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DIY Purifi Amp builds

pos

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The DAC board is an idea floating in the air since a while now. The NC500 datasheet even provides schematics on how to interface a voltage out DAC to the NC500.
It's in my to-do list, one day maybe.
Yes something like a CS43198 (or two?) would be a good match!
 

starfly

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Interesting! I wonder why they would offer this. It is not required for amp module evaluation. Or is it? Does an (even) lower noise Vreg provide any amp output improvements? Otherwise, it is transitioning into a space they said they would not occupy - end user solutions. Anyway, I like it for odd-channel DIY builds (1, 3, 5). Price???

They didn't mention price, but I'll ask. This whole conversation started around me asking about what power supply they'd recommend for a 3 channel setup, and they said to essentially go for a SMPS1200A400 + SMPS600N400 for the third channel. I'm considering building a 3 channel amp with a capability to selectively disable the 3rd channel when I'm not using it, to lower power usage.

Anyway, they said it's easiest to get the EVAL1 + SMPS1200 and then to add a separate power supply + amp for the 3rd channel, and that's when they mentioned the mono input buffer they're releasing soon.
 

starfly

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OK, Purifi gave me a few more details regarding this mono input buffer, and I'll just copy and paste it here from the email they sent me. Pretty sure they won't mind, as if this were confidential they likely wouldn't have shared it with me. It's free marketing for them :)
  • 14dB SE/Ballanced gain stage based on OPA1612 with Panasonic thin film 0.1% resistors and Kemet NP0 linear capacitors.
    total system gain is 27dB as for the EVAL1 kit
  • Gain stage can be bypassed
  • Very low noise and low output impedance linear regulators for the gain stage and for analog circuits on the 1ET400 module
  • Available with XLR/Speakon connectors or without
Prices aren't final yet and they hope to have it on the webshop by early June. Their current thinking is a price of 150USD for the fully stuffed version and around 135USD without XLR/Speakon connectors.
The board is manufactured and tested in DK
 

starfly

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I'm starting to plan my build and will use one of those Hifi2000 cases, and I plan on getting the front and back-panel machined with some cutouts so I don't have to drill those myself.

I want to include the following features in this amp, but this is the first time I'll ever be building an amp so just want to confirm a few things and get some help if possible:

* Standby/On switch at the front of the case with a built-in LED to indicate when it's on - for this I need a separate power supply right? Is that a 5V power supply?
* Will start with 2 channels in a dual-mono config with Neurochrome input buffers using the SMPS1200A400, but will eventually add a 3rd channel when I need it. For this I want to add a toggle switch to the front that will eventually allow me to switch between 2ch mode and 3ch mode. 2ch mode would turn off power to the 3rd channel.
* Use Neutrik XLR sockets in the back
* Use 5-way binding posts in the back that accepts banana plugs as well
* Have 2x 12V Trigger Inputs > these will need to be connected to the same standby power-supply that I would use to turn on the amp from the front button right?

Any suggestions for good online stores (US) where a lot of these parts can be bought, such as XLR sockets, speaker binding posts, trigger inputs, power switches / buttons, 5V power supplies, etc? Yeah there's always Ebay, but you're never really sure what you're going to get there.
 
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JimB

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OK, Purifi gave me a few more details regarding this mono input buffer, and I'll just copy and paste it here from the email they sent me. Pretty sure they won't mind, as if this were confidential they likely wouldn't have shared it with me. It's free marketing for them :)
  • 14dB SE/Ballanced gain stage based on OPA1612 with Panasonic thin film 0.1% resistors and Kemet NP0 linear capacitors.
    total system gain is 27dB as for the EVAL1 kit
  • Gain stage can be bypassed
  • Very low noise and low output impedance linear regulators for the gain stage and for analog circuits on the 1ET400 module
  • Available with XLR/Speakon connectors or without
Prices aren't final yet and they hope to have it on the webshop by early June. Their current thinking is a price of 150USD for the fully stuffed version and around 135USD without XLR/Speakon connectors.
The board is manufactured and tested in DK
Thanks. So, quite a bit more expensive than the EVAL1 per channel. @tomchr should be pleased.
 

beren777

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Any suggestions for good online stores (US) where a lot of these parts can be bought, such as XLR sockets, speaker binding posts, trigger inputs, power switches / buttons, 5V power supplies, etc? Yeah there's always Ebay, but you're never really sure what you're going to get there.

Take a look at Mouser.com. Just try to get it all in one order to limit your shipping costs.
 

phoenixdogfan

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Finally finished my build. A 5 to 12V compatible trigger allows me to turn everything on with my Okto Dac remote. Trigger is implemented using a SFH619A Darlington opto coupler which was wired inline and covered with heatshrink tubing and mesh. Thanks to @JimM for the ideas.

View attachment 60767
I just noticed you are using the OCTO 8 with your Purifi build. Since you're doing that did you bypass the buffer on the Eval, and, if you did, did you have Pavel set the Octo to output something higher than 4V RMS, and, if so, what voltage did you have him set the Octo to output?
 

phoenixdogfan

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You can always connect the board to the back. use XLR connectors to the FE02's inputs, and wire them to the XLR sockets the GHENT case. Same for the speaker outs: use very tight z-plugs.
Jim, I ordered two pairs of z-plugs shown here.

https://www.ebay.com/itm/390145977702

I've never used the product before, so my question is how I attatch the wires to the z-plugs. Do I solder them? And which end do I insert the wire into, and how far? I'm thinking the open end or z-end goes into the 4mm opening on the purifi and the wires get placed in the closed end and either soldered or crimped into place. Is my understanding correct?

