The dsl joey mod thread

[RickyLee]

I am still fine tuning my DSL100 Red channel Lead 1 & 2 modes - mostly by ear now. I ended up tinkering with three values of Sozo caps in place of the stock ceramic cap C16 4n7 MAIN PCB, which is the coupling cap coming directly after V1AA (second triode of V1 - I hate that labeling as I would rather call it V1B LOL) which is the second gain stage/extra stage that is only used on the Red channel. For this C16, it seems the .0022uF sounds the best between the other .0047uF & .0068uF. But . . .

My mods are quite similar to all the Joey Mods here on the front board. I went in and added the 1MEG to ground on the wiper of VR3 and jumpered R20 just a couple days ago. My Red channel was already the highlight of this amp before I added these last two mods, but I was having just a bit too much bottom end Girth on lead 1 & 2. My 1936 cab with G12-65's was resonating and vibrating a bit too much from all the low end. And when I would palm silence my low E, the bottom end would woof out similar to a Triple Rec.

So now I am thinking I will do that last front PCB Joey Mod of lowering C10 from .0047uF to .0022uF. But that will knock down the voicing I have now with the change to C16 which is after/downstream of the front PCB shaping/voicing circuit. Which means I might go back and raise up the value of C16 by ear and see what sounds best, which will allow to to drive the next gain stage with a bit more gain and bottom end while hopefully retaining the awesome clarity I now have in my mids and upper mids on full chords.

Also, I tinkered with lowering the value of the one mixing/summing resistor R79 470K which is on the MAIN PCB. It gave the Red channel a bit more gain - but I was looking to raise the volume of the red channel to be closer to the output volume of the green channel. It worked somewhat as this lowering also knocked down the volume of the Green channel as well LOL. But I did not like what it did to the gain response of the Green channel, so I left it alone for now. My Crunch channel volume (I have the Clean Crunch footswitch mod with a separate Crunch volume) usually gets set a lot lower lower than the Red channel volume. Crunch at about 3 and Lead 1 at 5 to 6 on their volumes.

Anyone else here tinker with that MAIN PCB C16?

 

[RickyLee]

I am still fine tuning my DSL100 Red channel Lead 1 & 2 modes - mostly by ear now. I ended up tinkering with three values of Sozo caps in place of the stock ceramic cap C16 4n7 MAIN PCB, which is the coupling cap coming directly after V1AA (second triode of V1 - I hate that labeling as I would rather call it V1B LOL) which is the second gain stage/extra stage that is only used on the Red channel. For this C16, it seems the .0022uF sounds the best between the other .0047uF & .0068uF. But . . .

My mods are quite similar to all the Joey Mods here on the front board. I went in and added the 1MEG to ground on the wiper of VR3 and jumpered R20 just a couple days ago. My Red channel was already the highlight of this amp before I added these last two mods, but I was having just a bit too much bottom end Girth on lead 1 & 2. My 1936 cab with G12-65's was resonating and vibrating a bit too much from all the low end. And when I would palm silence my low E, the bottom end would woof out similar to a Triple Rec.

So now I am thinking I will do that last front PCB Joey Mod of lowering C10 from .0047uF to .0022uF. But that will knock down the voicing I have now with the change to C16 which is after/downstream of the front PCB shaping/voicing circuit. Which means I might go back and raise up the value of C16 by ear and see what sounds best, which will allow to to drive the next gain stage with a bit more gain and bottom end while hopefully retaining the awesome clarity I now have in my mids and upper mids on full chords.

Also, I tinkered with lowering the value of the one mixing/summing resistor R79 470K which is on the MAIN PCB. It gave the Red channel a bit more gain - but I was looking to raise the volume of the red channel to be closer to the output volume of the green channel. It worked somewhat as this lowering also knocked down the volume of the Green channel as well LOL. But I did not like what it did to the gain response of the Green channel, so I left it alone for now. My Crunch channel volume (I have the Clean Crunch footswitch mod with a separate Crunch volume) usually gets set a lot lower lower than the Red channel volume. Crunch at about 3 and Lead 1 at 5 to 6 on their volumes.

