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DIY Purifi Amp builds

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Hi. I'm looking to buy a completed purifi amp but will need to run it from an Anthem AVR from phonos. What's the right way to wire balanced to phonos for this amp?
The sale is on here and includes a set of Mark Grant XLR L4E6S star quad balanced stereo cables. What's the best way to replace one end of them?
Thanks a lot
 

ABall

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You are right and sorry for my indefinite description; SMPS1200 J4.6 connects to EVAL1 J3.1 and SMPS1200 J4.10 to EVAL1 J3.3 it will give you soft start, eval board switch bypass features and SMPS can switch the power off when amplifier in trouble.

Same connectors contain +18V / -18V / GND for the eval board, just set jumpers to "unregulated power" on SMPS before use it;

SMPS1200 J4.1 -> EVAL1 J3.5 +18V
SMPS1200 J4.2 -> EVAL1 J3.6 GND
SMPS1200 J4.3 -> EVAL1 J3.7 -18V

5V DC supply; I did not use it, I had a 12-24V DC -> 5V DC supply in my electronic gadgets drawer :), so I use the SMPS 18V rail to feed external circuits with 5V and never let SMPS to go standby mode. If you have an AC 110-220V -> 5V DC supply, than you can do real standby mode.
Hi.
What du you mean by just set jumbers to "unregulated power" on SMPS. Does it mean that I have to do some soldering on both J6 and J7 (SMPS)?
Could you please add some nice picture of it?
 

Matias

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JimB

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Thread Starter #2,125
Hi.
What du you mean by just set jumbers to "unregulated power" on SMPS. Does it mean that I have to do some soldering on both J6 and J7 (SMPS)?
Could you please add some nice picture of it?
The positions of the jumper plugs on those pin headers - linking pins 2-3 on each one. The silkscreen pattern even shows instructions for this :

1614227613719.png
 

nimar

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I understand purifi says not to bridge their amps, but has anyone tried using two amps with bi-amp’able speakers?

Eg. left channel out of dac, y connector to both inputs, then one channel going to bass inputs, other to highs.

Or would balanced connections get out of whack going into two channels of an amp.

Edit. Never mind that 4x400 watts would also trip your average 1500watt plug. One assumes it would only get there at silly volumes.
 
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JimB

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Thread Starter #2,128
I understand purifi says not to bridge their amps, but has anyone tried using two amps with bi-amp’able speakers?

Eg. left channel out of dac, y connector to both inputs, then one channel going to bass inputs, other to highs.

Or would balanced connections get out of whack going into two channels of an amp.

Edit. Never mind that 4x400 watts would also trip your average 1500watt plug. One assumes it would only get there at silly volumes.
As I understand your question, there is no problem having both channels get the same input, and then having their two outputs go to range limited loads. Just don't invert the input to one of the two channels and then take a single output across the two positive terminals (no connection to ground).
 
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JimB

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Thread Starter #2,129
Has this been cited on this thread?

Purifi Class D: Junk?
https://forum.audiogon.com/discussi...=website&utm_source=sendgrid&utm_medium=email

Strictly FYI, from a satisfied Hypex NCore owner here.
A lot on nonsense there. Some of it is addressed in their replies. The Purifi is superb for purpose within it's rated power. Period. The equivalent amp, using the Purifi input buffer was reviewed on ASR here:
https://www.audiosciencereview.com/...easurements-of-purifi-1et400a-amplifier.7984/
 
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A lot on nonsense there. Some of it is addressed in their replies. The Purifi is superb for purpose within it's rated power. Period. The equivalent amp, using the Purifi input buffer was reviewed on ASR here:
https://www.audiosciencereview.com/...easurements-of-purifi-1et400a-amplifier.7984/
Quite a few defenders of “objective criteria” on this thread, and some even quoted ASR and reviews therein. AudioGon forum commenters - “the audiophile community” - very sensitive to the “subjectivist v objectivist” binary division, and it’s a hard crowd to work.
 
