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DIY Purifi Amp builds

mocenigo

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WELL! I find that interesting. Has anyone confirmed that these work as intended on the 1ET400A? And if so, will Hypex sell them for DIY?

I strongly doubt that they would (indirectly) help the competition
 

Massimo

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- SMPS1200 has Amp Ena and Amp Err I/O pins, these are compatible with Purifi Amp Ena and Err pins. If you connect them, these will replace the on/off switch on the eval board (not necessary to desolder that) and you can do soft power on/off from SMPS.

Can you please clarify how the standby mode operates. I'm reading the application notes on an iPhone so difficult to make out.
As I understand it, SMPS1200 J4.6 connects to EVAL1 J3.1 and SMPS1200 J4.10 to EVAL1 J3.3?
And 5V DC supply is connected to SMPS1200 J5.1 and J5.5?
Thanks, M
 
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pos

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I am curious. What happened?
I was consistently getting high pitch tones, whith slightly different pitch for different amps (I had four in total) and sources...
These were AMS1000 modules operating in bridged mode.
 

March Audio

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Beside the reciprocal trolling/agenda aspects here, I would still be interested in seeing that nc500 evaluation board measured.
IIRC at least the first nc500 offering (from Nord and the like, but also from boutique vendors) were using that board, probably unmodified.

Does the purifi evaluation board also have the same so-called limitations?
After all it is marketed as an "evaluation platform" just like the nc500 one.
In a simple test set up it will measure OK, nothing wrong with the op amp itself. The problem you have is it has no GBW limitation or input filtering. Without feedback caps it is wide open frequency response. Put it in a real world situation and you can see problems, RF, or other out of band noise (dacs) / IM. It will be unpredictable and many have commented on it sounding not great.

Other issue is the voltage regs. Assuming you are using the Hypex smps, simple 7812s have limited rejection at the switching frequency.
 
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Massimo

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In a simple test set up it will measure OK, nothing wrong with the op amp itself. The problem you have is it has no GBW limitation or input filtering. Without feedback caps it is wide open frequency response. Put it in a real world situation ad you can see problems, RF, or other out of band noise / IM. It will be unpredictable and many have commented on it sounding not great.

That's odd. I have not seen any comments about the Purifi modules with the eval board not sounding great. Can you please share a link.
 

Massimo

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I am referring to the Hypex Nc500 eval board that pos asked how it measured. The Purifi is fine in my experience.

Thanks for clarifying since pos asked "Does the purifi evaluation board also have the same so-called limitations?"
 

March Audio

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I was consistently getting high pitch tones, whith slightly different pitch for different amps (I had four in total) and sources...
These were AMS1000 modules operating in bridged mode.
Did they go away when you turned your dac off (I'm assuming directly connected)
 

pos

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Not sure anymore, but at least I think it was silent when the source was unplugged or the input was shorted.
 

Dudi

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Can you please clarify how the standby mode operates. I'm reading the application notes on an iPhone so difficult to make out.
As I understand it, SMPS1200 J4.6 connects to EVAL1 J3.1 and SMPS1200 J4.10 to EVAL1 J3.3?
And 5V DC supply is connected to SMPS1200 J5.1 and J5.5?
Thanks, M

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.
 

Dudi

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Thanks for clarifying since pos asked "Does the purifi evaluation board also have the same so-called limitations?"

Please let me to take a note about, Purifi eval board become very noisy when the DAC/source was disconnected, I don't know how it picks up that noise. It reduced to a very small hiss when source connected to the board. In normal use it is not an issue I guess.
 

Massimo

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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.

Thanks Dudi for the confirmation.
 
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March Audio

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Not sure anymore, but at least I think it was silent when the source was unplugged or the input was shorted.
Although this is conjecture as I am not familiar with the ams modules, It's possible in that case that is the problem I am describing with an unfiltered input. HF Dac noise.
 

BobPM

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Has anyone made any progress on one of these builds? I am trying to get a list of items to purchase and would appreciate any thoughts on additional items I might need.

From the Purif Shop, the 1ET400A Eval kit for DKK4700 (about $705 US);
from Hypex DIYclassD, the SMPS1200A400 for 180 euro (~ $200); and
from Ghent audio, the NCORE-SE(300W) case for $230 - its a little wider.

I will likely add the Purif cable for DKK75.00 (~$22.50). Not sure how much of the Ghent kit will be useful so may need additional cabling. Any other ideas? I know Hypex sells a softstart module, but not sure if its needed.

Also, can anyone tell me if there is a reason to use (or not) the SMPS1200A700 instead of the A400?

Thanks
 

mocenigo

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[...] can anyone tell me if there is a reason to use (or not) the SMPS1200A700 instead of the A400?

The SMPS1200A700 outputs +-85V. The 1ET400A module needs +-65V, which is what the SMPS1200A400 delivers.

Roberto
 
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JimB

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The SMPS1200A700 outputs +-85V. The 1ET400A module needs +-65V, which is what the SMPS1200A400 delivers.

Roberto
Right. The officially recommended values for the 1ET400A are +65V. They will not operate beyond 75V.
 
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JimB

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Has anyone made any progress on one of these builds? I am trying to get a list of items to purchase and would appreciate any thoughts on additional items I might need.

From the Purif Shop, the 1ET400A Eval kit for DKK4700 (about $705 US);
from Hypex DIYclassD, the SMPS1200A400 for 180 euro (~ $200); and
from Ghent audio, the NCORE-SE(300W) case for $230 - its a little wider.

I will likely add the Purif cable for DKK75.00 (~$22.50). Not sure how much of the Ghent kit will be useful so may need additional cabling. Any other ideas? I know Hypex sells a softstart module, but not sure if its needed.

Also, can anyone tell me if there is a reason to use (or not) the SMPS1200A700 instead of the A400?

Thanks
Good start. I do know that the Purifi cable set includes the housings for the SMPS1200A400 ends of the cables - you just have to insert the free, crimped ends into the proper holes. They do NOT include two free wires for the (highly recommended!) nampON and nFATAL connections described by Dudi:
https://www.audiosciencereview.com/...iy-purifi-amp-builds.10478/page-7#post-293025

That Ghent case (which I have) does support the SMPS1200 and will get switched power to it, but it does not accommodate this build, directly. Are you prepared to do your own mounting holes, and cabling to the back panel connectors? And have the front panel say ncore? I do believe Ghent will offer at least one good case option for us (hopefully, at least two), but I have not seen anything specific from them yet. Does anyone else have newer information on this?
 
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BobPM

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Adding the mounting holes seems easy enough, but I am not sure about the cabling to the back panel. I am unclear as to how those connections should go.

Is it likely that Ghent will have a Purifi case ready in the next month or so? I gave my old amp to my son and really need something soon.

Having NCORE on the case doesn't bother me since this equipment is really just for me, although I can see a small amount of false advertising since I will be using the Purif modules.
 
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