Anyone else here tinker with that MAIN PCB C16?

LOL . . . It looks as if I should find my DSL modding notes from many months ago. As I flipped around the front control PCB, I found that I had jumpered C10 as part of all my initial mods last year.

 

[rockgod212]

i returned to mostly stock values on my amp, but i did lower c16 to 2n2........
on my 4th stage i still have 2.2k with .47/.1 on a 3way switch, thinking of changing the .47u to .68u.......

thinking of adding the 1meg on vr3 or adding the 1meg to r30, how do those 2mods sound?

screens filters are stock, but im returning to stock mains filters, actually i have 100u/100u on the board and then i mounted a 3way standoff thing so i can add a 100u filter cap in parallell over the series caps, or adjust it from there, cause 165u is too much, but 50u total isnt enough........somewhere around 100uf total i imagine would be great for this amp, so well see.....im really looking to get more upper mids, like in the FJA clips.......i want it to scream......

havnt put the amp back together yet, so no sound test yet.....

ricky lee, i would leave the 2n2 on the main board and adjust from the pot board, remove c10, or i have switchable trebel peakers, and the 470k/470p does sound good with this amp.....so thats an option as well.....

 

[RickyLee]

i returned to mostly stock values on my amp, but i did lower c16 to 2n2........
on my 4th stage i still have 2.2k with .47/.1 on a 3way switch, thinking of changing the .47u to .68u.......

thinking of adding the 1meg on vr3 or adding the 1meg to r30, how do those 2mods sound?

screens filters are stock, but im returning to stock mains filters, actually i have 100u/100u on the board and then i mounted a 3way standoff thing so i can add a 100u filter cap in parallell over the series caps, or adjust it from there, cause 165u is too much, but 50u total isnt enough........somewhere around 100uf total i imagine would be great for this amp, so well see.....im really looking to get more upper mids, like in the FJA clips.......i want it to scream......

havnt put the amp back together yet, so no sound test yet.....

ricky lee, i would leave the 2n2 on the main board and adjust from the pot board, remove c10, or i have switchable trebel peakers, and the 470k/470p does sound good with this amp.....so thats an option as well.....

Well I got a touch less woofy Recto bottom end, so I am going to leave it where it's at until I can play out with this amp. I have C10 jumpered and I already lowered C8 on the MAIN board way down to 4n7 anyway. So I see no need for me to have a cap in that C10 position. Or am I not understanding something in that signal path? Front board C10 stock is 4n7 but it is directly following/in series with the very first coupling cap C8 MAIN board which stock was .022uF.

Adding that 1MEG to Ground did not give me a change I could hear. If you read up on Joey's explanation of the theory behind the change, it is effecting much lower frequencies which I figured would help with my low end heavy tone anyway. When I jumpered R20, I heard a very subtle gain increase. For the peaker, I like the higher value stock 2n2 across the 470K myself. I need the extra upper mids.

I was thinking about tinkering with the MAIN board R30 as well. I tried lowering it only in the past and did not like it - I like it with a bit more gain. I thought about trying a higher value for more beef as well.

 

[rockgod212]

im not sure on the trace, but on the main board C8 is the 1st stage coupler
(i would leave the stock 22n in there) and C8 on the pot board is for the green channel- so if you lower it to 2n2 the green would be less boomy without losing lows in the red.......C10 on the pot board affects the red lead's only- its really not needed, so i removed it- but if i find i need to cut bass out of the red i'll put it back in.........yeah you dont need that r20-47k that cuts the gain of the peaker.......

