Tweed Man clipping section

[eh là bas ma]

Hi,

I finished this build last week and i really like it.

I have been looking at the schematic lately, and I can't find any clipping section :

https://docs.pedalpcb.com/project/TweedMan.pdf

It can be a bit harsh, you know, so I would like to try and add a clipping switch, in order to have the option to smooth the distorsion just a bit. Mosfet clipping, germanium, scotchy diodes, or red leds maybe... that's what I have available in my hands right now.

Does it make any sense to add some clipping diodes ?

Where would be the best location to add some sort of clipping section in this circuit ?

Any help would be welcome !

 

[bowanderror]

You are correct in that there is no diode clipping stage as the overdrive sound comes from the JFET muamp stages (each pair of 2 vertically stacked JFETs is a muamp gain stage).

You could add a diode clipping stage, but there are some easier options to try first. The clipping character of this build will be affected by the amount of gain, the tone knob settings, and the Voice switch. Is the harshness you're hearing in the amount of distortion or in a specific frequency range - as in treble, mid, or bass frequencies?

Here are some easy things to try in the meantime:

1. Run at higher PSU voltage than +9V - +12/15/18V will result in higher headroom and a more gentle descent into distortion. I find some JFET muamp circuits to have too much distortion and get "mushy" quite quickly. Running at a higher voltage will help reduce the amount of distortion. - NOTE: Make sure C100 has a voltage rating ~1.5x that of your PSU voltage - i.e. 25V for +18V supply
2. Try different JFETs - Changing the type of JFET or trying JFETs with different Vp & Idss values will alter the clipping tone & amount. You can try 2N5457, 2N5458, J201, or really any other N-channel JFET. You can even use multiple types of JFETs in this build (i.e. 2N5458 in Q1/Q2, 2N5457 in Q3/Q4, and J201 in Q5) . Just make sure the 2 vertically stacked JFETs in each muamp are the same type.