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DIY Purifi Amp builds

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Are you referring to pin 1 of the XLR receptacle? Pin 1 of XLR is used only for connecting the cable shield to the chassis. It is not intended for signal.
Blue to the right, white to the bottom and shielded wire to the left (Ground), nAMPON to the gound. I might not say it right in terms of pin number.
 

PaulD

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The pin numbers are critical. Perhaps you should post photos.
As mSpot said - the pin numbers are critical - CRITICAL. In the link I can see at least one pin number on the rear of the socket. You need to refer to the pin numbers, no left-right business which is open to misunderstanding depending on how you look at it.

The standard for XLR cables is:
Pin 1: "Ground" or signal braid and chassis earth (smallest path)
Pin 2: "Signal +"
Pin 3: "Signal -"
 

NTK

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Here is a picture of the XLR connector with pin numbers. Looks like the signal connectors are OK.

XLR pinouts.jpg


Do you have a multimeter? Can you check the cable to make sure:
1. Connector J9 pin 1 (input signal +ve) is connected to XLR pin 2
2. Connector J9 pin 2 (input signal -ve) is connected to XLR pin 3
3. Connector J9 pin 4 (GND) is connected to XLR pin 1

With the NC400 module to the XLR receptacle cable connected, check:
4. Connector J9 pin 3 (nAMPON) is shorted to chassis, and the NC400 module mounting screws are also shorted to the chassis

NC400.PNG


[Edit] For step 4 above, I think it is easier to check (with the module to XLR cable installed)
4. From the back of the connector, J9 pin 3 and J9 pin 4 are shorted to each other
5. They are also shorted to the module mount screw, and to the chassis
7_nc400.jpg
 
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SMPS1200 jumpers must be set to unregulated.
The default is unregulated - I don't really understand what the manual said in this. So I should change J6 and J7 both to position 2-3? What is "fitted with HxR voltage regulators"?

I also shorted J3 because I'm in United States. Default J3 is open.

1617508589823.png
 
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Here is a picture of the XLR connector with pin numbers. Looks like the signal connectors are OK.

View attachment 121877

Do you have a multimeter? Can you check the cable to make sure:
1. Connector J9 pin 1 (input signal +ve) is connected to XLR pin 2
2. Connector J9 pin 2 (input signal -ve) is connected to XLR pin 3
3. Connector J9 pin 4 (GND) is connected to XLR pin 1

With the NC400 module to the XLR receptacle cable connected, check:
4. Connector J9 pin 3 (nAMPON) is shorted to chassis, and the NC400 module mounting screws are also shorted to the chassis

View attachment 121874

[Edit] For step 4 above, I think it is easier to check (with the module to XLR cable installed)
4. From the back of the connector, J9 pin 3 and J9 pin 4 are shorted to each other
5. They are also shorted to the module mount screw, and to the chassis
View attachment 121892
This is how I connected - green is the shielded ground from XLR. It is shorted with the nAMPON JP9.3 (Black from the left side to XLR) Initially I did this wrong.

IMG_8806.jpg
 

boXem | audio

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The default is unregulated - I don't really understand what the manual said in this. So I should change J6 and J7 both to position 2-3? What is "fitted with HxR voltage regulators"?

I also shorted J3 because I'm in United States. Default J3 is open.

View attachment 121910
Default is regulated. Install the jumpers to get unregulated as indicated on the PCB side to the jumpers.
HRx are Hypex voltage regulators. They are embedded on the NC400.
J3 shorting is good.
 
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Default is regulated. Install the jumpers to get unregulated as indicated on the PCB side to the jumpers.
HRx are Hypex voltage regulators. They are embedded on the NC400.
J3 shorting is good.
It is ..... WORKING!!!!!

I should let it run a while before I close the case? Anything I need to pay special attention to? The volume in my Emotiva was at 60-70 (Win10) with Emo's volume at 40. Now I can only do 10 under Win 10.
 

boXem | audio

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It is ..... WORKING!!!!!

I should let it run a while before I close the case? Anything I need to pay special attention to? The volume in my Emotiva was at 60-70 (Win10) with Emo's volume at 40. Now I can only do 10 under Win 10.
Well, double check that no connection is loose, then close and pay a lot of attention to enjoy the music.;)
 
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So If I have RCA source.....

My Denon 4500 has only RCA source (no XLR). Could I use RCA to XLR cables? Or is that a no-no?

Or let me ask this way, is it possible to build RCA input for NC400?
 

lealoureiro

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Hello, I'm quite new in this forum as you can see from my number of posts :)

After reading all this thread, I decided to embrace the adventure of trying to build my own Power Amp as well, based on Purifi 1ET400A and Hypex SMPS1200A400. I'm a software developer and like to play with embedded systems however my knowledge regarding electronics is still a bit limited! Alltough I started to learn a bit more recently.

My idea is to connect the amp to a digital pre-amp like the Matrix Audio MINI-I 3 PRO by XLR (4.1VRMS) and use loudspeakers about 87dB of sensitivity. Not planning to use single-ended RCAs.

