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Can an amateur DIY a Purifi monoblock or 3 channel?

Skyflexion

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Long time lurker and only today plucked up the courage to make an account and ask a question. Apologies in advance if this has been asked and answered before/elsewhere. I am currently rocking a very - very old AV receiver and am considering moving on to the Denon 3700 (4k/120 is not relevant to me), with external amplification for my 5 channel setup. One of the things I am looking into is DIYing either a triplet of mono-block or a single 3 channel purifi amp for the LCRs - with suitable input buffers (if that's the right term) to enable the RCA ~2V outputs from the AVR to drive the amp(s) to full power. I have tried to read through the Purifi DIY thread, but got very quickly lost.

I recognize that this is not easy/convenient DIY - but it's a thing I would like to experience doing if feasible. Hence my humble request for guidance to the people on here who know much more than me. Even if it is to say I really shouldn't be trying it :)

I think there are bits of the puzzle I have google-figured out, but I suspect I am missing the forest for the trees. Essentially - I believe the key components I need would be
  1. Purifi modules x3
  2. Input buffer x3 - I believe Neurochrome sells these for my use case - i.e. support lower voltage - unbalanced inputs
  3. Power supply(ies) - such as 1x SMPS3kA400 or 3x SMPS1200A400
There are many pieces of the puzzle I have no good ideas on
  1. Cases - I see Ghent does a case for the eval but none for monoblocks - so no idea how one goes about adapting a bare shell to one's requirements
  2. Heat sinks
  3. XLR/RCA inputs/selectors
  4. Everything else I am clueless about.
Ultimately, I could just suck it up and buy something off-the-shelf. But a quick check seemed to at least be worth it. I have some experience with DIY speaker builds and general "wrenching". So while not an expert - I am confident I can be lego assembly level competent quite quickly. So any guidance or pointers of how I can build something to call my own would be very welcome. Thanks!!
 

ctbarker32

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Unless, you have connections I don't know about, I don't think you will be able to DIY more cheaply than just buying an amp from VTV Purifi.
 

levimax

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Long time lurker and only today plucked up the courage to make an account and ask a question. Apologies in advance if this has been asked and answered before/elsewhere. I am currently rocking a very - very old AV receiver and am considering moving on to the Denon 3700 (4k/120 is not relevant to me), with external amplification for my 5 channel setup. One of the things I am looking into is DIYing either a triplet of mono-block or a single 3 channel purifi amp for the LCRs - with suitable input buffers (if that's the right term) to enable the RCA ~2V outputs from the AVR to drive the amp(s) to full power. I have tried to read through the Purifi DIY thread, but got very quickly lost.

I recognize that this is not easy/convenient DIY - but it's a thing I would like to experience doing if feasible. Hence my humble request for guidance to the people on here who know much more than me. Even if it is to say I really shouldn't be trying it :)

I think there are bits of the puzzle I have google-figured out, but I suspect I am missing the forest for the trees. Essentially - I believe the key components I need would be
  1. Purifi modules x3
  2. Input buffer x3 - I believe Neurochrome sells these for my use case - i.e. support lower voltage - unbalanced inputs
  3. Power supply(ies) - such as 1x SMPS3kA400 or 3x SMPS1200A400
There are many pieces of the puzzle I have no good ideas on
  1. Cases - I see Ghent does a case for the eval but none for monoblocks - so no idea how one goes about adapting a bare shell to one's requirements
  2. Heat sinks
  3. XLR/RCA inputs/selectors
  4. Everything else I am clueless about.
Ultimately, I could just suck it up and buy something off-the-shelf. But a quick check seemed to at least be worth it. I have some experience with DIY speaker builds and general "wrenching". So while not an expert - I am confident I can be lego assembly level competent quite quickly. So any guidance or pointers of how I can build something to call my own would be very welcome. Thanks!!

I really enjoy DIY and especially DIY power amps because they are dangerous and exciting but they are NOT where DIY people usually start for the same reasons. Usually a pre-amp or headphone amp is a better first project because of the lower voltages and power involved. None the less a built like you are talking about, mounting and wiring up some pre-made modules, is about as easy as a power amp can get. By far the hardest part of any DIY build is the case. I usually get dimensions of all the parts and lay them out as I want to figure what size case I need and then start hunting on ebay for a case that will work. There "may" be some pre-made cases (Google is your friend) but the ebay cases from China are hard to beat on quality and price but you are going to have to do a lot of planning and drilling to use them and figure out the hardware and stand offs and the like. The layout of components is also very important to how quiet the amp ultimately is. So even though it is an "easy" build there is still a lot to consider. You also won't save money on your first project.... the savings on DIY come later after you have built several projects and built up an inventory of components and hardware and can "add features" for free or re-use cases and the like.

