DSL 401 question

[qjg1965]

Hi,

I'm new to the forum and just purchased a DSL 401 combo amp from my local Sam Ash store. I was looking at the new MA model but liked this one a lot more.

The amp was a floor model and has a serial number of 2004-20 0532-B. I have read other post on the forum stating that the one's made from 2003 and on do not have the heating problems that the older ones had. I have to say this one runs really hot.

This is my first Marshall tube amp so I'm not real knowledgeable about them. I used to have a Fender Blues Jr. and it never got as hot as this amp. I love the tone of this amp especially when I use my Les Paul, but I'm wondering if I should take it back and get something else because of the heat.

Thx

 

[thrawn86]

They do tend to run hot. That seems to be a given unless they are modded. Mine is a pre-2003 model, and I simply keep a big fan on the tubes when I play for any length of time.

If you do a search on the Forum here with the keywords "DSL 401" you'll come up with not a few articles concerning the mods that can be done (such as removing resistors, etc.).

The most important thing is to make sure that it's biased properly and not too far on the hot side. Post-2003 models are supposed to be in the range of 550-850mV (I give such a wide spread because it is subject to debate by a few of our members).

DISCLAIMER:

Biasing is easy IF you are comfortable inside of an amp and are cautious of the electricity inside, which can injure or even kill, regardless of whether it is plugged in or turned on.

If you're savvy on this, we can help you check the bias. If not, you might want to take it to a tech for maintenance.

Another thing to consider is a tube change. Make sure you know when the last tube change was before you bought it.....if they don't know or it's been 3-4 years, a new set of both preamp and power tubes is a good idea, even if your current sets are in good order....never hurts to have a backup set.

In short, any tube amp will require more attention than a solid state amp, and if you're simply cautious, it will reward you with long life and incredible tone.

Hope that helps ya.....welcome to the Forum!!!

 

[qjg1965]

Thanks for the info, Sam Ash told me the tubes have not been replaced. So it looks like I will need to do that. Does anyone know a good amp tech in Southern California.

I have ran a fan behind it and it cools it down a lot. The amp does have incredible tone and fits my needs perfectly, so I really don't want to take it back.

 

[thrawn86]

I don't personally know anyone in SoCal, but one of our resident experts is from Rohnert Park, and he is an incredible amp tech/builder. Jon Wilder of Wilder Amplification. Could shoot him a PM and if you don't mind shipping it, he'll make sure everything is in tip-top shape.

Otherwise, just give it a day or so and someone will have a suggestion for a tech in your neck of the woods. If everything is sounding good, your tubes may be fine; checking the bias is just a necessary precaution.

So that amp has been sitting there as a floor model for six years? How much did you get it for?

 

[qjg1965]

I paid $700 and they gave me an extra year on the warranty for free. I know I paid more than I should have, but I loved the tone on it.

 

[thrawn86]

That's not really too bad. If you pick one off of fleabay, who knows what you might have to deal with. I got mine from there for about $530, which was good, but it's always a crapshoot.

The 401 is the 'black sheep' of the JCM2000's. But it's cooler than most people realize, especially when you dial it in properly and consider its' features, flexability, etc.

 

[JohnH]

I gigged my DSL401 on Saturday, and with an extra 1x12 cab under it it sounded really good in our 5-piece band. I got all the volume I needed by pushing the clean channel and master on about 6. Ive not modded it at all, except to mount some fans inside the upper grill, and add a small heatsink to the bridge rectifier, which solves the heat issue completely.

John

 

[amplifier]

Let's see, DSL 401, SamAsh, SoCal...hmm Please tell me it's not the one at Ontario Mills!

 

[qjg1965]

Amplifier,

yes, thats the one should I take it back?

 

[psphill27]

Thanks for the info, Sam Ash told me the tubes have not been replaced. So it looks like I will need to do that. Does anyone know a good amp tech in Southern California.

