audio-talk

Hope you get well soon Paul.

I want the 12V SMPS heater supply for another project I have in mind, so I decided to take it out of Amp no 45 and replace the heater supply with a bridge rectified DC supply off a 9V transformer. I figured that the light filament draw of only 900mA or so, would make a linear DC supply feasible and ...

Thanks chaps,
When I came to test it, I’d forgotten to put in the grid resistors for the output stages, which was quite interesting when it warmed up!
Eventually, I managed to figure out what I’d done, so I got there in the end.

The 1626s survived that particular slice of cruelty.

Got it finished:

Yep, I have a couple of Rod Coleman regs, but I think a DHT HPA with 45s will have to be a breadboard project, to make sure in the first instance, that I can get the noise down to silence before putting anything in a box. Meanwhile, Amp Number 45, which I know will be silent, is progressing nicely. ...

Keeping the things quiet would be the problem in a headphone amp.

Another headphone amp: IMG_0519.jpeg And looking back through my records, this appears to be my 45th amp, which, quite frankly, is fecking crazy, so the ‘45’ badge does mean something. The output transformers are Hammond 125FSEs which means they will drive 32 Ohm headphones ie the HiFiMan Sontara fr...

Great Prom last night with the BBC Concert Orchestra, playing the music of Henry Mancini, Burt Bacharach, Les Baxter, Esqivel and various other exponents of ‘Space Age Pop.’ Compere, Mel Giedroyc was a bit irritating, but the orchestra was superb and the music spoke for itself. Highly recommended fo...

Brazilian legend Sergio Mendes, best known for the worldwide, zillion selling “Mas Que Nada” has died aged 83.

I would also try standing signal ground off safety ground with another 100R (maybe with a bipass cap), see if that removes the need for transformers at the front. Thanks for that Nick. I no longer need the input transformers :) I added a 100nF bypass cap (maybe it should be 10nF?) in parallel with ...

Nick wrote: ↑Wed Aug 28, 2024 5:24 pm The pair of 100R to ground on the heater supply may still be worth doing.

OK Nick,
I'll try it tomorrow and see what happens.

Revised diagrams:

Remember when I said earlier in this thread that with this headphone amp, hum was almost completely absent with no music playing? Well I've since discovered that with headphones right next to one's ears, virtual silence between tracks is not good enough; absolute silence is the requirement, nothing ...

And so, the never-ending saga of the headphone amp continues: I have, I believe, got the best sounding version of the 1626 headphone amp so far. I've changed the input stage again; this time for a 12AX7 running at 1mA bias per triode. This means my HPA is almost the same as the Ampsandsound 'Kenzie'...

Cheers Mike.