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DIY Purifi Amp builds

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P.S. Have fitted an 8A slow blow fuse in the panel mount holder (this is for 240V mains supply). I assume fitting a 10A in the mains plug would be appropriate?
 
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Hi Jim,

I need to start researching active crossover components, what are you using and do you have any recommendations?

I looked at one unit......the Model K231 , Rev 3.2 Sublime Acoustic, LLC.

Thanks.

John
Have you settled on a crossover solution, and if so, what route did you take? I have found it difficult to find a solution that matches the capability of amps like the Purifi (granted the utility found in some of the digital options is fantastic and might outweigh issues with SINAD, etc.).

I purchased a K231 but found it to have a bit too much audible noise for my liking (which subjectively seemed higher in one channel than the other... maybe it had an issue). Aside from that, its construction seemed decent, and in-room measurements appeared to show it was likely working as intended as far as crossover points / slopes (obv. using in-room measurements to judge this isn't very exact).
 
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Have you settled on a crossover solution, and if so, what route did you take? I have found it difficult to find a solution that matches the capability of amps like the Purifi (granted the utility found in some of the digital options is fantastic and might outweigh issues with SINAD, etc.).

I purchased a K231 but found it to have a bit too much audible noise for my liking (which subjectively seemed higher in one channel than the other... maybe it had an issue). Aside from that, its construction seemed decent, and in-room measurements appeared to show it was likely working as intended as far as crossover points / slopes (obv. using in-room measurements to judge this isn't very exact).
Have you settled on a crossover solution, and if so, what route did you take? I have found it difficult to find a solution that matches the capability of amps like the Purifi (granted the utility found in some of the digital options is fantastic and might outweigh issues with SINAD, etc.).

I purchased a K231 but found it to have a bit too much audible noise for my liking (which subjectively seemed higher in one channel than the other... maybe it had an issue). Aside from that, its construction seemed decent, and in-room measurements appeared to show it was likely working as intended as far as crossover points / slopes (obv. using in-room measurements to judge this isn't very exact).
Hi DP,

Kind of on the back burner for now, interesting...the K231 may be noisy , maybe I dodged a bullet. Are you going to keep it or look for another solution?

Thanks!

John
 
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Hi DP,

Kind of on the back burner for now, interesting...the K231 may be noisy , maybe I dodged a bullet. Are you going to keep it or look for another solution?

Thanks!

John
I did not keep it. (Noise wasn't necessarily awful, but there was a subjectively apparent increase in noise output at the speaker when introducing the K231 to the system. At listening distances, it was inaudible; however, the increase at the speaker was significantly higher than what I have experienced when swapping other components, and that, combined with the fact that it was noticeably louder in one channel than the other, left me unsatisfied.)

I am currently using an SPL Crossover (I didn't, and wouldn't, pay MSRP). I don't have any complaints with the unit, but I am not sure it is an end-game solution for me.

Pros:
  1. It has some nice features, like 360 deg of phase control and level-adjustable VU meters which can be set to show total / low / hi signals (I have it set to show the hi output so that I can tell when I am pushing my amps towards clipping).
  2. SPL claims 138 dB of dynamic range, but it appears this is at max input / output of +32.5 dB, which as I understand it is approx. 11v RMS and well beyond any signal I might introduce to it (current digital source is a Topping D90). At ~4v input, my math shows it should give approx. 118 dB of dynamic range based on the published specs. Amir recently measured one of SPL's HPAs (Phonitor line), and the preamp section (rated for 135 dB of dynamic range, again at +32.5 dB) measured 112 dB of dynamic range at 4v (which if we adjust for the crossover's +3 dB of DR, puts us around 115, close to the 118 estimate).
Basically, you'll likely never drive the crossover to clip, and it might pair nicely with a low gain Benchmark or Purifi, but you need a source with sufficient output to take advantage of it. (RME ADI-2, maybe?)

Cons:
  1. Crosstalk is awful - published specs state ~75 dB down at 1k, similar to the specs listed for the Phonitor HPA Amir measured; his measurements showed that by 20k crosstalk was only 60dB down. I am assuming the crossover would show similar.

