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DIY Purifi Amp builds

shawnbd

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Hello everyone,
Here I share my Purifi Eval2 design plan. Thanks to Kim from Purifi for getting the module Eval2 smoothly.
The Design studied the pictures that shared before.
The basic design is as follows

1. Use TPS7A4700 3300 to adjust the AUX voltage from SMPS 1200A400 to +-15.
2. SMPS1200A400 HV+- connects to 8000uf capacitors as power supply bus pumping, and plans to upgrade to 15000uf each module in the future.
3 Speaker protection uses the UPC1237HA chip.
4. The traditional SOFT START solutions.
5. Trigger module and switch parts is still in the design
The test connection is successful.

My Dac is SMSL M400 and my Speaker is Kef R3, It sounds similar to my previous ICE POWER 50ASX2SE , but it’s clearer and more straightforward more power。
 

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boXem | audio

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Hello everyone,
Here I share my Purifi Eval2 design plan. Thanks to Kim from Purifi for getting the module Eval2 smoothly.
The Design studied the pictures that shared before.
The basic design is as follows

1. Use TPS7A4700 3300 to adjust the AUX voltage from SMPS 1200A400 to +-15.
Hello!
I guess this is not for Eval2 but for the other boards?
2. SMPS1200A400 HV+- connects to 8000uf capacitors as power supply bus pumping, and plans to upgrade to 15000uf each module in the future.
My understanding is that SMPS1200A400 is a 4 quadrant PS, thus not subjected to power supply pumping
3 Speaker protection uses the UPC1237HA chip.
This is already included in the 1ET400A
4. The traditional SOFT START solutions.
This is already included in the 1ET400A
5. Trigger module and switch parts is still in the design
The test connection is successful.

My Dac is SMSL M400 and my Speaker is Kef R3, It sounds similar to my previous ICE POWER 50ASX2SE , but it’s clearer and more straightforward more power。
Maybe simplifying your design by suppressing redundant functions a bit will allow a cleaner layout :).
 

shawnbd

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Hello!
I guess this is not for Eval2 but for the other boards?

My understanding is that SMPS1200A400 is a 4 quadrant PS, thus not subjected to power supply pumping

This is already included in the 1ET400A

This is already included in the 1ET400A

Maybe simplifying your design by suppressing redundant functions a bit will allow a cleaner layout :).
1. SMPS1200A400 Output Voltage Vaux are +20.5V -20.5V , I use the TPS7A4700 TPS7A43300 regulated to +15V, -15V, Eval2 asking the 15V input .

2. this idea come from ergo at #87
http://www.htguide.com/forum/showthread.php?44316-Purifi-class-D-amplifiers/page3.

3,4 Thx,Good advice, I didn't notice before
 

boXem | audio

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1. SMPS1200A400 Output Voltage Vaux are +20.5V -20.5V , I use the TPS7A4700 TPS7A43300 regulated to +15V, -15V, Eval2 asking the 15V input .
+/- 15V Typical, but maximum is +/- 25V, you do not need external regulators.
I could find why he did this, except the cool factor, which is a good reason when DIYing
3,4 Thx,Good advice, I didn't notice before
[/QUOTE]
You welcome :)
 
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1. SMPS1200A400 Output Voltage Vaux are +20.5V -20.5V , I use the TPS7A4700 TPS7A43300 regulated to +15V, -15V, Eval2 asking the 15V input .

2. this idea come from ergo at #87
http://www.htguide.com/forum/showthread.php?44316-Purifi-class-D-amplifiers/page3.

3,4 Thx,Good advice, I didn't notice before
Hopefully someone else will correct me if I'm wrong, but I believe the EVAL2 is expecting three different power inputs: power stage, gate drive, and unreg for the op amps. The A400 will output ~63V for power stage, 15.6 Vdc for gate drive, and 17Vdc-25Vdc for aux. This should all be in the ranges the EVAL2 is expecting for the matching inputs. Please take a look at the user guides for the EVAL2 (table 10) and 1200A400 to confirm, it should show the acceptable ranges.

I experienced poor results when I accidentally regulated Vaux feeding an EVAL1.
 

shawnbd

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Update from Purifi Kim
Eval2 have a transistor-zener preregulator before the LT30xx devices, so don‘t need to add an extra regulator, I can use the SMPS1200A400 with unregulated Vaux :).

in my case, I can sell my TPS7A4700 TPS7A43300 on ebay,
 
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JimB

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Thread Starter #2,089
Hopefully someone else will correct me if I'm wrong, but I believe the EVAL2 is expecting three different power inputs: power stage, gate drive, and unreg for the op amps. The A400 will output ~63V for power stage, 15.6 Vdc for gate drive, and 17Vdc-25Vdc for aux. This should all be in the ranges the EVAL2 is expecting for the matching inputs. Please take a look at the user guides for the EVAL2 (table 10) and 1200A400 to confirm, it should show the acceptable ranges.

I experienced poor results when I accidentally regulated Vaux feeding an EVAL1.
Right. The EVAL2 interface board is 'just' a single channel version of the EVAL1. I don't know if they degraded anything in the on-board regulator since it has to support only a single 1ET400A.
 
