Search found 5695 matches

by simon
Thu May 16, 2024 8:53 pm
Forum: Valves
Topic: Dying Rectifier?
Replies: 26
Views: 648

Re: Dying Rectifier?

Have you another rectifier to try? (Anything equiv to GZ33) Sadly I don't have any other suitable 5V rectifiers to try. Edit - yes I have one GZ37 somewhere I think. Have you done the unplug, spray with switch cleaner, re-plug in, check socket pins for loose fit, etc. (?) No, not yet but will do
by simon
Thu May 16, 2024 8:51 pm
Forum: Valves
Topic: Dying Rectifier?
Replies: 26
Views: 648

Re: Dying Rectifier?

Can't say I've ever heard of anything like that before. Oh dear, that doesn't bode well... Are you certain the 5V is always present at the rectifier? When the sound dies, are the heaters still lit? A GZ33 draws quite a bit of heater current and a dry joint in the heater wiring is always a possibili...
by simon
Thu May 16, 2024 6:08 pm
Forum: Valves
Topic: Dying Rectifier?
Replies: 26
Views: 648

Dying Rectifier?

I think I might have a dying Mullard GZ33, but I've never seen this behaviour before so I'm not sure. I first noticed the sound was slowing becoming quieter, over a couple of minutes or so. Eventually the music stopped and there was no HT. Measuring both heaters and HT winding confirmed there was 5V...
by simon
Thu May 16, 2024 5:52 pm
Forum: Computer Audio
Topic: Yay! New toy
Replies: 88
Views: 101517

Re: Yay! New toy

Looking good Tony. Do you have any tips for getting the connectors spaced accurately on your pcb to mount the I2SoverUSB board? I've played with an Arduino mega footprint in KiCad but I'm not convinced I've kept the accuracy. I probably don't know KiCad well enough.
by simon
Wed May 15, 2024 3:47 pm
Forum: Speakers
Topic: TG "The Loudspeaker" Build (Sort of)
Replies: 168
Views: 16751

Re: TG "The Loudspeaker" Build (Sort of)

Morgan Jones wrote: Wed May 15, 2024 1:43 pm I only have an ancient photocopy of the Tappan paper, but it really can be summarised by the "position braces to minimise the size of inscribed circles" idea.
:thumbright:
by simon
Wed May 15, 2024 12:34 pm
Forum: Speakers
Topic: TG "The Loudspeaker" Build (Sort of)
Replies: 168
Views: 16751

Re: TG "The Loudspeaker" Build (Sort of)

Very wise! There's a very interesting paper by Tappan about panel resonances. Essentially, braces should be added that minimise the diameter of inscribed circles. And that means that the most effective braces go along the length of a panel, not across the short dimension. An initially counterintuiti...
by simon
Tue May 14, 2024 6:31 pm
Forum: Speakers
Topic: TG "The Loudspeaker" Build (Sort of)
Replies: 168
Views: 16751

Re: TG "The Loudspeaker" Build (Sort of)

Blimey, once would be bad enough but twice is terrible. I hope you've recovered well.

Even simple valve amps end up heavy. What surprises me is how the same amps have become much heavier over the years when I pick them up.....
by simon
Tue May 14, 2024 5:40 pm
Forum: Speakers
Topic: TG "The Loudspeaker" Build (Sort of)
Replies: 168
Views: 16751

Re: TG "The Loudspeaker" Build (Sort of)

Morgan Jones wrote: Tue May 14, 2024 4:58 pm That's no boat anchor, that's quality stuff!
It was a reference to some of the back-breaking amps that we used to build rather than besmirching the fine turntable.
by simon
Tue May 14, 2024 2:29 pm
Forum: Valves
Topic: Valve amplifier service
Replies: 200
Views: 98754

Re: Valve amplifier service

Something for everyone. I quite like the sound of a 4 stroke sig gen, but £1.31 takes some beating.
by simon
Tue May 14, 2024 2:28 pm
Forum: Speakers
Topic: TG "The Loudspeaker" Build (Sort of)
Replies: 168
Views: 16751

Re: TG "The Loudspeaker" Build (Sort of)

Did someone say boatanchor? :-D
by simon
Tue May 14, 2024 12:34 pm
Forum: Valves
Topic: Valve amplifier service
Replies: 200
Views: 98754

Re: Valve amplifier service

Yeah, I was a little concerned about changing the feedback I must say, especially as I don't have much test gear. I could have used Audacity to generate square waves I suppose. In the end I only had my ears, which is a bit, erm, limited to say the least. The original circuit has a 20k resistor, whic...
by simon
Tue May 14, 2024 12:23 pm
Forum: Speakers
Topic: TG "The Loudspeaker" Build (Sort of)
Replies: 168
Views: 16751

Re: TG "The Loudspeaker" Build (Sort of)

So you did. You know better than to trust me these days ;-). The "problem" gets a whole lot simpler! Though the 25kg H&S limit must be in danger!
by simon
Tue May 14, 2024 9:01 am
Forum: Speakers
Topic: TG "The Loudspeaker" Build (Sort of)
Replies: 168
Views: 16751

Re: TG "The Loudspeaker" Build (Sort of)

Intriguing! You must have some impressive tools? I can't imagine much success with an angle grinder and diamond blade.
by simon
Mon May 13, 2024 10:36 pm
Forum: Speakers
Topic: TG "The Loudspeaker" Build (Sort of)
Replies: 168
Views: 16751

Re: TG "The Loudspeaker" Build (Sort of)

MistyBlue wrote: Mon May 13, 2024 10:09 pm disgruntled mutterings
Mmmm yes, we're all familiar with those...
by simon
Mon May 13, 2024 9:52 pm
Forum: Valves
Topic: Valve amplifier service
Replies: 200
Views: 98754

Re: Valve amplifier service

Dave reports the amp sounds "wonderful" and has been stable so far. Phew! If it was me, I would want to run some FR plots of the amp and see how it behaved with square waves. You may find the cap in the feedback network may need playing with as well. You mean along these lines?: https://so...