I have ran a fan behind it and it cools it down a lot. The amp does have incredible tone and fits my needs perfectly, so I really don't want to take it back.

I've owned my DSL 401 since 2000 and absolutely love the thing. I pretty much just use it now to practice with since it's easier on the ears than blasting my half stack all the time.

Now...here's some things to know. I had to finally replace my rectifier bridge in about 2008 because it finally burnt up on me. This is due to the heat. Also, you will need new tubes from what I'm reading above. If you like the tone...don't take it back...but here's what I would do:

1. Replace all the tubes. Whatever your preference is, but the TungSol preamp tubes with JJ power tubes seem to sound really nice in them. I've been running Groove Tubes in mine lately (last set of GTs I'll ever buy) and they sound good. (Reason is because I found out they buy tubes from other manufactuers and put their name on them.)

2. When you rebias the amp, set it at 800mV. This is plenty hot enough for great tone and will eliminate a big part of you heat problem.

3. You can also either have a small fan installed in the back, or even have a heat sinc put over your bridge rectifier to solve a lot of the problems.

Bottom line - great sounding amps and work really well when you get them set. I've had mine for 10 years now and don't plan on getting rid of it. And I own a lot of other Marshalls.

 

[amplifier]

Amplifier,

yes, thats the one should I take it back?

Didn't mean to scare you. Actually I had my eye on that one.
Well just know, even though it's yours now... I played it first!

 

[qjg1965]

Do you know how long it had been sitting at the store. The guy at Sam Ash didn't know.
I had another person tell me it was a return because of the heat issue.

 

[qjg1965]

Can anyone suggest a good tech that knows DSL 401's and is in the southern California area. I would rather spend the money and take it to a reputable tech that knows these amps then to have Sam Ash send it to an unknown.

I have been running a fan behind it and that makes a huge difference but I agree it should be checked out.

I am not going to return it, love the tone too much.

 

[JohnH]

Even the new ones get very hot, as my 2005 model did until I added a couple of small fans. So its probable that there is nothing abnormal about your amp.

John

 

[qjg1965]

Thanks John,

I've been reading more post on the forum and it sure sounds like these amps just run hot. The fan really helps, no heat problem at all when its on.

 

[zslane]

I live in Los Angeles and I decided that it would be far cheaper, and more educational, to learn how to perform the "heat mod" myself. I had never used a soldering iron before in my life and knew very little about electronics and how to assemble/repair them. But I took the time and learned and now I am self-sufficient when it comes to basic repairs and mods. You might consider doing the same; it's not nearly as hard as it might seem!

 

[thrawn86]

It's really not that bad to do. The most daunting task IMO is removing the board from the chassis to get to the solder joints for BR1. I marked all my wires I had to take loose, and you've just got to be careful when putting it all back in with all the jacks and knob pots.

 

[JohnH]

If the amp has not actualy had a problem, then theres no need to remove the board - just take the chassis out and put a small heat sink onto the bridge rectifier with heat-sink cement, or a self stick one. This plus fans will greatly cool the rectifier and other parts.

The stock BR1 rectifier is good for 10A if kept cool and I think only a small part of that current is needed, but its capacity reduces with heat to zero by about 150C, and also its solder connections can melt - so cooling helps it work reliably, as well as reducing heat stress on other components.

With the above measures, my DSL401, still on stock tubes, works reliably at high volume for hours, even in summer here in Australia

John

 

[thrawn86]

+1, Agree with JohnH. I actually wasn't going to bring up the BR1 subject unless a problem was apparent. A fan will help tremendously.

 

[amplifier]

Do you know how long it had been sitting at the store. The guy at Sam Ash didn't know.
I had another person tell me it was a return because of the heat issue.

Goodness, the first time I remember seeing that one was around 3 years ago. Looking at the first part of the serial number, 2004... the year it was made, it could have been sitting around even longer. It doesn't mean anything. I've seen a lot of things that have been there for years.