My Dual Rec only works on Clean channel

[Pmaurer]

So...I'm rather new to the whole tube-amp concept. I've had my Dual for only about 2-3 months. I went to turn it on today (the proper way) and nothing was coming from channel 2 or 3...upon closer inspection there was sound...but i had to put my ear really close to the cab to hear it at all. When I switched to the clean channel everything is fine...is this a sign of a bad tube? I've been checking around this board on different issues and want to try and create a FAQ on different Rec problems so that people aren't always asking the same questions (if the mods would add it to the top at some point). Any help is greatly appreciated!

 

[c.t.d-nicke]

create a FAQ

+1

 

[fluff191]

I second that as well. Just imagine..........A board with no more "It pops when I switch channels" questions!!!

 

[echoes420]

I second that as well. Just imagine..........A board with no more "It pops when I switch channels" questions!!!

HAHA! That was a good one!

But on the other side of that... have you ever tried using the search option for anything? Especially when you have a specific question? I have had trouble finding info too. You can't very well type questions in the search box. A FAQ is a great idea though.

I think the board could benefit greatly from a couple of modernization improvements.

 

[Pmaurer]

It's great that everyone likes this idea but can you please answer my problem?? haha.

 

[echoes420]

I am not an amp tech... but it doesn't seem like a normal tube issue to me. Sounds to be transformer related to me.

But I always say... when in doubt, take it to a tech.

 

[mikey383]

Try replacing V2 and V3 with a known good tube.

They're laid out as such:

V1a - input stage, all channels
V1b - clean channel

V2a - second input stage all channels
V2b - gain channels boost stage

V3 - gain channels boost stages

So if the gain channels aren't working, my money is laid on V2b or V3.

 

[Pmaurer]

could the tubes really have died within only 3 months of owning the dual? I bought it brand new and i never over-pushed them, no microphonic stages or anything.

 

[mikey383]

Tubes can go at any time. I've had new ones that were bad. I had one go bad last week just from pulling it and reinstalling it.

 

[Pmaurer]

Am I understanding this right? There are 4 6L6 tubes, 2 5u4Gs, and then 5 pre-amp tubes? the V2 and V3 are the small pre-amp tubes? located behind the power tubes?

 

[mikey383]

Yep. Those are the ones. V1 is located closest to the input jack, followed by V2, 3, and 4, then V5 is between those tubes and the power tubes.

 

[muramasa]

I had that same problem with my tripe rectifier once, it was just a bad preamp tube. just replace them and it should be fine. mainly V1 V2 or V3.

Hows the new Chevelle fourm going?

 

[Pmaurer]

I had that same problem with my tripe rectifier once, it was just a bad preamp tube. just replace them and it should be fine. mainly V1 V2 or V3.

Hows the new Chevelle fourm going?

Thanks, ill give it a try! Are they located under the silver containers? Just lift those up and pull the old tube out?

The forum is going nicely, stop by if you get the chance!

 

[muramasa]

Yup just get the tube covers off and gently wiggle the tubes out of the sockets. They should be in order left to right starting with V1, there should also be a little diagram on the inside of the headshell that tells you the order of the tubes.

 

[Pmaurer]

one more question, how do i remove the headshell?

 

[muramasa]

one more question, how do i remove the headshell?

If you look at the underside of the head you'll see 4 screws. before you unscrew them take the power and rectifier tubes out. And once you unscrew it becareful that you don't touch the insides of the chassie, there are big blue caps that have a charge still in them and if you get shocked they can kill you.

 

[dhorvath]

I just had the same exact problem. Listen to Mikey 383. He's right.
I replaced the preamp tube in the V2 position. All is well now.
No need to take the shell off at all. Make sure the amp is turned off first. Just remove the bar from the back of the head and pull out the 6L6 power tube so you can get to the preamp tube. Replace the preamp tube with a new one. Place the 6L6 power tube back in it's original position. Turn the amp on, and see if channel 2 comes back to life. If it does, you found the bad tube. If it doesn't, repeat the steps, and replace the preamp tube in the V3 position.
Once you found the bad tube. Reattach the bar on the back of the head. That's it.