BSIAB2 Mods

[mojotron]

I've been playing with this circuit.... I found a couple of mods that I thought were interesting - thought I would share them....

One, is to make the .068uF cap (C2 on the GGG schematic) switchable, it's like you have 2 really nice pedals in one - one of them being an overdrive and one being a distortion - both about the best at what they do - with some other mods...

Two, I use a much bigger cap for the 150pF cap (C6 @ GGG). I found that 220-470pF makes the low end a lot more punchy, while sacrificing tightness.

Also, using mod #2 above with all 2n5457s (no J201s) really gives you a lot of power, while sacrificing some gain....


This is an interesting circuit, does anyone else have some interesting mods?

[phillip]

I definitely like using all 2N5457s in the circuit.  I originally put them all in the accidentally...didn't notice the two J201s in the schematic.  I tried out the J201s, but I prefered the tighter, brighter sound of the 2N5457s.

Phillip

[j0shua]

I use 2N5458's and 250Pf caps

[mojotron]

I use 2N5458's and 250Pf caps

How does that change the sound from the standard BSIAB2?

[Phorhas]

Two, I use a much bigger cap for the 150pF cap (C6 @ GGG). I found that 220-470pF makes the low end a lot more punchy, while sacrificing tightness.

with my strat I get a really transperant feel with a 330pf there.

also, moving the tone stack between the 2nd Mu stage and Q5, makes a whole new beast


BTW - I'm still tring new stuff, while on the subject, mojotron

[mojotron]

...
BTW - I'm still tring new stuff, while on the subject, mojotron

Ah yes my patient friend...  :oops: that was 3 months ago... Sorry http://www.diystompboxes.com/sboxforum/viewtopic.php?p=195015&highlight=#195015 Thanks for getting me back on track!!

Well you said you were in no hurry... I'm looking into that tone control this week..

Try the switched cap thing - I bet that would go great with the 330pf cap...

More later.. I'll just keep posting to this thread.  

[Phorhas]

I just tried useing the first 2 stages - stock, then adding a Marshall style tone stack and then Joe's Diode comp stage.

Wierd thing, each stage acts great on it's own, but when I put them all together I get kind of a VERY LOW VOLUME tone, going from saturated amp to full on thrash metal tone

but why the low output?

[bean]

I replaced C6 with a 300pf cap and replaced the two J201's with 2N5457's and this pedal is sounding sooo sweet.

Thanks for the mod tips!

[Ed G.]

The all-2n5457 mod is a good idea, as the pedal has an abundance of gain. In fact, it gets to a point, where it doesn't get more distorted, only more compressed. The 2N5457s do not squash as much as the J201s and can sound more dynamic. I may ask JD to post that on the GGG site.

[j0shua]

I use 2N5458's and 250Pf caps

How does that change the sound from the standard BSIAB2?

well 2N5457 and 58 are same transistor just litle more stable in some cases and less noise.....

250 cap give to me more Treble control , i put a socket to change the CERAMIC CAP  150 TO 1500 PF , to my taste ...... 250 Pf and 500 Pf are cool .....

[j0shua]

about more gain or distortion in some effects i try some time ago the Howie's metal simplex  and my mod was :


Original transistors are ----------->   2N3904
my change ==============>  2N5088 AND 2N5089
Red Led --------change to -------->   Green Led
10 Uf electrolitic cap. ----- to ---->    4.7 uf electrolitic cap

And this is the final mod ( not tested), switch to get RED LED or GREEN LED

now this little circuit is a distortion monster , and when you mix whit compressor WOW!



Have a fun!

[Phorhas]

BTW, using the first stage as a booster, is really SWEET

[mojotron]

BTW, using the first stage as a booster, is really SWEET

Phorhas - Ya... I really like a lot about the whole circuit... I'm leaning toward mods to switch in the different stages, each one adds some great tones... So, what did you use for the Marshall tone stack?

Ed - this is some awesome work! So.. what have you been working on lately? I bet it has to be pretty interesting....

I'm finding that I mod one of the many of these I've built and think... That's different, but Hmm ... I kind of liked the original value(s) better.

[hilbi]

Two, I use a much bigger cap for the 150pF cap (C6 @ GGG). I found that 220-470pF makes the low end a lot more punchy, while sacrificing tightness.

Will this result in more bass?

I also use all 2n5457's in the bsiab2, i like that better then the two j201's a little less gain.

[mojotron]

Two, I use a much bigger cap for the 150pF cap (C6 @ GGG). I found that 220-470pF makes the low end a lot more punchy, while sacrificing tightness.

Will this result in more bass?
....

Not really, it just gives you a little more upper mids that make the low end a little more defined... it all comes down to what your ears like.

I use a few of these, one is the exact pedal that Ed designed, another has the mods I really liked, and a few others have various things done to them that I am working on... I have a stack of BSIAB and Tube Driver experiments in fact....

So, far I like a lot of the mods I have tried from this thread - Thanks!! I'm still experimenting

[barret77]

I'm sorry for asking this; I'm an absolute newbie with very little experience.

Red Led --------change to --------> Green Led

Is this a joke? Can it be possible for a led color to influence the sound? Pure mojo?

[Torchy]

Different colour LEDs have different forward voltage and current ratings so will give a different clipping characteristics.

[barret77]

dang! I didn't knew about it!

guess I have to study more...

Thanks!

[mojotron]

dang! I didn't knew about it!

guess I have to study more...

Thanks!

But, that comment was not in the context of the BSIAB2 - there's no LEDs in the signal path. But, for circuits where a clipping diode is used, it is a good idea to try every kind of diode (LEDs, Zener, Rectifier, as well as the 1n914s....).. they will all give a slightly different sound and that change is different depending on if they are used in a feedback loop (TS) or as a shunt to a common AC ground (DS1, Gov'nor...).

Study the archives here... there are a lot of really good findings that you would not know to ask sometimes..

[hilbi]

thanks, i'm not looking for more bass, so maybe it is worth trying the 330pf cap.