fatboostered more gain ?

[mat]

Hi,

I just finished the Fat Boostered http://www.generalguitargadgets.com/diagrams/joam_lo_big_fb.gif and while i like it very much i was wondering if there would be a way to get more drive out of it with swapping some part(s) ?

The gain pot behaves almost as a volume giving only very minor grit to the sound.

I know this is booster, not an overdrive but would like to know if there is something i could try ? Or is the only way to put diodes to ground for clipping ?

I tried to change the gain pot to 470k but the result was same as with the 10k.I thought that it would resist more signal not to go to ground. I also tried different fets on the Q1, Q2 and for Q3.

The parts are as in the schem execpt the C8 is 680nF instead of 1uF.

So it is working as it should but would like to know if it can be modded for more ...drive...  :oops:

mat

[amz-fx]

Try an NTE458 or 2SK117 for the lower jfet...  they will give you more gain but still will not push it too far into overdrive.   That's about all you can do with the basic circuit.

You could put an LPB-1 in front of it and get some serious overdrive!

regards, Jack

[mat]

Try an NTE458 or 2SK117 for the lower jfet...  they will give you more gain but still will not push it too far into overdrive.   That's about all you can do with the basic circuit.

You could put an LPB-1 in front of it and get some serious overdrive!

regards, Jack

Jack, thank You for the answer.

All right I'll try with LPB1 and with minibooster in front of it (I have both built and boxed). The NTE458 is hard to find component here but at least one electric shop carries the 2SK117.

I'll let You know when I'm trough experimenting.

mat

[WGTP]

A while back someone was putting a Mosfet boost in front of that ciruit and making them switchable.  I think AMZ just happens to have one of those.  

[Khas Evets]

I've tried a mosfet boost in front of a minibooster and found it too brittle.

You could also take a look at minibooster 2.5 or BSIAB which cascades miniboosters. Maybe add a switch that bypasses the first stage. Or change the input buffer in the Fat Boostered to a gain stage.

I think a BJT based booster would go nicely with this circuit. I've used Gus's NPN boost with it with good results. One consideration is the order of the effects. Jfets have higher input impedance than bipolars. The experts around here can give more detail on that.

[mat]

Thank You for Your suggestions

For now i tried LPB1 in front of the fatboostered and was not so happy with it. Then i tried the mini booster in front of the FB and was quite happy with result  
I like the FB itself more and more and maybe i'm not going to mod it but some kind of switchable gainboost-thingy might come in consideration  :roll:

thanks,
mat

[dosmun]

Try building one of Dragonfly's Sparkle boosts.  Then maybe add some cliping diodes to it.

[PaulC]

An easy thing to do is to change the input source follower to a simple jfet gain stage.  That will give you more signal to hit the booster stage harder.

To be honest I only did that thing because I thought it was sort of lame when Jack's Booster showed up being mass produced.  All I tried to do was give it a little more gain while being able to roll back some low end if you were clipping it.  I only made the one, and gave the schematic  to Aron as a joke.  I thought it had a better name "Fat Bastard", but somehow it got changed!!

PaulC

[amz-fx]

mat,

I had another idea...  lower the power supply voltage to 3v and that will certainly increase the amount of distortion.  If you are using J201s or similar then it will work just fine and should self-bias.

There is an article about low voltage boosters in my Lab Notebook.

regards, Jack

[mat]

Try building one of Dragonfly's Sparkle boosts.  Then maybe add some cliping diodes to it.

Hi,

I did but it is still on debugging stage  :oops:  :roll: The small brothers (clone and stone) worked right away though :shock:

mat

[mat]

An easy thing to do is to change the input source follower to a simple jfet gain stage.  That will give you more signal to hit the booster stage harder.

To be honest I only did that thing because I thought it was sort of lame when Jack's Booster showed up being mass produced.  All I tried to do was give it a little more gain while being able to roll back some low end if you were clipping it.  I only made the one, and gave the schematic  to Aron as a joke.  I thought it had a better name "Fat Bastard", but somehow it got changed!!

PaulC

Hi,

While being novice enough i'm having har time to know what the 'input source follower' is  :oops: Maybe i should check the minibooster inspired circuits (blue magic, bsiab..) more closely.

thanks for Your input,
mat

[mat]

mat,

I had another idea...  lower the power supply voltage to 3v and that will certainly increase the amount of distortion.  If you are using J201s or similar then it will work just fine and should self-bias.

There is an article about low voltage boosters in my Lab Notebook.

regards, Jack

Thanks Jack, i'll try that one. Very nice reading on Your site. I just noticed that i have printed some Lab Notebook pages for further studying on last June when i found the hobby. I'll better to get back on them - then they kind of went over my head  :roll:

mat
http://koti.welho.com/mtiilama/