Diode clipping

[jestaudio]

Where would folks add a diode clipping circuit, output off one off the gain stages or mayby from the wiper on the gain pot to earth

[Structo]

I know the Silver Jubilee has them and I think a few other Marshalls have them.

You can use different diodes too, like LED's.

http://www.el34world.com/charts/Schemat ... w_2550.pdf

[Andy Le Blanc]

you put it in just after a gain stages coupling cap

then you go to ground or to the cathode of the previous stage

the trick is ti include a small electrolytic cap in series with the diodes

1 to 5 uf

[roberto]

You can use them in many many ways.

Marshall JCM900, JMP1 and Mesa Vtwin uses them just before a gainstage+cathodefollower, to obtain the grainy feel of diodes plus the tube feel of CF.

There are also some famous marshall mods based on zeners, diodes, fet used like diodes, leds, and so on.

[John_P_WI]

you put it in just after a gain stages coupling cap

then you go to ground or to the cathode of the previous stage

the trick is ti include a small electrolytic cap in series with the diodes

1 to 5 uf

Another trick is to add a series resistance before the diodes, such as 10k.

some more info here:

http://ampgarage.com/forum/viewtopic.ph ... ght=diodes

[dass101]

A zener clipping mode should be done together with a MV mod, to place it before the tone stack, right after the CF. This is because you generally want any tone shaping to be post clipping.
Look for Jose clipping mod, there is a lot of info on various sites.
I did it on a Marshall but found the 12V Zeners to be way too clipped, if I remeber correctly I ended up using 2 in series to get 24V clipping threshold. It sounds pretty good actually, it is a very useful tone.

[Reeltarded]

I build the Jose without a pot. Best place in the circuit, surely. I use the germanium 1n914 diodes in an opposing pair. Anything else feels wrong to my fingers and ears. If you want the effect with out the volume drop just open the master WFO.

[martin manning]

1N914 is a silcon diode with typical ~0.7V fwd voltage drop. Jus' sayin'...

[roberto]

Aren't 1N914 just the older version of 1N4148?

Anyway, except all stomp box clipping, you can find all the Jose-like mods and beyond, compliance and bonding included methods, on chapter 5 of O'Connor's TUT, pagg. 5-12 to 5-18.

[Colossal]

I build the Jose without a pot. Best place in the circuit, surely. I use the germanium 1n914 diodes in an opposing pair. Anything else feels wrong to my fingers and ears. If you want the effect with out the volume drop just open the master WFO.

+1 on the post-cathode follower Jose clipping mod. Adds some nice hair and compression along with a nice volume drop. I've been using 20V germanium zeners (1N4747A), opposing pair, with resistance in front.

[Reeltarded]

1N914 is a silcon diode with typical ~0.7V fwd voltage drop. Jus' sayin'...

I thought so too, but the ones I bought a few months ago described them on the packaging as germanium. Back to 'I thought so'.

[skeezbo]

Here is an idea: I put the clippers in the tone stack on the mid pot. I have the standard post cathode-follower FMV setup.

I think it sounds pretty natural. It sure thickens up my Tele, but you can keep a little clean sparkle on top by tweaking the treble, and some fuzz-free warmth down below if you want it with the bass knob. If you back off the mids enough, the overdrive sort of disappears, but the amp still feels greasier, like you are playing loud, even if the tone is mostly clean.

If you want the full bore overdrive, you can max out the mid knob and back off the treble and bass to zero. The Duncan tone stack simulator suggests that the mid knob now has control of the entire bandwidth and the diodes sound like they are probably clipping the entire audio range.
Skeezbo

[Deric]

Skeezbo,

Sounds very interesting. So....what kind of amp? And....what kind of diodes?

Thanks!

[skeezbo]

I built a tweed fantasy 1x12 in a tweed super cab. It has the bassman preamp, the super/deluxe inverter. fixed bias, kt66s, no negative feedback.

The diodes are silicon rectifiers; I'll bet germanium would sound great, too, but I didn't have any to experiment with.

I was getting the frying bacon sound in the amp, so I took the mod out, but that wasn't the problem. One of these days I'll get back to it.

Skeep

[M Fowler]

I know the Silver Jubilee has them and I think a few other Marshalls have them.

You can use different diodes too, like LED's.

http://www.el34world.com/charts/Schemat ... w_2550.pdf

In case some else is building a 2550 Silver Jubilee I recently got this custom built cab from Scott Splawn and the workmanship is great $225 shipped.

Mark