Well I got a touch less woofy Recto bottom end, so I am going to leave it where it's at until I can play out with this amp. I have C10 jumpered and I already lowered C8 on the MAIN board way down to 4n7 anyway. So I see no need for me to have a cap in that C10 position. Or am I not understanding something in that signal path? Front board C10 stock is 4n7 but it is directly following/in series with the very first coupling cap C8 MAIN board which stock was .022uF.

Adding that 1MEG to Ground did not give me a change I could hear. If you read up on Joey's explanation of the theory behind the change, it is effecting much lower frequencies which I figured would help with my low end heavy tone anyway. When I jumpered R20, I heard a very subtle gain increase. For the peaker, I like the higher value stock 2n2 across the 470K myself. I need the extra upper mids.

I was thinking about tinkering with the MAIN board R30 as well. I tried lowering it only in the past and did not like it - I like it with a bit more gain. I thought about trying a higher value for more beef as well.

 

[rockgod212]

for anybody that knows.......

on the pot board........what value do you have for R38, on my schematic it says 10k, but i have a 470k in my amp- that just doesnt make sence, so what is the correct value and is that resistor really even needed? im thinking it should be 100k, as that is a pretty common resistor to add to 800's....

 

[Jason77]

So I see no need for me to have a cap in that C10 position. Or am I not understanding something in that signal path?

Ricky, I think this may help. In this thread (which is where the Joey mods originated):

http://www.marshallforum.com/workbench/11566-dsl-info-2.html

Joey's response to c10 being redundant is:

NO! It is absolutley NOT redundant and it needs to be there in that circuit or else the OD channel gain will be fizzier, and buzzier!!!

Passing more bass early in the chain causes this for many different reasons, and cutting the bass early actually makes it smoother because when bass frequencies distort, their harmonic content when mixed will sound buzzier especially when distortion involved, and you can potential encourage blocking this way, and nothing sounds worse than that! you will notice most of the best designers actually cut a lot of bass earlier, and then deal with putting it back later.

 

[RickyLee]

im not sure on the trace, but on the main board C8 is the 1st stage coupler
(i would leave the stock 22n in there) and C8 on the pot board is for the green channel- so if you lower it to 2n2 the green would be less boomy without losing lows in the red.......C10 on the pot board affects the red lead's only- its really not needed, so i removed it- but if i find i need to cut bass out of the red i'll put it back in.........yeah you dont need that r20-47k that cuts the gain of the peaker.......

Yes. I lowered the first interstage coupler C8 on the MAIN PCB from .022uF down to .0047uF. This affects ALL channels/modes. AND, C10 on the front pot PCB is tied to this/in series going into the Red channel. So that is why I see no need to have that C10 on the pot board. Which reminds me that I should check and see what I did last year on the Green channel's C8 on the pot board? I might need to jumper that now. But before I lowered preceding MAIN PCB C8 from .022uF down to .0047uF, I demo'ed various values there first
because it does affect ALL channels/modes. Which brings me to Jason's input LOL.

Ricky, I think this may help. In this thread (which is where the Joey mods originated):

http://www.marshallforum.com/workbench/11566-dsl-info-2.html

Joey's response to c10 being redundant is:

Yes, I understand Joey's explanation. BUT, that is with the coupling cap that is upstream of C10 (C8 on the MAIN PCB) being the .022uF value and letting through more lower frequencies. I have this MAIN PCB C8 lowered down to .0047uF. So basically I am already cutting out this fizz ect. before it gets to the front control PCB. Really, it would be great to hear what Joey would have to say about what I did. I can see an argument for needing to take the jumper off of my front control PCB C10 and install a .0047uF - which being in series with that upstream/preceding MAIN PCB I lowered to .0047uF = .00235uF LOL.

for anybody that knows.......

on the pot board........what value do you have for R38, on my schematic it says 10k, but i have a 470k in my amp- that just doesnt make sence, so what is the correct value and is that resistor really even needed? im thinking it should be 100k, as that is a pretty common resistor to add to 800's....

You are referring to the resistor just before/upstream of the two Master Volumes?

