DLM (reprise)

[Colossal]

I've been mining the lore of the Dirty Little Monster. Looking at the tube compliment...

2 ECC83 (GT Yugo)
1 EL 34 (Mullard xf2 )
1 GZ34 (Mullard)

Q: Why do you suppose Ken went with a GZ34 for the rectifier? There is no appreciable sag in a SE circuit and a GZ34 has the lowest anode resistance (about 50R) so will give very low voltage loss. Was it:

a) For the tone?
b) No diode rectifier hash noise in a SE circuit?
c) Ken's love of Mullard GZ34s?
d) All of the above?

Second, the knob compliment in the DLM included a Slope setting. This implies that the mid "slope" resistor in the tone stack was made variable, probably via a fixed resistor in series with a pot (maybe 10k->100kB). The amp is said to be wonderfully clear and mid rich. In a JCM800, a 47k slope resistor yields a thick, mid rich tone.

Q: Do you think there was a fixed value for where the mid pot would sit in a tone stack, assuming this was a TW Express or Marshall tonestack (ref: the amp is specifically quoted as being much more a JCM800 than an Express).

Opinions, ideas, and speculation welcome.

[zambo]

on all my dlm wanna be amps i noticed the tone controls dont act very much on the tone. i think the slope knob just has to add mre control over the bass and mids. all my amps could be more bassy and i would love it. i am thinking of adding the slope control. i dont use tube recto's so i have no idea. interested for sure though. is the tone stack after v1a ?

[Colossal]

Zambo,

I was hoping you'd chime in. Your SE Wreck-lite amps sound great. I was really wondering about the low end. Wreck amps are very bright as is so wondered how a SE version might be.

I was going to ask if you (bothered) with a bright switch on your versions? Did you add negative feedback into your 1/2 PI? If so, have you tried adding say 0.0033uF in front of the feedback resistor as a fixed depth mod? I wonder if this would recover some low end...You said you didn't have much use for the presence added on your 1/2 PI right?

In just reading the DLM information, I am kind of guessing that the amp could very well be like a Komet Concorde which is quite Marshally sounding. Tone stack just after V1a, 2k7/0.68uF on the first stage. Possibly 10k in the middle and then maybe 1k5/22uF or maybe even 820R/0.68uF on the third stage. This would essentially be a JCM800 but with the stack in the front, no cathode follower. Just guessing wildly however.

[zambo]

Hey thanks! I am starting to like the presence on the 6v6 version. Its kinda cool for the volume roll off. Yeah the low end is tricky. i did realize I used 10uf bypass caps on the first two gain stages. I need to up those for sure. I just havent wanted to tear into my working amps.Lol. I think the dlm must be a express / liverpool pre. I think the tube recto was a try at softening the power supply cause they are quite stiff. A little sag would go a long way on these. I tried the resonance knob on my 5 watt 6v6 wersion and it was ok. I think i need to start tweaking coupling caps a little here and there. just a bit more low end would be sweet. maybe a bit warmer on the fake pi too.so much to try! I do love the se design for its simplicity. With the treble at about 12 oclock and the mids at 9 and bass dimed they sound pretty good and kind of jcm 800 ish i think. The el34 version id the best so far. i am going to try a 6l6 and a kt88 version soon.

[zambo]

oh yeah, i do add a 2 postion bright switch and its almost always on the brightest setting so i can roll back the treble knob as it adds more bass somehow.

[Colossal]

Hey thanks! I am starting to like the presence on the 6v6 version. Its kinda cool for the volume roll off. Yeah the low end is tricky. i did realize I used 10uf bypass caps on the first two gain stages. I need to up those for sure. I just havent wanted to tear into my working amps.Lol. I think the dlm must be a express / liverpool pre. I think the tube recto was a try at softening the power supply cause they are quite stiff. A little sag would go a long way on these. I tried the resonance knob on my 5 watt 6v6 wersion and it was ok. I think i need to start tweaking coupling caps a little here and there. just a bit more low end would be sweet. maybe a bit warmer on the fake pi too.so much to try! I do love the se design for its simplicity. With the treble at about 12 oclock and the mids at 9 and bass dimed they sound pretty good and kind of jcm 800 ish i think. The el34 version id the best so far. i am going to try a 6l6 and a kt88 version soon.