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JimB

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Update from Purifi Kim
Eval2 have a transistor-zener preregulator before the LT30xx devices, so don‘t need to add an extra regulator, I can use the SMPS1200A400 with unregulated Vaux :).

in my case, I can sell my TPS7A4700 TPS7A43300 on ebay,
Once it is done, let us now what your trigger solution is.
 
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Try a star-quad cable for analog mic applications, such as Canare L-4E6S. Many places offer good star-quad cables, including Ghent and Benchmark.
Not necessarily "a more audiophile choice ", it's more to do with its noise rejection and interference immunity properties. Wikepidia can explain it better than I can: https://en.wikipedia.org/wiki/Star_quad_cable :)
Thank you both very much. Today I have assembled the Canare star quad cables. The amp is dead silent now. It's unbelievable. The other cable was also a shielded Canare. Much thicker wires. But only two of them. Star quad really removes the mains hum. Now I can finally enjoy the amp. Thanks again .
 

Hogh

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I got all the main parts for my build; 2x1ET400A with Neurochrome input and a smps1200a400 and is now looking for a case to put it all in.

Im leaning towards the Mini Dissipante 2U 300mm placing the smtp against the heatsink on one side. The 300mm internal length
should just be enough for mounting both set sets of 1ET400A+buffer vertical on the other heatsink. Im thinking to put the two input buffers next to each other in the middel of the heatsink to keep them "away" from the high switching currents. This means one 1ET400A will have the little daughter board to toward the button and the other toward the top of the case.
Im thinking this should provide a good thermal solution and leave plenty of room for cabeling :)

Have anyone tried this approach or forsee any issues? Thanks

https://modushop.biz/site/index.php?route=product/product&path=284&product_id=725
 

LarsS

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I got all the main parts for my build; 2x1ET400A with Neurochrome input and a smps1200a400 and is now looking for a case to put it all in.

Im leaning towards the Mini Dissipante 2U 300mm placing the smtp against the heatsink on one side. The 300mm internal length
should just be enough for mounting both set sets of 1ET400A+buffer vertical on the other heatsink. Im thinking to put the two input buffers next to each other in the middel of the heatsink to keep them "away" from the high switching currents. This means one 1ET400A will have the little daughter board to toward the button and the other toward the top of the case.
Im thinking this should provide a good thermal solution and leave plenty of room for cabeling :)

Have anyone tried this approach or forsee any issues? Thanks

https://modushop.biz/site/index.php?route=product/product&path=284&product_id=725
Great idea, just go for it. You’ll solve challenges as you go, that’s what I did with my build ...
https://www.audiosciencereview.com/forum/index.php?threads/diy-purifi-amp-builds.10478/post-579018
 
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I got all the main parts for my build; 2x1ET400A with Neurochrome input and a smps1200a400 and is now looking for a case to put it all in.

Im leaning towards the Mini Dissipante 2U 300mm placing the smtp against the heatsink on one side. The 300mm internal length
should just be enough for mounting both set sets of 1ET400A+buffer vertical on the other heatsink. Im thinking to put the two input buffers next to each other in the middel of the heatsink to keep them "away" from the high switching currents. This means one 1ET400A will have the little daughter board to toward the button and the other toward the top of the case.
Im thinking this should provide a good thermal solution and leave plenty of room for cabeling :)

Have anyone tried this approach or forsee any issues? Thanks

https://modushop.biz/site/index.php?route=product/product&path=284&product_id=725
If this is a stereo build, why not use an EVAL1? Not that there's anything wrong with doing it differently, just wondering if you considered using the EVAL1 to make life easier. Results should be equal or superior and I think you can get the EVAL1 separately if you already own the amp modules.
 

Hogh

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If this is a stereo build, why not use an EVAL1? Not that there's anything wrong with doing it differently, just wondering if you considered using the EVAL1 to make life easier. Results should be equal or superior and I think you can get the EVAL1 separately if you already own the amp modules.
All the parts except the case are sitting on my desk so no going back on this approach. I did consider the Eval1 and even Eval2. I want SpeakOn and XLR and I wanted them proper mounted on the back panel without any way of stressing the PCB. Yes, I could desolder the Eval1 plugs and run a wire between the pcb and the plugs.. but the neurochrome buffer ticks all the boxes.

Less important; I also like that the neurochrome buffer can drive the 1ET400A to clipping with a single-ended signal (RCA). It looks like the EVAL2 copied the trick but then the price is about the same as neurochrome and I still would have to solder.
 

LarsS

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All the parts except the case are sitting on my desk so no going back on this approach. I did consider the Eval1 and even Eval2. I want SpeakOn and XLR and I wanted them proper mounted on the back panel without any way of stressing the PCB. Yes, I could desolder the Eval1 plugs and run a wire between the pcb and the plugs.. but the neurochrome buffer ticks all the boxes.

Less important; I also like that the neurochrome buffer can drive the 1ET400A to clipping with a single-ended signal (RCA). It looks like the EVAL2 copied the trick but then the price is about the same as neurochrome and I still would have to solder.
I’m very happy with my Neurochromes and you’ll get great support from @tomchr.
 
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