Search found 10585 matches

by Cressy Snr
Wed Apr 03, 2024 1:16 pm
Forum: Everyones Projects
Topic: OK…so I’m on wi’ summat
Replies: 195
Views: 47972

Re: OK…so I’m on wi’ summat

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.
by Cressy Snr
Sat Mar 30, 2024 9:12 pm
Forum: Everyones Projects
Topic: OK…so I’m on wi’ summat
Replies: 195
Views: 47972

Re: OK…so I’m on wi’ summat

I tried the silver mica caps from Simon, years ago. Didn’t like them I’m afraid: to call them screechy is being kind. :(
by Cressy Snr
Sat Mar 30, 2024 5:26 pm
Forum: Everyones Projects
Topic: OK…so I’m on wi’ summat
Replies: 195
Views: 47972

Re: OK…so I’m on wi’ summat

In the meantime, here is the newest version of the audio circuit:
EL34SEULNobypass.png
EL34SEULNobypass.png (52.58 KiB) Viewed 975 times
by Cressy Snr
Sat Mar 30, 2024 4:32 pm
Forum: Everyones Projects
Topic: OK…so I’m on wi’ summat
Replies: 195
Views: 47972

Re: OK…so I’m on wi’ summat

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...
by Cressy Snr
Sat Mar 30, 2024 2:38 pm
Forum: Everyones Projects
Topic: OK…so I’m on wi’ summat
Replies: 195
Views: 47972

Re: OK…so I’m on wi’ summat

Power supply now:
Screenshot 2024-03-30 at 18.25.55.png
Screenshot 2024-03-30 at 18.25.55.png (85.8 KiB) Viewed 963 times
by Cressy Snr
Sat Mar 30, 2024 2:36 pm
Forum: Everyones Projects
Topic: OK…so I’m on wi’ summat
Replies: 195
Views: 47972

Re: OK…so I’m on wi’ summat

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...
by Cressy Snr
Sat Mar 30, 2024 1:16 pm
Forum: Everyones Projects
Topic: OK…so I’m on wi’ summat
Replies: 195
Views: 47972

Re: OK…so I’m on wi’ summat

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...
by Cressy Snr
Sat Mar 30, 2024 11:10 am
Forum: Everyones Projects
Topic: OK…so I’m on wi’ summat
Replies: 195
Views: 47972

Re: OK…so I’m on wi’ summat

… 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...
by Cressy Snr
Fri Mar 29, 2024 10:35 pm
Forum: Everyones Projects
Topic: OK…so I’m on wi’ summat
Replies: 195
Views: 47972

Re: OK…so I’m on wi’ summat

… 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...
by Cressy Snr
Fri Mar 29, 2024 8:44 pm
Forum: Everyones Projects
Topic: OK…so I’m on wi’ summat
Replies: 195
Views: 47972

Re: OK…so I’m on wi’ summat

…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...
by Cressy Snr
Fri Mar 29, 2024 7:58 pm
Forum: Everyones Projects
Topic: OK…so I’m on wi’ summat
Replies: 195
Views: 47972

Re: OK…so I’m on wi’ summat

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...
by Cressy Snr
Wed Mar 27, 2024 7:52 pm
Forum: Assorted Stuff
Topic: Nothing In Particular
Replies: 16520
Views: 4902582

Re: Nothing In Particular

Hope everything works out Phil.
by Cressy Snr
Wed Mar 27, 2024 11:31 am
Forum: Everyones Projects
Topic: OK…so I’m on wi’ summat
Replies: 195
Views: 47972

Re: OK…so I’m on wi’ summat

Thanks for that Paul. I’ve started to realise that inadequately rated components and choke-input supplies don’t mix. It seems self-evident from the wobbler throwing telly, that the iron I have is not up to the job. A cap-input supply is perfectly adequate for my needs. The amp sounds great with the ...
by Cressy Snr
Tue Mar 26, 2024 8:51 pm
Forum: Everyones Projects
Topic: OK…so I’m on wi’ summat
Replies: 195
Views: 47972

Re: OK…so I’m on wi’ summat

So here are the mods: RC filters after the first cap now have 270R resistors as opposed to the previous 470R, which have been shifted onto the cathodes of the EL34s. EL34CinputPSU.png Because of the higher HT voltage, the OPT is now on the 5K tap, cathode resistor on the output valve has been change...
by Cressy Snr
Tue Mar 26, 2024 7:24 pm
Forum: Everyones Projects
Topic: OK…so I’m on wi’ summat
Replies: 195
Views: 47972

Re: OK…so I’m on wi’ summat

I don't know what the hell has been going on with this amp, but it was putting out some kind of electromagnetic pulse every time it was powered down. It has been doing this ever since I built it with the choke input supply. It got that bad on two occasions, that on power down, accompanied by a crack...