Dumble Cleans on Super Reverb

[jayrayjr]

Hey Guys!

I have a Super Reverb Reissue and i just want to make it bolder more like the Dunmble clean tone like...i know i cant get very far because of the pcb ie. cant do the tonestack mod.

What other things could i do to get it more in the direction?

I have the feeling that i dont like the 270V on V1+V2 on the super, i find the tone kind of harsh especialy in the top end (wgs vintage 10s).

Would going down to say 190V-200V be benefitial for me and get a smoother tone? A lot of Dumble schematics ive seen and some Two Rocks have got the preamp voltage around 200V and less.

Help would be greatly apreciated any little suggestion would be awesome,

best
Johnny Ray

[10thTx]

Is the amp you are asking about in this post the same one that is mentioned with numerous mods in this thread?

https://ampgarage.com/forum/viewtopic.php?f=8&t=31374

Looking at this schematic: https://el34world.com/charts/Schematics ... reverb.pdf

I think lowering the plate voltages could help.

And you might try a 250p to 390p "smoothing cap" on the 3rd gain V4-B from plate to cathode? You might try an "enhance cap" of 220p across the R54 82k plate resistor going into the LTPI? I think both of those mods would be easy to do and may help tame harsh "highs".

https://el34world.com/Forum/index.php?t ... #msg153636

You might consider changing the the cap C25 (going into the LTPI) from .001 to .01 - .02 range.

IF you're wanting your Super Reverb "smoother" then I think that's possible. If you're wanting your SR to sound like Dumble cleans, I don't think you'll get there with a Super Reverb topology.

With respect, 10thtx

[martin manning]

I would say yes that is an essential part of the D sound. You can try it out easily by increasing R68 until you get in the right range.

[martin manning]

IF you're wanting your Super Reverb "smoother" then I think that's possible. If you're wanting your SR to sound like Dumble cleans, I don't think you'll get there with a Super Reverb topology.

Why not? The clean channel topology is exactly the same as the ODS: Gain Stage->Tone Stack->Volume Control->Gain Stage->PI. A large grid stopper and LNFB could be added to the second gain stage to make it more similar, going further in the smooth direction.

[10thTx]

Why not?

When I was referring to topology, I was meaning there is a need to change the tone stack configuration to be similar to a Dumble.

IF it's just a matter of changing values or something like adding smoothing caps, then yes I think it can be very similar. However, if it involves changing how things are wired up (which is what I meant by topology) then something like the mid pot to ground on a Dumble vs. the mid pot on the Fender is a different "topology" in my thinking.

With respect, 10thtx

[jayrayjr]

@10thTx Thank you for your suggestions, i will consider some of that! Yes thats my amp, just to clarify for other people reading this:
i did 2.2uf Cathode Caps on V2A+B and .022uF on the PI Output to get rid of exsessive bass which helped wonderfull (going to go 5uF on the other cathodes except the reverb driver),
i also installed a Solid State Recitifier and i am going to install 2x220uf Filter Caps. I dont use the tremolo or the normal channel so they both are disconnected.

@martin manning Hey man, i read alot of stuff that you posted here, allways good infos thank you for that!!
Awesome i allways thought that the preamp voltage had a lot to do with the sound. As soon as i get time off i will increase R68, maybe 10K-12K gets me around 200v i will see.

Would you be so kind to elaborate a little bit on the larger grid stopper and LNFB, or give me a link if there is where i can find some info maybe?

Sorry for my english guys im german hope its not too bad

[jayrayjr]

Yea i wish i could do the tonestack mod, it would be so awesome, i find one can get a lot more tones out of it than with the stock fender tonestack. For now i at least have a 20K midpot installed to get a lilttle phatter mids if needed.

As for other cap changes, do you have any other suggestions for me, i basicly wanna change as much values that make sense as i can to get it more in the smoother dumble direction.

[martin manning]

Re the LNFB and grid stopper, heck out the #124 schematic in the Dumble files section, specifically the second stage of the clean.

