jcm2000 dsl401 mods

Tom2toner · 07-10-2011, 08:54 PM

Anyone know of some easy mods or any mods?

sccloser · 07-10-2011, 09:49 PM

No mods, but some tips.

jj tubes will cut down some on the brightness. JJ el844's will help you gain a little bottom end while sacrificing some volume. You can tape a 6 inch coffee can lid over the center of the speaker to act as a diffuser and cut down on the highs and some of the fizz. If you run a patch cable to jump your fx loop, you can get some boost to your sound by turning up the fx volume.

Other than experimenting with those things, I leave mine stock.

Tom2toner · 07-10-2011, 10:22 PM

thanks, what about the speaker. Do you have a sug. for a speaker with more bass?

coldsteal2 · 07-10-2011, 10:23 PM

Heritage G12H reissue

Buggs.Crosby · 07-10-2011, 10:31 PM

most of the mods on the "Joey mods thread" can be converted for use in the 201/401 amps
read some of the thread and see what seems to apply to your needs....then just ask what the conversion is

thrawn86 · 07-11-2011, 01:56 AM

NOS tubes make it sing. And try it with a 4x12 cab too.

sccloser · 07-14-2011, 11:27 PM

Jumping the fx loop really makes a big difference to my ears.

sccloser · 07-14-2011, 11:30 PM

As far as speakers are concerned, some guys like the v 30s in them. I have not changed speakers in mine, but I have thought about it.

I've played mine through a 1960 cab with 75's in it a while back but I would not say it was really an improvement in tone, or at least I cannot recall that it was which means that any real difference was pretty minute or I would have remembered it more than likely.

bxt403 · 07-22-2011, 11:25 AM

The most important mod for the DSL401 is the bridge rectifier mod (replacing the old BR and putting a new one with a heat sink) and/or putting in a fan at the rear.

The problem seems to be that the power tubes & BR are located near each other- and due to the layout of parts- there's a lot of excess heat build-up that will result in cold solder joints and premature failure of components (and the fact that earlier versions of the amp were biased hot doesn't help). Later versions fixed the overheating problems by being biased colder but it seems that the colder biased 401's (after 2004, i think) don't sound as sweet as the hotter biased version.

So regarding the OP's question regarding any mods (i.e. the not easy ones)- depending on the year of make of the 401- you should consider getting a colder bias, new bridge rectifier with a heat sink, and/or a fan. That last one is the easiest mod since you could use an ordinary oscillating fan (locked in position, of course), pointed at the amp's back.

Regarding tone- the speaker swap is the obvious choice. Personally, the Celestion Vintage 30 in my 401 (that's now seen enough hours to be nicely broken in) has definitely improved the sound. The harder sound improving mods are installing new power and output transformers, and choke (I know Mercury Magnetics make a drop in upgrade for the 401).

The two fans at the left/closest to the power socket are sucking air out while the one on the farthest right is blowing air in (so there's good air circulation).
FYI- the two fans next to each other are blowing in opposite directions.

The BR with heat sink- notice the brown spot from all the heat the old one produced.

Since I did the BR and fan mods- I don't have to go through with changing other component values so that it's biased colder.

I was thoroughly impressed with how much ballsier my 401 is with MM PT, OT & choke.

I just picked up a Blackstar HT 20H because I thought I needed an EL34 equipped amp- and I'm kind of regretting buying it as I've been playing it side by side to my 401. Using my Sansamp- the EL84 DSL401 is pulling off the Marshall growl much better than the Blackstar is (although the Blackstar's overdrive channel is impressive). I was thinking it'd be the other way around since the HT 20 uses EL34's.

JohnH · 07-22-2011, 08:28 PM

I reckon, if the front panel gets too hot to touch, then do a mod to add some fans, and add a small heatsink to the bridge rectifier. My version of the fan mod is two 80mm mains fans, in series, inside the rear grill. One blows on the tubes, the other sucks out from the other end. They each only get 1/2 mains voltage so they run quietly, and I have them wired to the mains switch. I can post photos if you want.

The following is from a previous similar thread:

There's the usual options for speaker changing (a V30 for me), and tubes of course.

