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DIY Purifi Amp builds

phoenixdogfan

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Yes - measure straight at the pins on the SMPS itself. I don't think not having a ground connection would not matter to operation. DO measure the other voltages noted by @wineds.
Yes - measure straight at the pins on the SMPS itself. I don't think not having a ground connection would not matter to operation. DO measure the other voltages noted by @wineds.
Ok thanks will do. One more question: Should I just turn the SMPS on, leave it on for a time, and then measure the pins, or do I need to turn the amp on each time, have the meter probes already on the pins and observe what happens?
 
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JimB

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I'd just plant the probes in the contacts, then switch on and watch the reading.
 

raton78

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Here's 2 pair of mono's built with a SMPS 1200A400 power supply, Neurochrome IET400A buffer and IET400A amp module grafted into a ghent NC400 amp case each. Mods to the ghent case were very light - drill off & csk 12 holes in the base. Got some 50mm longer 10pin ribbons coming to tidy the routing. They run so cool they're barely above room temp and the detail revealed from the lack of noise floor is striking.
Hello Black_Flag,
great feedback!
I'm considering the exact same setup (smps1200a400, 1et400, neurochrome input buffer, ghentaudio ncore cases) to build 3 monoblocks and have some questions :
- what case did you exactly buy from ghentaudio? ncore-mx2, ncore-mx3, ... ?
- is there any particular reasons to put the SMPS in this position? Why didn't you reuse the pre-drilled holes in the ghentaudio case (90 degrees rotation) ? is it better in terms of thermal dissipation or EMI?
- did you use the hypex cable set? did you have to buy anything else (in addition of the 10pins ribbons)?
- are the XLR and speaker binding posts the default ones that come with the ghentaudio kit or did you put special ones?
that's quite a lot of questions actually :)
thank you and best wishes to you all!
Olivier
 

JaapDeventer

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Today I gave the Purifi Eval1 a go. Terribly shocked how loud is was.

I have a question about Eval1 J3. I connected Eval1 J3 5,6,7 to respectively SMPS1200 J5 3,5,7. What is the function of this connection?

Others have shown how to additionally connect Eval1 J3 1,3 to SMPS1200 J4 6,10. What is the function of the extra connections?

I did browse through the whole thread. Found a lot of how to's, but no answer to these questions.

Greetings,
Jaap

2021-01-09 14.00.32.jpg
 

KarVi71

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Today I gave the Purifi Eval1 a go. Terribly shocked how loud is was.

I have a question about Eval1 J3. I connected Eval1 J3 5,6,7 to respectively SMPS1200 J5 3,5,7. What is the function of this connection?

Others have shown how to additionally connect Eval1 J3 1,3 to SMPS1200 J4 6,10. What is the function of the extra connections?

I dont understand that you would be shocked, I don't find mine particularly loud?

But its allways a good idea to start at a low volume setting when using a new amp for the first time.

The connections can all be found in the documentation.

Here are my understandings of the connections.

The first 3 you mention are VAUX+, GND, and VAUX-
Basically power for the frontend's opamp circiutry.
Make sure you have the SMPS jumpers J6 and J7 set for unregulated VAUX, as the SMPS will otherwise supply to low a voltage. From the picture it seems to be right.

The last two are "Amp enable" and "DC error".

The first turns the amps on when the SMPS's voltages have stabilized, and the last reports back to the SMPS if the power amps are generating DC on the speaker terminals (or are otherwise malfunctioning), after which the SMPS will turn off to protect both the amps and your speakers.
These last two connections are not absolutely necessary, the amp will work without them.
 
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JaapDeventer

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Here are my understandings of the connections.

The first 3 you mention are VAUX+, GND, and VAUX-
Basically power for the frontend's opamp circiutry.
Make sure you have the SMPS jumpers J6 and J7 set for unregulated VAUX, as the SMPS will otherwise supply to low a voltage. From the picture it seems to be right.

The last two are "Amp enable" and "DC error".

The first turns the amps on when the SMPS's voltages have stabilized, and the last reports back to the SMPS if the power amps are generating DC on the speaker terminals (or are otherwise malfunctioning), after which the SMPS will turn of to protect both the amps and your speakers.

Thank you for the reply.
So the first are necessary for the Eval1 to output sound.

Amp Enable turns the Eval1 on after SMPS has stabilised. Using Amp Enable switch S1 is no longer required and can be removed?

