Heater Elevation/Relay Circuit

[Littlewyan]

I am currently designing an amp that will use a relay circuit for channel switching. The relay circuit has its own PSU (rectifier with a cap) and was going to run off of the Heater circuit (6.3VAC). The issue I've got, is I was going to elevate the heaters to minimise hum and buzz, however, In my head I can't see this working. If I elevate the heaters by attaching the heater centre tap to the HT through a voltage divider, will the relay circuit still work? Obviously it can only be grounded in once place and the HT is technically the 'ground' for the heater circuit.

What are your thoughts?

Will I have to abandon the heater elevation?

Is heater elevation even worth it or am I wasting my time there?

[TUBEDUDE]

As long as the relay supply negative reference is at the heater common it will work. But, your footswitch jack must be isolated. It isn't a good idea as there is the potential for trouble. If the footswitch contacts the chassis your elevation is grounded. It's even worse if you derive the elevation from the power tube cathodes (if cathode biased). The tubes will redplate.

[Littlewyan]

That is an excellent point. Even with an isolated jack, I still wouldn't be happy with that.

That brings us onto the next question. Is elevating the Heaters worth doing? Would I gain much by doing this? My other option would be to convert to DC just for V1 (My Transformer isn't man enough for all valves to be on DC) and run the relays off of that.

[erwin_ve]

At the Dumble section wer had some similar discussion; maybe this: https://ampgarage.com/forum/viewtopic.p ... 65#p398524

[TUBEDUDE]

I do it and have found good.noise reduction.

[hako]

I do it and have found good.noise reduction.

So do I, (almost) always. I use transformers with another 5 (not used rectifier tube) or 12V winding for the relay stuff, which works fine without hassle....

[Littlewyan]

Thanks for your help guys. I think I'm going to convert to DC for V1 and run the relay off of that. Ill know for sure once I've started to draw my layout.

[TUBEDUDE]

Unless your amp is a very high gain design the d.c. heater is overkill. Heater elevation should suffice. Heater elevation reduces the noise conducted from heater to cathode in ALL tubes, vs. the d.c. on V1 only.

[Littlewyan]

Sorry I thought I replied to this!

I am going with heater elevation, as like you say, it gives noise reduction on all valves.

As for the relays, I'm going to use this power supply I found on tube-town.net

https://www.tube-town.net/ttstore/Kits/ ... :8593.html