After reading the thread so far, I'm still not sure if I should go for EVAL1 using the FE02 Input Board or Neurochrome 1ET400A Input Buffer Board. Are there any major differences on sound quality etc or something else to consider? I don't need the S1 switch in FE02 and I want to use "normal" binding posts, and to be honest I don't feel very confident in unsoldering the onboard switch and banana connectors. The Neurochrome Input Buffer seems more flexible in that regard (also placement of the components). I'm still not very familiar with regarding how to match components... The input source for the amp should play a role on decision which input board to chose?

Regarding the case I'm planning to use the Modus GX388 330 x 280, with custom holes for XLR connects, binding posts etc.

I'm also planning to use a Microcontroller to interface the Amp over the Network (like some REST API). Something like a Arduino or Raspberry Pico. I'm planning also to place a push button with LED to turn on the amp, in front of the case, connected to this Microcontroller. I don't need 12V trigger. Still researching for a good Microcontroller with support for Ethernet using network cable since I don't feel good stuffing a WiFi chip inside the amp. And to achieve this, I believe I should use another external 12Vdc power supply.

I would like to interface the Amp modules using i2c (Software Mode) as it seems to be have cool stuff to play with including the main "turn on amp" feature as in hardware mode. I read that using FE02 some resistors need to solder to set the i2c addresses of the modules. Someone here already played with it? What could be the wiring to connect the Microcontroller to the i2C interface of the modules assuming both are on 3.3 Logic levels? Does the Neurochrome input buffer board also supports this?

Really sorry for the long post, but I'm just starting and there is so much information to gather and research, hope my ideas are not to much ambitious :)

I would be more than happy to share my progress and my designs the moment I start building it :)
 

LarsS

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Hello, I'm quite new in this forum as you can see from my number of posts :)

After reading all this thread, I decided to embrace the adventure of trying to build my own Power Amp as well, based on Purifi 1ET400A and Hypex SMPS1200A400. I'm a software developer and like to play with embedded systems however my knowledge regarding electronics is still a bit limited! Alltough I started to learn a bit more recently.

My idea is to connect the amp to a digital pre-amp like the Matrix Audio MINI-I 3 PRO by XLR (4.1VRMS) and use loudspeakers about 87dB of sensitivity. Not planning to use single-ended RCAs.

After reading the thread so far, I'm still not sure if I should go for EVAL1 using the FE02 Input Board or Neurochrome 1ET400A Input Buffer Board. Are there any major differences on sound quality etc or something else to consider? I don't need the S1 switch in FE02 and I want to use "normal" binding posts, and to be honest I don't feel very confident in unsoldering the onboard switch and banana connectors. The Neurochrome Input Buffer seems more flexible in that regard (also placement of the components). I'm still not very familiar with regarding how to match components... The input source for the amp should play a role on decision which input board to chose?

Regarding the case I'm planning to use the Modus GX388 330 x 280, with custom holes for XLR connects, binding posts etc.

I'm also planning to use a Microcontroller to interface the Amp over the Network (like some REST API). Something like a Arduino or Raspberry Pico. I'm planning also to place a push button with LED to turn on the amp, in front of the case, connected to this Microcontroller. I don't need 12V trigger. Still researching for a good Microcontroller with support for Ethernet using network cable since I don't feel good stuffing a WiFi chip inside the amp. And to achieve this, I believe I should use another external 12Vdc power supply.

I would like to interface the Amp modules using i2c (Software Mode) as it seems to be have cool stuff to play with including the main "turn on amp" feature as in hardware mode. I read that using FE02 some resistors need to solder to set the i2c addresses of the modules. Someone here already played with it? What could be the wiring to connect the Microcontroller to the i2C interface of the modules assuming both are on 3.3 Logic levels? Does the Neurochrome input buffer board also supports this?

Really sorry for the long post, but I'm just starting and there is so much information to gather and research, hope my ideas are not to much ambitious :)

I would be more than happy to share my progress and my designs the moment I start building it :)
Researched how to implement Software mode when I built my amp https://www.audiosciencereview.com/forum/index.php?threads/diy-purifi-amp-builds.10478/post-579018 without luck! So just went ahead with HW mode. There’s tons of useful information to retrieve in SW mode, not so much control (4 bits to set). Would be really cool if you succeed, wish you luck!
 

lealoureiro

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Researched how to implement Software mode when I built my amp https://www.audiosciencereview.com/forum/index.php?threads/diy-purifi-amp-builds.10478/post-579018 without luck! So just went ahead with HW mode. There’s tons of useful information to retrieve in SW mode, not so much control (4 bits to set). Would be really cool if you succeed, wish you luck!
I see you also used the Neurochrome Input boards. How did you tried to make the i2c connection? I can't find datasheet for those boards, to see the pinout.

Assuming the Microcontroller is 3.3v Logic Level, and then you connect SDA, SDC and GNDs and don't connect the Voltage pins?
 

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