Adding a clipping section to an AMZ booster

[alderbody]

Tried it last night with a Ge and a Si diode and was quite good.

I will try several diode combinations and once i settle to one, i think i'll go for it.

Of course, the clipping section will be switchable for a booster/dist option.

I use MPF102 FETs and i got the best sound when i ran the pedal @ 18V.


btw, could i use a BS170 MOSFET wired as a diode for the clipping section?

[alderbody]

I forgot to add that the diodes to ground are placed after the 0.22uF Output cap and before the volume pot.


...could it be placed anywhere else in that circuit?

[DuncanM]

I'm breadboarding something similar at the moment - a Mosfet booster with clipping diodes to ground on the output.
I found that I needed a jfet buffer after the volume pot to keep the tone consistant and another booster (sparkleboost) in front to really get things cooking.

After some experimenting, I've settled on one Si and one red LED as my preferred combination of diodes.

I'll be building it up (when I have the time and parts) using a mosfet boost instead of the sparkleboost in front, and a third (mosfet ?) stage as a switchable post boost - hoping to end up with something like the "box of rock" in terms of functionality.

[alderbody]

I found that I needed a jfet buffer after the volume pot to keep the tone consistant.

Yes, the diodes suck a bit of the output level, but i kinda prefer it like that because the booster gives a huge volume pump
and my twin reverb doesn't seem to like it very much (in terms of a sweet breakup and stuff...)

After some experimenting, I've settled on one Si and one red LED as my preferred combination of diodes.

hmmm, interesting combination.
I'll give that one a try, too.

[KB]

Hi

If your breadboarding then look at:

Warp control
Tone Clippers

Over at AMZ you'll find them in the lab note books section.
Jack has done a lot of experimenting.  I added a warp control to a OD250  - ( hard clipping diodes to ground) allows you to dial in the clipping and also the type (LED or silicon).  Might be useful for your builds.

Kevin

[alderbody]

those AMZ files are indeed great!

I really have to dedicate some time to them before i move on.

In a quick test last night, i tried a pair of LEDs and a pair of 1N60 Ge diodes.

The LEDs gave a very "gentle" breakup, which i liked very much, while the Ge pair went really hot and creamy
(excellent tone, but needs some kind of a post-clipping boost to compensate the significant level drop!).

Both were great, but i kinda prefer the softer clipping because i don't need too much saturation.


anyway, the research goes on....

[alderbody]

btw, any comment on the BS170 mosfet_as_a_diode?

[d95err]

(excellent tone, but needs some kind of a post-clipping boost to compensate the significant level drop!).

Try two diodes in series in each direction. That should give you twice the output level.

Or, why not go asymetric - try three Ge diodes in one direction and two in the other.

[WGTP]

Yes you can use Mosfets as diodes, several different ways.   

http://www.elixant.com/~stompbox/smfforum/index.php?topic=38581.0

[alderbody]

Thanks for the link...   

[alderbody]

I finally settled with two switchable diode combinations.

I used a DPDT on/off/on toggle switch, so it's LED/stock booster/diode.

The diode part is a pair of 31DQ06 Schottky rectifiers i had lying around (scavenged from a device's power supply).
These things are huge, but i liked the sound (almost like Ge because of the similar turn-on voltage).

So now there is: soft clipping / clean boost / thick saturation (with a significant level loss)

cool addition IMHO.