[ 'Dead CRATE BV- need help! ]

[Sea Chief]

Have you been testing with the reverb disconnected ? Have you checked the FX loop ? These may not have anything to do with the noise ,but I know they can cause issues in other amps. Wish you had a sound clip of the noise. When I think crunch I think good sound

Ive not had reverb plugged in for all tests (noise there with it from beginning). Ive cleaned FX sockets, and plugged GTR in to rtn for the major test: yes the noise did cease doing this.

*We then narrowed the noise down (by a string of thoughragh shorts, jumper, and component removal tests/ repeated all too as final conclusion seemed odd) to it being between MV and V2.
*Then narrowed noise down even further (and oddly too) to not one triode but BOTH triodes V2 a and V2 b.

And there I be stuck. So much so I blanket replaced most all of V2 stuff to hopefully fluke the one bad sod..no joy/ noise exactly the same. Its like a bad snowstorm noise, a crunchy stream of crap/ dirt noise. Best I can describe. thx SC

[gtrplayr1976]

Ive not had reverb plugged in for all tests (noise there with it from beginning). Ive cleaned FX sockets, and plugged GTR in to rtn for the major test: yes the noise did cease doing this.

*We then narrowed the noise down (by a string of thoughragh shorts, jumper, and component removal tests/ repeated all too as final conclusion seemed odd) to it being between MV and V2.
*Then narrowed noise down even further (and oddly too) to not one triode but BOTH triodes V2 a and V2 b.

And there I be stuck. So much so I blanket replaced most all of V2 stuff to hopefully fluke the one bad sod..no joy/ noise exactly the same. Its like a bad snowstorm noise, a crunchy stream of crap/ dirt noise. Best I can describe. thx SC

And didn't you say the noise wasn't affected by controls ? There's a lot of flat cables on these too. Hate those things. I correct myself. I looked at some gut shots I have ,and those aren't flat cables just lots of wires.

[gtrplayr1976]

Yes indeed it is. A head version, older blue tolex type. Nasty lookers tbh. And the mini-pots are bad plastic. But I like.

One last thing Ive not ruled out is a bad MV pot itself (250k Lin). Can I sub in a 10k A to test? (only mini one I have to fit).

Might be good enough just to see if it were bad.

I was even thinking of asking crate if there's any chance of a pcb I could buy.. & Id take a week and shift the lot over to that. It can only be the V2 socket now afaict (a bitch to rplace/ cant find the same type so not worth it)... or a pcb track contamination thing you see/ my last gasp.

I doubt Crate has anything like that ,but wouldn't hurt to ask.

[Sea Chief]

Fwiw..

Only MV pot will affect the noise. Ie turning down = noise progressively less/ no noise at all at 0.

Turning Vol ch1 (solely one vol only/ MV only wired up with ch2 Gain) & GainVol ch2/ both do not affect noise: ie at 0 or 11 the noise is steady.

No tone pots ch1 or ch2 affect noise at all.

[gtrplayr1976]

Fwiw..

Only MV pot will affect the noise. Ie turning down = noise progressively less/ no noise at all at 0.

Turning Vol ch1 (solely one vol only/ MV only wired up with ch2 Gain) & GainVol ch2/ both do not affect noise: ie at 0 or 11 the noise is steady.



No tone pots ch1 or ch2 affect noise at all.

Maybe something in the MV circuit ?

[Sea Chief]

Hi gtrP. My (& all those who've helped Im sure) first suspicions too.

I think Ive tried every test/ possible thing in the MV localised area tho. Last ev for eg I subbed in a 10k pot for the MV (noise less due to not being 250k but resolutely there still), then subbed C14 (just 'down a bit'/ not in MV circuit but links to MV so give it a go). Neither any difference/ noise the same. Im open to anything I may have missed absolutely tho.

As a layman Im wondering about the V3 circuit (simply as this not considered yet) but not clued up on whether anything here (such as for eg the 2 plate R's) could affect 'back' to the preamp, to give the symptoms afaict that have firmly narrowed to V2 a & b. (Or go a step back say, & even more firmly narrowed as we did, to "between C16 & MV").

[gtrplayr1976]

Wasn't it said somewhere in here that removing V2 stopped the noise ?

[Sea Chief]

Wasn't it said somewhere in here that removing V2 stopped the noise ?

Just redone this test/ pulled V2: yes noise ceases.

[gtrplayr1976]

Just redone this test/ pulled V2: yes noise ceases.

Also said that when you jumpered around V2 the noise stopped ? If that is true the V3 wouldn't be an issue. The noise is on both channels ?

[Sea Chief]

Also said that when you jumpered around V2 the noise stopped ? If that is true the V3 wouldn't be an issue. The noise is on both channels ?

Yes jumpered around V2 and noise stopped. Yes noise on both channels. Ok so I can cross V3 off.. thats good for my brain at least. thx SC

[gtrplayr1976]

Yes jumpered around V2 and noise stopped. Yes noise on both channels. Ok so I can cross V3 off.. thats good for my brain at least. thx SC

I've been reading these posts over ,and over trying to see what may have been missed. What happens when you take V1 out ?

[Sea Chief]

I've been reading these posts over ,and over trying to see what may have been missed. What happens when you take V1 out ?

Thanks gtrP Im grateful for a fresh look-over this intractable prob.

V1 removed: Noise remains.

Crunchy noise 'like a steady crappy snowstorm-with-popping-&-splattering noises often all mixed in'. Like a Xmas cake mixture, but not nice (& fairly loud- defo not just a minor hum or buzz at all/ I could maybe live with that).

Im thinking it really is a 'Voodoo 50' amp.. & maybe it'll go once I get to 50 godam components Ive swapped!

[gtrplayr1976]

Thanks gtrP Im grateful for a fresh look-over this intractable prob.

V1 removed: Noise remains.

Crunchy noise 'like a steady crappy snowstorm-with-popping-&-splattering noises often all mixed in'. Like a Xmas cake mixture, but not nice (& fairly loud- defo not just a minor hum or buzz at all/ I could maybe live with that).

Im thinking it really is a 'Voodoo 50' amp.. & maybe it'll go once I get to 50 godam components Ive swapped!

No worries. I know what it's like to struggle with these things. I have demons I'm working with now ,and I'm not an expert at this either. Popping noise can be caused by a few different things . Check this site. It's pretty handy.
Tube Amplifier Debugging Page

[Sea Chief]

Thanks for that link- funnily enough I found that site today also, pretty good basics/ useful to bookmark.

Popping noises are not so prominent/ not a 'signature' of the sound, just part of the overall mush of the 'dirty' crunchy-like noise (it sounds sort of like maybe really bad dirt is s'where, then amplified.. V2 socket pins Ive sprayed with contact cleaner & pin contact checked).