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Purifi / Triple Eval2 DIY power supply choice?

beren777

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If one were thinking of assembling a 3-channel Purifi amp out of three EVAL2 units, would a SMPS3KA400 be an appropriate power supply to use instead of wiring up three separate ~600W power supplies?

Would it make sense to try to mount the EVAL2's vertically to save width, or would that result in a unit that is too tall for common aesthetics? 35mm vs 59.5mm, but in reality you'd save less space because some of the savings would be taken up by a vertical mounting plate. It'd also result in the onboard XLR connector having its tab at the left or right instead of "top" unless you remove them from the board.
 

tomchr

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You should be able to run three 1ET400A from one SMPS1200A400. The SMPS3kA400 would be good too.

I put my 1ET400A build in a 90ish mm tall chassis. Looks great. The chassis has heat sinks along the side and I put the 1ET400A and the Neurochrome Purifi/Hypex Input Buffer on a small aluminum plate that I then mounted to the heat sink. That turned out pretty nice.

Tom
 

Matias

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VTV has done this with an SMPS3k and optionally an NC252MP for surrounds. Looks very nice.

https://vtvamplifier.com/product/vt...io-1et400a-amplifier-32-purifi-hypex-nc252mp/

IMG_8389.jpg
 
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beren777

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I saw this note in the SMPS3K product guide. Have you seen this cause a problem at listening levels any typical user will want?

"The SMPS3K is intended to power our range of high power amplifier modules, such as UcD2K and NC2K. As a
result, this SMPS product does not feature the 2-quadrant operation as most of our other SMPS products do.
Therefore, they are unable to handle large reverse currents generated by half-bridge amplifiers operated at
low frequencies. For this reason, it is not advisable to use this SMPS to power half bridge amplifiers like our
UcD700 and UcD400 modules when used in the frequency range below 100Hz. A workaround for this could be
using the UcD700/UcD400 in bridge mode, or reversing phase for half of the modules."

If I use 1 SMPS1200A400 for 3 Purifi modules:
  1. Would it be advisable to add a logic circuit which would read AMPON and FATAL on all three Purifi modules and pass through the appropriate signals? I'd want to make sure a failure on any single amp would shutdown power, and that the amps power on together with the SMPS.
  2. Do I need to do anything to prevent power backfeeding between the amp modules? I'll need to use a splitter to feed the 3 amps from one output on the SMPS (both for main and aux power), but do I need to plan on using diodes or something to isolate the amp modules from each other?
If I use 3 600W Hypex SMPS or 1 1200 + 1 600 instead, they'll be wired in parallel with the mains, right? Is it recommended to do anything to isolate the SMPS from each other?
 
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beren777

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So at the risk of showing off that I know absolutely nothing about PCB design, is something like this in the right direction for getting the three amps connected, short of wire nuts? Goal is to produce a 4 port B0GP-VL distribution board, 6 oz cu trace thickness, everything connected in parallel. Assumes no isolation needed here between the loads. SMPS connects to port 1, EVAL2's connect to ports 2-4, using the commonly available Ghent EVAL1 cables. I don't know, for example, if the ground pins need to be kept separate.

pcb-sample1.png
 

JimB

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You should be able to run three 1ET400A from one SMPS1200A400. The SMPS3kA400 would be good too.

I put my 1ET400A build in a 90ish mm tall chassis. Looks great. The chassis has heat sinks along the side and I put the 1ET400A and the Neurochrome Purifi/Hypex Input Buffer on a small aluminum plate that I then mounted to the heat sink. That turned out pretty nice.

Tom
Pictures, or it didn't happen! :D
 

tomchr

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So at the risk of showing off that I know absolutely nothing about PCB design, is something like this in the right direction for getting the three amps connected, short of wire nuts?
Looks like you have the dots connected. I would try to avoid the acid traps, though. Granted, those aren't the issue they used to be, but why push the process? You have an acid trap whenever you have an acute angle corner in the copper.

This may interest you: https://neurochrome.com/collections/connectors-parts/products/hypex-smps-splitter
SMPS_Splitter_1500x688.jpg




Pictures, or it didn't happen! :D
I'll get there. I plan to build a second amp as part of a "Here's How to Build a Purifi Amp" page for my website.

Tom
 
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beren777

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Looks like you have the dots connected. I would try to avoid the acid traps, though. Granted, those aren't the issue they used to be, but why push the process? You have an acid trap whenever you have an acute angle corner in the copper.

This may interest you: https://neurochrome.com/collections/connectors-parts/products/hypex-smps-splitter
SMPS_Splitter_1500x688.jpg





I'll get there. I plan to build a second amp as part of a "Here's How to Build a Purifi Amp" page for my website.

Tom

Thanks Tom! This is exactly what I was looking for. Is anyone making a board to safely consolidate the AMPON and FATAL signals? Or am I overthinking the complexity?
 

tomchr

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You don't need a board for that. Just make a ribbon cable that's long enough to reach all buffers and the power supply. You buy the cable and connectors and just press the connectors onto the cable.

Digikey is your friend in need:
Cable: 3M157815-5-ND (5 feet, 10-conductor, 0.050” pitch ribbon cable)
Connector: LKR10H-ND

Buy a few extra connectors in case you screw up.

Tom
 

crymencch

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I saw this note in the SMPS3K product guide. Have you seen this cause a problem at listening levels any typical user will want?

"The SMPS3K is intended to power our range of high power amplifier modules, such as UcD2K and NC2K. As a
result, this SMPS product does not feature the 2-quadrant operation as most of our other SMPS products do.
Therefore, they are unable to handle large reverse currents generated by half-bridge amplifiers operated at
low frequencies. For this reason, it is not advisable to use this SMPS to power half bridge amplifiers like our
UcD700 and UcD400 modules when used in the frequency range below 100Hz. A workaround for this could be
using the UcD700/UcD400 in bridge mode, or reversing phase for half of the modules."

