WANTED - Marshall DSL15 Schematic

[ninjaking67]

Ladies and Gents,

Sometime ago I moved to a fully digital HeadRush rig and sold off ALL of my amps except a Marshall Lead 12 SS that I converted to a head from a 10" combo. It is a fun little amp that excels at '80's and '90's Marshall tones (think modded JCM800).

Lately I have been suffering from some Marshall TUBE ENVY (yes, it really is a THING!). I have recently picked up an older Marshall DSL15H that is in nearly brand new condition. It is a 2 channel amp that utilizes the Clean channel and the OD2 channel from the DSL40. As many others have noted, the clean is really great but the OD2 is WAY too much gain. Most users are modding these to convert the OD2 channel to be like the OD1 channel on the DSL40 to have a much more usable gain structure. I plan on doing these mods to mine.

Also, I have purchased a tube buffered effects loop kit from Trinity Amps here in Brighton, Ontario and will be adding this to the amp. Here is a link to the kit: Tube Effects Loop

That is where my need for the DSL15 schematic comes in. The Trinity efx loop kit requires a 6.3V heater supply to the effect loop board. I need to both ensure that the Marshall uses a 6.3V heater supply (very likely) and where I can pick up that supply in the circuit. I have been unable to locate the schematic online though I know that it exists as I have seen it before. I also am almost 100% positive that the circuit is virtually the same for the DSL15, DSL40 and DSL100 versions.

Does anyone here have a link to the schematic or a copy that they are willing to share?

 

[67plexi]

I don't see where you would have room for a efx loop

 

[Amp Mad Scientist]

Ladies and Gents,

Sometime ago I moved to a fully digital HeadRush rig and sold off ALL of my amps except a Marshall Lead 12 SS that I converted to a head from a 10" combo. It is a fun little amp that excels at '80's and '90's Marshall tones (think modded JCM800).

Lately I have been suffering from some Marshall TUBE ENVY (yes, it really is a THING!). I have recently picked up an older Marshall DSL15H that is in nearly brand new condition. It is a 2 channel amp that utilizes the Clean channel and the OD2 channel from the DSL40. As many others have noted, the clean is really great but the OD2 is WAY too much gain. Most users are modding these to convert the OD2 channel to be like the OD1 channel on the DSL40 to have a much more usable gain structure. I plan on doing these mods to mine.

Also, I have purchased a tube buffered effects loop kit from Trinity Amps here in Brighton, Ontario and will be adding this to the amp. Here is a link to the kit: Tube Effects Loop

That is where my need for the DSL15 schematic comes in. The Trinity efx loop kit requires a 6.3V heater supply to the effect loop board. I need to both ensure that the Marshall uses a 6.3V heater supply (very likely) and where I can pick up that supply in the circuit. I have been unable to locate the schematic online though I know that it exists as I have seen it before. I also am almost 100% positive that the circuit is virtually the same for the DSL15, DSL40 and DSL100 versions.

Does anyone here have a link to the schematic or a copy that they are willing to share?

1. Well, what you can do is change 12AX7 to lower mu tubes like
12AT7
12AU7
and you can reduce the input sensitivity of any stage.
12AX7 - ECC83, 7025, ECC803, E83CC, 6681
12AT7 - ECC81, 6201, 6679
12AY7 - 6072
12AV7 - 5965
12AU7 - ECC82, 5963, 5814, 6189


A lot of those newer schematics are secret....

The plate resistor (pins 1 and 6) of any stage can be reduced, this will lower the available voltage drop...
The cathode resistor increase value (pins 3 and 8) of any stage will reduce the sensitivity.

To pre-test the values, you can use the simulator / calculators:

Cathode Bypass Capacitor Calculator

www.ampbooks.com

It lets you install any value part in a simulation, and test the results for gain or frequency response..

2. The preamp tubes filaments, depends on which tube.
Frequently in "high gain" amps, the first preamp tubes are DC filaments.
The first stages in the preamp may be 6VDC, DC voltage, test between pins 4/5 and 9.
The phase inverter is going to run on AC filaments. Yes it's going to be 6.3VAC approximately.

So if you want 6.3VAC you can tap that from the phase inverter tube socket, or the power tube socket pins 2 and 7.

 

[ninjaking67]

Thank you for the responses 67plexi and AMS. A special thanks to Syscokid who PM'd me the schematic.

 

[ninjaking67]

I don't see where you would have room for a efx loop

Plexi,

Lots of folks have already done the mod using the EFX loop board from Metropoulos Amps. I don't know if anyone has used the Trinity EFX loop but I am gonna give it a shot.

Here is a link to one of the videos. It shows location at approximately the 15:07 mark of the video.

 

[Inspector #20]

Plexi,

Lots of folks have already done the mod using the EFX loop board from Metropoulos Amps. I don't know if anyone has used the Trinity EFX loop but I am gonna give it a shot.

Here is a link to one of the videos. It shows location at approximately the 15:07 mark of the video.

No amp should be without an FX Loop.

@syscokid put one on my 50 watt Master Volume build.

 

[syscokid]

I don't see where you would have room for a efx loop

View attachment 83753

After looking at that pic, it does look like it will be a nightmare to implement. BUT... I do see some space between the half-power switch and the IEC. Not sure if the fx loop module will clear those radial e-caps. Maybe move the half-power switch right next to the IEC... Which unfortunately presents other problems obviously.

Trinity's tube fx loop board:


EDIT: I just viewed the video posted by ninjaking. Hopefully the Trinity module is not any bigger than the Metro module...

 

[ninjaking67]

I have a hammer and a REALLY BIG shoe horn! We'll get it in there somehow!

 

[Inspector #20]

Mojotone Discrete Hi-Voltage Series Effects Loop for Vacuum Tube Amplifiers

Optimized for insertion between your preamp and phase-inverter stages, this low noise, non-clipping effects loop utilizes a discrete, high voltage buffer and a return gain stage. Includes true bypass.

www.mojotone.com

 

[Inspector #20]

Here's how the Metro FX Loop appears in my 50 watt master volume build....

 

[ninjaking67]

Thanks for that Robert. I already have the amp and the Trinity EFX loop board so I will somehow shoehorn that into the chassis. The version that I have also has the hard bypass switch just like the Mojotone version.