amplifier.

Yes all jumpers must be set to 1-2 to bypass the OPA.
In that case, the Gain+ jumper do nothing.

There is no 12V trigger on Purifi amps !?

 

[somebodyelse]

There is no 12V trigger on Purifi amps !?

I guess people assume the 'Trigger' silkscreen on the back panel means it has a 12V trigger. It's not clear in the website photos whether there's a recessed socked or a blanking plug above these.

 

[TabCam]

Got a quick respnse but not that clear in detailing which jumper has which function. Also asked about OPA alternatives like the OPA1612. This is their response (within three hours!).

Yes all jumpers must be set to 1-2, in that case the signal goes directly to the amp, to the final gain is 12.8dB
Gain + jumper add 6dB when you are in the position 2-3

We ordered some OPA1612 with DIP8 adapter, but still not arrived.
When you have a DIP8 version yes you can use it, any double OPA that can run with +/-15V

 

[Vincentponcet]

the trigger is not wired on the Eval1 ... but between no trigger which is a comfort option and a buffer powered by simple regulators, the choice is quickly made ...

Which has "a buffer powered by simple regulators" ?

 

[Koeitje]

https://vacuumtubevalues.com/product/27564/

And suddenly Audiophonics seems expensive.

 

[Matias]

https://vacuumtubevalues.com/product/27564/

And suddenly Audiophonics seems expensive.

Wow, unbelievable, fierce competition!

 

[kaka89]

https://vacuumtubevalues.com/product/27564/

And suddenly Audiophonics seems expensive.

Default 7db gain, I like that. And adjustable!

 

[mikebarney]

Default 7db gain, I like that. And adjustable!

https://vacuumtubevalues.com/product/27564/

And suddenly Audiophonics seems expensive.

That price seems wrong - its the same as for his monoblock.

 

[kaka89]

That price seems wrong - its the same as for his monoblock.

They have multiple version

Stereo with buffer $1290: https://vacuumtubevalues.com/produc...h-purifi-1et400a-and-vtv-custom-buffer-input/
Stereo with no (?) buffer $879: https://vacuumtubevalues.com/product/27564/
Mono with buffer $879: https://vacuumtubevalues.com/produc...i-1et400a-module-and-vtv-custom-input-buffer/

 

[Vincentponcet]

They have multiple version

Stereo with buffer $1290: https://vacuumtubevalues.com/produc...h-purifi-1et400a-and-vtv-custom-buffer-input/
Stereo with no (?) buffer $879: https://vacuumtubevalues.com/product/27564/
Mono with buffer $879: https://vacuumtubevalues.com/produc...i-1et400a-module-and-vtv-custom-input-buffer/

That's US price, ie without VAT.

By the way, after seeing the amazing work done by Purifi with their Eval1 (two levels discrete voltage regulators, differential buffer using 2 opa1612a per channel), I do not think "custom buffer" are that much valuable. Most of them sounds like inferior on the paper.
Why builder just do not directly use EVAL1 ?