MOD-50 Distord Problem

[Val]

Hi all,
!!! Happy New Year !!!

I'm having a problem with all channels on my MOD-50. The amp has this weird distortion that's not normal. Sounds like power tubes going, but they look fine??? Before I buy some, could it be any other tube?

Is there a schematic of all the tube locations and what they are for the MOD-50?

Thanks

 

[EWSEthan]

Get some Tung-Sol 5881s. Your tone will improve dramatically from the Sovteks.

 

[Val]

Thanks

Get some Tung-Sol 5881s. Your tone will improve dramatically from the Sovteks.

The new Tung-sol 5881 are 23 watt and plate rating of up to 400 Vdc, is this ok to use on the mod-50?
I'm not sure of how high the Vdc voltage goes on the MOD50.

 

[Buckeyedog]

Yes, they will do fine as many of us have them. I'd also recommend the TS 6550's as well. Unreal tube for all the modules.

 

[jmgman69]

Yes, they will do fine as many of us have them. I'd also recommend the TS 6550's as well. Unreal tube for all the modules.

I also concur

 

[Val]

Yes, they will do fine as many of us have them. I'd also recommend the TS 6550's as well. Unreal tube for all the modules.

I also concur

Thank you for the suggestions. I do have some Svetlana 6550 that I got from Eric. I will try that and order some TS-6550.

Thank you

 

[jkdsteve]

Svet 6550s are killer...

If you get a hankering for TS5881s...I have a pair with less than 2 hours on 'em that I just don't dig (second time around...LOL!) so don't pay new prices

 

[bruce egnater]

Have you checked the bias on the rear to be sure both tubes are working? Do you know how to do it? If not, do you have the manual?

 

[Val]

Have you checked the bias on the rear to be sure both tubes are working? Do you know how to do it? If not, do you have the manual?

Bruce, Yes, I checked the bias and it was set to 30-34 (5881) which is good. I just swapped out the tubes and put svet 6550 and biased at 41-44 and that distorded problem is gone now. I guess the 5881's just had enough of my playing...lol.

Thanks Bruce and all!

 

[Roddy]

Your distortion issues sound like a bad 12AX7, not the power tubes......just my opinion....

 

[Val]

Your distortion issues sound like a bad 12AX7, not the power tubes......just my opinion....

At first I thought that also, but it was doing it on all 4 channels. I have swapped out the power tubes and all sounds ok now, but I will keep that in mind in case it starts doing it again.

Thanks