DIY Purifi Amp builds

[maty]

Same audio room and Jacques Loussier - Little Fuge in G Minor theme but with Pass Labs X150.8

3:50 - 6:38 - Jacques Loussier - Little Fuge in G Minor

Much better sound to me.

 

[beren777]

 

[antcollinet]

Same audio room and Jacques Loussier - Little Fuge in G Minor theme but with Pass Labs X150.8

3:50 - 6:38 - Jacques Loussier - Little Fuge in G Minor

Much better sound to me.

Any difference you are hearing (if they are there at all) will be from the programme material (recording). If the material is the same, then most likely to be positional differences between the Mike and speakers. Even differences of the placment of objects in the room will alter the reflections, and hence what the microphone picks up.

These effects will dwarf any (almost certainly inaudible) differences between the amps.

 

[maty]

Trust me, I can hear the differences between amplifiers in my cheap (but very optimized, without bottlenecks) second audio system.

Other example. NAD M23 uses Purifi modules. The difference is clear again, more with vocals:
0:11 - 3:29 - Hey Now - London Grammar

Sample Test - NAD M23 vs Pass Labs X150.8 Power Amplifier - Class D vs Class A/B

 

[SIY]

Trust me, I can hear the differences between amplifiers in my cheap (but very optimized, without bottlenecks) second audio system.

ABX logs or other actual data?

Hahahahaha, I crack myself up.

(for Tony, no "uh-huh")

 

[maty]

Before with the Alpha Audio videos. Now with the original samples, FLAC 24/48.

 

[SIY]

Before with the Alpha Audio videos. Now with the original samples, FLAC 24/48.

Where's the ABX logs or data? Making the same evidence-free dubious claims over and over gives exactly zero extra credibility to them. And makes them seem even more dubious.

 

[Julf]

Trust me

Are you perhaps a politician?

 

[Vavilen]

Hey guys!
I’m still thinking about building my Purifi-based amplifier. I have all the parts, except a case. And options from aliexpress or audiophonics start from 100 euro. And it looks aliexpress-ish, in my opinion.
Have you considered buying any 30-50 euro defect used amp (marantz from 200x yy looks nice for me, for example) from local ebay and use the case for your diy-amps?
wdyt?

 

[Count Arthur]

Hey guys!
I’m still thinking about building my Purifi-based amplifier. I have all the parts, except a case. And options from aliexpress or audiophonics start from 100 euro. And it looks aliexpress-ish, in my opinion.
Have you considered buying any 30-50 euro defect used amp (marantz from 200x yy looks nice for me, for example) from local ebay and use the case for your diy-amps?
wdyt?

I don't see why not, although you might have to be a bit patient to find something suitable. A lot of integrated amp cases are going to have a lot of knobs and switches you don't really want.

A power amp case might be better:

Quad 306 | eBay

<p dir="ltr" style="margin-top:0; margin-bottom:0;">Quad 306.</p> <p dir="ltr" style="margin-top:0; margin-bottom:0;">Later Grey case version, scratches and some </p> <p dir="ltr" style="margin-top:0; margin-bottom:0;">Surface corrosion to case. </p> <p dir="ltr" style="margin-top:0...

www.ebay.co.uk

 

[mrdrewk]

@starfly did you end up getting the 12v trigger installed?

 

[starfly]

@starfly did you end up getting the 12v trigger installed?

Yes. It should be there in one of my posts in this thread. Don't recall the details, it's been a while since I built this thing. But it still works perfectly every time I use it.

 

[mrdrewk]

Yes. It should be there in one of my posts in this thread. Don't recall the details, it's been a while since I built this thing. But it still works perfectly every time I use it.

I saw that post here but you’d used a whole nother board to accomplish the trigger functionality? What board?

 

[starfly]

I saw that post here but you’d used a whole nother board to accomplish the trigger functionality? What board?

No I'm still using that same red relay board in the top right corner in that image I posted.

The comment about another board was only in relation to the power distribution. And only if I were to do it all over again, which I'm not planning on doing unless something breaks. My build is still just as it is in that picture.

If I had to start from scratch there's really a few things I'd do differently. Instead of the SMPS1200, I'd probably get two SMPS600 power supplies for a true dual-mono setup (or whatever the equivalent is). Would probably skip the standby power 12VDC, and just use the relay to send the full 120V to the power supply when triggered (uses less power overall, as standby consumes some power, whereas skipping standby mode altogether would consume 0 power).

