Search found 1073 matches

by deltafred
16 Feb 2024, 18:05
Forum: Amplifiers
Topic: Small Push Pull tube amp build, advice sought.
Replies: 28
Views: 6961

Re: Small Push Pull tube amp build, advice sought.

No progress has been made on the amp, I see it every time I go in my store cupboard and it reminds me that one day I will have to get back to it.

I've just had a PM for info on Partridge transformers so am posting what I have in case anyone else needs it.
Partridge info.pdf
(3.27 MiB) Downloaded 25 times
by deltafred
25 Jan 2024, 19:19
Forum: Pedal Debugging & Troubleshooting Support
Topic: Capactitor Questions
Replies: 3
Views: 639

Re: Capactitor Questions

Putting electrolytic capacitors "back to back" creates a non polarised electrolytic which can handle both forward and reverse voltages.

Polarised capacitors can only handle a small reverse voltage before they start conducting (become a resistor).
by deltafred
24 Jul 2023, 08:25
Forum: Amplifiers
Topic: Crate - CPB150 Powerblock [schematic]
Replies: 12
Views: 13847

Re: Crate - CPB150 Powerblock [schematic]

Sorry for the delay, life's been getting in the way this past year.

This is everything I have on the PB150.
Crate PB150.zip
(8.29 MiB) Downloaded 186 times
by deltafred
20 Jun 2023, 16:42
Forum: Amplifiers
Topic: Crate - CPB150 Powerblock [schematic]
Replies: 12
Views: 13847

Re: crate CPB150 Powerblock schematics [schematic]

I'll have a look through my old hard drives when I get chance.
by deltafred
10 Jun 2023, 16:10
Forum: Pedal Debugging & Troubleshooting Support
Topic: Tc electronic stereo chorus flanger low volume problem with mono output
Replies: 8
Views: 846

Re: Tc electronic stereo chorus flanger low volume problem with mono output

Do you think it is normal to have 6v on the mono output signal? You should have NO DC offset on the output signal. Trace the output back. There will most probably be an electrolytic capacitor between the final opamp or transistor and the output. If this capacitor is leaky then it will not block the...
by deltafred
05 Jun 2023, 17:09
Forum: Pedal Debugging & Troubleshooting Support
Topic: Foxxtone low output
Replies: 2
Views: 386

Re: Foxxtone low output

Thanks for coming back to report what the problem was, not everyone can be bothered.
by deltafred
16 May 2023, 08:53
Forum: Amplifiers
Topic: Fake 6l6gc's
Replies: 5
Views: 2436

Re: Fake 6l6gc's

Zombie thread alert! Fake 6L6GCs are still doing the rounds. Not_Brimar_6L6GC.jpg TL:DR Back story. My internet had been down for 12 days and I had an amp on my bench that needed a pair of 6L6GCs. I don't have enough mobile (cell phone) signal to use it indoors so was stood in out in the middle of t...
by deltafred
03 Mar 2023, 11:53
Forum: Boutique Stompboxes dissected...
Topic: The Beatles Pedal
Replies: 32
Views: 4289

Re: The Beatles Pedal

blackcorvo wrote: 02 Mar 2023, 04:33 Are you sure it's not a circuit inspired by the tube sound overdrive?
https://nexp.pt/arsenio.html
Could explain the two transistors.
That would make a lot more sense as it would give more of the pushed valve (tube) amp sound.
by deltafred
13 Feb 2023, 09:28
Forum: Boutique Stompboxes dissected...
Topic: The Beatles Pedal
Replies: 32
Views: 4289

Re: The Beatles Pedal

CheapPedalCollector wrote: 13 Feb 2023, 06:32 What is this pedal trying to achieve?
Sales! :lol:
by deltafred
11 Feb 2023, 19:37
Forum: Debugging 101
Topic: Easy (and possibly free) signal generator.
Replies: 0
Views: 943

Easy (and possibly free) signal generator.

I do quite a few pedal and amp repairs for a music shop so built a 1 kHz 2 transistor multivib signal generator with a 386 amplifier and a 3 inch speaker all in a re-purposed plastic box. It works fine but the 1 kHz tone gets on your nerves after about 10 seconds so I started using my Strat as a sou...
by deltafred
06 Jan 2023, 00:18
Forum: Amplifiers
Topic: Davoli - 535 Petit aka Jolly - 2x8" EL84 Vibrochamp [schematic]
Replies: 8
Views: 1643

Re: Davoli - 535 Petit aka Jolly - 2x8" EL84 Vibrochamp [schematic]

Yes they look very like the old 50's/60's radio speakers.

