Fender Super Reverb Mods

[Bob-I]

Not exactly a Super Reverb, a Weber 6A40 kit. I replaced all the caps with 715's and a good number of the resistors with carbon comp, but basically it's a Super Reverb with Weber iron.

I decided that a total gutting wasn't necessary for a Fender and I'm using this platform as a test. I modded the vibrato channel by swapping the mid pot from 10k to 100k, adding the 220k/390pF series into V2b grid. (remember that V2 will be CL1 and CL2 and V1 will be OD1 and OD2)

I then used the normal channel faceplate holes for drive, ratio and master controls, and wired V1 for OD1 and OD2 with 70's specs. Plate load and cathode's are unchanged. I used the normal channel bright sw as a channel switch for now, I'll build a relay system later.

I'm not thrilled, but I think I've proven that this is possible. I also learned that there's no way that the 4x10 Weber Alnico's will work with a Dumble. I recorded this clip with my trusty Celestion G12H80's.

http://www.patmedia.net/bob-ingram/DClo ... bleMod.mp3

[fabiomayo]

Sounds good to me, Bob-I.

You may be on to something...

Curious about the speaker thing. What Webers are in there?
Also, could you describe (or record something ) the differences
and the reason you don't think it's right?


All the best

[Bob-I]

These are the Weber signature Alnico's. So that Ted doesn't get upset with me... again.... there's nothing wrong with the speakers, they sound great clean. In OD mode they are too brittle and sound almost like an SS fuzz box. I'll record a clip tomorrow, right now folks are sleeping

I'm thinking of making a 2x12 baffle, which I think will work if the speakers are diagnal.

[jelle]

Bob, does this superreverb has a reverb mixer tube with a 4.7m (or 3.3m)bypassed with a 10pf? This changes the sound. Or are you running the dumble preamp into the pi?
Jelle

[Darkbluemurder]

These are the Weber signature Alnico's. So that Ted doesn't get upset with me... again.... there's nothing wrong with the speakers, they sound great clean. In OD mode they are too brittle and sound almost like an SS fuzz box. I'll record a clip tomorrow, right now folks are sleeping

I'm thinking of making a 2x12 baffle, which I think will work if the speakers are diagnal.

It makes me feel a bit more comfortable that I am not the only one having problems with the 10'' speakers from Weber in combination with an ODS. I really like the Jensen Neo 10s. 4 of them could be paired with a 100W amp. That would be a real monster ...

[Darkbluemurder]

I decided that a total gutting wasn't necessary for a Fender and I'm using this platform as a test. I modded the vibrato channel by swapping the mid pot from 10k to 100k, adding the 220k/390pF series into V2b grid. (remember that V2 will be CL1 and CL2 and V1 will be OD1 and OD2)

I then used the normal channel faceplate holes for drive, ratio and master controls, and wired V1 for OD1 and OD2 with 70's specs. Plate load and cathode's are unchanged. I used the normal channel bright sw as a channel switch for now, I'll build a relay system later.

I'm not thrilled, but I think I've proven that this is possible.

The only disadvantage I see at the moment is that you will have the signal from V2 cross back to V1 and then traverse again over V2 to reach the other tubes. This will likely cause some leads to be quite long. Shielding may be necessary but my experience is that the ODS is not as prone to oscillations as other circuits.

[Bob-I]

The only disadvantage I see at the moment is that you will have the signal from V2 cross back to V1 and then traverse again over V2 to reach the other tubes. This will likely cause some leads to be quite long. Shielding may be necessary but my experience is that the ODS is not as prone to oscillations as other circuits.

It's actually not as bad as you might think. I shielded a few leads but in general the leads are fairly short as the input to the reverb is directly across from the master volume.

[Bob-I]

Bob, does this superreverb has a reverb mixer tube with a 4.7m (or 3.3m)bypassed with a 10pf? This changes the sound. Or are you running the dumble preamp into the pi?
Jelle

It has a 3.3M / 10pF. I tried several values in this position and I didn't get an improvement, only a change in the reverb level.