DC Error can be connected for speaker protection. I understand this is advisable.
 
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NTSOS

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J4.jpg


I want to make sure.....for the SMPS J4 connector, is the top row of pins numbered 2-4-6-8-10 and the bottom row 1-3-5-7-9?

Is there anywhere else to connect J3's Pins 1 and 3, besides J4's Pins 6 and 10?

Thank you! :)

John
 
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JimB

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I want to make sure.....for the SMPS J4 connector, is the top row of pins numbered 2-4-6-8-10 and the bottom row 1-3-5-7-9?

Is there anywhere else to connect J3's Pins 1 and 3, besides J4's Pins 6 and 10?

Thank you! :)

John
Yes. And it's because the wires in the ribbon go 1-10, sequentially, across.

No. Why?
 
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JimB

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... The connections can all be found in the documentation. ... The last two are "Amp enable" and "DC error".

The first turns the amps on when the SMPS's voltages have stabilized, and the last reports back to the SMPS if the power amps are generating DC on the speaker terminals (or are otherwise malfunctioning), after which the SMPS will turn off to protect both the amps and your speakers.
These last two connections are not absolutely necessary, the amp will work without them.
Thanks for that. I would have said this was addressed, adequately, long ago (though maybe too hard to find these days):
https://www.audiosciencereview.com/...iy-purifi-amp-builds.10478/page-9#post-298679

But reading your reply, you have addressed why these signals are available, not just engineering names.
 

NTSOS

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Yes. And it's because the wires in the ribbon go 1-10, sequentially, across.

No. Why?

Ok, good.......no reason other than curiosity. Thank you Jim! :)
 
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JimB

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Thank you for the reply.
So the first are necessary for the Eval1 to output sound.

Amp Enable turns the Eval1 on after SMPS has stabilised. Using Amp Enable switch S1 is no longer required and can be removed?

DC Error can be connected for speaker protection. I understand this is advisable.
Yes, yes and yes. The extra two control interface signals are optional, and they are "pull-downs" (hence the n at the start of their names, for not). As noted long ago, the amp enable signal is wired with its input paths in parallel. Once you allow the power supply to pull down the signal, opening S1 does nothing - it is superfluous, but it does no harm, other to maybe mislead people that it will actually put the amp into standby, which is why I removed mine. There is a quick and easy way to remove it.
https://www.audiosciencereview.com/...y-purifi-amp-builds.10478/page-25#post-344882
https://www.audiosciencereview.com/...y-purifi-amp-builds.10478/page-25#post-344897
There is a lot in this DIY topic, so many over a year+, it's become hard to find everything you might want.

The amp should shut-down when power is bad, but adding the DC error line gives a definite signal to the amp to protect, immediately.
 

Aardappel

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Today I gave the Purifi Eval1 a go. Terribly shocked how loud is was.

I have a question about Eval1 J3. I connected Eval1 J3 5,6,7 to respectively SMPS1200 J5 3,5,7. What is the function of this connection?

Others have shown how to additionally connect Eval1 J3 1,3 to SMPS1200 J4 6,10. What is the function of the extra connections?

I did browse through the whole thread. Found a lot of how to's, but no answer to these questions.

Greetings,
Jaap

View attachment 104811
Hi Jaap,

You may want to step away from those banana plugs and throw them in the bin as they are ferrous/magnetic, having failed the magnet test.

Purifi themselves state:

Nearly all binding posts and/or banana plugs available we found to be magnetic and added measurable hysteric distortion. The cheapest plastic speakON passed the test. It seems that Benchmark Media Systems came to the same conclusion with their very low distortion AHB2 amplifier.

Source: https://www.soundstagehifi.com/index.php/opinion/1420-purifi-audios-pint-sized-powerhouses

Other than that, enjoy your amp!
 

NTSOS

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Hi Jaap,

You may want to step away from those banana plugs and throw them in the bin as they are ferrous/magnetic, having failed the magnet test.

Purifi themselves state:

Nearly all binding posts and/or banana plugs available we found to be magnetic and added measurable hysteric distortion. The cheapest plastic speakON passed the test. It seems that Benchmark Media Systems came to the same conclusion with their very low distortion AHB2 amplifier.

Source: https://www.soundstagehifi.com/index.php/opinion/1420-purifi-audios-pint-sized-powerhouses

Other than that, enjoy your amp!