I've blown more of those than I care to remember back when I started playing and couldn't afford anything better. (All harvested from scrap radios.)
by deltafred
04 Jan 2023, 20:04
Forum: Amplifiers
Topic: Davoli - 535 Petit aka Jolly - 2x8" EL84 Vibrochamp [schematic]
Replies: 8
Views: 1643

Re: Davoli - 535 Petit aka Jolly - 2x8" EL84 Vibrochamp [schematic]

A neon is pretty much a high voltage tunnel diode. It starts to conduct when there is somewhere around 90v across it and stops conducting when the voltage drops to around 60v. (All voltages from memory and probably dependant upon the neon used.) To make an oscillator you put a capacitor across the n...
by deltafred
04 Jan 2023, 11:48
Forum: Amplifiers
Topic: Davoli - 535 Petit aka Jolly - 2x8" EL84 Vibrochamp [schematic]
Replies: 8
Views: 1643

Re: Davoli - 535 Petit aka Jolly - 2x8" EL84 Vibrochamp [schematic]

It was probably fitted with a selenium plate bridge rectifier originally, which has been replaced by a modern silicon bridge much more recently. There is a space on the board where it was probably mounted. If memory serves me correctly you could usually tell when a selenium rectifier had burned out ...
by deltafred
17 Nov 2022, 09:14
Forum: Modern Stompbox Effects (1975 - ...)
Topic: Fender - Yngwie Malmsteen Overdrive
Replies: 41
Views: 18955

Re: Fender - Yngwie Malmsteen Overdrive

I don't see a schematic in this thread, can you post one please.
by deltafred
17 Nov 2022, 09:08
Forum: Modern Stompbox Effects (1975 - ...)
Topic: Tech21 Character Series [schematic]
Replies: 462
Views: 332742

Re: Tech21 Character Series [schematic]

Guroots wrote: 16 Nov 2022, 17:55 Finally I understood the aim of the input/output diodes. (It is written in this topic) ; There aim is to limit voltage to the TLC2264 input/output... but with passive instrument they have no use.
They are there for static protection so have as much use with passive instruments as active ones.
by deltafred
29 Oct 2022, 09:05
Forum: DIY Projects
Topic: BAJA Ampeg SVT bass amplifier pedal 9v 010418 [documentation]
Replies: 75
Views: 211798

Re: BAJA Ampeg SVT bass amplifier pedal 9v 010418 [documentation]

Please excuse my lack of knowledge on electricity but if I substitute the 3u3 in the Mid Freq control with a polarized Tantal, where would the + leg go? The easiest way if it is not immediately obvious from looking at the schematic is to fit a capacitor and measure the voltage across it with a mult...
by deltafred
15 Oct 2022, 08:47
Forum: Pedal Debugging & Troubleshooting Support
Topic: Help! Circuit making white noise ROG May Queen
Replies: 4
Views: 477

Re: Help! Circuit making white noise ROG May Queen

mauman wrote: 14 Oct 2022, 19:06 We've all been there.
An old guy I used to work with always said that if you never made any mistakes it was because you never did anything.
by deltafred
28 Sep 2022, 08:13
Forum: Davidoff Library
Topic: Craig Anderton, Tube Sound Fuzz, in: Guitar Player Magazine, February 1977 🇺🇸
Replies: 11
Views: 3464

Re: Craig Anderton, Tube Sound Fuzz, in: Guitar Player Magazine, February 1977 🇺🇸

There's one on Ebay in the USA at $6.99 BIN or offers - item number 314129336424

No idea what postage is within the USA but it's silly money to the UK.
by deltafred
08 Jul 2022, 09:54
Forum: DIY Projects
Topic: Baja Music Man guitar and bass onboard preamps [documentation]
Replies: 503
Views: 183412

Re: Baja Music Man guitar and bass onboard preamps [documentation]

There was a problem with the very early preamps where the opamp was sometimes damaged when a guitar lead was plugged in. Adding the 1k resistor cured the problem.

Leave it out at your own risk.