I'm happy with the utility of the crossover, and I have no complaints re: distortion, etc., but I question whether there is any value in having 115-130 dB of dynamic range if crosstalk is only down 60-70 dB. Might I actually get better total performance out of a different unit with less dynamic range (or input headroom) and better crosstalk + functionality?

Unfortunately, there do not seem to be many options available that are all-in-one, so-to-speak. MiniDSP SHD comes to mind, but the SINAD / DR isn't up to par with new DACs or Purifi / Ncore / Benchmark amps. Audiolense + a couple high-performance DACs might be best, but I believe you need a PC involved for that.
 
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I did not keep it. (Noise wasn't necessarily awful, but there was a subjectively apparent increase in noise output at the speaker when introducing the K231 to the system. At listening distances, it was inaudible; however, the increase at the speaker was significantly higher than what I have experienced when swapping other components, and that, combined with the fact that it was noticeably louder in one channel than the other, left me unsatisfied.)

I am currently using an SPL Crossover (I didn't, and wouldn't, pay MSRP). I don't have any complaints with the unit, but I am not sure it is an end-game solution for me.

Pros:
  1. It has some nice features, like 360 deg of phase control and level-adjustable VU meters which can be set to show total / low / hi signals (I have it set to show the hi output so that I can tell when I am pushing my amps towards clipping).
  2. SPL claims 138 dB of dynamic range, but it appears this is at max input / output of +32.5 dB, which as I understand it is approx. 11v RMS and well beyond any signal I might introduce to it (current digital source is a Topping D90). At ~4v input, my math shows it should give approx. 118 dB of dynamic range based on the published specs. Amir recently measured one of SPL's HPAs (Phonitor line), and the preamp section (rated for 135 dB of dynamic range, again at +32.5 dB) measured 112 dB of dynamic range at 4v (which if we adjust for the crossover's +3 dB of DR, puts us around 115, close to the 118 estimate).
Basically, you'll likely never drive the crossover to clip, and it might pair nicely with a low gain Benchmark or Purifi, but you need a source with sufficient output to take advantage of it. (RME ADI-2, maybe?)

Cons:
  1. Crosstalk is awful - published specs state ~75 dB down at 1k, similar to the specs listed for the Phonitor HPA Amir measured; his measurements showed that by 20k crosstalk was only 60dB down. I am assuming the crossover would show similar.

I'm happy with the utility of the crossover, and I have no complaints re: distortion, etc., but I question whether there is any value in having 115-130 dB of dynamic range if crosstalk is only down 60-70 dB. Might I actually get better total performance out of a different unit with less dynamic range (or input headroom) and better crosstalk + functionality?

Unfortunately, there do not seem to be many options available that are all-in-one, so-to-speak. MiniDSP SHD comes to mind, but the SINAD / DR isn't up to par with new DACs or Purifi / Ncore / Benchmark amps. Audiolense + a couple high-performance DACs might be best, but I believe you need a PC involved for that.
Thank you for the detailed analysis/review DP.

What are your thoughts on this Nelson Pass designed DYI kit? I could machine a case for it to match my mono blocks.

https://diyaudiostore.com/products/diy-biamp-6-24-crossover
 
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Thank you for the detailed analysis/review DP.

What are your thoughts on this Nelson Pass designed DYI kit? I could machine a case for it to match my mono blocks.

https://diyaudiostore.com/products/diy-biamp-6-24-crossover
Not really sure - I'd love to see measurements on a well-completed kit (and certainly if you can get a case to match your amps, that would look great, too). Typically, I am all for DIY, but soldering is where I've drawn the line up to this point, as it is not a skill I've practiced. So, I don't think that's a route for me. It looks very cost-effective, though so if you're comfortable with assembly, I doubt you'd get better value / $ elsewhere. It might be worth the try.
 
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Not really sure - I'd love to see measurements on a well-completed kit (and certainly if you can get a case to match your amps, that would look great, too). Typically, I am all for DIY, but soldering is where I've drawn the line up to this point, as it is not a skill I've practiced. So, I don't think that's a route for me. It looks very cost-effective, though so if you're comfortable with assembly, I doubt you'd get better value / $ elsewhere. It might be worth the try.
Here is one that is already built......for a measly $1500.......yikes!

https://www.pureaudioproject.com/pap-c1-custom-active-analog-crossover-open-baffle/
 

nimar

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The hole for the Ghent filtered mains entry is larger than for the simple switch. So, the is a gap if trying to go from a filtered unit to a switch. Had you wanted to go the other way, at least you could have filed out the hole.