Bottom line is research everything as much as possible before you start. There is a lot of information on line... some good some bad but the information is there. Check out Elliot Sound Products for general information and DIY audio..... you may be able to find people that have all ready done what you want and have documented the process. Most importantly you are going to be dealing with potentially deadly voltage and current so read up on it and if you not comfortable start with something else.

Hope this helps and have fun.
 
OP
S

Skyflexion

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Unless, you have connections I don't know about, I don't think you will be able to DIY more cheaply than just buying an amp from VTV Purifi.

Absolutely have no connections: so that's good insight to have.

I really enjoy DIY and especially DIY power amps because they are dangerous and exciting but they are NOT where DIY people usually start for the same reasons. Usually a pre-amp or headphone amp is a better first project because of the lower voltages and power involved. None the less a built like you are talking about, mounting and wiring up some pre-made modules, is about as easy as a power amp can get. By far the hardest part of any DIY build is the case. I usually get dimensions of all the parts and lay them out as I want to figure what size case I need and then start hunting on ebay for a case that will work. There "may" be some pre-made cases (Google is your friend) but the ebay cases from China are hard to beat on quality and price but you are going to have to do a lot of planning and drilling to use them and figure out the hardware and stand offs and the like. The layout of components is also very important to how quiet the amp ultimately is. So even though it is an "easy" build there is still a lot to consider. You also won't save money on your first project.... the savings on DIY come later after you have built several projects and built up an inventory of components and hardware and can "add features" for free or re-use cases and the like.

Bottom line is research everything as much as possible before you start. There is a lot of information on line... some good some bad but the information is there. Check out Elliot Sound Products for general information and DIY audio..... you may be able to find people that have all ready done what you want and have documented the process. Most importantly you are going to be dealing with potentially deadly voltage and current so read up on it and if you not comfortable start with something else.

Hope this helps and have fun.

Thanks for the encouragement, and good perspective. The whole matter of life and death, is something to give me pause :) . Nonetheless, I will continue to poke around. At minimum, I will get an education.
 
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  1. Purifi modules x3
  2. Input buffer x3 - I believe Neurochrome sells these for my use case - i.e. support lower voltage - unbalanced inputs
  3. Power supply(ies) - such as 1x SMPS3kA400 or 3x SMPS1200A400

That's pretty much it right there. The only real DIY part of the build is the case, as you rightly recognize, the rest is plugging in connectors. I think levimax has good recommendations for the case.

You'll be perfectly fine with a single SMPS1200A400, the purifi modules don't come close to pulling that much power, just do your research on how to wire it up properly with three power modules.

Far be it for me to downplay the potential dangers of mains voltage, but as far as builds go, this is on the low risk side end of the spectrum. Stop an think before you do something and you'll be fine.

Cheers,
Seb
 
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Skyflexion

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That's pretty much it right there. The only real DIY part of the build is the case, as you rightly recognize, the rest is plugging in connectors. I think levimax has a good recommendations for the case.

You'll be perfectly fine with a single SMPS1200A400, the purifi modules don't come close to pulling that much power, just do your research on how to wire it up properly with three power modules.

Far be it for me to downplay the potential dangers of mains voltage, but as far as builds go, this is on the low risk side end of the spectrum. Stop an think before you do something and you'll be fine.

Cheers,
Seb

Thank you Seb, great input and yes - stopping and thinking is good life advice in general :)

As a point of clarification - did you mean that a single SMPS1200A400 would suffice for a 3 channel build - and if yes, by extension, does that mean that a single SMPS3kA400 would be 'bullet-proof' for my intended use case. Just trying to understand if these things scale linearly or if there are other considerations that start to factor in. Thank you!
 
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Well, from the Purifi datasheet, one 1ET400 has a maximum output power of 425 W into 4 Ohm at a minimum efficiency of 94 %. That gives you a maximal potential power draw of 452 W, x3 is ~1350 W. Ok, I should have done the numbers before I posted.

Now, would there ever be a real life situation where both front channels and the centre were pulling full power? I don't know, but none of us are in this hobby because we like things just good enough...

All the datasheets are available from Hypex and Purifi, I've been reading through them again, particularly the Hypex SMPS1200 datasheet, section 7. 1200 W is the output at which the power supply takes 10 s to heat up to 95°C. That's with no additional cooling. Continuous output with no cooling at 95°C stabilized temperature is 325 W. So it's really more a thernal management consideration than a power one.

