How to increase distortion on a Fender Super Twin Reverb 180W

[kagliostro]

A friend that has an amp service shop has a Fender Super Twin Reverb 180W on the bench, the owner is asking him to increase distortion

we were discussing about the less invasive way to reach a higher distortion level on this amp

(that has a dedicated pot labeled distortion whose circuit I don't understand .....)

http://el34world.com/charts/Schematics/files/fender/Fender_super_twin_reverb_180w_schem.pdf

I was thinking to use larger resistors values feeding the G2 of the power tubes, but there is an UL connection ....

Do you think that the trick to increase those resistor will have effect also if the UL connection is present ?

Disconnecting G2 from OT intakes and connecting it to a proper voltage will reach the desired result ?

There are other simply ways to reach more distortion on this amp ?

Thanks


K

[eleventeen]

I think I would try pedals before messing with the amp. It has a master volume, no? That amp is designed to be super clean. A person could spend a lot of Euros trying to get that amp to play dirty.

[John]

I'm guessing the owner doesn't want to just put a Tubescreamer in front of it? 

[Willabe]

Yep, pedal.   

[xm52]

As was mentioned, the amp is designed to be clean. There's good and bad distortion, you want the right type.


A set of 6L6GC power tubes with an early onset of distortion will provide less headroom and distortion at lower volume levels. That's an expensive option.


Less drive capacity from power tube driver V5 will result in more distortion. Perhaps try a different tube in this position.


There is a pot to adjust the power tube balance. If the tubes are not balanced, there will be more harmonic distortion.

[MakerDP]

A couple ideas come to mind...

1) Replacing the 47k/12k voltage divider before V3C with a 50k pot should enable some overdrive in V3C.

2) Converting V3A into a more traditional preamp gain stage.  I'd also move it so it's before the reverb.

3) If he doesn't want to use a pedal, build a Tube Screamer circuit directly into the amp. 

That is a VERY bizarre distortion scheme. Is that V3C stage playing with the bias of the CF to induce some sort of clipping?

[DummyLoad]

emg active pickups.


--pete

[John]

You know, maybe the owner just wants "earlier breakup" and is describing it as "more distortion". If so, would increasing the K resistors in the preamp help with that? Cooler biasing might lead to earlier or easier clipping? 

[kagliostro]

Many Thanks to ALL

May be I've done something wrong, because I posted a message yesterday but it is no present on the tread, sure may fault

I agree with the fact that the amp is a very clean one (it has also the UL configuration, if the rest were not enough already)

and, to me, the better choice of the owner will be to sell the amp and buy one other at his taste 

The idea I had were about tailoring aroud the values of the PI plates resistor as to have the PI unbalanced and to ingrease the G2 resistors

to reach easily compression

---

Personally I like what you say, keep the amp as is and use a pedal or emg active pickups 


Franco

[Willabe]

to me, the better choice of the owner will be to sell the amp and buy one other at his taste 

+1   

A pedal steel player might like that amp as it is now, or even a keyboard player.