24 volts fets help requested

[screamersusa]

I need to whip up a few bs170 j201 and mpf102 distortion circuits to run at 24v.  I will be using them powered off
an RDL 24v wall wart because they will be mixed with RDL da amps, eq's, mixers, and relay switches.
I'm doing this due to loss of shop space and parts and I need a single box guitar od/dist solution that AINT digital.
I also want to play with some paralell distortions so "my" tones are in one box along with known pre packaged (rdl)
interface modules.

Any help in adjusting the basic SHO, Peppermill, and AMZ? Mpf102 to run at 24v would really be appreciated.
Thanks.

[psychedelicfish]

I might be wrong, but I think the voltage gain of a FET amplifier is dependent on the supply voltage of the circuit. Any non FET parts of the circuit will probably have more clean headroom, which is not a bad thing since they most likely aren't meant to distort anyway.

[ggedamed]

The SHO and the AMZ Mini-Booster (which I assumed you're talking about) should work without modification at 24V.
In the Peppermill you might need to increase the value of the drain trimmer.
Of course, they'll all work at bigger currents.
psychedelicfish is right, JFETs will have bigger gains.
Be aware that MPF102's maximum voltage rating is 25V. If your power supply is not stabilized, it can fry the MPF102.

[psychedelicfish]

^I'm assuming that's the max working voltage, so it will probably be fine if you don't run it at >25v for long periods

[Bill Mountain]

Make sure you check the voltage of all of your transistors.  Most small signal FETs max out in the 20 volt range.  I know there are some high voltage MosFETs but I'm not sure about the BS170.

[screamersusa]

Thanks.
I was also concerned about the 5v zener protection in the sho circuit. Since it's between the two 1meg resistors to V+,
I assumed it would have to be upped to a 12v. 
Hmm I thought the mfp102 was higher voltage than the J201?
I still have a bout 30-40 of each , Bs170, Mfp102, J201 left.
I will probably be trying to add a Carvin eq ripped out of the XV100 or that 4 band schematic thats
floating around. I guess since I have to make vref, I could also use that vref as a 12v If I needed to. 

I wanted to use an Mfp102 as the first stage (instead of bs170) as I want to eliminate needing a tube buffer
for that glassy tone. The signal will then be distributed around the rest of the pedal from there and manipulated
as required.

Part of the project is getting a sound similar to Volbeat's warrior. One dark timbre distorted guitar,
One clearer brighter timbre, playing exactly the same thing. I'm thinking two different distortions
one all fet, one with clippers mixed should get close. That will be fed by an rdl DA so I'll have up to
3 feeds for 3 different distortion types, actively mixed on the end as one tone.
The clean and blues stuff would all be fets through a different path.
It's a bit of a pain project but I'm sick of tweaking modelers. Going for a "boxed" set of "my" tones
with a master eq so I can just plug into anything and only need to mess with the master
eq most or the time. 

[ggedamed]

Best way is to download datasheets for every transistor (e.g. J201, MPF102, BS170) and study them a little bit.
I used J201 at 24V (after a voltage trippler with MAX1044) and they worked fine.

Your project sounds like one of those two-year projects of mine. Make it modular or you'll lose the interest in it. I started a preamp + chipamp (two channels, loop, reverb, footswitch for all of them, and so on) in 2010, I think . It's still not finished, because everytime something is better than what I'm working on .

[screamersusa]

ggedamed, love the signature, I always wondered who originally said that.

In the end, I'm keeping this simple. Six buttons and an eq.
Every thing else will be under cover. Maybe a couple of gain controls
and an input pad. Clean (bypass), sparkle, light dist, rock1, rock hell, Fury, lead (cry or scream)
and hotshot (switches the lead channel in with a momentary). Master eq.
Outputs hiz low z w pad, stage, fx loops. Probably will add a preset eq for driving a
non effect loop enabled amp.

[space_ryerson]

You could take a look at the preamp section of the red channel of the Randall RG-80/100. It uses 2N5484's at 24V. The 'sustain boost' made up of the 1N914 diodes can be a bit much, so you can try limiting how much it clips replacing the on/off switch with a pot.

[screamersusa]

I will look at the randall for clues.
Ironically I just got an RX75r for $25.00 with the randall speaker.
Fixed it already and am about to switch gears to mod that with fets while
working on the pedal.
Now it gets interesting..