And my bining posts on the Ghent Chasis have no set screws for the wires, so it looks like I just solder them into the cup? That appears to be what you did on your Nc 400 build in the 200 mm Ghent case. Is that correct?
 

wineds

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I just noticed you are using the OCTO 8 with your Purifi build. Since you're doing that did you bypass the buffer on the Eval, and, if you did, did you have Pavel set the Octo to output something higher than 4V RMS, and, if so, what voltage did you have him set the Octo to output?

No I haven't bypassed the buffer. I am using 12db of room eq by convofs running on my clone synology nas. My speakers are troels dtqwt mk3 @94 db sensitivity. Most listening is with the dac at about -25db. -20db is quite loud so I have volume limited the dac to -15db max in the settings. Maybe I could bypass the buffer but I suspect it may not go loud enough if I do that?
 

SIY

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please try to bypass it ... and come back and tell us ...
you will see the scene take relief ... the voices are textured, the buffer is good, but without it is even better
Evidence for this claim?
 
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JimB

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Jim, I ordered two pairs of z-plugs shown here.

https://www.ebay.com/itm/390145977702

I've never used the product before, so my question is how I attatch the wires to the z-plugs. Do I solder them? And which end do I insert the wire into, and how far? I'm thinking the open end or z-end goes into the 4mm opening on the purifi and the wires get placed in the closed end and either soldered or crimped into place. Is my understanding correct?

And my bining posts on the Ghent Chasis have no set screws for the wires, so it looks like I just solder them into the cup? That appears to be what you did on your Nc 400 build in the 200 mm Ghent case. Is that correct?
I don't use Z plugs, but, solder the speaker cable inside the red zone, and insert the green zone into the socket:
1590074450800.png

Others might have more specific advise.

And yes, most binding posts I have seen in Ghent cases are solder cup.

Please give us some photos of how it all worked out once you are done. :)
 

phoenixdogfan

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I don't use Z plugs, but, solder the speaker cable inside the red zone, and insert the green zone into the socket:
View attachment 64642
Others might have more specific advise.

And yes, most binding posts I have seen in Ghent cases are solder cup.

Please give us some photos of how it all worked out once you are done. :)
Thanks. I've received the SMPS and reset it to unregulated, set the jumper for 115v, and assembled the main cable harnass, and the back panel of the chassis. All I need now is to get the bottom drilled for the eval 1, and I'll be able to complete assembly. After the Z-plugs arrive neve week, it won't take long at all.
 

phoenixdogfan

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No I haven't bypassed the buffer. I am using 12db of room eq by convofs running on my clone synology nas. My speakers are troels dtqwt mk3 @94 db sensitivity. Most listening is with the dac at about -25db. -20db is quite loud so I have volume limited the dac to -15db max in the settings. Maybe I could bypass the buffer but I suspect it may not go loud enough if I do that?
I can't verify that the heaven's will open up, but if I were you, I'd try it just to see what it sounded like, and if I had adequate gain using it that way.

If you don't already know it, Octo can set the gain on the Pro 8 all the way up to 17 volts (or anywhere between 4 an 17 for a small fee) which would ensure you could use the Eval 1 with the buffer bypassed and still get enough pristine voltage to drive it into clipping.
 

wineds

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I can't verify that the heaven's will open up, but if I were you, I'd try it just to see what it sounded like, and if I had adequate gain using it that way.

If you don't already know it, Octo can set the gain on the Pro 8 all the way up to 17 volts (or anywhere between 4 an 17 for a small fee) which would ensure you could use the Eval 1 with the buffer bypassed and still get enough pristine voltage to drive it into clipping.

Thanks I am aware of that. I think I may have mentioned it earlier in this thread or the okto thread. I may give it a shot this weekend.
 
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mocenigo

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Jim, I ordered two pairs of z-plugs shown here.

https://www.ebay.com/itm/390145977702

I've never used the product before, so my question is how I attatch the wires to the z-plugs. Do I solder them? And which end do I insert the wire into, and how far? I'm thinking the open end or z-end goes into the 4mm opening on the purifi and the wires get placed in the closed end and either soldered or crimped into place. Is my understanding correct?

And my bining posts on the Ghent Chasis have no set screws for the wires, so it looks like I just solder them into the cup? That appears to be what you did on your Nc 400 build in the 200 mm Ghent case. Is that correct?

When I was using the FE02, I crimped the cable to the Z-plug. But soldering should be better. Now I use a pair of boards (Neurochrome) in place of the single FE02 .
 

starfly

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I'm thinking of also using the Hypex soft-start module (DIYclassd.com) to go with the SMPS1200A400, as then standby power draw will be 1.2W vs. 9W without it. Also makes wiring up push-button+LED on the front pretty straightforward.

I also want to use a 12V trigger though, and I emailed Hypex about whether their soft-start modules supports that, and they said no. Does anyone here think it would still be possible to use a 12V trigger with this soft-start module?

And otherwise, is a soft-start module really necessary? It offers in-rush current protection. What is the risk of not using a soft-start module? Because without it there are some posts in this thread I can try to follow to still get the standby feature + push-button on front + 12V trigger to work.
 
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JimB

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I'm thinking of also using the Hypex soft-start module (DIYclassd.com) to go with the SMPS1200A400, as then standby power draw will be 1.2W vs. 9W without it. Also makes wiring up push-button+LED on the front pretty straightforward. ... And otherwise, is a soft-start module really necessary? It offers in-rush current protection. What is the risk of not using a soft-start module? ...
It is not normal to use this with an SMPS1200A400. It is certainly NOT necessary.
 
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