Sweet...

[Funkalicousgroove]

As far as the "Correct" schematic goes:

The "Hybrid" amp is Very Close, THere are a few values that the schem gives you choices on, these are where there is inaccuracy in that Every amp is different, and truly tuned to the player. Most amps with a black chassis and 6L6 output tubes have the "skyliner" 220K/3K3, 150K/2K2 plate and cathode resistors on both stages, provided that they don't have the internal trimmers. The cathode bypass resistors vary, some amps have 5uf on all stages, some have a 1uf on V1B. Not all amps have the Local Feedback loop on V1B, but it should be noted that the correct configuration for this is 22M, .047uf, 22M (Mouser stocks these resistors in 1/2W carbon film). The Grid Stopper resistor on V1B can be bypassed anywhere from 330pf(My favorite) to 470pf depending on taste, but there are quite a few amps out there that use 390pf. It is important to note that 715 Orange drops and M150's don't work well in this design, and it seems that the more generic the caps the better the sound. I have great luck with 225P orange drops, 6PS orange drops, and Xicon Brown caps (NTE).

Contrary to the schematics that are out there, none of the amps have both Mid Boost and Deep switches, and unless you're using the "Skyliner" tonestack values(.01 mid cap/250KLOG mid pot) the original values are quite a huge boost. Alot of cloners use the .001/500pf combo for a mid boost with good results.

I can tell you that the Two-Rock Amps I've been in use the traditional Fender Plate/cathode resistor values (100K/1K5) as well as the "70's" ODS's, which makes for a less responsive amp. Using the "Skyliner" values (above) yields an amp that will go from clean to scream with pick attack in the Overdrive mode.

The later amps with the HRM mod use a whole different set of values in the OD section, and the posted schematics are pretty correct. If you're after the "Robben" or "Larry" tone then I reccommend an amp without the post OD tonestack. Sonny Landreth has an amp with the post OD tonestack(Bluesmaster mod I think) and his tone is much crunchier.

[toddyjoe]

So the Dumble discussion forum ended up getting the thumbs-up. Not a bad thing, I guess.

So what are your thoughts on the David Lindley lap-steel Dumble tone? Unlike most, I prefer slide Dumble tones from Lindley, Landreth, Lowell George, etc., to Robben Ford and Larry Carlton. I assume the 70's circuit or even the 60's circuit would be more appropriate for Lindley's dirty (not clean) Dumble work in the past? I suppose I could always retolex my tweed Deluxe in snakeskin and call it close enough.

[Robert]

Thank You Omar! This forum was way over due.

[Omar]

Everyone
You are all more than welcome! I want to make this your forum. I'm for anything that can make this community grow into 'the' place for tube amp building. I think we all have learned so much from each other with the Trainwreck builds. Hopefully that will happen as well with the Dumble builds.

Omar

[pedro]

Omar,
this is great,

I have been building tube amps for a few years now as a hobby and have built good plexis, 18 watters, bassman champs etc .
Robben Ford is my favourite player and so I got interested in the *umbles.
I tried to find as much info as I could but could never really decide if the schems available at schem heaven and blue guitar were going to be worth the effort in case they were inaccurate. I started getting e-mail correspondence from few people in the know who have guidede me towards a schem which may be pretty close.

I'm building it right now so this forum is goinbg to be great for feedback and sharing experience.

I just got my tubes through the mail this morning - great timing - TAD Black plate STR 6L6's which Ive read good things about in this kind of amp.

Looking forward to seeing how others get on with their amps.

cheers
Pete C

[Funkalicousgroove]

I believe that the "1977" schematic would get you the David Lindley/Lowell George tone, But I happen to know from a Tonequest report Interview that Sonny Landreth has Internal Trimmers. I saw him A couple months ago from about spitting distance and his tone was definiteley "Crunchier" than Larry's, robben played that show too but he played a pair of twin reverbs and a zendrive.

FWIW a two-rock custom with no reverb and no loop "is" the 1977 schematic.

[MarkB]

Now I have to finish my Bassman/Wreck head so I can get on to the Dumble.

But first, I have to finish my Gilmore 1W build.

And then there's the 5V6GTs I just got today, with the 6AQ5s.





Damn!

[v00d00blues79]

Funk... so you're saying that the Hybrid-a schem is essentially a 2Rock Custom?

Thanks,

Andy

[Funkalicousgroove]

Not the "Hybrid" amp, the 1970's schematic. I'll post it in the files section.

[Robert]

Funk,
Thanks for the 1977 schematic. I don't think I have ever seen that one. I posted what I was told is the TR Emerald Pro schematic in the files section. Amazing a company can be made building amps from the public domain.

[toddyjoe]

But I happen to know from a Tonequest report Interview that Sonny Landreth has Internal Trimmers. I saw him A couple months ago from about spitting distance and his tone was definiteley "Crunchier" than Larry's

I have read a few interviews where Landreth talks about the internal trimmers as well. I saw him at a club in Minneapolis in April of this year and I know what you mean about that crunch. Of note, he was using a Demeter mid-boost pedal in front of the Dumble at that show with a newer (rental?) Marshall 4x12" cab -- no Matchless in sight. His backup amp was a Marshall DSL 2000 head.

[Funkalicousgroove]

The 1997 Schem I believe is from a fellow who opened up a 1997 Overdrive special with EL34's, The Emerald Pro I saw the guts of used the typical 100K/1.5K plate/cathode resistors, and CLOTH COVERED WIRE!!! The thing about Two-Rock is they do nice work, but they sure are proud of them! They build a clone of an SSS and get $9,000 for it!!!

[v00d00blues79]

Which model of there's is supposed to be a SSS clone?

[Funkalicousgroove]

It's called the Sterling, it's not a production amp, they only did 9 or 10 of them.

[v00d00blues79]

Holy Crap! That amp looks awesome! Do you know somebody that owns one or did you just find the picture on the net?