My schematic shows 470K and that is what's in my amp as well. What schematic are you looking at? Do you have an earlier revision of this amp?

FYI: I played around with lowering the value of that resistor. Added quite a bit more volume to an already loud and beastly amp.

 

[rockgod212]

do me a favor ricky......look on your pot board and tell me what value you have for R38....its the resistor before the master volumes.....my schem says 10k, but i have 470k in my amp.......

 

[RickyLee]

do me a favor ricky......look on your pot board and tell me what value you have for R38....its the resistor before the master volumes.....my schem says 10k, but i have 470k in my amp.......

LOL I put my amp back together already. I have to have my Gal help me lift my gear around as well as my Doctor has part of my restrictions as not lifting over 5 pounds (L5/S1 herniated disc) even though I am doing much better than that now. LOL that would mean I can't pour a glass of water from a gallon of Sparklett's drinking water.

I am quite certain mine is 470K (I did not double check the color code though) as it measured about half that value, but it was in the circuit with other components influencing its value/parallel.

I will probably get inside ithe DSL100 here soon. It is going to band rehearsal with me tomorrow along with my Ceriatone 2555 Jubilee that I currently have opened up AGAIN LOL. I was just AB'ing the Ceriatone 2555 against my '89 Marshall 2550 once again. Found some interesting results this time comparing them. And it made me take out a couple mods I had done to the Ceriatone as well (lowered B+ to the preamp & cathode bypass cap added to V2A).

 

[rockgod212]

thanx ricky, i looked up some other schem's of the amp and they all had 470k, though i do wonder why that resistor is even there......whats its purpose?


well after returning my amp to basicly stock, its dead......i get very little sound with the green master cranked.......tried several other pre-tubes, checked my work on the pot board 3 times- that was ok, time to check the main board.......

 

[RickyLee]

thanx ricky, i looked up some other schem's of the amp and they all had 470k, though i do wonder why that resistor is even there......whats its purpose?


well after returning my amp to basicly stock, its dead......i get very little sound with the green master cranked.......tried several other pre-tubes, checked my work on the pot board 3 times- that was ok, time to check the main board.......

Yeah. These amps are a pain in the ass for soldering work. Double check the solder pads you worked, that your solder is not making contact with the adjacent solder pad of the component next to it. Bummer is, that if you find two adjacent pads that are making contact/continuity, you have to distinguish if it is supposed to make contact. Or did you accidentally make them have continuity.

Also check for lost solder pads. I lost a couple on this amp myself.

That 470K is in series in that circuit - which means it is knocking down a bit of voltage but the current remains the same. When I tried lowering it a bit, the amp got REALLY LOUD. And this amp is already a loud beast anyway. That could be the reason it is in there.

 

[rockgod212]

got it working, but i have some other issues to work out......red gain is unresponsive and i lost lead2, as i changed r21=150k to 470k i need to change it back.....also on the red it seems like its farting out on the low notes.....i should probably remove 4n7 fixed resonance.....i wont know more till i crank it up and see what needs to be tweaked......so far it sounds like the old dsl i used to know.....lots of gain with xtra 500k pot.......that fixed some issues.....still need red gain fixed.....

 

[rockgod212]

i tracked my issues down to a bad gain pot and some bad trace/ solder pads around red channel gain circuitry, so i hard wired in a pot and bam the amp was back in working order........and it sounds killer now........i returned the amp back to mostly stock, stock voltages and sorta stock filters, but i left a few of my mods alone........the added 500k pot right before the last stage really opens the amp up and makes it scream, but i had to change the R41 reverb mix resistor to 120k to lower the reverb effect......it just kills now, cant wait to get a mini pot for my red lead gain and put it back together......
it needs new pots anyway.....

 

[Nedrick]

Wow rockgod, what a journey you have been on......and to wind up at almost the beginning. May I ask what are your mods at this time? I've been pouring over the posts for the last couple days trying to decide what I should do. It was kind of a surprise to end up at yours.

