More crunch/gain from a TS808 - or any distortion

[zpyder]

Howdy ya'll,

I put together a TS808 on a tonepad PCB last week, everything went pretty well, and as a bonus I started experimenting with encolsure painting methods...

Circuit seems to work fine, and looks good, but I noticed that compared to my Marshall Shredmaster, this pedal's pretty tame.  That's fine since they're different pedals altogether, but it raised the question: In general, how would I get more gain or crunch from any distortion circuit?  First three things that come to mind:

1) Different clipping stage - use LED's instead of the silicon 1N4148/914's
2) Different gain/drive pot value.  Current one is 500k log.  Would I want bigger or smaller?  My guess is smaller...
3) Re-bias the gain stage.  The TS808 is TL072-based, so I don't believe that'd be an option in this case.

Any suggestions/ideas?

Also, my Shredmaster has a "Contour" knob which seems to set the flavor of the crunch from fat and wide to razor-sharp.  I don't know what this component actually does circuitry wise- anybody?

cheers,
zpyder

[Seljer]

The Tubescreamer and many other distortion pedals with opamps use it in a non-inverting setup
http://www.google.com/search?hl=en&q=non-inverting+opamp&btnG=Google+Search

the gain of the thing is defined by the transistor in the feedback loop

making the pot larger would would increase the gain, however easier than chaning the pot, is chaning the 4.7k resistor to something smaller for more gain


Though chaning the diodes used will have most effect on the actual characteristic of the sound IMO

as for the shredmaster: contour usually denotes some kind of tone control
(looking at the schematic is seems to work as a mid cut)

[AL]

http://www.geofex.com/Article_Folders/TStech/tsxtech.htm

AL

[mojotron]

http://www.geofex.com/Article_Folders/TStech/tsxtech.htm

AL

Right, give this a serious read; you want to go bigger on the gain pot - not smaller - and about the contour knob - (refering to http://www.generalguitargadgets.com/pdf/ggg_its8_sc.pdf schematic) - replace C3 with a .022uF cap and R6 with a 10kB pot - that will do the contour thing on the TS 

[ubersam]

http://www.generalguitargadgets.com/pdf/ggg_its8_sc.pdf

Going by the schematic in the above link, I replaced R6 with a 1.5K for more gain, and replaced C3 with 0.22uf to bring the highpass knee down to 482 HZ for more bass. I also replaced R7 w/ a 10K so that the low drive setting will remain similar to the stock TS.

Another thing you can try is to move the clipping diodes, I've been experimenting with this on a Guv'nor but not on the TS, theoretically it should work. In the Guv'nor, the stock placement of the clipping diodes (along with other component values) result in a very sharp crunch. I moved it after the first opamp stage (in addition to changing some other component values) and the clipping smooths out a little but not quite as smooth as a TS. For the TS, move the clipping diodes after C5 or after R18 (this would be the similar spot in the Guv'nor). This, along with the other mods, should in theory give the TS more agro capabilities.

[zpyder]

Thanks for the links and suggestions guys... good stuff.

One correction - I mistakently stated that

The TS808 is TL072-based

This is incorrect, the TS808, by all schematics I've seen, use a JRC4558 (aka NJM4558).

cheers,
zpyder

[Melanhead]

What i did was change the Gain pot to A1M, changed C3 to .22, left R6 at 4.7K but placed a 470 ohm res and B10K pot in parallel with R6 for a "fat" control ... More fat = less gain and more bottom end, and vice versa ...

It's all in this schematic called the "M.O.D" ...

http://aronnelson.com/gallery/melanhead/M_O_D_Lite?full=1

[bean]

One correction - I mistakently stated that

The TS808 is TL072-based

This is incorrect, the TS808, by all schematics I've seen, use a JRC4558 (aka NJM4558).

cheers,
zpyder

The TL072 sounds really good in this circuit. I tend to use that one over JRC4558 or the Brown Burr. I think it's fairly subjective, though...it seems like the 072 is a little more rich in harmonics but I could just be fooling myself.

[JHS]

For more crunch try this simple trick fist. Just add a 1N914 to the first opamp stage, anode to the non-inverting input, cathode to the inverting input.

A small 47-100p in series with one of the clipping diodes gives a bit more crunch and a clearer sound too.
The TS produce more crunch if the part values after the output of IC1a on the 2nd opamp stage are changed to BOSS SD-1 specs.
A RC 1458P or JRC 072 produce a bit more crunch than the softer sounding JRC 4558D.

JHS

[zpyder]

I love you guys   

[differo]

this is an old thread but I'll give it a try. What is the rather simple way to implement of all these thing with a small dpdt or spdt toggle switch?
I was thinking to add a switch which adds more gain to my ts808, I already have 1M pot for gain and two diodes. increase this value even more(adding some resistor in series)?
lowering 4.7k resistor or..?
Also how would you describe the difference between symm/asymm clipping? I tried it but its rather subtle for me to hear any difference, maybe I'm half deaf who knows heh

[Al Heeley]

recently posted about putting together a T/S808 modded for bass. that had 2 dpdt switches installed, one added another diode for asymmentric clip, the other switched in a bigger cap for better bass response.
I use a 1meg levle pot on my T/S to give more drive.
The asymmentric clipping gives a softer, smoother distortion as you would expect from a wave form clipping then having the sharp corners rounded, and this also gives a drop in output/gain. But you do get a really nice smooth rich distortion a lot less harsh, and its a simple mod that takes 5 minutes.
Beavis Audio site has sime good info on adding different or asymmetric clipping. http://www.beavisaudio.com/bboard/projects/bbp_DiodeMods.pdf