HOW TO BIAS getting first tube amp!! Marshall DSL 40 EL34'S

Re: HOW TO BIAS getting first tube amp!! Marshall DSL 40 EL34'S

I guess I should have said I received an electric shock, rather than electrocuted. I looked up the definition, since I wasn't sure.


  1. Electrocution is death caused by electric shock, electric current passing though the body. The word is derived from "electro" and "execution", but it is also used for accidental death. The word is also sometimes used to describe non-fatal injuries due to electricity.
 
Re: HOW TO BIAS getting first tube amp!! Marshall DSL 40 EL34'S

The Marshall forum has a thread about that specific amp and how to bias, I don't have the link to that thread but I had seen it before. As other have said, be very careful, and if possible take some basic electronics course before engaging into something like this if you don't have the skills. Swapping pickups is one thing but the voltage inside of tube amp can hurt or kill.
 
Re: HOW TO BIAS getting first tube amp!! Marshall DSL 40 EL34'S

DSCN4005-L.jpgDSCN4182-L.jpg Here is the inside of the amp Im talking about two trim pots etc...
 
Re: HOW TO BIAS getting first tube amp!! Marshall DSL 40 EL34'S

Yeah i found it these are pics from it
 
Re: HOW TO BIAS getting first tube amp!! Marshall DSL 40 EL34'S

Some of you need to relax IMHO.

When working with electronics, here's some basic safety guidelines and most idiots (even me) will be fine. I've yet to ever be shocked when working on stuff:

- Wear closed-toe rubber soled shoes. This one gets overlooked a lot, but it isolates you from ground when exposed to DC (but not AC which can travel through the natural capacitance of the air to ground).
- AC will blow you off your ass, DC will make your muscles contract. Know which one you're working with. If both are present in the circuit, know what parts of the circuit are which.
- Never touch anything that is connected to the mains (duh).
- Wear rubber gloves when possible.
- Rubber gripped tools.
- Never work when wet (be it water, or if you're sweating). In the case of water, the metals and minerals in tap water are present enough to conduct electricity. In the case of any liquid, moisture will lower your skin's natural resistance by a very large margin. This is why you can short a 9V battery across your skin and feel nothing, but short it across your tongue and feel it tingling.
- The same rule about working with wet skin applies to open wounds. The tissues under your skin have a much lower resistance and you will feel the shock.
- Drain filter capacitors before beginning work, and use a voltage meter to make sure the capacitors actually discharged.
- Wear a condom; you don't want that to get shocked.
- There are two types of circuits: Ones that are harmful, and ones that are harmless. Treat all circuits with the respect and caution as if they were harmful.
- Keep one hand in your back pocket, and work with the other whenever possible. This isn't to play pocket-pool while working, but to reduce the chance of any electricity seeing the shortest path to ground as "through the heart".

Really, most of it is common sense.
 
Re: HOW TO BIAS getting first tube amp!! Marshall DSL 40 EL34'S

It looks as if that particular amp has bias points you can read with a volt meter. It's those 3 prongs: pos/neg/pos. Left to middle is one tube, and right to middle is the second tube.

That means you don't necessarily need a bias tool to bias that amp. Many newer amps have that convenient feature.
 
Re: HOW TO BIAS getting first tube amp!! Marshall DSL 40 EL34'S

It looks as if that particular amp has bias points you can read with a volt meter. It's those 3 prongs: pos/neg/pos. Left to middle is one tube, and right to middle is the second tube.

That means you don't necessarily need a bias tool to bias that amp. Many newer amps have that convenient feature.

Yes, and your not really exposed to any dangerous voltages.

I wish I had known how and understood it better back in the day. I would have had a better tone more nights and not destroyed so many NOS tubes, and saved a bunch of cash. I thought you had to have a scope and load to properly bias back then. Now I have my old amps set up so I can do it myself with a multimeter and some math. I haven't ever been zapped but I'm careful every time regardless.
 
Re: HOW TO BIAS getting first tube amp!! Marshall DSL 40 EL34'S

I wanted to know this is off subject from biasing but is it worth buying a demo version of this amp if its 70-80 bucks cheaper?? I was just curious.
 
Re: HOW TO BIAS getting first tube amp!! Marshall DSL 40 EL34'S

Yeah I believe someone said dont forget also that the left trim pot actually adjusts the right tube and vice versa
 
Re: HOW TO BIAS getting first tube amp!! Marshall DSL 40 EL34'S

Man.....some of you guys.......
He WANTS to learn how to bias an amp.
It's New.?
One of the power tubes Could Easily crap out tomorrow.
He may want to try different tubes, or he may (good on him) just Want To Learn.
EVERYBODY has to start.
There is absolutely no reason a competent beginner cannot be taught to bias an amp.
The number of stars that would have to align for somebody To Die from working on an amp is large.
Yes, he CAN injure himself, and he knows it. He is obviously proceeding with caution, and that is encouraging.
This is not the SDF of old I guess.

I agree. Some guys in this thread assume that he's an inept idiot that couldn't melt solder with a hot iron.

But then again, I was raised to be self sufficient. The transmission in my Bronco went out, so I rebuilt the transmission. I wanted my JVM to sound different, so I tore it apart and modded it. I've swapped out pickups in several of my guitars, made adjustments to the setups, ect. I've fabricated parts for the farm machinery my Dad & I had when we farmed together.

I could go on.

And I'm not trying to brag myself up. I'm just trying to point out that the average guy can work on his own gear if he does his homework and learns how to do it properly.
 
Re: HOW TO BIAS getting first tube amp!! Marshall DSL 40 EL34'S

It's impossible to judge someone's intellect from an internet posting.
You always default to caution.
Can never tell who else will read the.post and try it themselves.
Stupid people usually don't realize their limitations because of their disability


*(Sent from my durned phone!)*
 
Re: HOW TO BIAS getting first tube amp!! Marshall DSL 40 EL34'S

My tubes been crackling I put some new EH power tubes in the DSL 40 to see if it would solve the problem and it worked! I did check all preamp tubes first and I still got this nasty static sound. But now its just fine and I didnt bias it! it still sounds and feels the same cranked. No red plating and the amps not running any hotter then before. People prb think im crazy but I figured if it still sounds like before I might be good and if not I would take it in. Played for a hour and problems but I will be looking at the tubes for issues.
 
Re: HOW TO BIAS getting first tube amp!! Marshall DSL 40 EL34'S

An old electrician once taught me to approach a questionable circuit with one hand in my pocket, so as not to present a ground loop through the chest. Not that making ground through arm and leg was pleasant, just slightly less liable to be fatal.

I would amend your statement to say that it is pretty scary to enjoy the sensation of current vibrating through your body for a second. I'm one of those kids who enjoyed licking 9v batteries and holding on to horse coral wires for the longest. Is that TMI?

way i was instructed when i went to school for electronics a few years back
 
Re: HOW TO BIAS getting first tube amp!! Marshall DSL 40 EL34'S

Go to YouTube/ How to bias a Marshall dsl40c bam you are there! Listen closely though you can save your life if you do!!

Sent from my LGMS395 using Tapatalk
 
Re: HOW TO BIAS getting first tube amp!! Marshall DSL 40 EL34'S

Just wanted to say thanks for bumpin this one up. The dsl40 thead on the marshall forum is wonderful, but nearly impossible to fnd things in (its over 150 pages)
 
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