Dirty Little Monster

[mcrracer]

Hey, I am glad to see the interest is still here. I still have the Rocket eyelet board done from when I took apart my first attempt. I have just been so busy with other builds that I wanted to get to. I still have parts I staged two or three months ago that I have not assembled yet. I have sort of settled on a couple of three designs to continue building that the local guys like and want. There are other designs I have drawn up schematics and layouts for that I just have not had time to get to. Plus doing repairs and restorations. And I am retired!!!! Still not enough time. Take a stab at it and let us know how your attempt came out.

[RJ Guitars]

I'm still up for it... just buried in twenty nine other amp building efforts.

I had a run of chassis made and was hoping to get stared way back when... you know how that goes!

I'd love to follow along as folks toss out their iterations.

rj

[mcrracer]

Hey RJ, were those chassis for a SE version of the Rocket or your "Rockster" amp?

[RJ Guitars]

Hey RJ, were those chassis for a SE version of the Rocket or your "Rockster" amp?

MC,

I had some Express chassis' made with only one output tube drilled... in the end I think I drilled out the other power tube hole and they turned into Express or Rockster amps. Not because I didn't want to build a DLM, just cuz the demand for the chassis was more immediate than any likelihood of me building my DLM.

I haven't settled in my own mind what a DLM circuit would look like but the Rocket preamp is basically the same as a Bassman preamp, which is basically the same as the old Marshalls... so probably a Rocket preamp into a single KT-88 would be my inclination.

I think Blind Lemon had a very good SE circuit with parallel 5881's that would be worth a look at for a DLM type build.

rj

[JamesHealey]

Schematic updated 2/28/09 to Rev. 1B

Thanks to all of you for starting this tread on the DLM, it is just what I want to build as well.

Anyone with better skills than me, would you please draw up a JCM front end to SE and spec which trannies that I should used, RJ, Zippy anyone?

I would greatly be indebted to you.

Mark

Mark,

Please make a big note to self as you read the "Unverified Draft" part of the attached schematic - I don't really know if this is a good idea much less a build-able amp. On top of that it's probably got a few mistakes and there was a lot of shooting from the hip... so proceed with caution!

I'll probably start out with something like this but I can say that it's really similar to the DLM. It has a lot of plexi to it but I dropped the "B" input. I've also added a gain stage just before the master volume and note that I used a 12AY7 for the cathode follower tube as well as that extra gain stage.

The extra gain stage serves as far as a "Hot Rod" adjustment to the plexi but I wouldn't want too much of a good thing so the 12AY7 seems right... of course were not going to be able to stop some over the top shredder kid from putting a 12AX7 in there and scorching our ears with the thing... I don't know how many times you gotta tell'em, we all know all the notes and it's not a contest to see how many of them you can cram into one song - Listen to some Neal Young and see what you can do with just one note!

I've got the treble bleed feature like we read about for the DLM, but I have no idea if it's wired it up right.

I'll be curious what you actually build and if anybody builds this tell me how it works out... and what I need to change to make a good drawing.

rj

I built something very similar to this recently and it was a killer amp!
used fender champ OPT and original mustard caps

[M Fowler]

JamesHealey,

I would be interested in what you used to base your version, do you have a schematic or layout?

Mark

[kec]

JamesHealey,

I would be interested in what you used to base your version, do you have a schematic or layout?

Mark

+1

[JamesHealey]

Fender Champ Power Section
Trainwreck Express Preamp
No Phase Inverter tube.

Following Tweaks:

15k Cathode resistor on V2 instead of 10k
0.047uF coupling caps everywhere there was 0.1 or 0.022
0.047uF caps in tonestack
470p and 47k Tonestack instead of 100k 500p
500k vol, treble & bass pot
25k mid pot as per usual
0.0022uF coupling cap as usual
500pF and 100pF switchable bright caps
1M and 220k switchable grid leak resistor to the EL84

pretty sure that was it, used nos Erie filter caps all 50uF and Nos Mustard caps.

very nice sounding little amp.

[bigsmitty]

In Gerald Webers second book KF says he has a champ with bigger transformers a 6550 a hot marshall style preamp and a master volume. Could this be the dlm?

[M Fowler]

That does sound the DLM description.

[RJ Guitars]

In Gerald Webers second book KF says he has a champ with bigger transformers a 6550 a hot marshall style preamp and a master volume. Could this be the dlm?

Bigsmitty,

That jives with everything I have heard about the DLM.

Bigger transformers would be needed to supply the 6550, I wish we could figure out a bit more about what was used. I have heard that a princeton output tranny might have been used single ended style. This is not so efficient but would be adequate for the 7 or 8 watts the 6550 would deliver.

The 6550 is a close relative to the KT-88, which I understand was one of Ken's favorite tubes and also has been mentioned in other posts as the DLM power tube.

If I recall correctly the 59 Bassman, Marshall 45, AC-30, and the Rocket all share a similar architecture with each other. It doesn''t take much of a stretch to figure that a hot rod Marshall preamp could share some layout characteristics with a Rocket preamp board. Especially since all the Wrecks seem to use the common preamp board, chassis, and cabinet.

We've got some pictures of one DLM amp and it definitely has a master volume as well as the standard Trainwreck look to it.

I have heard of a few of the early mods that Ken did to old Fender, Marshall, and Hiwatt amps. Could be that Gerald Weber saw the DLM prototype in champ cabinet. If I recall, the only known report on the amp claims there were only two made.

rj

[bigsmitty]

BTW he also says it has a10" celestion and a presence control. This is on page 258 of the book Tube amp talk for the guitarist and tech under Fender Champ master volume. And this was Ken talking.

[KellyBass]

I took an Express pre up to an including the .022 coupling cap off the second 12AX7 tube. I took that into a 1Meg Master vol into a 5.6k into pin 5 of the KT88. I think I used a 1000uf cathode bypass cap and a 300 ohn 5 watt resistor. Fed b+2 through a 1k 2watt resistor to pin 4

To make it more like a SE version of the express, would you need to add an extra gain stage for the PI gain, NFB and fixed bias?

(Note that this is not a built or working amp)

[img:512:384]http://www.cakes-of-joy.com/Pics/SExpress.jpg[/img]

This design intrigues me!...Fixed bias single ended?...or settle for cathode biased...

[mcrracer]

Build it and see. Mine is built and working great. I have had several Pro players play it in gig situations with outstanding results...goes clwan to mean. I am very happy with it.

[KellyBass]

Alright...I confess. I sorta did build it. But, I'm stuck on how to handle the power supply. With the iron I've got on hand, I think I'm gonna try it full wave bridge rectifier/cathode biased at first and see how it goes.