audio-talk

Enjoy the music, Steve, that sounds like a good plan for staying off the slippery slope. Yeah that would have been nice; in fact it was very nice indeed...that is until last Thursday afternoon. The telly was on, Melanie was watching "Impossible," I was upstairs, not having turned the amp ...

Enjoy the music, Steve, that sounds like a good plan for staying off the slippery slope. The combination of this amplifier, the Mac Mini and the RTZ DAC (with the higher quality op-amps) is producing the best sound I’ve had in this room…ever! I think, trying to wring anything extra out of the amp m...

There is nothing simple, that can’t be made more complex. I needed to take a step back and ask myself if what I wanted to do was actually necessary? I seemed to be planning to up my solder connections, up the parts count, double my chances to make a mistake. Double my chances for failure, so I thoug...

Was going to go fixed bias (Gawd knows why.) Got all the way to building a pair of bias supplies. Tested them, they worked faultlessly then I wondered what I was playing at and thought, sod it!

Just enjoying the music instead.

I tried the silver mica caps from Simon, years ago. Didn’t like them I’m afraid: to call them screechy is being kind.

In the meantime, here is the newest version of the audio circuit:

I've fitted a dual 220uF, BG as the bypass cap(s) for the output stages and removed the bypasses from the input stage, which has reduced the gain, but the amp is so sensitive it's no great loss. It's the best I can do at the moment. Not tried it on music yet. That'll have to wait until later tonight...

Power supply now:

A layer of hash has been removed as it was last time. I have to ask. Did the layer of hash come back when you put the electrolytics back in last time? Yes, it was just a slight bit of fuzz around the treble. It's not a night and day difference with the motor runs in place but it's there nonetheless...

You knew I wouldn’t be able to resist didn’t you! :lol: :lol: :lol: :thumbright: And could you hear any difference? I'm guessing not as you didn't comment? Yep, there was a difference. I knew there would be as I'd commented before when I took the electrolytics out of the PSU. A layer of hash has be...

… I don't think I'd be able to resist trying the 80uF after the stacked lytics, to see if it sounds better than the electrolytics as the last cap in the audio circuit. :D You knew I wouldn’t be able to resist didn’t you! :lol: :lol: Enter 2 30uF 440VAC motor run caps in parallel, giving 60uF, which...

… the fading away thumping noise on switch off suggests low frequency oscillation. But not sure how. Could have been the PSU doing weird things, and amplified by the o/p stages. Just guessing. Aye it’s been a saga but I’m enjoying the fault finding and the general argy-bargy involved in wrestling r...

…I don't think I'd be able to resist trying the 80uF after the stacked lytics, to see if it sounds better than the electrolytics as the last cap in the audio circuit. :D Or I could just bung another blue LCR motor run in as the final cap and remove the electros altogether. Look…you’ve set me off ag...

Was getting more weirdness yesterday: a series of soft thumps at warmup and again on power-down. The thumps faded out as the HT drained away. I've finished up simplifying the power supply to a single channel but with an extra choke. Changed the rectifier to a GZ34 to keep the same voltages as before...

Hope everything works out Phil.