Sweet...

[Craig Reid]

I recently got a chance to see the guts of a Two-Rock Custom Reverb Signature.

Does anyone know what transformer company has the prefix 166?

The PT is labelled 166-0451 / 40-16961 50W Multitap w Relay Winding and the OT is labelled 166-0409 / 40-16849 4-8-16 Taps.

Both the PT and the OT looked identical to Blackface Bassman iron.

Craig

[dogears]

The CR Sig is essentially a Hybrid A with the 220/150 combo values.

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

Thanks,

Andy

[dogears]

I firmly believe that Robbens amp absolutely has the post OD stack. Especially if you listen to live Jing Chi. My Glaswerks SOD50 amp is switchable between 80s and 90s voice and I am getting pretty damn close to the Jing Chi grail voice I have been searching by using the post OD stack. The hair and artifacts give it away. There is just no way to get that low end thing with no stack.

As far as the 80s amps, there are plenty of non HRM amps that use the .01 midcap and have 25uf bypass caps on Cl1 and Cl2.

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.

[Funkalicousgroove]

you wrote
"As far as the 80s amps, there are plenty of non HRM amps that use the .01 midcap and have 25uf bypass caps on Cl1 and Cl2.


Do you know this from fact? or hearsay? I'm not positive if Robben's amp has/does not have a post OD stack, what I can tell you is that I have an amp that is a pretty exact clone with the .047 mid cap and 5uf, 1uf, 5uf,5uf and it NAILS the RF tone, I also play a Hollow Alder Guitar with a Spruce cap. I have also Played Real Dumbles with and without the HRM mod and can say without a doubt that the HRM amps do sound different and crunchier. I have NEVER EVER EVER heard of an ODS with a 25uf bypass cap.[/quote]

[dogears]

Fact. I have degooped pics of several. I also have played every circuit iteration of Dumbles. I'd love to hear some clips of your .047 midcap amp nailing the late era Robben tone. I have to hear it to believe it. You may get in the ballpark, but I am talking about really nailing it. Shoot me an email and we'll talk. I'd love to compare notes. Imo, it is impossible to get the exact, not similar, but exact Robben tone without that .01 midcap.

If you have an anonymous email, post it and I'll email my # to you.

you wrote
"As far as the 80s amps, there are plenty of non HRM amps that use the .01 midcap and have 25uf bypass caps on Cl1 and Cl2.


Do you know this from fact? or hearsay? I'm not positive if Robben's amp has/does not have a post OD stack, what I can tell you is that I have an amp that is a pretty exact clone with the .047 mid cap and 5uf, 1uf, 5uf,5uf and it NAILS the RF tone, I also play a Hollow Alder Guitar with a Spruce cap. I have also Played Real Dumbles with and without the HRM mod and can say without a doubt that the HRM amps do sound different and crunchier. I have NEVER EVER EVER heard of an ODS with a 25uf bypass cap.

[/quote]

[Funkalicousgroove]

Funkalicousgroove_at_hotmail.com, I'd LOVE to have those de-gooped pictures!!

[dogears]

email sent.

hit me back. i'll be at that addy for another 30 minutes

[glasman]

DOGEARS?! I damn near fell off my bar stool here at the airport... LOL

[glasman]

I recently got a chance to see the guts of a Two-Rock Custom Reverb Signature.

Does anyone know what transformer company has the prefix 166?

The PT is labelled 166-0451 / 40-16961 50W Multitap w Relay Winding and the OT is labelled 166-0409 / 40-16849 4-8-16 Taps.

Both the PT and the OT looked identical to Blackface Bassman iron.

Craig

I have been trying to find that out as well (166). I will say that it is the same company that CE dist uses for their transformers. The marshall 100 and 50 watt transformers are marked 166-.

Maybe I will give them a jongle on Monday.

[Craig Reid]

[quote="dogears"]The CR Sig is essentially a Hybrid A with the 220/150 combo values.


I have to say that this is true. When I traced out the curcuit I had every intention of drawing it up from scratch. As I got in there, I realized it was the Hybrid A schem, and just imported it in to Corel Draw. It was easier to just put in the values they used from that schem out of the optional ones, than draw the whole thing up as new.

I gotta say that, a) that amp sounds fantastic, b) the workmanship is top notch (even tho the board material looks like the arborite off someones kitchen table), and c) they used good components. They even have the foil end of each film cap marked.

Craig

[Bennypapa]

What's the HRM mod?

[glasman]

What's the HRM mod?

The HRM stands for "Hot Rubber Monkey". This was used on the newer (not sure if on all of them) Dumbles. It basically adds a modified (values) fender tone stack to the output of the OD section. This makes the sound a little crunchier with a given amount of "hair/fuzz" around the notes. This gives the sound a little more diffused tone, a least to my old ears.

Gary

[Bennypapa]

I had heard that called the "Skyliner" EQ

thanks, Bennypapa

[dogears]

I think "skyliner" refers to the .01 midcap, 250ka mid pot, and 500ka bass pot with .001 cap across it. Plenty of non HRM amps exist that use the skyliner stack. THere are numerous Dumbles and even the Two Rock CR Sig uses it. So does the Glaswerks SOD and plenty of cloners.

HRM is the post od stack.

Of course I may be all wrong on the names, but the above stuff is true.

I had heard that called the "Skyliner" EQ

thanks, Bennypapa

[glasman]

I think "skyliner" refers to the .01 midcap, 250ka mid pot, and 500ka bass pot with .001 cap across it. Plenty of non HRM amps exist that use the skyliner stack. THere are numerous Dumbles and even the Two Rock CR Sig uses it. So does the Glaswerks SOD and plenty of cloners.

HRM is the post od stack.

Ol' Dogears is completely correct, shall we get into the Robben Ford Mod..... my lips are sealed..... wel'll now separate the men from the boys.....