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by Cressy Snr
Fri Apr 19, 2024 1:08 pm
Forum: Everyones Projects
Topic: More NVA Board Based Stuff
Replies: 3
Views: 176

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: 3
Views: 176

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: 193
Views: 43868

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...
by Cressy Snr
Wed Apr 17, 2024 6:43 pm
Forum: Everyones Projects
Topic: OK…so I’m on wi’ summat
Replies: 193
Views: 43868

Re: OK…so I’m on wi’ summat

Potted 4H choke can just about be seen to the rear of the VR tube:
IMG_0409.jpeg
IMG_0409.jpeg (135.25 KiB) Viewed 181 times
by Cressy Snr
Wed Apr 17, 2024 5:13 pm
Forum: Everyones Projects
Topic: OK…so I’m on wi’ summat
Replies: 193
Views: 43868

Re: OK…so I’m on wi’ summat

Right then...OK...Er...Here we go again :D I've reverted the power supply to choke input, but this time, before doing anything, I made extensive use of PSUD, feeding in the parameters of the chokes I have, looking at all the waveforms, both current and voltage for any sign of trouble. I ended up wit...
by Cressy Snr
Mon Apr 15, 2024 10:41 pm
Forum: Everyones Projects
Topic: OK…so I’m on wi’ summat
Replies: 193
Views: 43868

Re: OK…so I’m on wi’ summat

Aye,
keeping the space between both HTs constant seems to work beautifully. Guess it’s one of those happy accidents.
by Cressy Snr
Sun Apr 14, 2024 2:08 pm
Forum: Everyones Projects
Topic: OK…so I’m on wi’ summat
Replies: 193
Views: 43868

Re: OK…so I’m on wi’ summat

The idea came from the fact that the 6SL7s are drawing around 1mA each and I wanted to use a series VR105 tube to knock around 100V off the HT. I wanted that tube simply because unlike the 7pin VR tubes, it looks great when lit and I only have the one. I had to think of some way to make the tube pas...
by Cressy Snr
Sat Apr 13, 2024 9:08 pm
Forum: Everyones Projects
Topic: OK…so I’m on wi’ summat
Replies: 193
Views: 43868

Re: OK…so I’m on wi’ summat

A little more experimentation with the power supply today. I've seen series VR tubes used to feed the input stages of commercial amps such as those from Decware and Icon Audio, so I thought I'd give one a try in my own amp: EL34SEULSimplifiedPSU.png 22K shunt resistor makes sure around 15mA is flowi...
by Cressy Snr
Thu Apr 11, 2024 3:17 pm
Forum: Everyones Projects
Topic: EL34 SE
Replies: 6
Views: 306

Re: EL34 SE

Glad they got to you in one piece. :D
by Cressy Snr
Tue Apr 09, 2024 10:32 pm
Forum: Everyones Projects
Topic: OK…so I’m on wi’ summat
Replies: 193
Views: 43868

Re: OK…so I’m on wi’ summat

I don’t think they pose any danger Simon. My hairy-arsed soldering is probably to blame for the problems with mine.
by Cressy Snr
Tue Apr 09, 2024 9:16 pm
Forum: Everyones Projects
Topic: OK…so I’m on wi’ summat
Replies: 193
Views: 43868

Re: OK…so I’m on wi’ summat

I’m glad I got it going again with the JJ and the Sprague caps. It’s a great little amp and the ultimate quality of the sound doesn’t seem to depend on whether or not electrolytic caps or foil in oil caps are used. Yes, of course it is slightly better in the treble, with foil in oil caps but the dif...
by Cressy Snr
Tue Apr 09, 2024 3:25 pm
Forum: Everyones Projects
Topic: PSE EL84 Amplifier
Replies: 43
Views: 1365

Re: PSE EL84 Amplifier

Nope,
Still the same as it was.
by Cressy Snr
Tue Apr 09, 2024 1:11 pm
Forum: Everyones Projects
Topic: PSE EL84 Amplifier
Replies: 43
Views: 1365

Re: PSE EL84 Amplifier

Not got the text Paul.
by Cressy Snr
Tue Apr 09, 2024 8:21 am
Forum: Everyones Projects
Topic: PSE EL84 Amplifier
Replies: 43
Views: 1365

Re: PSE EL84 Amplifier

Hi Paul,
PM your address and I’ll get them off to you.
by Cressy Snr
Mon Apr 08, 2024 9:16 pm
Forum: Everyones Projects
Topic: PSE EL84 Amplifier
Replies: 43
Views: 1365

Re: PSE EL84 Amplifier

I have 4 x NOS, PL36 if you want them Paul. They are Thorn or Mazda (can't be sure until I dig them out) never been used. They have 25V heaters. Might be useful?