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DIY Purifi Amp builds

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JimB

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Apologies if this has been asked but there are 103 pages ;

Im interested in setting one of these stereo amps up - is there a running gear list (BOM) you guys have figured out of everything required to get a stereo amp up and running?
People have done various, interesting builds. The simplest that I know, is:
One of EVAL1 from Purifi - https://purifi-audio.com/vare/eval1/
One of SMPS1200A400 from Hypex - https://www.diyclassd.com/product/smps1200a400/10
One of case and cable harness from Ghent - http://www.ghentaudio.com/kit/purifi-eval1-se.html
- http://www.ghentaudio.com/kit/purifi-eval1-harness.html
Plus your own IEC mains cable.

EDIT: Also, IF you have an unbalanced source, this type of XLR-only input amp will need suitable converting cables, such as these:
http://www.ghentaudio.com/part/a15.html
Many places make these (I have them from a few sources). Theirs have good parts, assembled to the right design, and are easy to your order if you are already getting their case and harness (no need for a purchase from a fourth place, with added shipping, etc.).


People have also pointed out that one can buy a prebuilt equivalent for less than the sum of these parts. So, unless you just want the satisfaction of doing it yourself, you could buy one (start reading backwards through these pages...). If you want one with different details, then you are on your own to decide what to do differently, and pursue that. Enjoy!
 
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Hi, @JohnM-73. I didn't choose them. They were provided, unexpectedly, as an upgrade bonus on my special cases from Ghent. They proved to be both good and bad as a substitution of a plain input switch. I addressed it here:
https://www.audiosciencereview.com/...y-purifi-amp-builds.10478/page-98#post-617372

Exactly what to do to disconnect the internal caps grounding in a specific device can vary. While I did it for the ones I was given, I won't detail this because I don't really want to encourage it.
Thanks Jim, will take a look at that link.
 
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I rigged a temperature test of my "vane" build today, with both channels outputting 98W into 8 ohm resistors for 90 minutes (~50% maximum - MUCH more than can be used for ANY unclipped music). The temperature rises over ambient were ~:
SMPS, 14.7C
Amp, 13.6C
Case, 10.7C
The dissipation here corresponds to about 25% of maximum power into 4 ohms (about the limit for almost any music, unclipped), and about 12% of maximum power into 2 ohms (1/8th - about the limit for 'normal' music, unclipped - the level Purifi references).

I am PLENTY happy with these figures! I'll have NO thermal concerns for these amps under any conditions I can run. The case is doing it's job, WELL! :cool:

Over to you, @beren777 to compare the same parts, but without my added pin-heatsinks (fiddly, not recommended for most people) and without my thermal compound (easy!).
Just got a dual channel Proster PST095 off Amazon for cheap, hopefully it's "good enough" for this purpose. 2 Cutequeen resistors arrived as well to which, ironically, I'll be sure to attach some larger heat sinks. Should be ready to give it a try later this week or over the weekend. What voltage were your speaker outputs for the 98W so I don't have to do math?

Multimeter says these 8 ohm resistors are actually 8.3 ohms. Good enough?
 
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JimB

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Sure.
Just got a dual channel Proster PST095 off Amazon for cheap, hopefully it's "good enough" for this purpose. 2 Cutequeen resistors arrived as well to which, ironically, I'll be sure to attach some larger heat sinks. Should be ready to give it a try later this week or over the weekend. What voltage were your speaker outputs for the 98W so I don't have to do math?

Multimeter says these 8 ohm resistors are actually 8.3 ohms. Good enough?
28.03VAC on 8.05 ohms (cold). So, for you, equivalent power output would be ~28.47V.
 
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Hello everybody,
I will try to be clear in my message, I am not very comfortable in English so I will let google take care of it ...

I found someone who makes purifi based amps near my house. He sent me pictures, it looks very clean. For AOP, he uses MUSES 02. 6 in total.
Suddenly I wanted to know if you already knew them and your opinion on these AOPs and if at any risk you had made comparative listening between them and those that I could see in the various assemblers, 1612, Sonic Imagery or Sparkos Labs ? I understood that the best but also the most expensive were the Sonics, but what about the Muses 02 that I can't see anywhere?
If I understood correctly, it is ultimately via the AOP that the sound of the purified changes, a bit like changing the tubes of an amp.

Excuse me if this kind of question has already been asked, I admit not having found an answer .... Thank you for your help!
 
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Hello everybody,
I will try to be clear in my message, I am not very comfortable in English so I will let google take care of it ...

I found someone who makes purifi based amps near my house. He sent me pictures, it looks very clean. For AOP, he uses MUSES 02. 6 in total.
Suddenly I wanted to know if you already knew them and your opinion on these AOPs and if at any risk you had made comparative listening between them and those that I could see in the various assemblers, 1612, Sonic Imagery or Sparkos Labs ? I understood that the best but also the most expensive were the Sonics, but what about the Muses 02 that I can't see anywhere?
If I understood correctly, it is ultimately via the AOP that the sound of the purified changes, a bit like changing the tubes of an amp.

