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noise problem & V1 & V2 flash bright on power up
Posted: Sat Oct 15, 2011 12:24 am
by mask_music
Ok the build is done and I have a couple of issues. First when I power up the heaters the v1 & v2 tube flash and then glow normal. I let them heat up and turn the standby switch on. Everything sounds with no input you can turn both I and II up and no noise issues. Normal tube amp noise. When a guitar is plugged in and with the volumes either channel are on 0 you can hear a little bit of guitar. When I turn it up to 1 everything sounds like a guitar. Any past 1 on the volume is is a noise that it is hard to explain. Veery loud and very harsh noise. Not guitar noise's. I changed pre-amp tubes and guitar cords. Any ideas where to start to look?
Steve
Re: noise problem & V1 & V2 flash bright on power up
Posted: Mon Oct 17, 2011 10:26 am
by Big Mike
Best bet is to post some pictures. Some of the eagle eyes around here can try to spot any thing amiss.
Re: noise problem & V1 & V2 flash bright on power up
Posted: Mon Oct 17, 2011 10:30 am
by myfoot
+1 and post your voltages too. Could be something out obvious to the guys around here.
Re: noise problem & V1 & V2 flash bright on power up
Posted: Mon Oct 17, 2011 1:15 pm
by neikeel
myfoot wrote:+1 and post your voltages too. Could be something out obvious to the guys around here.
+2
Most Mullard preamp valves will flash on first fire up and then settle to normal glow so I doubt that is a worry.
Similarly most pots will let a little signal through even though they are supposed to be turned off.
Pictures are really useful, with lots of eyes someone will spot the likely issue. New builds are usually easier to debug than amps that work normally and then fail for no obvious reason.
Make sure you tell us what parts were used show shots of board, valve base connections and potentiometer connections as well as OT wiring (I am thinking reversed OT primaries etc)
Re: noise problem & V1 & V2 flash bright on power up
Posted: Mon Oct 17, 2011 8:14 pm
by mask_music
Alright I found my issue. I used Classic Tone transformers. I have no idea if that was a mistake or not. But their colors are differnt and I messed up. I had the common crossed with on of the primary wires on the output transformer. This bad boy screams al the way up to 10 now. I do have a hume in the #2 input top jack. The bottom one works fine. Any ideas. no pics today I took to the studio and I am now at home.
Re: noise problem & V1 & V2 flash bright on power up
Posted: Mon Oct 17, 2011 8:29 pm
by toner
mask_music wrote:I do have a hum in the #2 input top jack.
Check wiring and solder joints on the jacks, especially the grounds. Also check lead dress around V1. Keep grid wires (pins 2 and 7) away from heater wires and plate wires (pins 1 and 6).