DSL401 converted to head

Brian9 · 10-27-2009, 05:35 PM

Using a table saw, I cut the bottom off just above the plastic corners. Then I cut the middle just below the first rear top metal grill. Then drilled four holes and connected with 21/2 inch lags.

I retained that top metal grill, but had to snip some holes to straiten the area where my fan goes.

The bottom rear metal grill I put on the front, flipping upside down so the L shaped part butted the bottom of the amp chassis. I had to reposition the reverb tank to the middle to avoid touching the fan.

I pulled the Marshall emblem off the front cloth, snipped off the pegs and glued it to the front.

It may have looked better if I would have cut a piece of wood and covered it with black cloth and the emblem, but with overheating in mind, the bottom grill, with its holes, allowed the fan to exhaust the chassis nicely.

The last picture is of the bridge rectifier mod I had done. A technician devised a way to lift the BR off the board somehow, thus (he says), eliminating possibility of heat related failure.

American Viking · 10-27-2009, 05:39 PM

Pretty neat.

thrawn86 · 10-27-2009, 08:30 PM

That's pretty freakin' rad!

BTW, your tech probably just bought a new BR102 and put it in; they come with legs that are about 1 1/2 inches long. When I did mine, I just soldered it further out, which does get it off the board very well.

carnada · 10-27-2009, 11:04 PM

you are a genious

JohnH · 10-28-2009, 01:32 AM

It does look good - well done. So what cab is it driving for you and how does that sound?

John

Lindgren · 10-28-2009, 03:36 AM

Very nice.

Brian9 · 10-28-2009, 07:04 AM

Quote:

Originally Posted by JohnH

So what cab is it driving for you and how does that sound?

John

I purchased a 1X12 custom cabinet that has dimensions based on the bottom of the combo. (The combo's top is narrower than the bottom) Black tolex, black corners, nickel hardware, 3/4 back and V30.

I found with the V30 in the combo, it didn't sound as good as putting it in the cab and no speaker in the combo. Which is why I did the conversion. My guess is that the combo's back is too open...?

Sounds great, by the way. I'm now running two amps together which give me tones I'm happy with.

Brian9 · 10-28-2009, 07:11 AM

Before and after...

van · 10-28-2009, 10:49 AM

looks good!

Puffer Fish · 10-28-2009, 12:40 PM

Another one! I love it! I have thought about making one of these myself. I am really happy with my 401. It would be great to have a head version of the amp to more conveniently take places. Typically I have plenty of access to extension cabs where I practice or perform... if I had a head to plug in, I'd be all set.

To me, this project looks like you mainly need to take your time--assuming you can operate a table saw. I like the metal grill idea for the front for the sake of air flow. I always thought this amp would benefit from some sort of a grill on the TOP of the box for better air flow/ to allow heat rising from around the circuit board.

Zman · 10-28-2009, 02:40 PM

I am using my DSL401 as a head as well. I still have the internal speaker, but I disconnected it and I run it through an Avatar 2/12. It sounds amaziing. I would be nice as a head only though. I had issues with the internal speaker causing the tubes to rattle. Now it is perfect. I have them side by side and I can always hook up the internal.

MadHatter · 01-12-2010, 09:02 AM

This has got to be the cleverest thing! I really like my 40W DSL, but hate the open back speaker configuration. The Head version of the DSL401 is a dream.

I'm not sure that i have the skill to pull it off tho...

Ken · 01-12-2010, 09:07 AM

I saw one on eBay a couple years back and I even bid on it. It ended up selling for around $500.

Ken

MKB · 01-12-2010, 11:10 AM

Great job on the conversion!! If you can handle the inconvenience of having to carry two objects instead of one, converting a combo amp to a head is the by far best thing to do.

BTW, you could help the reliability of the bridge rectifier even more if you attach a heat sink to it. Also, many bridge rectifiers (and diodes in general) without heat sink attachments basically radiate the heat from their leads; by cutting the leads you are making it run hotter. So in many cases it is helpful to leave the leads as long as you can.

thrawn86 · 01-12-2010, 11:46 AM

The only thing I'd do differently than Brian is instead of sawing off the sides of the combo, I'd leave them a little longer and cut the bottom to fit inside. That way, you wouldn't see the tiny bit of edge in the back just above the corner caps and everything would line up right. I'd probably also salvage the grille cloth for the front. And just maybe I'd be a smartass and turn the '1' in '401' into an 'H'.

MartyStrat54 · 01-12-2010, 12:55 PM

You'd be a smartass. (My first post of the day...I made it a good one.)

thrawn86 · 01-12-2010, 01:41 PM

I am a smartass! HEEHAWWW!

