fet boy

[3nity]

Alright i'm building me another pair of FET-boys here...
DO you know guys if theres mods we can perform on those suckers?
Like output trimmer??
I'm mainly need something to have different tones out of it...
Look at Neeno versions:

 

[jensenmann]

Kubi always recommends to built a pot as negative feedback gain control around these amps. Lower gain then means less distortion.

 

[3nity]

would it need a rev log pot then??
thanks

 

[Silvas]

would it need a rev log pot then??
thanks

Or a log pot wired backwards,

I done that on my first hamptone style pre and labeled it "Color" (thanks chrissugar for the advice on the "harmonics" knob) ! .  Worked great. But, most of the time, the "Color" knob, is parked fully CW (in my case, it works backwards, less gain on the 1st gain stage). This thing already has LOTS of gain !

I dropped the "color" knob for the dual hamptone pres i´m working on now (will post later about this) and left a jumper on the PCB, which i labeled "MORE GAIN" as you can see.

The extra knob just did not gave me that much tonal variation...

And that knob in the middle, is a load on the input trafo.

Good luck

 

[3nity]

A color knob how cool is that? is it really colored when on or what?
THe More gain is just using the 470uf caps? like the ones used on some Fet-boy mods?
What i really like to do is crank the input and like the neve 1290 uses a trimmer....thats what i want...
I need to look closer to the schems..

 

[fucanay]

Well, all of the problems I've had were indeed the PSU. JLM TREX and JLM 48v 380mA SMPS did the trick. No noise anymore. Sad that I wasted so much time on a PSU that never worked correctly, but so goes DIY and this is a finicky little guy.

So, ummm, it's been so long I forgot why I built these in the first place. What are the popular uses of the fetboy? ;D ;D ;D

Matt

 

[fucanay]

So I brought these fetboys to the studio last night and damn are they bright. Didn't sound half as good as the RME Fireface pres on snare drum. Is there anything I could have done wrong that would make them so bright or maybe rob some of the bottom out of them?

Matt

 

[3nity]

something wrong indeed....have a listen at matta sample..

 

[abby normal]

Anyone build one of these with Keef's 9K PSU subbing the LM78/7918 regulators for LM78/7924's?

 

[fucanay]

something wrong indeed....have a listen at matta sample..

Hmm, I guess I'll have to open it up again. Something is wrong for sure. I don't think I would use them much if this is what they sound like. Any idea of where to look for problems when it has these symptoms?

Matt

 

[jarlehal]

My fetboys are also bright.

abbey: I used 9K PSU for it

 

[abby normal]

Hmm, I guess I'll have to open it up again. Something is wrong for sure. I don't think I would use them much if this is what they sound like. Any idea of where to look for problems when it has these symptoms?

Matt

What schematic did you build these off of? Link?

My fetboys are also bright.

abbey: I used 9K PSU for it

Thanks Jarlehal, did you change anything up?

 

[fucanay]

Hmm, I guess I'll have to open it up again. Something is wrong for sure. I don't think I would use them much if this is what they sound like. Any idea of where to look for problems when it has these symptoms?

Matt

What schematic did you build these off of? Link?

I used Fabio's boards and his schematic and BOM.

They can all be found here. http://www.diyfactory.com/projects/fetboy/fetboy.htm

See anything in the schematic that could be a place to look? Usually it would be a cap that would filter a frequency, right? And to me it looks like there are only 2 caps in the signal path, C2 and C4.

Matt

 

[Silvas]

So I brought these fetboys to the studio last night and damn are they bright. Didn't sound half as good as the RME Fireface pres on snare drum. Is there anything I could have done wrong that would make them so bright or maybe rob some of the bottom out of them?

Matt

Maybe undersized coupling caps?

my units sounds amazing on almost everything...

i'm using oversized caps, plus a metallized poly .1 for bypass.

 

[abby normal]

See anything in the schematic that could be a place to look? Usually it would be a cap that would filter a frequency, right? And to me it looks like there are only 2 caps in the signal path, C2 and C4.

Matt

Are you using those 220nf's off those 47k resistors? If so and just for shits and grins could you disconnect those to see if your issue is resolved? Or at best could you tell me the difference between them being in the circuit or not?

 

[Svart]

The fetboys run off of +24/0.  They don't use negative voltage.

Mine aren't bright but they start to distort at moderate gain.  It seems that the input section clips the output section too easily.  If you could run the output section at a higher voltage that would be a cool mod to do.

 

[Silvas]

The fetboys run off of +24/0.  They don't use negative voltage.

Mine aren't bright but they start to distort at moderate gain.  It seems that the input section clips the output section too easily.  If you could run the output section at a higher voltage that would be a cool mod to do.

i'm using 28 volts, and -24dB for the pad. No distortion (with pad engaged) even on very hot signals. Unless is extremely hot !

 

[abby normal]

The fetboys run off of +24/0.  They don't use negative voltage.

Hey Svart, I'm using that supply to also power a Forssell opto comp that needs a -24V neg voltage. Sorry for the confusion.

 

[Svart]

ah no problem!

I can plug my passive guitar right into my fetboy DI and before I have the knob 1/4 the way up I'm already distorting.  About half way I am clipping my A/D input.

 

[abby normal]

ah no problem!

I can plug my passive guitar right into my fetboy DI and before I have the knob 1/4 the way up I'm already distorting.  About half way I am clipping my A/D input.

Did you see Chris's modular layout design? I'm implementing basically the same thing for deferent reasons. Modular PCB's will let you experiment with different input and output designs. There has been several suggestions for changes to the output section, some with completely new designs. You could set these up modular an experiment with what suits you.  Sounds like good fun anyway.