Muddy 5150 : bias adjustment or power tubes changing ?

[Sly]

My 5150 sounds very good but each time I record it I have really too much low mids coming out of it. I have to cut a lots of them to get it to sound right.
I can post a clip maybe.

I bought it used a few years ago and it had Svetlana 6L6 in the power section. When the tubes died, I switched to JJ 6L6 (I bought paired JJs but changed the tubes myself without any bias adjustement), the amp sound good now but a bit muddy. I never tried to record the amp when I had Svetlanas into it, but my memory tells me that the amp sounded grittier with more bite.
I always kept the original preamp tubes so I guess it's not the issue there.

Should I :
- Keep the JJ and go to a tech with my amp for a bias adjustment ?
- Swap the JJ and get more agressive power tubes ?

What do you think ? Thanks for helping me out !

 

[J.DavisNJ]

My 5150 sounds very good but each time I record it I have really too much low mids coming out of it. I have to cut a lots of them to get it to sound right.
I can post a clip maybe.

I bought it used a few years ago and it had Svetlana 6L6 in the power section. When the tubes died, I switched to JJ 6L6 (I bought paired JJs but changed the tubes myself without any bias adjustement), the amp sound good now but a bit muddy. I never tried to record the amp when I had Svetlanas into it, but my memory tells me that the amp sounded grittier with more bite.
I always kept the original preamp tubes so I guess it's not the issue there.

Should I :
- Keep the JJ and go to a tech with my amp for a bias adjustment ?
- Swap the JJ and get more agressive power tubes ?

What do you think ? Thanks for helping me out !

Yooo Sly,

Does your 5150 have the bias mod? If not, then the bias isn't adjustable.

I'd recommend the bias mod though. It helps tame the fizziness/coldness/harsh nature of the 5150, and if you don't dig it you can still set the amp for it's original bias values.

-Joe

 

[phatfil]

if it seems like you can't use as much gain as you did with the Svetlana's, get it re-biased. JJ's have a higher plate voltage. i had to re-bias my Krank when i went to JJ's. now my amp sounds better than ever.

 

[phatfil]

fixed bias, oops...

yeah, a bias mod would be the first thing i'd do.

 

[Metaltastic]

Selling it for a Dual Rectifier or Krank would be the first thing I'd do