Overdrive reverb variants

[rootz]

Guys, mainly out of curiosity (and maybe for a future build) I'd like to discuss some ORDS derivatives. We all know about #13 and #60 and those are pretty well documented by now.

When working on my latest build, someone posted a gut shot of the Bloomfield Drive from Two Rock. I think this is an interesting amplifier for a couple of reasons. To me it looks like a typical low plate classic, but the reverb is different. Reverb drive is two stages, ala for example the Wonderland (just one triode is transformer loaded, 3k9 in the cathode). What surprised me is that the reverb driver is fed from the output of the clean gain pot, also like the wonderland. So that would be the usual case for a pre OD reverb like in #13, right? One more clue that it's a #13 in disguise: V1 is the clean preamp, V2 is the reverb driver, V3 is the mixing stages and V4 is the OD stage.

Anybody who knows if the reverb is actually pre OD like #13 and Two Rock skimped on the mixing stage?

[Colossal]

Rootz,

I am definitely interested in this. The Bloomfield Drive sounds very good. I really like #102 but want to build at least a JM for cleans if not a full ODS reverb variant.

[rootz]

Take a look at this schematic. Essentially it's a Wonderland with added OD stage. To keep the tube count the same, I took the reverb entrance from the output of the relay and can thus ditch the triode in front of the reverb tank driver of the Wonderland. I kept one triode from a 12AT7 to drive the tank, the other triode is used as reverb recovery. The signals involved should be about equal to the Wonderland.

What I can't really account for is the difference in high end when comparing this design to the Wonderland. The first triode of the reverb circuit, the 12AX7 coming of the gain pot, loads the signal down a bit due to Miller capacitance I think. That effect is not present in the design below. No idea how it would sound. Pretty good I'd think, need to try it out soon.

[Bombacaototal]

InterestingThread. Just out of curiosity regarding the schmatic. I noticed that on the reverb driver tube the 10K grid stopper is insdte the LNFB. Any reason for that? I am asking beause I always had the suspicion SSS number 4 was wired the same

[rootz]

I couldn't notice much difference when simulating the position of the 10k resistor. The Wonderland hasn't got that feedback loop, the 004 does. However, I see both ways being done in the 004. Ceriatone, Two Rock (Sterling), Hartman place the 10k before the loop, but in the Dumbleland and 002 schematics and layouts I have the 10k is in the loop. FWIW, I could use one lug on the tag strip less when placing the 10k in the loop, you'd need two lugs the other way.

Maybe someone else will give more insights on this matter, it's an interesting question!

[Bombacaototal]

I couldn't notice much difference when simulating the position of the 10k resistor. The Wonderland hasn't got that feedback loop, the 004 does. However, I see both ways being done in the 004. Ceriatone, Two Rock (Sterling), Hartman place the 10k before the loop, but in the Dumbleland and 002 schematics and layouts I have the 10k is in the loop. FWIW, I could use one lug on the tag strip less when placing the 10k in the loop, you'd need two lugs the other way.

Maybe someone else will give more insights on this matter, it's an interesting question!

Very interesting indeed. The Ceriatone actually does something weird, although the 10K is out of the loop they place the resistor on the plate and the capacitor after the 10K, which is the opposite of what one would expect.

As in Dumbleland, do you mean the Silver Alligator Amp (which technically is a SSS due to the style of PI)? Or is it another model?

[rootz]

This is the possible Dumbleland schematic I mean.

[lovetone]

Just wondering if anyone has been inside a bloomfield Drive?

Any schematic info

[professormudd]

I am not sure if this is helpful/useful to you, but the Brown Note Blue Monkey 44 I just finished has reverb. It's a bluesmaster/HRM.

[lovetone]

Thanks for the layout.

I'll take a look, I played a Bloomfield a few weeks ago and really liked the amp.

[samrock55]

Thanks for the layout.

I'll take a look, I played a Bloomfield a few weeks ago and really liked the amp.

What kind of reverb tank and where does the 390pf cap connect to? The layout is abit unclear about where the tie points are?

[samrock55]

Just wondering if anyone has been inside a bloomfield Drive?

Any schematic info

That inductor looks interesting? Wonder how many henries that is? Resonance smoothing circuit?

[samrock55]

I am not sure if this is helpful/useful to you, but the Brown Note Blue Monkey 44 I just finished has reverb. It's a bluesmaster/HRM.

What reverb pan and transformer did you use??

[professormudd]

I am not sure if this is helpful/useful to you, but the Brown Note Blue Monkey 44 I just finished has reverb. It's a bluesmaster/HRM.

What reverb pan and transformer did you use??

ClassicTone 40-18034 with a Belton 9AB2C1B tank

[samrock55]

Thank you