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JimB

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Quite a few defenders of “objective criteria” on this thread, and some even quoted ASR and reviews therein. AudioGon forum commenters - “the audiophile community” - very sensitive to the “subjectivist v objectivist” binary division, and it’s a hard crowd to work.
I'm certainly not going to entertain that in this topic (DIY Purifi builds). I will stand on my statement that the Purifi amps are far from junk regardless of any subjectivist claims to the contrary. I am confident that they would hold up well in any reasonably accepted listening test.
 
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Sorry if this sounds like a stupid question. Just been reading and catching up on the purify stuff. The cost of a putting a DIY together seems to be $1000 for Eval1 1et400 Stereo + $250 for Ghent audio kit + SMPS $250; totally $1500 appx. Vendors like VTV and Marchaudio are already selling in the same price range. What am I missing? Is this purely a fun project with not necessarily a saving angle? Thanks in advance. Also not sure if I should post this as a new thread.
 

Matias

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Sorry if this sounds like a stupid question. Just been reading and catching up on the purify stuff. The cost of a putting a DIY together seems to be $1000 for Eval1 1et400 Stereo + $250 for Ghent audio kit + SMPS $250; totally $1500 appx. Vendors like VTV and Marchaudio are already selling in the same price range. What am I missing? Is this purely a fun project with not necessarily a saving angle? Thanks in advance. Also not sure if I should post this as a new thread.
I reached the same conclusion a while ago.
 
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JimB

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Thread Starter #2,134
Sorry if this sounds like a stupid question. Just been reading and catching up on the purify stuff. The cost of a putting a DIY together seems to be $1000 for Eval1 1et400 Stereo + $250 for Ghent audio kit + SMPS $250; totally $1500 appx. Vendors like VTV and Marchaudio are already selling in the same price range. What am I missing? Is this purely a fun project with not necessarily a saving angle? Thanks in advance. Also not sure if I should post this as a new thread.
While the pricing is not quite a bad as you suggest, it is still true that you can buy one, built, for less than the DIY parts.
https://www.audiosciencereview.com/...purifi-1et400a-amp-modules.18273/#post-620060
 

nimar

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I built an eval-1 from parts and ordered the same from vtv. With import duties, exchange rates etc etc, it’s about 20% cheaper to go with VTV which boggles the mind but that’s the nature of doing things in bulk.
How do you feel about the VTV build quality? I know there have been some negative experiences with his other amps, but it seems like with the EVAL1 board there's less opportunity for issues.
 
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JimB

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I built an eval-1 from parts and ordered the same from vtv. With import duties, exchange rates etc etc, it’s about 20% cheaper to go with VTV which boggles the mind but that’s the nature of doing things in bulk.
Yes. And the discounts to the OEM still leave them enough money to be a profitable business.
 

nimar

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How do you feel about the VTV build quality? I know there have been some negative experiences with his other amps, but it seems like with the EVAL1 board there's less opportunity for issues.
Hasn’t arrived yet but will let you know when I get it. As far as I know the components are exactly the same. Eval-1, two iet400a boards and a hypex 1200 psu. Not really any build quality for VTV to get wrong or right. Just assembly and a couple cables.
 

nimar

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I got my VTV build, and if it wasn't already confirmed, its 100% a Ghent case. I wanted my face plates to match and originally thought I would just order a second VTV one, but they wanted $50 so instead got a plain one from Ghent for $35 (including shipping).

I am new to amp building (and arm chair electrician'ism to boot) and curious why the Ghent / VTV boards are wired slightly differently. Both are using pins 1-3, but Ghent cable is also using pins 5 and 7 while VTV isn't. Having voltage regulation sounds like a good thing, is there any reason VTV might have excluded this, and should I add these wires?

Screenshot 2021-03-03 at 11.19.26 AM.png


Ps. As for build quality, it all looks fine. The faceplate was screwed on rather hard, almost stripped the screws getting them out and the cable positions have already been discussed. And it looks to be using a filtered IEC inlet which may need to be replaced
 
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