I think conceivably, for a home theatre application, if you have low efficiency 4 Ohm speakers running full range and you like things really, really loud and you're watching an action movie with all sorts of planes, explosions, snakes, Vin Diesels and the like, you might just hit the termal limits of the SMPS1200.

So yeah, I guess the SMPS3k would give you piece of mind. What is the price difference between the two anyway?

Cheers,
Seb
 
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Skyflexion

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Well, from the Purifi datasheet, one 1ET400 has a maximum output power of 425 W into 4 Ohm at a minimum efficiency of 94 %. That gives you a maximal potential power draw of 452 W, x3 is ~1350 W. Ok, I should have done the numbers before I posted.

Now, would there ever be a real life situation where both front channels and the centre were pulling full power? I don't know, but none of us are in this hobby because we like things just good enough...

All the datasheets are available from Hypex and Purifi, I've been reading through them again, particularly the Hypex SMPS1200 datasheet, section 7. 1200 W is the output at which the power supply takes 10 s to heat up to 95°C. That's with no additional cooling. Continuous output with no cooling at 95°C stabilized temperature is 325 W. So it's really more a thernal management consideration than a power one.

I think conceivably, for a home theatre application, if you have low efficiency 4 Ohm speakers running full range and you like things really, really loud and you're watching an action movie with all sorts of planes, explosions, snakes, Vin Diesels and the like, you might just hit the termal limits of the SMPS1200.

So yeah, I guess the SMPS3k would give you piece of mind. What it the price difference between the two anyway?

Cheers,
Seb

You sir, are a gentleman and a scholar! Thank you so very much for the insight. The price difference is about EUR 70 between the two. Honestly, the thing that draws me to the 3000 is the fact that there are 3 molex looking connectors on the 3000 that I guess would plug in directly to the neurachrome buffer boards. This way - it's a little more lego for someone like me - as against figuring out how to shuffle around 1 power cable to the three buffer boards. Onwards to more research.
 
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I'm glad you found my input useful!

Honestly, the thing that draws me to the 3000 is the fact that there are 3 molex looking connectors on the 3000 that I guess would plug in directly to the neurachrome buffer boards.

I completely understand, that alone would be worth the 70 € to me as well.

Cheers,
Seb
 

NTK

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Ghent offers a mono case that should fit an SMPS-1200 (or SMPS-600) and a Purifi 1ET400A with a buffer board. You will most likely have to drill some holes to mount the Purifi board and buffer. Below are pictures from Ghent showing how an NC500 and NC1200 with PS will fit inside the case. The case, however, says N-core on its face plate.
http://ghentaudio.com/kit/ncore-mx.html

smps600-nc500.jpg
smps1200-nc1200.jpg
 
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Skyflexion

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Ghent offers a mono case that should fit an SMPS-1200 (or SMPS-600) and a Purifi 1ET400A with a buffer board. You will most likely have to drill some holes to mount the Purifi board and buffer. Below are pictures from Ghent showing how an NC500 and NC1200 with PS will fit inside the case. The case, however, says N-core on its face plate.
http://ghentaudio.com/kit/ncore-mx.html

View attachment 96500 View attachment 96501
Thanks, I will check it out. Not too sussed about the badge
 

phoenixdogfan

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Absolutely have no connections: so that's good insight to have.



Thanks for the encouragement, and good perspective. The whole matter of life and death, is something to give me pause :) . Nonetheless, I will continue to poke around. At minimum, I will get an education.
If you need 3 channels, you could do the Eval 1+Hypex SMPS1200+ Ghent Case for two of them and buy a VTV Monoblock for the third channel. I personally don't think it's worth trying to beat the performance of the Eval 1, and I haven't seen anything documented anywhere that beats it for the Purifi modules.

Lots of claims, but no measurements to back them up.
 
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Skyflexion

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If you need 3 channels, you could do the Eval 1+Hypex SMPS1200+ Ghent Case for two of them and buy a VTV Monoblock for the third channel. I personally don't think it's worth trying to beat the performance of the Eval 1, and I haven't seen anything documented anywhere that beats it for the Purifi modules.

Lots of claims, but no measurements to back them up.

Thanks for the perspective @phoenixdogfan - I will look into the details :)
 

tomchr

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The Purifi amps tend to come together pretty easily. There are two wires that need to connect to the mains. The brown one goes to the terminal marked L (live) and the blue goes to the one marked N (neutral). Then the 6-pin power harness connects to the input buffer (pin 1 to pin 1, 2 to 2, etc.). The aux power supply needs to be brought over as well. That's done by a 10-pin ribbon cable. Then all you need to do is to connect up the input XLR connector and speaker outputs.