Brian9 · 01-12-2010, 03:59 PM

Quote:

Originally Posted by thrawn86

turn the '1' in '401' into an 'H'.

Like this?

thrawn86 · 01-12-2010, 05:10 PM

Close enough!

MadHatter · 01-18-2010, 07:09 AM

If anybody has DSL401, DSL50 and a 4x12 cab sitting around, it would be really interesting to hear an A/B test: DSL401 with 4x12 cab VS DSL50 with 4x12 cab.

bloosman1 · 01-18-2010, 07:17 AM

Brian9, that is awesome work dude!

martin6string · 01-18-2010, 06:47 PM

Looks pretty cool. Nice job.

robinsoncaruso · 01-25-2010, 10:53 PM

I know this is an old post, I just joined and am excited about your work!

Well done.

Quick question,

Is your fan blowing over the tubes, or is it exhausting heat?

I did the fan mod to my DSL401, and noticed that exhausting seemed to do very little as far as heat dissipation. The amp faceplate still was very hot to the touch. Or does anyone have any general suggestions on the fan mod?

Brian9 · 01-26-2010, 10:51 AM

Quote:

Originally Posted by robinsoncaruso

I know this is an old post, I just joined and am excited about your work!

Well done.

Quick question,

Is your fan blowing over the tubes, or is it exhausting heat?

I did the fan mod to my DSL401, and noticed that exhausting seemed to do very little as far as heat dissipation. The amp faceplate still was very hot to the touch. Or does anyone have any general suggestions on the fan mod?

The fan blows across the tubes and out the front. I used the bottom metal grill off the back to use on the front so that the holes would allow the air to escape.

As far as hot to touch, have you checked the bias? I'll guess that its too high causing the excessive heat. Get it down to around 800mv. If yours is pre-2003, I recommend changing the 2 bias related resistors as well.

robinsoncaruso · 01-26-2010, 11:20 PM

Quote:

Originally Posted by Brian9

The fan blows across the tubes and out the front. I used the bottom metal grill off the back to use on the front so that the holes would allow the air to escape.

As far as hot to touch, have you checked the bias? I'll guess that its too high causing the excessive heat. Get it down to around 800mv. If yours is pre-2003, I recommend changing the 2 bias related resistors as well.

I believe mine is a 2001, but I'm not exactly certain. Is the serial number in the barcode on the back of the amp? Or do I have to remove the back grilles and reach inside to take a look.

Since I turned my fan around to blow across the tubes and it stays at a very nice 'warm' temperature. Not viciously hot like it would otherwise.

You mention checking the bias, I've seen some instructions on forums. I don't have a multimeter. Is it worth it to get this checked out. I did just change my tubes also.

Thanks for the input.

Bill

JohnH · 01-26-2010, 11:45 PM

If you have changed power tubes then you do need to check bias. A multimeter and two insulated alligator leads are all that is needed, and the inexpensive digital type are fine.

Your amp was biased by adjusting a pot on the board, and setting the voltage across a certain 10Ohm resistor to 1.35V. This was very hot, ie that setting indicated a very high steady current going through the tubes. Post 2003, they changed a couple of resistors and biased them at 0.55V. This is very low!.

I have my 2005 dsl401 biased at 0.8V, with fans, and it runs fine. You may be able to turn your bias down to this level, which will be cooler than it was.

If you do this yourself, some step by step details could be found. It will involve removing back panels, unscrewing the chassis and lifting it out, clipping the multimeter to a test point on the board reconnecting speaker and mains and adjusting a pot with a screwdriver, all the time being careful of lethal voltages that exist in a tube amp.

Its actually not difficult or dangerous, if you are methodical and careful, but if you are not careful, then it is dangerous.. It does not involve disconnecting or soldering anything on the board.

John

Brian9 · 01-28-2010, 11:28 AM

Quote:

Originally Posted by robinsoncaruso

I believe mine is a 2001, but I'm not exactly certain. Is the serial number in the barcode on the back of the amp? Or do I have to remove the back grilles and reach inside to take a look.

Since I turned my fan around to blow across the tubes and it stays at a very nice 'warm' temperature. Not viciously hot like it would otherwise.

You mention checking the bias, I've seen some instructions on forums. I don't have a multimeter. Is it worth it to get this checked out. I did just change my tubes also.

Thanks for the input.

Bill

The year of the amp is on the back, top right, under the barcode. It's the first four numbers after the first letter. Mine is "M-2000-xx-xxxx-X", meaning its a 2000. The rest of the sequence is supposed to tell you more regarding month or exact date, I just don't care. The year is the only issue.

If yours is a 2001, it is in need of a bias check. IMO, don't go to a tech for this. If you're going to own a tube amp, you should learn how to bias it. It's really easy. I'm half retarded (maybe more) and I can do it in just a few minutes. Save the coin you'd spend at the amp shop and buy a simple multi-meter (got mine for $10).