Other than that, what would you like? I havent modded my circuitry, but I have a neat little patch cable for the FX loop that will give you a kick of extra bass on the OD channels - so long as you dont use the loop for other reasons.

All it is is two jack plugs joined by a short cable like a pedal board patch lead, but within the jack barrels, at each end is a 10nF capacitor from hot to ground, and at one end only, a 47k resistor in the hot line.

What it does is to use the extra gain that is provided when patching the FX loop, and filter the signal down to just bass, so when you turn up the parallel FX loop, you get extra bass. Its useful, simple, cheap and risk free!

John

auburnshredder · 07-27-2011, 06:20 PM

Picked up a DSL401 Combo about three months ago. Swapped all the tubes out for JJ's, added a fan, swapped out the goldback for a G12 H Anniversary and added a a Marshall 1x12 ext cab (V30).

Love it !!

Blcws6 · 07-31-2011, 04:54 PM

I think the biggest difference for mine was a tube swap both pre amp and power tubes. The preamp change made a huge difference in its tonal character. I placed a NOS JAN Phillips in V1 and in V3 and a black plate raytheon in V2. Changed the power tubes to JJ's. My advice would be to change the preamp tubes.

My next change will either be to change the speaker to a V30 or get a sealed back extension cab with V30s as the open back sound is not something I particularly like.

auburnshredder · 08-25-2011, 04:05 PM

Looking for opinions...

I have a DSL401 and a Marshall closed 1x12 extension cab.

I'm running a G12H Anniversary in the combo and a V30 (chinese) in the extension cab. Not entirley thrilled with the lack of high end.

Perhaps I should switch the speakers?

I'm thinking the V30 in the open back will bring out the treble?

FYI, no other mods except swapped out all the tubes with JJs.

Thanks

sccloser · 08-25-2011, 09:34 PM

The JJ preamp tubes will make the amp sound a bit darker. I used them to tame the highs in my 401. Try using a different tube in the v1 position. Did you use the JJ el844's or el 84's? The 844's I think give it a bit more bass response as well.

Archer993 · 01-18-2012, 11:30 AM

I wonder if anyone has replaced some of those capacitors with better American made components? I have used Mallory and Sprauge on other projects with great success. At least the power supple caps could be upgraded.

I love those Mercury tranny upgrades but the cost is staggering.

I replaced my stock speaker with a Celestion G12 Century (neodymium magnet) Vintage. Significant improvement in tone.

07-10-2011, 08:54 PM	#1 (permalink)
Tom2toner Junior Member Join Date: Jul 2011 Posts: 5	jcm2000 dsl401 mods Anyone know of some easy mods or any mods?

07-10-2011, 09:49 PM	#2 (permalink)
sccloser Senior Member Join Date: May 2010 Location: South Carolina Posts: 2,076	Re: jcm2000 dsl401 mods No mods, but some tips. jj tubes will cut down some on the brightness. JJ el844's will help you gain a little bottom end while sacrificing some volume. You can tape a 6 inch coffee can lid over the center of the speaker to act as a diffuser and cut down on the highs and some of the fizz. If you run a patch cable to jump your fx loop, you can get some boost to your sound by turning up the fx volume. Other than experimenting with those things, I leave mine stock. __________________ 1986 Marshall JCM 800 2205 1991 Marshall JCM 900 Mkiii 2500 2003 Marshall JCM 2000 DSL 401 2010 Marshall Class 5 Combo JCM 800 Lead Series 1960b cab JCM 900 Lead Series 1960a cab 1960 ax cab (greenbacks)

07-10-2011, 10:22 PM	#3 (permalink)
Tom2toner Junior Member Join Date: Jul 2011 Posts: 5	Re: jcm2000 dsl401 mods thanks, what about the speaker. Do you have a sug. for a speaker with more bass?

