Search found 10585 matches

by Cressy Snr
Fri May 17, 2024 3:17 pm
Forum: Valves
Topic: Dying Rectifier?
Replies: 26
Views: 569

Re: Dying Rectifier?

Holy cow, when did GZ37s get so expensive? Something else I wish I'd bought a crate of 20 years ago... Makes SiC diodes look cheap. I’ve got a few GZ37s Simon. I got them for nothing due to the incredible generosity of a guy I built a couple of OTLs for, so I could let you have one. It wouldn’t be ...
by Cressy Snr
Wed May 15, 2024 8:25 pm
Forum: News
Topic: Jimmy James R.I.P.
Replies: 0
Views: 131

Jimmy James R.I.P.

Jimmy James of ‘Jimmy James and The Vagabonds’ fame has passed away aged 84. He’s best known in the UK, for his 1970s records, “Now Is The Time” and “I’ll Go, Where Your Music Takes Me.” Of course I have both the original singles on PYE :) I saw him twice; once at Batley Variety Club and again on Sa...
by Cressy Snr
Wed May 15, 2024 1:48 pm
Forum: Speakers
Topic: TG "The Loudspeaker" Build (Sort of)
Replies: 168
Views: 16708

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

Constrained Layer Damping:
A layer of elastic material is sandwiched between two stiff materials. Basically the elastic material turns the vibration of the two stiff outer layers into heat.
by Cressy Snr
Fri May 10, 2024 8:30 pm
Forum: Everyones Projects
Topic: More NVA Board Based Stuff
Replies: 17
Views: 1411

Re: More NVA Board Based Stuff

Spent a couple of days rearranging the inside, starting with this sub-assembly, intended to allow the volume and selector switch to be moved to the rear of the case. There had been a slight hum, caused by my rather silly oversight of putting the mains transformer too near the input selector and volu...
by Cressy Snr
Wed May 08, 2024 6:11 pm
Forum: Everyones Projects
Topic: More NVA Board Based Stuff
Replies: 17
Views: 1411

Re: More NVA Board Based Stuff

Just a bit of rearranging of the equipment and it all looks a lot better:
IMG_0425.jpeg
IMG_0425.jpeg (120.47 KiB) Viewed 288 times
I’m over on the dark side until the Autumn. 🍂
by Cressy Snr
Mon May 06, 2024 4:49 pm
Forum: Everyones Projects
Topic: More NVA Board Based Stuff
Replies: 17
Views: 1411

Re: More NVA Board Based Stuff

Perforated top plate fitted:
IMG_0422.jpeg
IMG_0422.jpeg (159.14 KiB) Viewed 285 times
And playing in the system:
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This is the summer amp. :sunny:

Next project will be the buffer preamp courtesy of Ray.
by Cressy Snr
Mon May 06, 2024 4:43 pm
Forum: Everyones Projects
Topic: More NVA Board Based Stuff
Replies: 17
Views: 1411

Re: More NVA Board Based Stuff

All wired up: IMG_0421.jpeg Mains transformer is a 30-0-30V, 300VA job. These are bog standard NVA boards. However the input is cap-coupled with Nichicon ‘Muse’ bipolar electrolytics and the speaker outputs have the traditional 10R, 100nF Zobel network across them. Case is being used as the heat sin...
by Cressy Snr
Fri May 03, 2024 8:57 pm
Forum: Everyones Projects
Topic: More NVA Board Based Stuff
Replies: 17
Views: 1411

Re: More NVA Board Based Stuff

Progress so far:
IMG_0418.jpeg
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by Cressy Snr
Fri May 03, 2024 8:21 pm
Forum: Everyones Projects
Topic: OK…so I’m on wi’ summat
Replies: 195
Views: 47953

Re: OK…so I’m on wi’ summat

I got out the 1950s, grey glass KT66 again, deciding to go fully with old valves. The 6SL7 input/driver is a wartime Sylvania VT 229 and the rectifier is a 1952, ‘fat bottle’ CV378 (GZ37.) They’re all at least 70 years old. Used in isolation, I’ve not really been able to get the sound I like with th...
by Cressy Snr
Sat Apr 27, 2024 8:49 pm
Forum: Everyones Projects
Topic: More NVA Board Based Stuff
Replies: 17
Views: 1411

Re: More NVA Board Based Stuff

Ray P wrote: Sat Apr 27, 2024 8:18 pm Steve, if you're in need of a buffer I can send you this FoC - i have a spare pair of BUF-03 devices I'll include too. Volume pot is an Alps Blue. It needs a +/-15V supply.
Yes please Ray. :)
by Cressy Snr
Sat Apr 27, 2024 5:30 pm
Forum: Everyones Projects
Topic: More NVA Board Based Stuff
Replies: 17
Views: 1411

Re: More NVA Board Based Stuff

OK I’m on with the job. There are six inputs. The cathode follower buffer is MIA for now.
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IMG_0415.jpeg
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Mains toroid is in plus some of the mains wiring. Mains input socket is a filtered item with insulating boot.
by Cressy Snr
Tue Apr 23, 2024 11:18 am
Forum: Everyones Projects
Topic: More NVA Board Based Stuff
Replies: 17
Views: 1411

Re: More NVA Board Based Stuff

Spent the last few days trying various internal layouts and have decided on one that should be OK. I've ordered a selector switch and phono sockets for the buffer, if I can be arsed with it. If don’t do the buffer then the parts are still there for an integrated job.
by Cressy Snr
Fri Apr 19, 2024 1:08 pm
Forum: Everyones Projects
Topic: More NVA Board Based Stuff
Replies: 17
Views: 1411

Re: More NVA Board Based Stuff

Thanks for that warning Nick. I’ll put a couple of back-to-back Zeners across the output to clamp the voltage to a safe level. It’s just a matter of deciding the values to clamp it at, so that on the one hand I don’t introduce distortion and on the other I don’t burn out the input stages. The BC182s...
by Cressy Snr
Fri Apr 19, 2024 11:41 am
Forum: Everyones Projects
Topic: More NVA Board Based Stuff
Replies: 17
Views: 1411

More NVA Board Based Stuff

Started yesterday on this project by bending up a chassis and sorting out some kind of layout: NVABoards.jpeg Heatsinks need trimming to fit but that's no great problem. 16000uF of capacitance per rail. The chassis will follow my current styling, with wooden side cheeks. Top will be perforated alumi...
by Cressy Snr
Wed Apr 17, 2024 9:39 pm
Forum: Everyones Projects
Topic: OK…so I’m on wi’ summat
Replies: 195
Views: 47953

Re: OK…so I’m on wi’ summat

Maths is not my strong point, so I turn to PSUD. I also found a nice book http://www.tubebooks.org/Books/Schure_Rectifiers.pdf which helped me out no end. The bit on page 46 concerning fitting a bleeder resistor that draws a constant 10% of the full rated DC current output caused things to drop into...