Send me a PM if you want specifics on how to bias it. I'd be glad to email you pictures or whatever.

STAVROS · 01-31-2010, 02:57 PM

Very cool job Brian. Ive been toying with the idea myself for a few weeks with my 401. I run it through a 2x12 cab without the internal speaker and man for a little amp it just honks! Did a quick search and yours is first one that came up. So yeah, brilliant job dude. and very inspiring. cant wait to get stuck into mine now!!

Im a brand new member. this is my first post! thanks to you. although ive been surfing here for along time now. nice to fianlly be part of it.

thrawn86 · 01-31-2010, 03:06 PM

Quote:

Originally Posted by STAVROS

Very cool job Brian. Ive been toying with the idea myself for a few weeks with my 401. I run it through a 2x12 cab without the internal speaker and man for a little amp it just honks! Did a quick search and yours is first one that came up. So yeah, brilliant job dude. and very inspiring. cant wait to get stuck into mine now!!

Im a brand new member. this is my first post! thanks to you. although ive been surfing here for along time now. nice to fianlly be part of it.

This will probably be my next tinker project. Welcome aboard STAVROS.

dugger · 01-31-2010, 04:02 PM

Neat job man! I'm always thinking and or doing stuff like this! Only thing I would do different is center the logo more toward the faceplate.

10-27-2009, 05:39 PM	#2 (permalink)
American Viking Senior Member Join Date: Jan 2009 Location: RICHMOND, VIRGINIA Posts: 2,031	Re: DSL401 converted to head Pretty neat. __________________ Transformers inside amplifiers were not originally designed to be in there, and the tube was not created for the guitar amp. ANY recommended idle current is a guideline and in no way a necessary requirement. There is no skeleton key for any tube amp.

10-27-2009, 11:04 PM	#4 (permalink)
carnada Senior Member Join Date: Dec 2008 Location: 22 Acacia Avenue Posts: 1,199	Re: DSL401 converted to head you are a genious

10-28-2009, 01:32 AM	#5 (permalink)
JohnH Senior Member Join Date: May 2008 Location: Wollongong NSW Posts: 781	Re: DSL401 converted to head It does look good - well done. So what cab is it driving for you and how does that sound? John __________________ DSL401 8412 cab Crate Powerblock 1 x 12 Vintage 30 cab '76 Shergold Masquerader '93 Les Paul Studio '83 Roadstar

10-28-2009, 03:36 AM	#6 (permalink)
Lindgren Member Join Date: Sep 2009 Location: Artic circle - Sweden Posts: 36	Re: DSL401 converted to head Very nice. __________________ ESP Eclipse NR1 ESP Eclipse NR2 ESP Eclipse NR3

10-28-2009, 10:49 AM	#9 (permalink)
van Junior Member Join Date: Oct 2009 Posts: 11	Re: DSL401 converted to head looks good!

Today
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10-28-2009, 12:40 PM	#10 (permalink)
Puffer Fish Member Join Date: Jan 2009 Posts: 71	Re: DSL401 converted to head Another one! I love it! I have thought about making one of these myself. I am really happy with my 401. It would be great to have a head version of the amp to more conveniently take places. Typically I have plenty of access to extension cabs where I practice or perform... if I had a head to plug in, I'd be all set. To me, this project looks like you mainly need to take your time--assuming you can operate a table saw. I like the metal grill idea for the front for the sake of air flow. I always thought this amp would benefit from some sort of a grill on the TOP of the box for better air flow/ to allow heat rising from around the circuit board.

10-28-2009, 02:40 PM	#11 (permalink)
Zman Member Join Date: Nov 2008 Location: Southern Ontario Posts: 54	Re: DSL401 converted to head I am using my DSL401 as a head as well. I still have the internal speaker, but I disconnected it and I run it through an Avatar 2/12. It sounds amaziing. I would be nice as a head only though. I had issues with the internal speaker causing the tubes to rattle. Now it is perfect. I have them side by side and I can always hook up the internal.

01-12-2010, 09:02 AM	#12 (permalink)
MadHatter Junior Member Join Date: Jan 2010 Posts: 10	Re: DSL401 converted to head This has got to be the cleverest thing! I really like my 40W DSL, but hate the open back speaker configuration. The Head version of the DSL401 is a dream. I'm not sure that i have the skill to pull it off tho...