If I use 1 SMPS1200A400 for 3 Purifi modules:
  1. Would it be advisable to add a logic circuit which would read AMPON and FATAL on all three Purifi modules and pass through the appropriate signals? I'd want to make sure a failure on any single amp would shutdown power, and that the amps power on together with the SMPS.
  2. Do I need to do anything to prevent power backfeeding between the amp modules? I'll need to use a splitter to feed the 3 amps from one output on the SMPS (both for main and aux power), but do I need to plan on using diodes or something to isolate the amp modules from each other?
If I use 3 600W Hypex SMPS or 1 1200 + 1 600 instead, they'll be wired in parallel with the mains, right? Is it recommended to do anything to isolate the SMPS from each other?
For future reference, I would like to confirm the SMPS3K is not suitable for the Purifi 1et400A.

I built a pair of LX521, a 4-way speaker with electronic crossover, which require 5 amps per channel. I chose to DIY with Purifi and took the convenience of using SMPS3K as it has 3 power outputs. The sound was great but the bass was not tight compare with my old amp. Worst of all, when I play louder, a bad distortion was heard from the woofer. I was thinking the Seas woofer unit and the Purifi should be better than that, then I found this thread. I overlooked the important note @beren777 stated above. Eventually, I changed the power supply driving the woofers to SMPS1200A400 and everything works well.
 
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JimB

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For future reference, I would like to confirm the SMPS3K is not suitable for the Purifi 1et400A.

I built a pair of LX521, a 4-way speaker with electronic crossover, which require 5 amps per channel. I chose to DIY with Purifi and took the convenience of using SMPS3K as it has 3 power outputs. The sound was great but the bass was not tight compare with my old amp. Worst of all, when I play louder, a bad distortion was heard from the woofer. I was thinking the Seas woofer unit and the Purifi should be better than that, then I found this thread. I overlooked the important note @beren777 stated above. Eventually, I changed the power supply driving the woofers to SMPS1200A400 and everything works well.
Can you tell us how you connected the modules and power supplies for 5 channels per speaker? I have Orion 3.2 and am now down to three amps per channel (paralleled tweeters and the midrange on an Benchmark AHB2 and woofers paralleled with a monoblock Hypex NC400, so two AHB2s and two NC400s).
 

crymencch

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I built 2 sets of 2x EVAL1 (stereo) + 1x EVAL2 (mono) modules in a chassis for 5 channels with the SMPS3K which has 3 power output. Now added 1 SMPS1200 per chassis for the woofer section.
 

crymencch

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BTW, I did not try the suggested solution of reversing phase for half of the modules as the EVAL1 for woofers are in separate chassises.
 

JimB

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I built 2 sets of 2x EVAL1 (stereo) + 1x EVAL2 (mono) modules in a chassis for 5 channels with the SMPS3K which has 3 power output. Now added 1 SMPS1200 per chassis for the woofer section.
Has the added PSU solved your bass distortion problem?
 

JimB

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Looks like you have the dots connected. I would try to avoid the acid traps, though. Granted, those aren't the issue they used to be, but why push the process? You have an acid trap whenever you have an acute angle corner in the copper.

This may interest you: https://neurochrome.com/collections/connectors-parts/products/hypex-smps-splitter
SMPS_Splitter_1500x688.jpg





I'll get there. I plan to build a second amp as part of a "Here's How to Build a Purifi Amp" page for my website.

Tom
How's your build-an-amp page coming, Tom?
 

tomchr

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olbobcat

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For future reference, I would like to confirm the SMPS3K is not suitable for the Purifi 1et400A.

I built a pair of LX521, a 4-way speaker with electronic crossover, which require 5 amps per channel. I chose to DIY with Purifi and took the convenience of using SMPS3K as it has 3 power outputs. The sound was great but the bass was not tight compare with my old amp. Worst of all, when I play louder, a bad distortion was heard from the woofer. I was thinking the Seas woofer unit and the Purifi should be better than that, then I found this thread. I overlooked the important note @beren777 stated above. Eventually, I changed the power supply driving the woofers to SMPS1200A400 and everything works well.
I wanted to have a four-channel Purifi for bi-amp speakers. VTV list this very amp on his website and a picture of the 3k power supply being tapped with two outputs coming off the one plug. I was considering buying this Amp and upgrading the buffers to the Neurochrome later if I felt I needed to. It seems pretty cost-effective to me. Now you got me thinking that I better ask them some questions.
 

fluid

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Can you tell us how you connected the modules and power supplies for 5 channels per speaker? I have Orion 3.2 and am now down to three amps per channel (paralleled tweeters and the midrange on an Benchmark AHB2 and woofers paralleled with a monoblock Hypex NC400, so two AHB2s and two NC400s).
I made an 8 output Hypex UcD based amp for my LX521, I only ever used it as 3 way even though I added the extra amp to make it four way. Woofers were paralleled to UcD400.

2 x SMPS1200 power supplies, I used the lower voltage ones so all the amps could use the same supplies. P.S I like Tom's amp's more.

Power supply bus pumping could be mitigated by wiring different channels out phase but 2 x SMPS 1200 seems a better solution that avoids the issue entirely.

If you make your own cables by buying the JST crimps and housings you can get three or four cables into one of the biggest gauge crimp terminals. No super expensive crimp tool is needed just a decent type that rolls the sides in not just crush them. Only one amp was daisy chained, the rest ran back the power supply.

IMG_0219.jpg


IMG_0220.jpg
 
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