07-10-2011, 10:23 PM	#4 (permalink)
coldsteal2 Senior Member Join Date: Sep 2007 Location: Chico, CA Posts: 1,908	Re: jcm2000 dsl401 mods Heritage G12H reissue __________________ Playing Marshall's since 1969 Vintage Modern 2266, JCM-800, JCM-900,1960A(G12H's), DSL-401,AVT-50combo , CLASS 5 Head,Orange Rockerverb 50, and cab My Youtubes......ColdSteal II on Soundclick.com

07-10-2011, 10:31 PM	#5 (permalink)
Buggs.Crosby Banned Join Date: May 2009 Location: S.Jersey Posts: 6,363	Re: jcm2000 dsl401 mods most of the mods on the "Joey mods thread" can be converted for use in the 201/401 amps read some of the thread and see what seems to apply to your needs....then just ask what the conversion is

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07-11-2011, 01:56 AM	#6 (permalink)
thrawn86 Senior Member Join Date: Aug 2009 Location: Far Nor Cal Posts: 7,613	Re: jcm2000 dsl401 mods NOS tubes make it sing. And try it with a 4x12 cab too.

07-14-2011, 11:27 PM	#7 (permalink)
sccloser Senior Member Join Date: May 2010 Location: South Carolina Posts: 2,076	Re: jcm2000 dsl401 mods Jumping the fx loop really makes a big difference to my ears. __________________ 1986 Marshall JCM 800 2205 1991 Marshall JCM 900 Mkiii 2500 2003 Marshall JCM 2000 DSL 401 2010 Marshall Class 5 Combo JCM 800 Lead Series 1960b cab JCM 900 Lead Series 1960a cab 1960 ax cab (greenbacks)

07-14-2011, 11:30 PM	#8 (permalink)
sccloser Senior Member Join Date: May 2010 Location: South Carolina Posts: 2,076	Re: jcm2000 dsl401 mods As far as speakers are concerned, some guys like the v 30s in them. I have not changed speakers in mine, but I have thought about it. I've played mine through a 1960 cab with 75's in it a while back but I would not say it was really an improvement in tone, or at least I cannot recall that it was which means that any real difference was pretty minute or I would have remembered it more than likely. __________________ 1986 Marshall JCM 800 2205 1991 Marshall JCM 900 Mkiii 2500 2003 Marshall JCM 2000 DSL 401 2010 Marshall Class 5 Combo JCM 800 Lead Series 1960b cab JCM 900 Lead Series 1960a cab 1960 ax cab (greenbacks)

07-22-2011, 11:25 AM	#9 (permalink)
bxt403 Junior Member Join Date: Aug 2010 Location: Calgary, AB Canada Posts: 15	Re: jcm2000 dsl401 mods The most important mod for the DSL401 is the bridge rectifier mod (replacing the old BR and putting a new one with a heat sink) and/or putting in a fan at the rear. The problem seems to be that the power tubes & BR are located near each other- and due to the layout of parts- there's a lot of excess heat build-up that will result in cold solder joints and premature failure of components (and the fact that earlier versions of the amp were biased hot doesn't help). Later versions fixed the overheating problems by being biased colder but it seems that the colder biased 401's (after 2004, i think) don't sound as sweet as the hotter biased version. So regarding the OP's question regarding any mods (i.e. the not easy ones)- depending on the year of make of the 401- you should consider getting a colder bias, new bridge rectifier with a heat sink, and/or a fan. That last one is the easiest mod since you could use an ordinary oscillating fan (locked in position, of course), pointed at the amp's back. Regarding tone- the speaker swap is the obvious choice. Personally, the Celestion Vintage 30 in my 401 (that's now seen enough hours to be nicely broken in) has definitely improved the sound. The harder sound improving mods are installing new power and output transformers, and choke (I know Mercury Magnetics make a drop in upgrade for the 401). The two fans at the left/closest to the power socket are sucking air out while the one on the farthest right is blowing air in (so there's good air circulation). FYI- the two fans next to each other are blowing in opposite directions. The BR with heat sink- notice the brown spot from all the heat the old one produced. Since I did the BR and fan mods- I don't have to go through with changing other component values so that it's biased colder. I was thoroughly impressed with how much ballsier my 401 is with MM PT, OT & choke. I just picked up a Blackstar HT 20H because I thought I needed an EL34 equipped amp- and I'm kind of regretting buying it as I've been playing it side by side to my 401. Using my Sansamp- the EL84 DSL401 is pulling off the Marshall growl much better than the Blackstar is (although the Blackstar's overdrive channel is impressive). I was thinking it'd be the other way around since the HT 20 uses EL34's.