Interesting report, thanks for the details! Have you tried beefing or paralleling a second cap across the second stage's coupling cap or just moving up to a higher value? That location is noted as a spot for getting a bit more umph/low end; that would be C8 on the Express schematic.

What value did you try for resonance? Was it fixed or variable (via a pot)? When you say "more warm" on the PI, do you find 22k to be a bit too fizzy?

Thanks.

[zambo]

i am going to try parallel at c8 for sure. and on the pi, yeah i think 22 may ba a bit fizzy. it might be what makes it sound good, i just dont know enough yet. i would like to try between 15 and 20 k experiments. so have you built something like this? what are your thoughts?

[Colossal]

i am going to try parallel at c8 for sure. and on the pi, yeah i think 22 may ba a bit fizzy. it might be what makes it sound good, i just dont know enough yet. i would like to try between 15 and 20 k experiments. so have you built something like this? what are your thoughts?

The low plate load (47k) on your PI is interesting in combination with the 22k. That stage is moving a bit of current. Did Iain mention the rationale behind that choice (47k/22k)? Perhaps, just simulating the drive of a full sized PI in 1/2 section? I have cold biased Marshall PIs before and it controls the magnitude of the output (reducing volume) but does seem to add some warmth perhaps at the cost of a bit of clarity/increased fizz. I personally like compression though. I have not built one of these (SE Wreck/DLM wannabes) amps yet, but am planning to and have the iron to do so. My OT is a multi-primary so I'll be able to switch from 6L6 to EL34 to KT88 etc. I am also adding variable bias so with each tube change, I can dial in the desired bias. My PT is 275-0-275.

[M Fowler]

Thinking of going with a Edcor PT from rjguitar on this DLM project to get the plate voltage up.

So the question is JCM800, Express or Komet preamp?

In talking with colossal I am now inclined to believe that perhaps the Komet circuit was used as that would certainly get you in the JCM800 vibe.
From the description of the first DLM that is the sound they were hearing.

Mark

Trainwreck Experience #5

At some point after I got my Liverpool, Ken played the "original" Dirty Little Monster for me over the phone. As I remember, he mentioned the amp in his Trainwreck pages.
It was a little Fender (Champ?) that he totally "NUKED". Wow, what was that, he told me it's a amp called the Dirty Little Monster that he gave to his brother. The amp was in the shop for a little servicing. Raunchy Rock n Roll at it's finest. I believe he said that it was a rock n roll machine with no real clean sound, I didn't care, that amp sounded GREAT! I asked if his brother was interested in selling the amp, I'd like to be the 1st in line, he laughed and said that the amp was not for sale.
Later, he mentioned that he planning to design an amp for an nationally known amplifier company. This was after the Kendrick Climax (heartache) and before Komet got off the ground (story was an experience). He was calling it the Dirty Little Monster. It was designed to be a guitarist 1st real low powered true tube amp. I heard the Prototype DLM just after he built it. He told he had decided not to do the deal with the company and was planning to just keep the amp. I asked him that if he ever decided to sell the amp to give me the 1st call. As it was with my one of a kind Komet, he told that he wasn't going to sell the amp at this point, but agreed to give me the 1st call. And about a year later, he gave me the call. Interestingly, he sold the amp to me for the price of the parts. He was being a good friend and he knew I was a struggling musician. I ended up sending him twice the asking price. I know that he got lots of offers for that amp and could have made a fortune on a regular sale. But Ken was always true to his word.
INFO: Front Panel

Input
Gain
Treble
Bass
Master
Harmonics (Presence)
Slope (Midrange)
On Switch
Pilot Light


Back Panel

Power Cable
Fuse
Ext speaker
Main Speaker (8ohm)

2 ECC83 (GT Yugo)
1 EL 34 (Mullard xf2 )
1 GZ 34 (Mullard)

Single ended (EL34/6L6/6550) 8 to 10 watts
note: the original used a 6550
this Prototype sounded best with an EL34

The Prototype Dirty Little Monster that he built was very different from the Original. He described it as a Killer Plexi with Trainwreck clarity and voicing with the master disengaged. Using the master gave it a more JCM 800 flare. This Prototype wasn't as gained out as the Original. There was a trade off more tone and clarity less raw distortion. This would be a great recording amp and takes pedals really well (Menatone Blue Collar was killer combination). There is definite vintage plexi Marshall vibe to this amp. Great amp



Steve, Ken did the Dirty Little Monster for a big, well known amp manufacturer. There were several successfull prototypes made, but the project was eventually abandoned because the target price couldn't be met.

