Help!!! Dual Rec Rev. G Orange Channel Problem

[sdgiffin]

Hey guys,

I've got a 2ch Dual Rec and I am experiencing a problem with the Orange channel. When the amp is on this channel, it produces a low fluttering sound similar to a motorcycle on idle. It's not very loud, but you can feel it and is at a very low frequency. When I switch over to the Red Channel, it disappears and when in vintage or high gain mode on the Orange Channel, it's almost non-existent but still there. Any thoughts? I rarely use the Orange Channel but I want this fixed in case I ever decide to sell the beast.

Thanks guys,

Scott

 

[mikey383]

Have you tried swapping preamp tubes? Sounds like one is on it's way out.

 

[AudioMonk]

Hi Scott. Try Mikey's suggestion first. The first thing that is always checked in a situation like this are the preamp tubes. I hope it is a preamp tube as that would save you some aggravation. However, what you are describing sounds like a capacitor related oscillation. Both channels of the dual rec share all preamp tubes, so it would make sense to assume the oscillation you hear, if described correctly, would be present on both channels. The only things not shared are the gain controls, masters, and eq sections of the orange and red channels. Perform this experiment: While switched to the orange channel turn gain and master controls mid way, now turn gain control down, does the oscillation go away? If it does then chances are it has to do with the treble bleed cap going to the gain control, or it could be a faulty component in the eq section.

 

[YellowJacket]

Hey guys,

I've got a 2ch Dual Rec and I am experiencing a problem with the Orange channel. When the amp is on this channel, it produces a low fluttering sound similar to a motorcycle on idle. It's not very loud, but you can feel it and is at a very low frequency. When I switch over to the Red Channel, it disappears and when in vintage or high gain mode on the Orange Channel, it's almost non-existent but still there. Any thoughts? I rarely use the Orange Channel but I want this fixed in case I ever decide to sell the beast.

Thanks guys,

Scott

You don't use the Orange Channel? I have found that the vintage mode is great for elastic liquid leads and the crunch when Orange is set to modern is unbelievable! Totally get that fixed!!!

 

[sdgiffin]

Hi Scott. Try Mikey's suggestion first. The first thing that is always checked in a situation like this are the preamp tubes. I hope it is a preamp tube as that would save you some aggravation. However, what you are describing sounds like a capacitor related oscillation. Both channels of the dual rec share all preamp tubes, so it would make sense to assume the oscillation you hear, if described correctly, would be present on both channels. The only things not shared are the gain controls, masters, and eq sections of the orange and red channels. Perform this experiment: While switched to the orange channel turn gain and master controls mid way, now turn gain control down, does the oscillation go away? If it does then chances are it has to do with the treble bleed cap going to the gain control, or it could be a faulty component in the eq section.

Thanks Audio Monk, I'll most definitely try that.

Mikey, I've replaced all of the preamp and power tubes and the problem is still there :/