Marshall DSL 401 Losing Gain

[astrozombie]

Tubes right? Tubes.

There is no loss of volume from what I can perceive, just a loss of gain on tap.

Nothing has changed in my setup.

Would this be a pre amp tube? My tube amps have been so nice to me that I don't even know how to troubleshoot them when something goes wrong.

 

[Boogie Bill]

Re: Marshall DSL 401 Losing Gain

Could be.

Try using a new 12ax7 that you know is good, and start with the V1 preamp tube (which will be the one closest to the input). Hit STANDBY, then try substituting the good tube in, one socket at a time. Play and listen. If no change, STANDBY, then put the old one back in and go on to the next socket. It should be obvious if you have a bad one.

Good luck!

Bill

 

[Chickenwings]

Re: Marshall DSL 401 Losing Gain

dude you should do some tube swapping before asking for advice.
You don't call the electrician when a light globe blows in your house.

 

[Gearjoneser]

Re: Marshall DSL 401 Losing Gain

JeffB discovered that this model is biased wrong from the factory, which Marshall has always been guilty of.

First, replace all the pre tubes. Then, get a bias tool and volt meter. Get the EL-34's reading 36mA, and the amp will sound good....and the power tubes will last longer.

 

[jmh151]

Re: Marshall DSL 401 Losing Gain

JeffB discovered that this model is biased wrong from the factory, which Marshall has always been guilty of.

Before you do anything else, get a bias tool and volt meter. Get the EL-34's reading 36mA, and the amp will sound good....and the power tubes will last longer.

If I'm not mistaken, the 401 is the original incarnation with EL84's

 

[JeffB]

Re: Marshall DSL 401 Losing Gain

Yup, I own the newer 40c. Which is notorious for whackadoo bias which kills the tone and tubes.The Marshall forum is full of folks who have tubes biased off the deep end.

The 401 is el84s. Don't recall if its cathode biased or adjustable.

 

[Gearjoneser]

Re: Marshall DSL 401 Losing Gain

Yeah, I forgot that model is probably EL-84.

That simplifies things a bit.

Buy a whole set of tubes and the problem will likely be solved. According to tube guru Myles Rose, JJ makes the best modern EL-84.

 

[astrozombie]

Re: Marshall DSL 401 Losing Gain

dude you should do some tube swapping before asking for advice.
You don't call the electrician when a light globe blows in your house.

butttttt duddddddeeeeeee

this little combo is a pain in the ass to take apart :'(

 

[astrozombie]

Re: Marshall DSL 401 Losing Gain

yeah this amp uses 84s.

 

[astrozombie]

Re: Marshall DSL 401 Losing Gain

Yup, I own the newer 40c. Which is notorious for whackadoo bias which kills the tone and tubes.The Marshall forum is full of folks who have tubes biased off the deep end.

The 401 is el84s. Don't recall if its cathode biased or adjustable.

\

the bias is adjustable

I have it kind of hot but not as hot as the internet will recommend. I can't recall the reading off the top of my head.

this amp has heating issues, mine heats up but it doesn't burn you when you touch it, etc..

 

[Kamanda~SD]

Re: Marshall DSL 401 Losing Gain

butttttt duddddddeeeeeee

this little combo is a pain in the ass to take apart :'(

It's a few screws. you don't need to take the whole chasis out to do this.

 

[Shooter.556]

Re: Marshall DSL 401 Losing Gain

I didn't even know they had electricity in Puerto Rico?

 

[JeffB]

Re: Marshall DSL 401 Losing Gain

It's a few screws. you don't need to take the whole chasis out to do this.

you do on the 40c. pita.

 

[JeffB]

Re: Marshall DSL 401 Losing Gain

\

the bias is adjustable

I have it kind of hot but not as hot as the internet will recommend. I can't recall the reading off the top of my head.

this amp has heating issues, mine heats up but it doesn't burn you when you touch it, etc..

The 401 and especially the 201 are known for excessive heat. might want to install a small.fan/point one at the back on gigs.

 

[Kamanda~SD]

Re: Marshall DSL 401 Losing Gain

Ah my bad, I was looking at the 401.

With that said, I still dont see why you cant just take the back panel off and flip it...am I missing something here?

Also, those come stock with Celestion 70/80's? Do yourself a huge favour and replace that sucker.

 

[Chickenwings]

Re: Marshall DSL 401 Losing Gain

butttttt duddddddeeeeeee

this little combo is a pain in the ass to take apart :'(

lol astro. You are awesome!:lmao:

 

[Laimac]

Re: Marshall DSL 401 Losing Gain

Ah my bad, I was looking at the 401.

With that said, I still dont see why you cant just take the back panel off and flip it...am I missing something here?

Also, those come stock with Celestion 70/80's? Do yourself a huge favour and replace that sucker.

+1 on the 70/80's - they sound horrible even to a noob like me. Very flat and no character at all. I have seen some folks describing then as better suited for hifi gear which may sound strange as that would imply they just output what your amp produces without colouring the sound but it is actually pretty accurate and makes them quite bland in reality. I swapped the one I had in my 1x12 for a Scumback and it made a world of difference!


Sent from my iPad using Tapatalk