When I read your post, I immediately ran out to the garage and retrieved a magnet and luckily the banana plugs I purchased on Amazon passed the test. Turns out they're gold plated copper with gold plated brass set screws and apparently the gold plating doesn't contain any iron, cobalt, or steel as the plugs did not react at all to the magnet. About $37 for a set of four.

Viborg VB401G Audio Pure Copper Gold Plated Banana Plug

Viborg VB401G Audio Pure Copper Gold Plated Banana Plug.jpg
 

w1000i

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When I read your post, I immediately ran out to the garage and retrieved a magnet and luckily the banana plugs I purchased on Amazon passed the test. Turns out they're gold plated copper with gold plated brass set screws and apparently the gold plating doesn't contain any iron, cobalt, or steel as the plugs did not react at all to the magnet. About $37 for a set of four.

Viborg VB401G Audio Pure Copper Gold Plated Banana Plug

View attachment 104981

This option is a complete set ( binding post & like banana plug )

Electra Cable Tube Connectors (gr-research.com)

Also
KLE Innovations Classic Harmony banana plugs (Set of 8) - Analogue Seduction
 
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JaapDeventer

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Desoldering tip for the Deltrons: Use a little solder to meld the solder on the pins quicker. Use a banana plug for leverage. Ease front pin down a little first. Then back pin a little (see picture). Then front pin loose. Then back pin loose. This was quick and easy. Where as using a vacuum pump didn't work at all.
20210110_112105.jpg
 
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JimB

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Desoldering tip for the Deltrons: Use a little solder to meld the solder on the pins quicker. Use a banana plug for leverage. Ease front pin down a little first. Then back pin a little (see picture). Then front pin loose. Then back pin loose. This was quick and easy. Where as using a vacuum pump didn't work at all.
Right! I found that, too (though I didn't use your good idea of adding a plug-handle :) - I used a Philips head screwdriver). You need good heat transfer to melt all the way down to the opposite trace, and that takes full wetting, with solder. If desired, one can vacuum and wick out the hole after removing the posts. Just be very careful not to apply too much pressure when working them out - you really don't want to tear out the via plating.
 
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NTSOS

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JimB

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Hi,

Finished my amp....yay, the last two connections added were /AMPON and /FATAL (Amp Enable and DC Error). I didn't add an on/off switch on the chassis, electing instead to use a wireless remote as I'm lazy. Waiting for speakers now.

John

https://pbase.com/iolair/image/171341630

https://pbase.com/iolair/image/171341629

https://pbase.com/iolair/image/171341631

https://pbase.com/iolair/image/171341632

https://pbase.com/iolair/image/171341636
I suspect your cooling will be adequate. :D

You are running it "inverted" - components down, rather than up, right? Did you use any thermal transfer paste under the SMPS and amp modules?

How will you remote control the power? Any plans for cosmetic modifications while waiting for speakers?
 
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NTSOS

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I suspect your cooling will be adequate. :D

You are running it "inverted" - components down, rather than up, right? Did you use any thermal transfer paste under the SMPS and amp modules?

How will you remote control the power? Any plans for cosmetic modifications while waiting for speakers?

Yes, the cooling should be adequate since it was originally designed to cool my Raptor stepper motor drivers. :)

No cosmetic mods for this one, I'm going to build two more cases for the mono-blocks and I will use either a glass beading finish or maybe a highly polished aluminum look or a powder coat.

Yes, I did use thermal paste.

I will use this remote.....click it and about two or three seconds the amps fire up after the SMPS voltages stabilize. Next two will also use a latching type button with the MicroAudio SMPS.

https://pbase.com/iolair/image/171341791

https://pbase.com/iolair/image/171341790
 

MicroAudio

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Yes, the cooling should be adequate since it was originally designed to cool my Raptor stepper motor drivers. :)

No cosmetic mods for this one, I'm going to build two more cases for the mono-blocks and I will use either a glass beading finish or maybe a highly polished aluminum look or a powder coat.

Yes, I did use thermal paste.

I will use this remote.....click it and about two or three seconds the amps fire up after the SMPS voltages stabilize. Next two will also use a latching type button with the MicroAudio SMPS.

https://pbase.com/iolair/image/171341791

https://pbase.com/iolair/image/171341790


Looking nice & clean setup.

But I still have doubts on that remote switch if it will survive the inrush current at each start up cycle on the long run.

Just to keep things safe!
 
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