01-12-2010, 09:07 AM	#13 (permalink)
Ken Senior Member Join Date: Feb 2009 Location: Arlington Heights, IL Posts: 1,171	Re: DSL401 converted to head I saw one on eBay a couple years back and I even bid on it. It ended up selling for around $500. Ken

01-12-2010, 11:10 AM	#14 (permalink)
MKB Senior Member Join Date: Jul 2008 Posts: 290	Re: DSL401 converted to head Great job on the conversion!! If you can handle the inconvenience of having to carry two objects instead of one, converting a combo amp to a head is the by far best thing to do. BTW, you could help the reliability of the bridge rectifier even more if you attach a heat sink to it. Also, many bridge rectifiers (and diodes in general) without heat sink attachments basically radiate the heat from their leads; by cutting the leads you are making it run hotter. So in many cases it is helpful to leave the leads as long as you can.

01-18-2010, 07:09 AM	#20 (permalink)
MadHatter Junior Member Join Date: Jan 2010 Posts: 10	Re: DSL401 converted to head If anybody has DSL401, DSL50 and a 4x12 cab sitting around, it would be really interesting to hear an A/B test: DSL401 with 4x12 cab VS DSL50 with 4x12 cab.

01-18-2010, 07:17 AM	#21 (permalink)
bloosman1 Senior Member Join Date: Dec 2008 Location: Austin, TX Posts: 298	Re: DSL401 converted to head Brian9, that is awesome work dude! __________________ Amps: JCM 2000 DSL 100 1960 A Cab. Fender Hot Rod Deville Fender Pro Jr. Pignose Axes: Fender 2009 American Standard Strat Fender 81 modified strat Fender 98 mim modified strat Fender 04 Highway 1 strat Gibson Swamp Ash Les Paul Studio Gibson Black Les Paul Studio Gibson SG Gothic Taylor Accoustic Washburn Accoustic Dobro 'M' Series Effects: Everything from a PODxt to analog...too darn many

01-18-2010, 06:47 PM	#22 (permalink)
martin6string Junior Member Join Date: Jul 2009 Location: Central PA Posts: 5	Re: DSL401 converted to head Looks pretty cool. Nice job. __________________ How To Modify Effects Pedals

01-25-2010, 10:53 PM	#23 (permalink)
robinsoncaruso Junior Member Join Date: Jan 2010 Location: Northeast USA Posts: 5	Re: DSL401 converted to head I know this is an old post, I just joined and am excited about your work! Well done. Quick question, Is your fan blowing over the tubes, or is it exhausting heat? I did the fan mod to my DSL401, and noticed that exhausting seemed to do very little as far as heat dissipation. The amp faceplate still was very hot to the touch. Or does anyone have any general suggestions on the fan mod?

01-26-2010, 11:45 PM	#26 (permalink)
JohnH Senior Member Join Date: May 2008 Location: Wollongong NSW Posts: 781	Re: DSL401 converted to head If you have changed power tubes then you do need to check bias. A multimeter and two insulated alligator leads are all that is needed, and the inexpensive digital type are fine. Your amp was biased by adjusting a pot on the board, and setting the voltage across a certain 10Ohm resistor to 1.35V. This was very hot, ie that setting indicated a very high steady current going through the tubes. Post 2003, they changed a couple of resistors and biased them at 0.55V. This is very low!. I have my 2005 dsl401 biased at 0.8V, with fans, and it runs fine. You may be able to turn your bias down to this level, which will be cooler than it was. If you do this yourself, some step by step details could be found. It will involve removing back panels, unscrewing the chassis and lifting it out, clipping the multimeter to a test point on the board reconnecting speaker and mains and adjusting a pot with a screwdriver, all the time being careful of lethal voltages that exist in a tube amp. Its actually not difficult or dangerous, if you are methodical and careful, but if you are not careful, then it is dangerous.. It does not involve disconnecting or soldering anything on the board. John __________________ DSL401 8412 cab Crate Powerblock 1 x 12 Vintage 30 cab '76 Shergold Masquerader '93 Les Paul Studio '83 Roadstar

01-31-2010, 02:57 PM	#28 (permalink)
STAVROS Junior Member Join Date: Jan 2010 Location: AUCKLAND NEW ZEALAND Posts: 1	Re: DSL401 converted to head Very cool job Brian. Ive been toying with the idea myself for a few weeks with my 401. I run it through a 2x12 cab without the internal speaker and man for a little amp it just honks! Did a quick search and yours is first one that came up. So yeah, brilliant job dude. and very inspiring. cant wait to get stuck into mine now!! Im a brand new member. this is my first post! thanks to you. although ive been surfing here for along time now. nice to fianlly be part of it.

01-31-2010, 04:02 PM	#30 (permalink)
dugger Senior Member Join Date: Jan 2010 Posts: 199	Re: DSL401 converted to head Neat job man! I'm always thinking and or doing stuff like this! Only thing I would do different is center the logo more toward the faceplate.

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