The fuse on the Ghent version is certainly replaceable. I'd be surprised if the one that VTV uses was not. You could confirm with them.
I got my Ghent IEC Inlet and its an exact match to the VTV one, replaced without any filling / wiggle room. Doesn't look like the VTV inlet has a fuse at all, just a y capacitor filter. Posted in VTV form https://www.audiosciencereview.com/...ifi-1et400a-updates.17564/page-12#post-710990
 

Skriabin

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One question I have is whether or not the DIY Purifi 1ET400A gives these annoying pop/click sounds in your speakers when you power up this amp.
My Behringer A800 amps have those annoying pops when powering up.....
 

daniboun

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One question I have is whether or not the DIY Purifi 1ET400A gives these annoying pop/click sounds in your speakers when you power up this amp.
My Behringer A800 amps have those annoying pops when powering up.....
With mine, I have nothing to complain with it. No pop when switching ON / OFF. Absolutely silent amp.
 

TimoJ

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One question I have is whether or not the DIY Purifi 1ET400A gives these annoying pop/click sounds in your speakers when you power up this amp.
My Behringer A800 amps have those annoying pops when powering up.....
Speakers output small click when you power up the amp.
 
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Finally done with my build using Neurochrome input modules mounted in a Mini Dissipante 2U 300mm modushop case.

Some light metalwork were required which took longer than expected :facepalm: The SMPS is bolted to the front 10 mm alu panel. Tapped holes in the front panel and drilling extra holes in the L-Bracket. The 1ET400A/input is clamped vertically to the side heat sinks with one bolt in front and the two bolts from the the case bracket. Seems to provide sufficient contact pressure. The bracket holding the case together had to be trimmed otherwise the 1ET400A heatsink wouldnt fit. Fused with a 5 A fast fuse (230v).

As expected cooling seems very good. At my not super high listening level I could barely feel it heating up.

20210321_160816.jpg
20210321_142927.jpg
 

nimar

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I skimmed the 109 pages of this thread, went through a couple fights, a couple attempts to discredit Hypex and came out with somewhat inconclusive info regarding bypassing the input gain.

I appreciate removing them drops the gain, and impedance but are there any downsides, other than requiring more power to reach max output.

Does it indeed also bypass EMI filtering?. In short, what are the real world impacts of using the bypass.

My original motivation was to limit the possibility of blowing speakers with the rather jumpy volume on the topping D70s (and its max 5v out). Though this is somewhat mitigated by adding a Topping A90 to the picture to have enough power without the eval1's additional gain. I believe the A90 has enough output to make up for the lack of the additional eval1 gain.
 
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boXem | audio

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Yes, it will bypass the EMI filtering.
EM are a thing from the real world in general. Are they a thing in your real world is not possible to answer from behind a keyboard.
A sensible approach would be to try bypassing the gain stage and listen whether some click/hum/noises are heard when your system is active but nothing is playing.
 
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Finally done with my build using Neurochrome input modules mounted in a Mini Dissipante 2U 300mm modushop case.

Some light metalwork were required which took longer than expected :facepalm: The SMPS is bolted to the front 10 mm alu panel. Tapped holes in the front panel and drilling extra holes in the L-Bracket. The 1ET400A/input is clamped vertically to the side heat sinks with one bolt in front and the two bolts from the the case bracket. Seems to provide sufficient contact pressure. The bracket holding the case together had to be trimmed otherwise the 1ET400A heatsink wouldnt fit. Fused with a 5 A fast fuse (230v).

As expected cooling seems very good. At my not super high listening level I could barely feel it heating up.

View attachment 119578 View attachment 119579
Your build is very nice, the layout in the Mini Dissipante was a clever build. I am working on a similar project. How do you combine the two ribbon cables from the Neurochrome buffers to the SMPS connector?
 
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