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DIY Purifi Amp builds
- Thread starter JimB
- Start date
Same as this. Except Ground is on the third pin from the left. nAMPON is the far right. Ground and nAMPON connected together.
https://www.diyaudio.com/forums/construction-tips/345855-nc400-xlr-advice-please.html
https://www.diyaudio.com/forums/construction-tips/345855-nc400-xlr-advice-please.html
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 -"
The standard for XLR cables is:
Pin 1: "Ground" or signal braid and chassis earth (smallest path)
Pin 2: "Signal +"
Pin 3: "Signal -"
Here is a picture of the XLR connector with pin numbers. Looks like the signal connectors are OK.
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
[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
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
[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
Last edited:
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
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
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
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
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