Search found 5599 matches

by simon
Fri Feb 09, 2024 10:55 pm
Forum: Valves
Topic: Valve amplifier service
Replies: 176
Views: 84666

Re: Valve amplifier service

I'm not sure I really understand the full circuit - there appears to be two circuit ground connections to mains supply ground. One through the bridge, R and C - the other from the bridge via a cap. Is the single cap C14 to allow ripple currents in the bridge to have an easy path to mains supply eart...
by simon
Fri Feb 09, 2024 10:49 pm
Forum: Everyones Projects
Topic: C3g Aikido Phono
Replies: 319
Views: 81866

Re: C3g Aikido Phono

Will do. It'll be a journey of discovery! Maybe.
by simon
Fri Feb 09, 2024 8:22 pm
Forum: Valves
Topic: Valve amplifier service
Replies: 176
Views: 84666

Re: Valve amplifier service

Found the Tubecad blog which has values

https://www.tubecad.com/2019/11/blog0482.htm
by simon
Fri Feb 09, 2024 8:19 pm
Forum: Valves
Topic: Valve amplifier service
Replies: 176
Views: 84666

Re: Valve amplifier service

My gut feeling is lifting the amp ground might well solve some problems, but it's a bit of an involved job.

That looks like it's a Tubecad dwg? Any suggestions for values of the cap and resistor? I think I might use this in my amps rather than a simple resistor.
by simon
Fri Feb 09, 2024 8:14 pm
Forum: Everyones Projects
Topic: C3g Aikido Phono
Replies: 319
Views: 81866

Re: C3g Aikido Phono

Good points, I do struggle to think in terms of current. Took me long enough with voltage! Any suggested reading? I probably need something at the basic end to start...
by simon
Fri Feb 09, 2024 8:45 am
Forum: Everyones Projects
Topic: C3g Aikido Phono
Replies: 319
Views: 81866

Re: C3g Aikido Phono

Thanks Steven, you're not wrong. Expert advice from Nick was required!
by simon
Thu Feb 08, 2024 7:43 pm
Forum: Everyones Projects
Topic: C3g Aikido Phono
Replies: 319
Views: 81866

Re: C3g Aikido Phono

Thanks Mike :-)
by simon
Wed Feb 07, 2024 11:04 pm
Forum: Everyones Projects
Topic: C3g Aikido Phono
Replies: 319
Views: 81866

Re: C3g Aikido Phono

No, pressing the cans doesn't make any difference. But this time I approached the amp from the other side of the amp and the buzz seems to be coming from the one of the transformers. This would make a lot more sense. Doubting myself I listened from the other side again and sure enough it sounded lik...
by simon
Wed Feb 07, 2024 9:21 pm
Forum: Everyones Projects
Topic: C3g Aikido Phono
Replies: 319
Views: 81866

Re: C3g Aikido Phono

There was some mechanical buzzing though. It seemed to be coming from the audio section/valves but I didn't want to get my head too close tbh. I used a probe to see if I could feel any vibration anywhere but couldn't. I think it might be coming from one or both C3gs. It doesn't feel like a good thin...
by simon
Wed Feb 07, 2024 9:18 pm
Forum: Everyones Projects
Topic: C3g Aikido Phono
Replies: 319
Views: 81866

Re: C3g Aikido Phono

This has been on a back-burner whilst the humming amp has been with me but I took it to Nick's this weekend and had a good chat about it and the earthing "challenges". I learnt a lot! I made a few amendments to the wiring and placement of the transformers. Two boards would probably be best...
by simon
Tue Feb 06, 2024 8:37 pm
Forum: Your Fave Artists
Topic: What Are You Listening To Right This Minute?
Replies: 6152
Views: 1876438

Re: What Are You Listening To Right This Minute?

Groovy Dave.

(Can we have a tour of all your boxes with knobs and labels? Looks fascinating.)
by simon
Sun Feb 04, 2024 4:32 pm
Forum: Valves
Topic: Valve amplifier service
Replies: 176
Views: 84666

Re: Valve amplifier service

Whilst the bottom was off I disconnected the coupling caps between phase splitter and output valves in order to isolate the output stage, and with the AC wiring to the side and rear of the amp there was little detectable hum. This is what the scope picked up. . 20240204_160827.jpg . Not much really ...
by simon
Sun Feb 04, 2024 4:25 pm
Forum: Valves
Topic: Valve amplifier service
Replies: 176
Views: 84666

Re: Valve amplifier service

Well, I don't know. I had a trip to Nick's yesterday for a scope lesson and the good news is it's operator error not scope error - the scope looks to be okay and the low level mush is most likely my inexperience. So I had the bottom off the amp again today with the last lap in sight, but before I di...
by simon
Thu Feb 01, 2024 6:04 pm
Forum: Assorted Stuff
Topic: General health matters.
Replies: 784
Views: 190600

Re: General health matters.

Blimey that doesn't sound good Brian, hope the recovery goes well.
by simon
Tue Jan 30, 2024 6:17 pm
Forum: Valves
Topic: Valve amplifier service
Replies: 176
Views: 84666

Re: Valve amplifier service

Well, there you go. (Weren't the words I actually used...) I cleared my desk again and set up the audio stuff and took the bottom off the amp. The mains AC cables to the front on/off switch are fast-on type connectors - removing them with pliers and care, a wire came straight out of one of the spade...