Search found 10547 matches

by Cressy Snr
Fri Mar 29, 2024 10:35 pm
Forum: Everyones Projects
Topic: OK…so I’m on wi’ summat
Replies: 156
Views: 33294

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: 156
Views: 33294

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: 156
Views: 33294

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: 16446
Views: 4677821

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: 156
Views: 33294

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: 156
Views: 33294

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: 156
Views: 33294

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...
by Cressy Snr
Thu Mar 21, 2024 8:14 pm
Forum: Everyones Projects
Topic: OK…so I’m on wi’ summat
Replies: 156
Views: 33294

Re: OK…so I’m on wi’ summat

There's a lot more room in the chassis than in the Mk1 version of the amp, so, copying Paul, I purged the power supply of electrolytic caps by installing a nice pair of LCR motor run caps in place of the electrolytics that decoupled the input stages. Didn't think it would make a lot of difference, b...
by Cressy Snr
Mon Mar 18, 2024 10:48 am
Forum: Everyones Projects
Topic: OK…so I’m on wi’ summat
Replies: 156
Views: 33294

Re: OK…so I’m on wi’ summat

It’s back in the system after the cosmetic facelift and power supply upgrade.
Sounds great with the LCRCRC supply. Glad I searched out the 450V transformer, despite the head scratching over the primary phasing.
IMG_0389.jpeg
IMG_0389.jpeg (142.2 KiB) Viewed 495 times
by Cressy Snr
Sun Mar 17, 2024 7:41 pm
Forum: Everyones Projects
Topic: OK…so I’m on wi’ summat
Replies: 156
Views: 33294

Re: OK…so I’m on wi’ summat

Circuits:

1. Audio Circuit with measured voltages:
EL34Audiocct.png
EL34Audiocct.png (52.41 KiB) Viewed 590 times

2. Choke input power supply:
EL34LCinputPSU.png
EL34LCinputPSU.png (82.34 KiB) Viewed 590 times
by Cressy Snr
Sun Mar 17, 2024 7:38 pm
Forum: Everyones Projects
Topic: OK…so I’m on wi’ summat
Replies: 156
Views: 33294

Re: OK…so I’m on wi’ summat

Amp undergoing soak testing in the system.
Soaktesting.jpeg
Soaktesting.jpeg (161.48 KiB) Viewed 590 times
by Cressy Snr
Sun Mar 17, 2024 7:37 pm
Forum: Everyones Projects
Topic: OK…so I’m on wi’ summat
Replies: 156
Views: 33294

Re: OK…so I’m on wi’ summat

Thanks chaps.
Amp is finished. Last two jobs were to cable the input sockets to the selector switch and to put a reinforcing piece of anodised aluminium L section along the bottom edge of the rear panel, to match the one at the front:
Interior6.jpeg
Interior6.jpeg (143.69 KiB) Viewed 590 times
Rearpanel.jpeg
Rearpanel.jpeg (109.7 KiB) Viewed 590 times
by Cressy Snr
Sat Mar 16, 2024 8:22 pm
Forum: Everyones Projects
Topic: OK…so I’m on wi’ summat
Replies: 156
Views: 33294

Re: OK…so I’m on wi’ summat

All the circuitry is done. Just the four inputs to cable to the selector switch.
It all works and biases up correctly:
IMG_0380.jpeg
IMG_0380.jpeg (167.86 KiB) Viewed 701 times
IMG_0381.jpeg
IMG_0381.jpeg (100.04 KiB) Viewed 701 times
by Cressy Snr
Sat Mar 16, 2024 1:02 pm
Forum: Everyones Projects
Topic: OK…so I’m on wi’ summat
Replies: 156
Views: 33294

Re: OK…so I’m on wi’ summat

Cheers Ray.
Should be finished by Sunday.
by Cressy Snr
Fri Mar 15, 2024 9:17 pm
Forum: Everyones Projects
Topic: 6550 SE Amplifier
Replies: 110
Views: 9608

Re: 6550 SE Amplifier

👍