Excuse me if this kind of question has already been asked, I admit not having found an answer .... Thank you for your help!
Hello, @maniolo. This is a DIY topic, and not so much about the sonic benefits of various inputs. You might get better feedback in either of these two other places:
https://www.audiosciencereview.com/forum/index.php?threads/ultimate-1et400a-purifi-amplifier-sonic-shootout-€820-to-€8-344.14048/
https://www.audiosciencereview.com/forum/index.php?threads/purifi-1et400a-decisions-decisions.15739/
Also in later pages here:
https://www.audiosciencereview.com/...easurements-of-purifi-1et400a-amplifier.7984/
 
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Thread Starter #2,068
Hello everybody,
I will try to be clear in my message, I am not very comfortable in English so I will let google take care of it ...

I found someone who makes purifi based amps near my house. He sent me pictures, it looks very clean. For AOP, he uses MUSES 02. 6 in total.
Suddenly I wanted to know if you already knew them and your opinion on these AOPs and if at any risk you had made comparative listening between them and those that I could see in the various assemblers, 1612, Sonic Imagery or Sparkos Labs ? I understood that the best but also the most expensive were the Sonics, but what about the Muses 02 that I can't see anywhere?
If I understood correctly, it is ultimately via the AOP that the sound of the purified changes, a bit like changing the tubes of an amp.

Excuse me if this kind of question has already been asked, I admit not having found an answer .... Thank you for your help!
I can just add that asking about a device is not sufficient. It will also matter how the circuit is implemented, including circuit design, types and quality of other components, and layout, etc.. So, I don't think you can get useful feedback based on only the op-amp (unless it is widely known to be bad, or much more expensive than other comparable devices). Maybe you can try-out what your local source offers?
 
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Hi, I do have a question on grounding. The metal plate of the SMPS1200 does not make contact with smps ground.
The metal plates of the Purifi modules do have connection with ground.
The black coating of the Modushop case is quite resistant.
So without making a connection between the Purifi modules and the bare metal of the case somewhere the Purifi modules and the smps aren't connected to the ground of the case and mains ground at all. Could that be a problem?
 

Count Arthur

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You can remove some of the coating or anodising with some wet and dry sandpaper, or even a knife, where you want to make a good ground/earth connection.

Some cases come with patches that are already prepared:

1612105643246.png
 
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I asked my question about grounding because I have a little hum from my Purifi Eval1 amp. I did make blank spots at the screws of both the Purifi modules and the smps.

Because of the little hum I disassembled the amp today. I started wondering when I measured the smps seperately and it did not have ground connected to the metal plate.

While reassembling the amp I turned the smps around. Rewired the mains. But it hasn't helped. The amp still hums a little when I hold my ear just in front of a speaker.

Without anything connected its quiet. But as soon as I connect the Ares Il dac with xlr it starts humming.

Any tips?
 

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I asked my question about grounding because I have a little hum from my Purifi Eval1 amp. I did make blank spots at the screws of both the Purifi modules and the smps.

Because of the little hum I disassembled the amp today. I started wondering when I measured the smps seperately and it did not have ground connected to the metal plate.

While reassembling the amp I turned the smps around. Rewired the mains. But it hasn't helped. The amp still hums a little when I hold my ear just in front of a speaker.

Without anything connected its quiet. But as soon as I connect the Ares Il dac with xlr it starts humming.

Any tips?
Does it hum without power ground connected?
 
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JimB

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I asked my question about grounding because I have a little hum from my Purifi Eval1 amp. I did make blank spots at the screws of both the Purifi modules and the smps. ... Without anything connected its quiet. But as soon as I connect the Ares Il dac with xlr it starts humming. Any tips?
So, it's quiet with no input? Good. Either the hum is in the source, or it's to do with the connection.
 
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So, it's quiet with no input? Good. Either the hum is in the source, or it's to do with the connection.
Yes, totally silent with only speakers connected.
I suspect the xlr cables a little. I assembled them myself. The hum is clearly louder when the xlr cables are very close to the mains cable. It's the first time I'm using xlr so I don't know what to expect. I used the Canare cable below.
Screenshot_20210131-193458.png
 
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Yes, totally silent with only speakers connected.
I suspect the xlr cables a little. I assembled them myself. The hum is clearly louder when the xlr cables are very close to the mains cable. It's the first time I'm using xlr so I don't know what to expect. I used the Canare cable below. View attachment 109677
Try a star-quad cable for analog mic applications, such as Canare L-4E6S. Many places offer good star-quad cables, including Ghent and Benchmark.
 
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The Canare DA206 is a twin core designed for digital signals, isn't it?

I'm very happy with the Mogami 2534 sarquad cables I got from Design Cable: https://www.designacable.com/studio...iophile-neutrik-balanced-xlr-to-xlr-lead.html

They also sell it, and other starquad cable, unterminated if you want to re-use your existing XLR connectors.
I did not really know what to buy as analog xlr cable. Did I buy the wrong cable or is starquad a more audiophile choice?
 
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