I also tried the Dumble pre into the PI with the reverb just after CL2, nothing but oscillation so I abandoned that idea.

[jelle]

Bob,

It is possible to take the signal from CL2, send it through the reverb and then send it through the overdrive circuit. But the layout and shielding has to be very good as Darkbluemurder indicated.
Not everybody likes the signal to be contain reverb before the OD especially when a lot of overdrive is added.

Right now you are running the total ODS preamp via the global master volume into the reverb mixer? I think this is the way to go.

Have you considered taking off the 10pf cap of the reverb mixer to reduce the extra upper frequencies?

Jelle

[jelle]

one more thing....the phase inverter, is it still fender? How about changing the 470 ohm resister into a 820 and stick a 12AX7 in it and maybe even add a presence circuit?

Just a thought,
Jelle

[Bob-I]

Bob,

It is possible to take the signal from CL2, send it through the reverb and then send it through the overdrive circuit. But the layout and shielding has to be very good as Darkbluemurder indicated.
Not everybody likes the signal to be contain reverb before the OD especially when a lot of overdrive is added.

I tried that but couldn't stop the oscillations. I'm not really sure that I agree with your assessment though. Many of these amps have the one tube reverb just before the PI and sound great.

Right now you are running the total ODS preamp via the global master volume into the reverb mixer? I think this is the way to go.

Yes.

Have you considered taking off the 10pf cap of the reverb mixer to reduce the extra upper frequencies?

Jelle

I've played a lot with the reverb mixer. In general the best sound I have is the standard Fender setup, 3.3M/10pF bypass. I tried no bypass, smaller mixer resistor all the way down to 1M.

[Bob-I]

one more thing....the phase inverter, is it still fender? How about changing the 470 ohm resister into a 820 and stick a 12AX7 in it and maybe even add a presence circuit?

Just a thought,
Jelle

I've thought about this, but haven't had the time to do it. I'll also change the 100 ohm to a 390 and the 22K to a 24K plus the plate loads from 82k/100k to 91k/110k. Lots to do but I'm just happy that I have the OD channel operational.

[Darkbluemurder]

Just a few thoughts:

1) In my modded Deluxe the one tube reverb was much less prone to oscillations than the traditional Fender reverb. I always had a mosquito sound in the clean channel before I switched to the one tube reverb. Due to the fact that it has one gain stage less it also has a lot less wiring. The Concert works well with the Fender reverb circuit though.

2) I don't think that the isolated change of the PI tail resistor from 22k to 24k is audible. The change of the cathode resistor from 470R to 820R should bring the gain down a little. All in all it seems that both phase inverters are designed to be as clean as possible.

Good luck
Stephan

[jelle]

Bob,

I'm sorry if I was unclear about the reverb. I meant most people like the sound when the reverb comes just before the pi.

Like this:

clean preamp - overdrive stages - fender reverb - phase inverter.

This is the same setup as the amps with the one tube reverb only this one uses the fender reverb.

When the reverberated signal is heavy distorted afterwards (reverb before OD stages) most people do not like the sound.

These amps can be fun! I gigged a AB763 fender vibroverb clone with the 70's ODS values and reverb before the pi for some time. I liked it a lot.

Have fun!
Jelle

[Bob-I]

Bob,

I'm sorry if I was unclear about the reverb. I meant most people like the sound when the reverb comes just before the pi.

Like this:

clean preamp - overdrive stages - fender reverb - phase inverter.

Yes, that's how it's structured.

These amps can be fun! I gigged a AB763 fender vibroverb clone with the 70's ODS values and reverb before the pi for some time. I liked it a lot.

Have fun!
Jelle

That's exactly my plan.

It's also my plan to come up with a layout that can be easily installed on the standard Fender eyelet board. So far it seems do-able.