CRATE BV amp Ch1 prob- "Crunchy" Noises.

[Sea Chief]

Chaps- I have an older Crate Blue Voodoo bv50 head just bought for cheapish off ebay (UK). Bit annoyed as all pots v noisy/ crackly, som bad hum on reverb increacing when turned up, & most of all some bad Ch1 noise persistant & tbh amp not playable (sold as 'all working good' of course 'oh sorry to hear/ working fine b4' etc etc.. Im tired of this sort of ebay thing). If i can fix tho Im not too pissed off as I like these amps.

Done the pots clean: Ch2 all fine. Prob remains with Ch1 tho: noises are a (fairly loud but not excessive/ no loud pops) background persisitant 'crunchy' & 'white-noise' sound. Prob in Ch1 section alone I assume? I swapped in a good 12ax7 for V1: innitially amp sounded great (bar the reverb hum) so thought this had done the trick.. but similar noise creeping back, tho 1/2 as bad as with orig V1 tube. Seller said send it back then, but posting costly/ hassle so I may as well try & fix. Damned ebay! 2nd amp in 2 weeks Ive bought with an obvious issue *Only buy a used tube amp after playing- no Q about it*.

Any ideas? Also why would reverb hum as its pot increaced?

Thx SC

[soundguruman]

Chaps- I have an older Crate Blue Voodoo bv50 head just bought for cheapish off ebay (UK). Bit annoyed as all pots v noisy/ crackly, som bad hum on reverb increacing when turned up, & most of all some bad Ch1 noise persistant & tbh amp not playable (sold as 'all working good' of course 'oh sorry to hear/ working fine b4' etc etc.. Im tired of this sort of ebay thing). If i can fix tho Im not too pissed off as I like these amps.

Done the pots clean: Ch2 all fine. Prob remains with Ch1 tho: noises are a (fairly loud but not excessive/ no loud pops) background persisitant 'crunchy' & 'white-noise' sound. Prob in Ch1 section alone I assume? I swapped in a good 12ax7 for V1: innitially amp sounded great (bar the reverb hum) so thought this had done the trick.. but similar noise creeping back, tho 1/2 as bad as with orig V1 tube. Seller said send it back then, but posting costly/ hassle so I may as well try & fix. Damned ebay! 2nd amp in 2 weeks Ive bought with an obvious issue *Only buy a used tube amp after playing- no Q about it*.

Any ideas? Also why would reverb hum as its pot increaced?

Thx SC

If you buy crate, expect issues. These are the most UN-reliable amps ever manufactured.
Most crate amps were built "for temporary use only*" OR "not for continuous operation*."
Re-solder the circuit boards, in the case where the board depends on screws to ground the board to the chassis, bypass the ground with a hard wire to the chassis.
Lots of Crates depended on sheet metal screws to ground the circuit boards. Solder a wire direct to the board, and ground it to the chassis with a ring terminal and a screw/nut/washer.

In the Voodoo, the output tubes may be plugged in, on a little output board. The connector pins fail all the time, and burn etc...best thing is to just install sockets on the chassis, bypass the connections to the board with soldered flying leads. Junk the plug-in board.

Hum in the reverb- the cables to the reverb pan may be defective. OR inside the reverb pan you have a broken spring or a broken wire.

* According to the Factory Crate Techs! They openly admitted that these amps were not built to use continuously, and would burn up if pressed to operate as such.

[Sea Chief]

Thanks for that- good info and in due time I will address the general layout, if needs be. Reverb: Ive checked the leads and the pan: all fine.

Its the Ch1 problem I need to address. Do the 'crunchy' noises seem symptomatic of anything in particular to anyone? (Ive checked the tube- not that). If Ch2 is fine, and Ch1 only has these noises, can I not significanlty narrow down the prob to ABC?

[52 Bill]

Reverb: Ive checked the leads and the pan: all fine.

Is the tank mounted with the output end as far away from the power transformer as possible?

Its the Ch1 problem I need to address. Do the 'crunchy' noises seem symptomatic of anything in particular to anyone?

I don't have a schematic for your amp so I can't give specific information, but a noisy plate resistor comes to mind.

[Sea Chief]

Bill hi- Thats a good idea.. the output is located furthest from the PT, as Id have thought it designed, but Illtry the tank away from amp and see if the hum goes. But I wouldnt be expecting it to.

The schematic isn't availabe afaict, a shame, but is the plate resisitor usually sited on the same V1 pin as a general rule? (pin 1 is it?). If so I I could change that for a try I guess. What wattage is the norm here?

thanks SC

[Jazz P Bass]

Crate BV50H Schematic

Here is the BV50H schematic if that will help.

[Sea Chief]

Thanks alot-

Oddly I cant see any of the V1/ preamp area on that though, I wonder if there's another page or s'thing?

[mozwell]

I have problems uploading files here, the upload file screen hangs & crashes IE7
PM me with your email address & i can send it to you, or email me at andymac1962 aaattt hotmail dddooottt com, remind me in hte email that you want the Crate BV50 sch

[Sea Chief]

Thanks Andy- just emailed you. most helpful.

[mozwell]

Sea Chief
the files are on their way to you, i also included the 60W and 120W versions, i hope the info helps you out.

Please reply to the post & attach the files here, so we can help others too.

I would have done this, but i only use IE7, and when i go to attach a file, the pop up box looks like it freezes & i have to close IE and start again

[Jazz P Bass]

I would have done this, but i only use IE7, and when i go to attach a file, the pop up box looks like it freezes & i have to close IE and start again

I have one of my computers running XP & IE8.
The same thing happens.
Upload bar gets half way & stops.

[Enzo]

Yeah, I been using the Chrome lately to get around that.

[Sea Chief]

Is the tank mounted with the output end as far away from the power transformer as possible?


I don't have a schematic for your amp so I can't give specific information, but a noisy plate resistor comes to mind.

Ive swapped a load of R's and C's in Ch1, both plate R's and the 22uf input C (a 0.1uf C and a 0.022uf too)... noises exactly the same. The noises are actually not narrowed to Ch1 either: turn up the MV and similar (but not as bad) noise there too. I noticed a small crack in a reverb gnd spade/ replaced.. this hum exactly the same too.

What I did see tho, is the 6L6 tubes I expected were in fact a pair of "5881WXT". Similar size/ shape so I thought they were 6L6s (markings on back/ didnt spot b4). That raised eyebrows. Can anyone tell me anything about these? possible cause of issues?? can I just swap back in a pair of 6L6 for a try, or is it now 'biased' for these 5881WXT's ? (no bias pot inside anwhere at all).

[Enzo]

5881 is just an industrial number for 6L6.

[Sea Chief]

Ah ok- right then I can rule the power tubes out (tried a different pair of 6L6's and bad background rustling/ crunchy noises still there).

Any ideas? I guess that if the MV vol (on Ch2) when turned up is noisy too, then I can rule out it being only a Ch1 prob: and Ive ruled out V1 and the pwr tubes.

V2 and V3 check is all I can physically do now- then Im totally stumped & need help.