Brainstorming Purifi 1et400a amps

[Jaytor]

@jaaptina - I think the best way to eliminate the chance of a ground loop would be to use your 12v signal (with gnd) to engage a relay, and then use the relay to switch the SMPS1200. This way, you've completely isolated the 12V power from the amp circuitry.

[jaaptina]

Originally Posted by Jaytor

@jaaptina - I think the best way to eliminate the chance of a ground loop would be to use your 12v signal (with gnd) to engage a relay, and then use the relay to switch the SMPS1200. This way, you've completely isolated the 12V power from the amp circuitry.

But in that case I would need 12V on the clean side of the relay too wouldn't I? Or am I missing something?

[Jaytor]

You're right. I hadn't look at the spec and didn't realize you needed to apply a voltage to the standby. That's not very convenient.

I assume you are using the streamer power just to provide a source for 12V? I ended up adding a 12V power module in my amp for accessory power, but I had some other things to power.

https://www.mouser.com/ProductDetail...UXtDcd8w%3D%3D

[jaaptina]

Originally Posted by Jaytor

You're right. I hadn't look at the spec and didn't realize you needed to apply a voltage to the standby. That's not very convenient.

I assume you are using the streamer power just to provide a source for 12V? I ended up adding a 12V power module in my amp for accessory power, but I had some other things to power.

Yes, the smps standby only needs a little power. So I think the streamer adapter is able to power both. This way I circumvent the use of an extra adapter.

But you set me thinking. Its no different powering smps standby from internal Mouser 12V smps or external 12V smps. Both are connected to mains on one side and +12V and amp GND on the other side I think.

[Jaytor]

Yes. The only issue is if you are also connecting the external SMPS ground to the streamer as well, and the streamer has ground connections through audio interconnects, you will have ground loops. You'd have to try it out to see if this results in audible hum or distortion.

[jaaptina]

Technically it works fine. Smps turns off with 12V on J5.1 (smps standby) and turns on again 12V is disconnected. I have not tested with music on. 20210114_202338.jpg20210114_202356.jpg

[noviygera]

VTV is selling with a tube input possibility. If we wait maybe there will be tube input boards for sale?

[Jaytor]

These are already available if you want, but fairly expensive.

VTV Amplifier Custom Vacuum Tube Input Buffer — NEW! | VTV Amplifier

I'm thinking about doing a mono input board that will use a circuit based on Salas's DCG-3 line-stage (essentially using two channels for balanced). I think this would be a good match to the Purifi modules. I'm planning on making a PCB with the appropriate connectors to use the Purifi module and standard power connections. However, to get the best performance with this circuit, you'll need more than +/-12V.

[noviygera]

Maybe Hagerman Audio can make an input board. He is familiar with solid-state and tube circuits.

[barrows]

Originally Posted by Jaytor

These are already available if you want, but fairly expensive.

VTV Amplifier Custom Vacuum Tube Input Buffer — NEW! | VTV Amplifier

I'm thinking about doing a mono input board that will use a circuit based on Salas's DCG-3 line-stage (essentially using two channels for balanced). I think this would be a good match to the Purifi modules. I'm planning on making a PCB with the appropriate connectors to use the Purifi module and standard power connections. However, to get the best performance with this circuit, you'll need more than +/-12V.

No reason not to do this, just use a separate linear power supply for the needed rail voltages, and use the aux power from the SMPS just to power the input power needs of the Purifi modules.