07-22-2011, 08:28 PM	#10 (permalink)
JohnH Senior Member Join Date: May 2008 Location: Wilton NSW Posts: 1,706	Re: jcm2000 dsl401 mods I reckon, if the front panel gets too hot to touch, then do a mod to add some fans, and add a small heatsink to the bridge rectifier. My version of the fan mod is two 80mm mains fans, in series, inside the rear grill. One blows on the tubes, the other sucks out from the other end. They each only get 1/2 mains voltage so they run quietly, and I have them wired to the mains switch. I can post photos if you want. The following is from a previous similar thread: There's the usual options for speaker changing (a V30 for me), and tubes of course. Other than that, what would you like? I havent modded my circuitry, but I have a neat little patch cable for the FX loop that will give you a kick of extra bass on the OD channels - so long as you dont use the loop for other reasons. All it is is two jack plugs joined by a short cable like a pedal board patch lead, but within the jack barrels, at each end is a 10nF capacitor from hot to ground, and at one end only, a 47k resistor in the hot line. What it does is to use the extra gain that is provided when patching the FX loop, and filter the signal down to just bass, so when you turn up the parallel FX loop, you get extra bass. Its useful, simple, cheap and risk free! John __________________ DSL401 Crate Powerblock 1 x 12 Vintage 30 cab '76 Shergold Masquerader '91 Les Paul Studio '83 Roadstar '10 American Special Strat HSS

07-27-2011, 06:20 PM	#11 (permalink)
auburnshredder Junior Member Join Date: Jun 2011 Location: Auburn,California Posts: 25	Re: jcm2000 dsl401 mods Picked up a DSL401 Combo about three months ago. Swapped all the tubes out for JJ's, added a fan, swapped out the goldback for a G12 H Anniversary and added a a Marshall 1x12 ext cab (V30). Love it !!

07-31-2011, 04:54 PM	#12 (permalink)
Blcws6 Senior Member Join Date: Mar 2011 Location: Tar Heel Country Posts: 247	Re: jcm2000 dsl401 mods I think the biggest difference for mine was a tube swap both pre amp and power tubes. The preamp change made a huge difference in its tonal character. I placed a NOS JAN Phillips in V1 and in V3 and a black plate raytheon in V2. Changed the power tubes to JJ's. My advice would be to change the preamp tubes. My next change will either be to change the speaker to a V30 or get a sealed back extension cab with V30s as the open back sound is not something I particularly like.

08-25-2011, 04:05 PM	#13 (permalink)
auburnshredder Junior Member Join Date: Jun 2011 Location: Auburn,California Posts: 25	Re: jcm2000 dsl401 mods Looking for opinions... I have a DSL401 and a Marshall closed 1x12 extension cab. I'm running a G12H Anniversary in the combo and a V30 (chinese) in the extension cab. Not entirley thrilled with the lack of high end. Perhaps I should switch the speakers? I'm thinking the V30 in the open back will bring out the treble? FYI, no other mods except swapped out all the tubes with JJs. Thanks

08-25-2011, 09:34 PM	#14 (permalink)
sccloser Senior Member Join Date: May 2010 Location: South Carolina Posts: 2,076	Re: jcm2000 dsl401 mods The JJ preamp tubes will make the amp sound a bit darker. I used them to tame the highs in my 401. Try using a different tube in the v1 position. Did you use the JJ el844's or el 84's? The 844's I think give it a bit more bass response as well. __________________ 1986 Marshall JCM 800 2205 1991 Marshall JCM 900 Mkiii 2500 2003 Marshall JCM 2000 DSL 401 2010 Marshall Class 5 Combo JCM 800 Lead Series 1960b cab JCM 900 Lead Series 1960a cab 1960 ax cab (greenbacks)

01-18-2012, 11:30 AM	#15 (permalink)
Archer993 Junior Member Join Date: Mar 2009 Posts: 3	Re: jcm2000 dsl401 mods I wonder if anyone has replaced some of those capacitors with better American made components? I have used Mallory and Sprauge on other projects with great success. At least the power supple caps could be upgraded. I love those Mercury tranny upgrades but the cost is staggering. I replaced my stock speaker with a Celestion G12 Century (neodymium magnet) Vintage. Significant improvement in tone.

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