Odd, When I turn it on with no input attached I get the oscillation. Then watch when I plug in the red RCA it changes frequency and when I plug in White it goes away entirely and is quiet (thats not normal for it) and then when I turn on the CD player we get the oscillation and the pulsing light in the tube again.
http://www.youtube.com/watch?v=RLXKP8BQ1BA
edit: So I just went over and turned it on with RCA plugs in but CD player off. Still it made the noise.
Well, I need some suggestions folks. I am going to go to Radio Shack and get 33pf to replace what I took out. Cant find them. Hopefully they have some.
On second thought a quick check on line shows they dont have them. I am going to trust Voltsecond on this that the 33pf is useless in this circuit.
http://www.youtube.com/watch?v=RLXKP8BQ1BA
edit: So I just went over and turned it on with RCA plugs in but CD player off. Still it made the noise.
Well, I need some suggestions folks. I am going to go to Radio Shack and get 33pf to replace what I took out. Cant find them. Hopefully they have some.
On second thought a quick check on line shows they dont have them. I am going to trust Voltsecond on this that the 33pf is useless in this circuit.
Noise in K-12
I just built one of these amps, and did most of Volt Second's mods, with the exception of removing the output ceramic caps. I mounted the power supply in a remote box, and routed the input jacks into the same box. I had a bad buzz that was coming from the RF around the power transformers. I solved by using a star ground in the box and also using coax--salvaged an old RCA audio cord. Sounds like you have a serous grounding problem. Check out this web-site, it has a relatively good discussion on grounding problems.
http://vacuumtubedesigns.com/VTD/Information.aspx
Good Luck!
I just built one of these amps, and did most of Volt Second's mods, with the exception of removing the output ceramic caps. I mounted the power supply in a remote box, and routed the input jacks into the same box. I had a bad buzz that was coming from the RF around the power transformers. I solved by using a star ground in the box and also using coax--salvaged an old RCA audio cord. Sounds like you have a serous grounding problem. Check out this web-site, it has a relatively good discussion on grounding problems.
http://vacuumtubedesigns.com/VTD/Information.aspx
Good Luck!
Thanks everyone, I really appreciate the suggestions. Yeah I think the problems are numbering more than one or two.
I did the enamel removing today and no change, but it needed to be done for sure.
The biggest problem was that the RCA jacks were not insulated and were making direct contact with my case which was causing a ground loop and terrible noise which you heard in my youtube post.
When I removed the RCA jacks and soldered directly to the RCA cable it was much better. Not fixed but better.
I had bought a stepped attenuator on ebay but when I ohmed it out on my DMM it looked bad, however my pot I was using was junk and I figured it couldnt hurt to try the attenuator. That solved the issue when I was on the 5th through 12th step of the attenuator. Other than those and it was still bad.
The tube is having issues and needs to be replaced. If you check my last youtube post you can see or at least hear the problems it has. It has steady glow and then when sustains or extra bass come in it gets an extra glow that pulses and I lose the sustain or bass.
So right now it sounds good at low to low/medium volume. Past that and I get weird pulsing.
Another issue is that I had rewired the whole board and I think that some solder joints on the pot are bad. Those will be fixed tomorrow and some of the voltsecond fixes will go back on.
I think it will be back to great if I redo the soldering on those pot wires and get a new tube.
Thanks for your help and I will keep you updated.
Uriah
edit: cool site meralain!
informative and I need that
I did the enamel removing today and no change, but it needed to be done for sure.
The biggest problem was that the RCA jacks were not insulated and were making direct contact with my case which was causing a ground loop and terrible noise which you heard in my youtube post.
When I removed the RCA jacks and soldered directly to the RCA cable it was much better. Not fixed but better.
I had bought a stepped attenuator on ebay but when I ohmed it out on my DMM it looked bad, however my pot I was using was junk and I figured it couldnt hurt to try the attenuator. That solved the issue when I was on the 5th through 12th step of the attenuator. Other than those and it was still bad.
The tube is having issues and needs to be replaced. If you check my last youtube post you can see or at least hear the problems it has. It has steady glow and then when sustains or extra bass come in it gets an extra glow that pulses and I lose the sustain or bass.
So right now it sounds good at low to low/medium volume. Past that and I get weird pulsing.
Another issue is that I had rewired the whole board and I think that some solder joints on the pot are bad. Those will be fixed tomorrow and some of the voltsecond fixes will go back on.
I think it will be back to great if I redo the soldering on those pot wires and get a new tube.
Thanks for your help and I will keep you updated.
Uriah
edit: cool site meralain!
informative and I need that 
Hi Udaily,
"I am going to go to Radio Shack and get 33pf to replace what I took out. Cant find them. Hopefully they have some.
On second thought a quick check on line shows they dont have them. I am going to trust Voltsecond on this that the 33pf is useless in this circuit."
I upgraded the output transformers on my K502 to Hammond 1609's also.Then I read somewhere that ceramic capacitors aren't sonically good enough to be used in the signal path. Here they are being used in the negative feedback part of the signal path I believe.So I removed the ceramics.I was going to replace them with silver mica caps of the same value but couldn't resist listening to the amp without them first. My old ears couldn't hear any difference so I never did put the silver micas in.Later I took out the Hammonds to use in another project and put the old stock transformers back in.WOW now I've got high pitched oscillation. Put in the silver micas and all was back to normal.I guess with stock output transformers these caps in the negative feedback are necessary.
You also say that having removed your ceramic caps you replaced them with copper wire.This would mean (IMHO - I'm no expert )that you have shorted out the feedback resister changing the level of feedback.I have looked at voltseconds mods but I never saw this one.
The only mod I can think of where a cap is replaced with a link is the first cap in the signal path (0.22uf)This cap stops unwanted dc from your music source getting into your amp. My cd player was clean of any dc so it was safe for me to remove the cap and replace with a piece of wire( clippings are good for this )
Hope this makes sense to you
Brgds
Bill
brgds
Bill
"I am going to go to Radio Shack and get 33pf to replace what I took out. Cant find them. Hopefully they have some.
On second thought a quick check on line shows they dont have them. I am going to trust Voltsecond on this that the 33pf is useless in this circuit."
I upgraded the output transformers on my K502 to Hammond 1609's also.Then I read somewhere that ceramic capacitors aren't sonically good enough to be used in the signal path. Here they are being used in the negative feedback part of the signal path I believe.So I removed the ceramics.I was going to replace them with silver mica caps of the same value but couldn't resist listening to the amp without them first. My old ears couldn't hear any difference so I never did put the silver micas in.Later I took out the Hammonds to use in another project and put the old stock transformers back in.WOW now I've got high pitched oscillation. Put in the silver micas and all was back to normal.I guess with stock output transformers these caps in the negative feedback are necessary.
You also say that having removed your ceramic caps you replaced them with copper wire.This would mean (IMHO - I'm no expert )that you have shorted out the feedback resister changing the level of feedback.I have looked at voltseconds mods but I never saw this one.
The only mod I can think of where a cap is replaced with a link is the first cap in the signal path (0.22uf)This cap stops unwanted dc from your music source getting into your amp. My cd player was clean of any dc so it was safe for me to remove the cap and replace with a piece of wire( clippings are good for this )
Hope this makes sense to you
Brgds
Bill
brgds
Bill
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