As a new member, let me first thank all of you for your contributions. A couple of questions about tightening. Many of these mods are to help with that. If you use all of them is it possible to get too tight? Also, it seems mostly related to the flabby bass. I can appreciate that, but to me everything could stand to be tightened. Maybe some of these are specific to mids and highs as well, but I could have missed that going through all these pages.

My amp has been gunny sack for over a month now. I was held up on trying to get the channel switching mods. Thank God I stumbled on here and was able to contact Graham directly to get that sorted out. I think I'll wait until that's done first before doing a whole lot of mods. Although I have a good general sense of what I want, this way it will be easy to A/B all the channels for a more accurate comparison. Plus, it's been a while since I've heard the damn thing. Interesting how we can have different ears listening to the same thing.


Thanks again to everyone for their input.

Regards

Ned

 

[RickyLee]

i tracked my issues down to a bad gain pot and some bad trace/ solder pads around red channel gain circuitry, so i hard wired in a pot and bam the amp was back in working order........and it sounds killer now........i returned the amp back to mostly stock, stock voltages and sorta stock filters, but i left a few of my mods alone........the added 500k pot right before the last stage really opens the amp up and makes it scream, but i had to change the R41 reverb mix resistor to 120k to lower the reverb effect......it just kills now, cant wait to get a mini pot for my red lead gain and put it back together......
it needs new pots anyway.....

Cool.

This pot you added before the last stage, did you put it in place of R40 as an adjustable grid load? And did you drill a hole for it in the chassis?

 

[mickeydg5]

do me a favor ricky......look on your pot board and tell me what value you have for R38....its the resistor before the master volumes.....my schem says 10k, but i have 470k in my amp.......

You are referring to the resistor just before/upstream of the two Master Volumes?

My schematic shows 470K and that is what's in my amp as well. What schematic are you looking at? Do you have an earlier revision of this amp?

FYI: I played around with lowering the value of that resistor. Added quite a bit more volume to an already loud and beastly amp.

There is that 470k R38 again.

Ricky, I am sorry I did not notice that later issue of the schematics. I thought that I had browsed around on only saw the 10k value.

Here is the deal.
An amplifier with the 10k R38 will have 680k at R47 and R48, after PI . (earlier amps)
An amplifier with the 470k R38 will have a LINK at R4 and R5, resistor spots after PI in the same locations. (later amps)

 

[rockgod212]

no...well sorta......i removed r40 and removed r39, that is the voltage divider for the previous stage into the next stage.....wire a 500k gain pot as the new voltage divider....changed r41 to 120k to adjust reverb mix......

also on r34- 2.2k cathode i have a .47u/.1u on a on/off/on switch, this really sounds nice with the added pot, i can really crank that pot up for more gain without using lead 2 and it sounds really nice with lead2 as well......

i also dont use the loop, so i completely bypassed it.....

Cool.

This pot you added before the last stage, did you put it in place of R40 as an adjustable grid load? And did you drill a hole for it in the chassis?

 

[RickyLee]

There is that 470k R38 again.

Ricky, I am sorry I did not notice that later issue of the schematics. I thought that I had browsed around on only saw the 10k value.

Here is the deal.
An amplifier with the 10k R38 will have 680k at R47 and R48, after PI . (earlier amps)
An amplifier with the 470k R38 will have a LINK at R4 and R5, resistor spots after PI in the same locations. (later amps)

Interesting. I have not looked at the earlier schematic myself. But with this scheme you are mentioning, the earlier version amps are getting the phase inverter hit a bit harder than the later version amps?

 

[mickeydg5]

Interesting. I have not looked at the earlier schematic myself. But with this scheme you are mentioning, the earlier version amps are getting the phase inverter hit a bit harder than the later version amps?

I would say that it does affect the PI some but the bigger concern for Marshall was lowering the signal for the loop.