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Post by DonaldDemon on Sept 3, 2010 20:14:53 GMT -5
Sorted thanks to Scott!
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Post by sasquatch on Sept 3, 2010 21:58:53 GMT -5
Bad (microphonic) preamp tube??? Check the preamp tubes first. Also check for ground loop hum if you're running F/X processors / pedals. I use a VHT Valvulator and Decimator ProRack-G. The valvulator converts the Hi-Z guitar signal to Lo-Z and has a ground loop switch. The Decimator works in the front end and in the loop to quiet things up. It also has a ground lift if needed, but usually the ground lift on the valvulator takes care of any issues.
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Post by DonaldDemon on Sept 4, 2010 10:44:31 GMT -5
Bad (microphonic) preamp tube??? Check the preamp tubes first. Also check for ground loop hum if you're running F/X processors / pedals. I use a VHT Valvulator and Decimator ProRack-G. The valvulator converts the Hi-Z guitar signal to Lo-Z and has a ground loop switch. The Decimator works in the front end and in the loop to quiet things up. It also has a ground lift if needed, but usually the ground lift on the valvulator takes care of any issues. My guess is the tubes. Plugged straight in with the efx loop turned off and still got the feedback. My pedalboard is very quiet as well. I guess I need to look into some new preamp tubes and start from there. Ughhh...I just went through this with power tubes. |
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Post by MetalHeart on Sept 4, 2010 15:15:20 GMT -5
Bad (microphonic) preamp tube??? Check the preamp tubes first. Also check for ground loop hum if you're running F/X processors / pedals. I use a VHT Valvulator and Decimator ProRack-G. The valvulator converts the Hi-Z guitar signal to Lo-Z and has a ground loop switch. The Decimator works in the front end and in the loop to quiet things up. It also has a ground lift if needed, but usually the ground lift on the valvulator takes care of any issues. My guess is the tubes. Plugged straight in with the efx loop turned off and still got the feedback. My pedalboard is very quiet as well. I guess I need to look into some new preamp tubes and start from there. Ughhh...I just went through this with power tubes. I feel your pain Dennis. |
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Post by DonaldDemon on Sept 5, 2010 10:44:28 GMT -5
My guess is the tubes. Plugged straight in with the efx loop turned off and still got the feedback. My pedalboard is very quiet as well. I guess I need to look into some new preamp tubes and start from there. Ughhh...I just went through this with power tubes. I feel your pain Dennis. Time to go SS! j/k I need the tubes! I also forgot to mention that my clean channel is for sh!t. Like no volume and sounds like a mousefart. I guess that could mean V1 preamp tube is no good? |
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Post by DonaldDemon on Oct 28, 2010 8:18:15 GMT -5
Ok, I (reluctantly) changed out the bias resistor to get my bias lower and it worked! I bought tubes that were too hot so I had to change the 15k resistor to a 10k resistor. It was kind of a pain but cheaper than buying new tubes yet again.
I biased the amp around 50 mA and it sounds better, not as muddy. As for the squealing...I'll find out Friday at the show! It was too late last night to really turn it up.
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Post by MetalHeart on Oct 28, 2010 15:44:37 GMT -5
Good news bro  |
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Post by DonaldDemon on Oct 29, 2010 7:31:34 GMT -5
YES
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Post by DonaldDemon on Dec 2, 2011 2:24:08 GMT -5
OK, I'm still getting the annoying feedback thing. I'm even playing on Gear 1, gain around 12:00 these days so it's not like I blasting major gain. Very weird. I generally play about 8-10' in front of my amp and the feedback starts as soon as I stop playing, which really blows when your songs have a lot of stops!  I'm starting to think that hum pot needs to be adjusted. Anyone else have this issue? |
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Post by speedemon on Dec 3, 2011 11:03:42 GMT -5
Hmm,
your bias looks a little hot IMO. Are you getting howling or squealing? Squealing could be a bum tube, even though you bought new ones. I use mounds of gain, so I combat howling by lowering the pickup height and an ISP G String in my signal chain. But my Sheraton will howl even on mild gain settings...lol
Good luck!
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Post by cecilbag on Dec 3, 2011 20:34:51 GMT -5
Do you have any spares preamp tubes to just swap down the line as another option. Sorry to hear about the squeals hope the gig goes better
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Post by DonaldDemon on Dec 6, 2011 16:12:13 GMT -5
Hmm, your bias looks a little hot IMO. Are you getting howling or squealing? Squealing could be a bum tube, even though you bought new ones. I use mounds of gain, so I combat howling by lowering the pickup height and an ISP G String in my signal chain. But my Sheraton will howl even on mild gain settings...lol Good luck! 48-50 is standard for KT88s but I guess I could try running it colder. It does it on all my guitars so it's definitely the amp. It's more howling than squealing I guess.  |
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Post by DonaldDemon on Dec 6, 2011 16:13:03 GMT -5
Do you have any spares preamp tubes to just swap down the line as another option. Sorry to hear about the squeals hope the gig goes better Yeah but I have tried that with no luck. I have a ton of preamp tubes and they all do the same. Might be time to send it to Scott.  |
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