audio-talk

Good luck Ray . PMA to be applauded.

Thanks all. I'm relieved I'm not going completely mad (just a little). I'm scratching my head with the mains txs I have, trying to work out options.

Why are they so expensive to buy now? (Rhetorical question.)

Yep, I get that. Maybe I'm just making this too complicated, in my own mind at least.

But yes I suppose if a CT trafo is rated at say 200mA, the two secondaries in series would have a capacity of 200/1.61 = 124.2mA. Better than half anyway.

Not really, but thanks Max. It's permissible Iac of the secondary that's eluding me - I think it's half the rating because the full winding is in use all the time with bridge rectification, whereas each half winding is on then off then on again etc. so full current rating for full wave rectification ...

I'm having a moment and can't convince myself I'm correct. With a traditional centre tapped mains transformer intended for full wave rectification, if the whole of the secondary is used with bridge rectification the current capacity of the secondary should be halved (compared to full wave CT ...

My idea of low voltage GM70 is different to yours Paul - 500V to 600V - but I've been wondering about a Barker-style 6EM7 driver/cathode follower. Haven't done any serious thinking about it though.

pre65 wrote: Thu Nov 21, 2024 8:44 am

simon wrote: Thu Nov 21, 2024 8:20 am Power consumption was one of the reasons I moved away from GM70 - heating the filaments of two in SE was 200W alone.

Am I missing something ?

GM70 is 20v @ 3A = 60W x 2 = 120W

Plus regulator overhead

Power consumption was one of the reasons I moved away from GM70 - heating the filaments of two in SE was 200W alone. The low power amp (6W or so) drew nearly half a kilowatt.

After that 45SE feels positively low energy .

D'oh! Double d'oh!

I've only hand-soldered SMD, and it's okay if big enough, an oven is a different league.

It's an interesting implementation Tony, some food for thought. And I thought I recognised the signs of KiCad and JLCPCB?

I'd like to add a separate PS for the JLSounds I2SoverUSB too but my DAC chassis is full. I might have to draft some PCBs for more compact regs. I haven't made the switch to SMD ...

I dunno Nick, still looks like a shunt to me. The input is connected to the output, and the regulating bit sits under the output. That's what it looks like to me, but obviously isn't.

Hmmm, I'd missed the transistor in the LT3045, yes series.

I wasn't sure but thought the LT3097 might be shunt as there's a direct connection between in and out. There's a transistor as well in a parallel connection so I couldn't quite work it out.

I don't think you can go overboard . It's an impressive bit of shoehornery though, no doubt.

Looking at the datasheets the LT3045 and LT3097 are shunt regs? Have you ever compared them to the Jung/Didden superregs?

Which boards have the LT3097s? I can't see an obvious looking chip.

I'm sure it's in the thread somewhere, and that I've read it, but can you remind me what the power supplies are please Tony?