The DLM is a single ended amp using a 6550 output tube. It puts out about 12 watts. One prototype was made with a different output transformer for a single EL34 putting out 8 watts. That's the one wreckboy owns and aron played.

Ken and I discussed making the DLM under the Komet name. We decided not to because if you look at the work and parts involved, it really is about the same for a 60 watt amp as it is for a 12 watt amp (give or take a couple of tubes). Who would pay $2500 for an amp that's too loud for an apartment and not loud enough for a stage. Hogy

[Colossal]

Mark,

The JCM shares two stages in common with the Express and Concorde: 2k7/0.68uF and the 10k(no bypass). The order in which they occur in the Express vs. the JCM however are different and of course this plays greatly into Ken's specific design for the Express.

What little information there is about the DLM, the one report says it was a bright amp even with the treble rolled back. I suppose if we were to base a speculative DLM build on what little is known, it might be on the prototype that was said to be more Marshally (the Original). I can't help but wonder if the tone stack occurs just after the first stage as in the Express just to keep the Trainwreck vibe, dynamic touch sensitivity, and incremental gain building. Since the DLM has two 12AX7 that gives us either four gain stages or three with a cathode follower. The cathode follower may be used to drive a tonestack (like in the JCM and Rocket) or may not (like in the Concorde). If it is used at the end of the preamp like in the Concorde, it would help drive the output stage but also would increase the gain of the preceeding stage by stealing a little current. I'm sure this is why Komet dropped the clipping stage from 10k to 3k3 when they added the cathode follower at the end of the line, that, and to beat on the PI. I suppose there is also the possibility that KF used three gain stages (with the plate-fed tonestack) and half of a PI as some builders of SE Wrecks (Darin, Zambo, et al) to maintain the clarity/feel/response/vibe intrinsic to his Trainwreck design philosophy.

All just wondering aloud...

[dartanion]

I actually have been using the full PI but feeding the outputs from one side. My goal was to make an SE version of the Express and maintain the gain structure of the preamp and PI. The current rev of this amp is cathode biased, however I have been toying with fixed bias.

Anyway, here are a few videos of the Absinthe in action for a tonal reference:

Cleanish Blues
http://www.youtube.com/user/MrTonicAmps ... 2aIXjySFYg

Mildly Distorted Noodling
http://www.youtube.com/user/MrTonicAmps ... rFuvP8P2Ww

Distorted Noodling
http://www.youtube.com/user/MrTonicAmps ... T3itawwRe0

Catfish Noodling
http://www.youtube.com/watch?v=zOjA8Puh ... re=related

[Colossal]

I actually have been using the full PI but feeding the outputs from one side. My goal was to make an SE version of the Express and maintain the gain structure of the preamp and PI. The current rev of this amp is cathode biased, however I have been toying with fixed bias.

Nice tones Dart. Are you using negative feedback into the tail? For cathode bias are you using a 1,000uF bypass cap to give it the fixed bias feel or something around 100-330uF?

[fperron_kt88]

Catfish Noodling: Yikes! (probably not for the sound/texture of it as much as for the idea of loosing a finger to a snapping-turtle or an arm and a leg to a gator of some sorts)

[dartanion]

I actually have been using the full PI but feeding the outputs from one side. My goal was to make an SE version of the Express and maintain the gain structure of the preamp and PI. The current rev of this amp is cathode biased, however I have been toying with fixed bias.

Nice tones Dart. Are you using negative feedback into the tail? For cathode bias are you using a 1,000uF bypass cap to give it the fixed bias feel or something around 100-330uF?

That all depends on for whom I am building the amp. I have used everything from a 200uF to 2700uF. Yes, there is NFB into the PI.

[zambo]

so then is there a presence knob? Great sounding amps!! How many watts are they? I know you use two 34's but not sure what that gives. like 25 watts ish?