I'd probably also attempt to build my own relay board as I can hear a high-pitched whine when I put my ear close to the case (assuming it's coil whine), and I'm pretty sure it's being generated by the relay board (a cheap one off Amazon I got). I built an audio circuit with relays last year (posted it somewhere here on ASR), so I'd be comfortable doing that again for power. Just the design specs would need be suitable for much higher voltages vs. a low voltage audio circuit.

If I ever finish my basement in the house and I finally have space to go to a real multi-channel speaker setup, I'll add another purifi module + power supply and that's when I might decide to clean up and simplify the design a bit.

 

[Rick Sykora]

No I'm still using that same red relay board in the top right corner in that image I posted.

The comment about another board was only in relation to the power distribution. And only if I were to do it all over again, which I'm not planning on doing unless something breaks. My build is still just as it is in that picture.

If I had to start from scratch there's really a few things I'd do differently. Instead of the SMPS1200, I'd probably get two SMPS600 power supplies for a true dual-mono setup (or whatever the equivalent is). Would probably skip the standby power 12VDC, and just use the relay to send the full 120V to the power supply when triggered (uses less power overall, as standby consumes some power, whereas skipping standby mode altogether would consume 0 power).

I'd probably also attempt to build my own relay board as I can hear a high-pitched whine when I put my ear close to the case (assuming it's coil whine), and I'm pretty sure it's being generated by the relay board (a cheap one off Amazon I got). I built an audio circuit with relays last year (posted it somewhere here on ASR), so I'd be comfortable doing that again for power. Just the design specs would need be suitable for much higher voltages vs. a low voltage audio circuit.

If I ever finish my basement in the house and I finally have space to go to a real multi-channel speaker setup, I'll add another purifi module + power supply and that's when I might decide to clean up and simplify the design a bit.

Sorry if I missed in this longish thread, but you used other Neurochrome parts, why did you not use his soft start and handle the trigger using it?

 

[starfly]

Sorry if I missed in this longish thread, but you used other Neurochrome parts, why did you not use his soft start and handle the trigger using it?

I wasn't really aware of it at the time I think. It's something I'd consider if I did a rebuild. For now it all works, though, and I have no time or desire to mess with it at this point.

 

[DonVinc3nzo]

Corrected per new Purifi Rev. 1.11 information, Jan. 4, 2020:
People have stated a desire for the buffer of the EVAL1 to provide half the standard gain, so that it would require 4V input to reach its rated power output, rather than 2V. That requires cutting the total gain to 20dB: ~13 dB from the 1ET400A, and 7dB from the EVAL1 FE02A. That corresponds to increasing R17 from the existing value of 1.5K to 5.36K (using available 0.1% R values).

Hello,
I'm newbies, but for 5Vrms or 5.2Vrms for what is value change ?
My PreOut (RCA) Anthem MRX540/740 specifications is 5.2Vrms, Bench Test Results is 5Vrms. (https://www.audioholics.com/av-receiver-reviews/anthem-mrx-740-1140-receivers)

Thank You Advance,
Vincenzo.

 

[JimB]

Hello,
I'm newbies, but for 5Vrms or 5.2Vrms for what is value change ?
My PreOut (RCA) Anthem MRX540/740 specifications is 5.2Vrms, Bench Test Results is 5Vrms. (https://www.audioholics.com/av-receiver-reviews/anthem-mrx-740-1140-receivers)

Thank You Advance,
Vincenzo.

You could make the change to 4V input range, but I wouldn't go more since the MRX540/740 curves show that its best performance is between 2-4 V, not higher. Really, you could just as well keep the stock EVAL1 values (2V input range) and have essentially optimum performance. Performance of the MRX540/740 is better at 2V out than at 5V.

 

[Hasse B]

I am new to this forum and have been looking at Purifi to build a 2 channel amp. However, I am a little confused about which buffers I should use. Listened to a clip in Youtube where Bruno Putzeys recommended that you can replace the existing OPA in Purifi's buffer table with the OPA1656 to get a different sound character. Others recommend Neurochrom's buffers and I suppose there are also other manufacturers. Those of you who have Purifi, which solution do you see as the best?

 

[Julf]

It would be a shame to give such a clean, transparent and accurate amp "character".