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DIY Purifi Amp builds

MicroAudio

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Hi All,
For the very first time in the known universe :cool:, Purifi amp powered by Micro-Audio SMPS with PFC function!
So many thanks to Sami for the help and for allowing me that world first :D I'm so glad with that build.
Now checking everything and finalizing layout, details. And then soon to play music!


Very nice build Luc, I am really impressed.

Keep us posted with your listening session results.
 

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kukocz

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It is a soft start module
I'm curious what is the advantage to use additional sof-start module in this case as SMSP1200 has built-in soft-start option? It is usually dedicated for transformer-based PS to limit initial current :rolleyes:.

Another question. What kind of screws are you using in your projects to mount XLR sockets in EVAL1? It looks like it should be A-type screw instead of machine screw? Mounting holes are not threaded as far as I can see.
 

tlag

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What kind of screws are you using in your projects to mount XLR sockets in EVAL1? It looks like it should be A-type screw instead of machine screw? Mounting holes are not threaded as far as I can see.

Yeah, officially, should be some sort of plastic-specific screw, but #4-40 machine thread seems to work just fine.
 

TimoJ

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Another question. What kind of screws are you using in your projects to mount XLR sockets in EVAL1? It looks like it should be A-type screw instead of machine screw? Mounting holes are not threaded as far as I can see.
I drilled the holes little bigger and tapped M3 threads.
 

pos

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Very nice build Luc, I am really impressed.

Keep us posted with your listening session results.
Could you please share some specs on that SMPS, and the advantages compared to an hypex one?
What about the efficiency curve at low levels? What is the idle power consumption?
 

boXem

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What about the efficiency curve at low levels? What is the idle power consumption?
While I perfectly understand your interest for efficiency at low levels, I don't really get the point with idling consumption. Is it because for whatever reason, you don't use the standby function?
 

Luc

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Very nice build Luc, I am really impressed.

Keep us posted with your listening session results.

Thanks!
Well, today was the D-day :D
I'm just so happy, so amazed with the sound quality of that little amp! Simply wonderful. I finally can enjoy my speakers. Those are 1.1m tall hybrid transmission line, 3 way built with satori drivers. Powerful, precise, clear and always soft and musical.
On this piece of Musica Nuda, a remake of Roxanne (https://tidal.com/browse/track/4523610), live recoding of great quality, I can hear the fingers attacking the cords of the contrabasso and all the vibrations of the cords ! And her voice..........
Music is perfectly balanced. There is nothing too strong nor weak.
Details are well present but it doesn't become analytical. With the applause, I have the feeling people are in my room... Incredibly realistic
Honeyview_Setup.jpg
 

pos

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While I perfectly understand your interest for efficiency at low levels, I don't really get the point with idling consumption. Is it because for whatever reason, you don't use the standby function?
Efficiency at low levels and idle come hand in hand, don't they. Looking at Hypex' efficiency curves for both their SPMS and amp modules, idle power consumption completely dominates any other variable when it comes to efficiency at "normal" listening levels.
 

kukocz

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Efficiency at low levels and idle come hand in hand, don't they. Looking at Hypex' efficiency curves for both their SPMS and amp modules, idle power consumption completely dominates any other variable when it comes to efficiency at "normal" listening levels.
I measured the SMPS1200A400 with Eval1 kit and there are the following:
  • SMPS in standby mode: ~10W
  • Eval1 kit operating (no music or music playing at low levels): ~24W
  • Eval1 standby (power stage off using S1): 20W
Is looks like even hypex SMPS standby mode is quite power consuming. I'm currently building my amp and really considering to use some relay with simple 5V switching power supply to go below 1W in standby mode.
 

MicroAudio

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Could you please share some specs on that SMPS, and the advantages compared to an hypex one?
What about the efficiency curve at low levels? What is the idle power consumption?

As the datasheet is still in progress and too busy assembling SMPS`s, I will do my best to get that data for you later at some stage.

Check the datasheet, and you will know the advantages.

I also would like to mention that HYPEX is a great company with great people and great products.

Thanks
 
D

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Thanks!
Well, today was the D-day :D
I'm just so happy, so amazed with the sound quality of that little amp! Simply wonderful. I finally can enjoy my speakers. Those are 1.1m tall hybrid transmission line, 3 way built with satori drivers. Powerful, precise, clear and always soft and musical.
On this piece of Musica Nuda, a remake of Roxanne (https://tidal.com/browse/track/4523610), live recoding of great quality, I can hear the fingers attacking the cords of the contrabasso and all the vibrations of the cords ! And her voice..........
Music is perfectly balanced. There is nothing too strong nor weak.
Details are well present but it doesn't become analytical. With the applause, I have the feeling people are in my room... Incredibly realisticView attachment 72443

Nice!
Try this version of Roxanne https://tidal.com/track/103856851
 

LondonLad

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Does anyone know how to add VU meters to this build? Or is that question deserving of its own thread?
 
OP
J

JimB

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Does anyone know how to add VU meters to this build? Or is that question deserving of its own thread?
I think the good information on this will not be specific to these types of amps. A new thread could be better to include more types of amps. Maybe something like “Adding VU meters to DIY Amps”?
 

kukocz

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An update.
Still no front power switch, leaving rear IEC switch on, switching using external power strip. Refreshingly quiet power up and down with barely a perceptible click out of 96dB/Wm speakers.
I also can hear noticeable “click” from speakers during power on cycle.
When S1 in EVAL1 is always on, clicking on power on cycle is audible. When I switch on S1 a while later manually then there is no click.
I also tested “amp enable” signal connected directly to SMPS. Clicking is also audible.
It looks like Purifi should be enabled a little bit later. I’m going to test that with additional relay with appropriate delay.
 

tlag

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I also can hear noticeable “click” from speakers during power on cycle.
When S1 in EVAL1 is always on, clicking on power on cycle is audible. When I switch on S1 a while later manually then there is no click.
I also tested “amp enable” signal connected directly to SMPS. Clicking is also audible.
It looks like Purifi should be enabled a little bit later. I’m going to test that with additional relay with appropriate delay.
Have you checked the output DC levels?
 

kukocz

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Have you checked the output DC levels?
R:-13.3mV
L:17.2mV
What is the maximum acceptable level?
Did you remove S1 for this test?
I switch it off duringThe test and amp enable signal enabled modules anyway. I performed similar test without S1 (I won’t use it in my project) and result is the same.

What interesting I also test the scenario where I connected amp enable signal manually (also through a relay) a few seconds after I turned on amplifier and clicking is also audible.
 

tlag

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R:-13.3mV
L:17.2mV
What is the maximum acceptable level?
Electrically, that's totally fine. Practically, depends on speaker/listener sensitivity, listening distance, and personal subjective threshold. With, say, 86dB/Wm speakers at 3ft, I would've thought it barely audible and not a big deal. But total guess; YMMV.

Edit: Just thought of something. Did you measure DC with input open or connected to upstream component? In the end, what matters is with it all hooked up.
 
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