While the project is somewhat costly and does carry some risk, most will be able to complete an amp successfully. If you have some car repair experience and can assemble IKEA furniture without stabbing yourself with the screwdriver, you should be good. :)

The ModuShop chassis are pretty decent for DIY work.

Tom
 
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Skyflexion

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The Purifi amps tend to come together pretty easily. There are two wires that need to connect to the mains. The brown one goes to the terminal marked L (live) and the blue goes to the one marked N (neutral). Then the 6-pin power harness connects to the input buffer (pin 1 to pin 1, 2 to 2, etc.). The aux power supply needs to be brought over as well. That's done by a 10-pin ribbon cable. Then all you need to do is to connect up the input XLR connector and speaker outputs.

While the project is somewhat costly and does carry some risk, most will be able to complete an amp successfully. If you have some car repair experience and can assemble IKEA furniture without stabbing yourself with the screwdriver, you should be good. :)

The ModuShop chassis are pretty decent for DIY work.

Tom

Thanks Tom. I am halfway confident about not stabbing myself with a screwdriver - so will keep at it. :)
 

JimB

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In addition to the DIY single input buffer from @tomchr, Purifi has now posted their single channel input buffer in the EVAL2 'kit' in their web store. It seems to be the same as the stereo EVAL1, but just a single channel. Is it better? The regulator supplies only one channel, etc.. Single channel inputs lend themselves to odd numbers of channels, 1, 3, 5, (7?), with corresponding challenges for power supplies, cabling and cases.
https://purifi-audio.com/vare/eval2/

The datasheet is available in the link on the product page:
https://purifi-audio.com/eigentakt/eval2/

As with other single channel solutions, a 2-channel amp built with two EVAL2s is quite a bit more expensive than a single EVAL1.
 
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JimB

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From @phoenixdogfan: The natural accompaniements are, I think, the Hypex SMPS600SN400 and a Hypex adapted mono case, or, if you want to make a 3 channel amp, an adaptation of the 300 mm case I bought. Hope Ghent get a case and hook up wire out there with all deliberate speed.

The very best thing, of course, would be for Purifi to make their own power supplies. That would enable them to put together easy to assemble DIY kits, the same way Hypex does.
 
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JimB

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From @phoenixdogfan:
The natural accompaniements are, I think, the Hypex SMPS600SN400 and a Hypex adapted mono case, or, if you want to make a 3 channel amp, an adaptation of the 300 mm case I bought. Hope Ghent get a case and hook up wire out there with all deliberate speed.

The very best thing, of course, would be for Purifi to make their own power supplies. That would enable them to put together easy to assemble DIY kits, the same way Hypex does.
The EVAL2 is even 'longer' than the EVAL1! With the Hypex SMPS600N400 in the 'crosswise' orientation that you would imagine for a GHENT mono case, it is still reasonable. But, in a 3-or-more channel case, you would want the SMPS to be rotated, and then the case length becomes - BIG.

I have considered using a single Hypex SMPS1200A400 for 3 channels (center and rear surrounds), which would suffice for my purposes. I started specific details of how that could be done in a reasonable adaptation of a Ghent 300mm wide case of common depth, including heat dissipation optimization schemes. I'm not sure I'll follow through just yet, as I'm still waiting for MY first Ghent cases (just binding posts, maybe available on their site by end of December) to build my own Purifi amps! Initially, I'll be using two stereo amps to power my three channels.
 
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JimB

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I think Ghent will start work on a mono case for the EVAL2 in the near future, but I have no information other than that someone (not I) will be loaning them an EVAL2 set to inspect. I don't know, but I would imagine they would drill the case bottom for both the Hypex SMPS1200A00 and the Hypex SMPS600N400 in a long (~315-330 mm?) Ncore-mx style case:
http://www.ghentaudio.com/kit/ncore-mx.html

It would be overkill on power supply and heat dissipation. Some people should like that. :D
 

tomchr

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Purifi has now posted their single channel input buffer in the EVAL2 'kit' in their web store.
Based on the prices of the 1ET400A and the EVAL2, the EVAL2 buffer is DKK 907 (USD 148). Looks like I hit the pricing on my Purifi/Hypex Buffer spot on then. :) I charge $129/each (QTY 1) with discounts starting at QTY 2 ($125/each for a stereo pair).

I would expect the EVAL2 to provide identical performance to the EVAL1.

Tom
 
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