[jayrayjr]

Cool thanks, i will!

[JD0x0]

IMO, you can get pretty Dumbly with the right tonestack and trimming up the bass ever so slightly through bypass caps and couplers, to keep it wide bandwidth, but eliminate any preamp flub. Grid stoppers will also do a good job, as you can reduce blocking (flub) as well as smooth highs a bit.

I also like to adjust couplers for the reverb a bit larger. IMO the Fender reverb is pretty much all upper mids, it could use a little more fullness, IMO. I also tend to prefer 3 spring tanks. Gives the amp a nice full smooth reverb without that nasty 'clash' or ugly 'Flutter' which personally, I'm not a fan of.


To me, low plate cleans are good Fender cleans, with more mids on tap, and all the 'ugliness' (ie. Flub, fartiness, overly loose bass, brittle/peaky highs) that the Fenders have is removed.

[skeezbo]

I was on the same quest a few years ago. I plugged in the Skyliner (if I Remember correctly) tone stack values into the Duncan tone stack calculator and was surprised to see the mid dip looked more like a tweed bassman than a typical blackface. The slope resistor value also seemed to flatten the bass, at least in the graph. Maybe you could try using .02 tone caps instead of the typical .1 and .047 (if that is what the reissue uses). I think the slope resister change was from 100k to 150k. I put the Skyliner stack in a Bassman 100 that was being used as a bass head. Didn’t seem to do much for bass, was loud and clean for guitar. I didn’t change the cathode bypass caps to the lower Dumble values, which I’ll bet also make a big difference in bass response, and there was no way that I could find to get the tone stack calculator to imagine what that change might do to the frequency response.

[roberto]

I've recently done the opposite: switched the first two stages of a Super-Reverb-like clean to the following specs:
220k 3k3//4u7
Fenderish tonestack with 470p treble cap
Volume
150k 2k2//4u7
Fenderish coupling
100k 1k5
Volume
Buffered output.

Has anyone done something similar?

[JD0x0]

I've recently done the opposite: switched the first two stages of a Super-Reverb-like clean to the following specs:
220k 3k3//4u7
Fenderish tonestack with 470p treble cap
Volume
150k 2k2//4u7
Fenderish coupling
100k 1k5
Volume
Buffered output.

Has anyone done something similar?

My twin has
220k/3k3/ 4u7
Fenderish TS with 650p treble cap, 250kA mid pot, 47nF bass cap, 39nF mid cap, 90k slope.
1M Vol
180k/2k2/4u7
3.3nF output coupler
unbypassed 1Meg voltage divider resistor as opposed to 3.3Meg/10pF network.
100k/1k5/4u7 on the mixer stage.

NOT super clean though. Nice drive stage, IMO. It cleans up well, but quite gainy.
Also worth noting I use 10nF on the input of the PI, not 500pF/1000pF BF values. I prefer to cut lows a bit earlier in the circuit, and less bass roll off at the PI input, personally.

I'd stick with low plate values and run LNFB on the mixer stage for cleans, personally.

[oj]

I would say yes that is an essential part of the D sound. You can try it out easily by increasing R68 until you get in the right range.

What I do is to give V1 is own node by adding a 10 uf cap and resistor 15-20k so I get 300V on node.
also change the 250 p to 330p in ton stack .
If he need more D-feeling then change the anod resistors to bigger 150-220 K

[roberto]

unbypassed 1Meg voltage divider resistor as opposed to 3.3Meg/10pF network.
100k/1k5/4u7 on the mixer stage.

Do you have local NFB on this stage? I left it unbypassed because I like the way it goes into overdrive when pushed, but bypass + local NFB was another option.

NOT super clean though. Nice drive stage, IMO. It cleans up well, but quite gainy.

I like the way it goes into saturation with single coils, and how it comes back to clean. I will raise the treble cap to higher values.

I prefer to cut lows a bit earlier in the circuit, and less bass roll off at the PI input, personally.

I do the same for hi gainers.