Blackstar EQ into a stomp?

[screamersusa]

Like many I'm really dissatisfied with a lot of standard tone circuits in stomps.
In addition you pretty much have to order all the pots as Rat shack doesn't have them.
I really like the blackstar EQ and the Carvin XV100 active eq.

Looking at the blackstar, it looks like the first buffer before the eq section may have some
pre eq eq going on. If so, how would you alter it to work with a single supply?

[defaced]

Schematics?

[giappui]

i want to know the i*F tone stack's pot and resistor value

i my opinion is one of the tone stack

http://revolutiondeux.blogspot.it/2012/05/blackstar-isf-control-whats-going-on.html

[JebemMajke]

My guess is that it started with marshall tone stack with it's mids at 0, hence no mid pot after bass pot. Since 4,7n and other caps are a bit bigger than usual and that sweep ( ISF ) is 10k my guess is everything is scaled x 10. So, if I;m right, treble is 22k, bass is 100k. Mid pot, is, prob the same as treble. But if not try 2.2k or any other value.

R2 and R3 probably have same values. Start with 1k. Which leaves R4 and R1. Now there is a possibility that they didn't want you to kill a great deal of treble with turning the pot ccw. So treble pot can be 10k and R4 can be 10k as well. That leaves R1. Which should be somewhere between 1k and 10k ... you should use 100k trim pot there.

So to recap
ISF 10k lin
Treble pot 10k log
Bass pot 100 k log
Mid pot 22k ?
R1 100k trim pot
R2,R3 probably 1k
R4 10k

Of course i might be wrong as @#$%, but it's a starting point.

[teemuk]

There are at least two versions of the "ISF" tone stack; a passive one (e.g. HT-5), which is similar to schematic depicted in the patent and a partially active one (e.g. HT Dual pedal), which functions identically but circuit-wise is very different and spread around about three different stages. Both schematics can be found with Google search.


...still... I'd rather build something like the tone stack of the channel #2 of this...
http://www.diyguitarist.com/Schematics/L5-Schematic.jpg
...because it can do EVERYTHING the ISF circuit does ...plus things that the ISF simply can't.  

Looking at the blackstar, it looks like the first buffer before the eq section may have some
pre eq eq going on.

It's a Blackstar amp so probably A LOT of pre and post EQ filtering going on. The EQ is just a minor "voicing" part of those amps.

[J0K3RX]

Something like this?

[J0K3RX]

You might consider the Framus Cobra tone stack... I have not tried it but heard it is better than the blackstar

[JebemMajke]

Cobra's kinda takes away volume when you reduce mids. Anyways cobra's tonestack is james, modified though.

Ps
I was right about pot values, at least. Remember scaled ten times

[screamersusa]

jok3rx,
  Nice post. I was hunting for that one. I have the parts for that except the 2sk's.
Its the sweep type function I really like.

[JebemMajke]

I think that he implemented blackstar's tonestack into his jfet distortion. So you really don't need 2sk30 or any other jfet. Just use the tonestack in something like ... tonemender project from run of groove. Replace the existing tonestack with blackstar's and you will have active eq .

[Thecomedian]

Like many I'm really dissatisfied with a lot of standard tone circuits in stomps.
In addition you pretty much have to order all the pots as Rat shack doesn't have them.
I really like the blackstar EQ and the Carvin XV100 active eq.

Looking at the blackstar, it looks like the first buffer before the eq section may have some
pre eq eq going on. If so, how would you alter it to work with a single supply?

you might be able to order them from rat shack online, but then you might as well go somewhere cheaper. The shack in the local area has only about 3 different types of pots, usually, so it's completely insufficient for any serious building. I have no idea why their selection is so low for walk-in.

[J0K3RX]

jok3rx,
 Nice post. I was hunting for that one. I have the parts for that except the 2sk's.
Its the sweep type function I really like.

You can ignore the 2sk30's... They are not part of the tone stack... I just clipped that image from another preamp schematic that I worked on and didn't cut out some stuff. Starts @ the 2.2uF cap and ends @ pin 2 of the master volume pot. You will have to incorporate it into your schematic.

By the way - C27 and C28 are a mistake in that schematic... there should be only one 2.2uF cap there

[screamersusa]

Cool
I have the parts out of some old soundtracs boards to whip up
a tester

Are the big caps in the active really 470 and 220 nf? Or is that a "intentional mistake"

[J0K3RX]

might want to check this out...
http://www.diystompboxes.com/smfforum/index.php?topic=53316.0;prev_next=prev

[J0K3RX]

Anybody ever try this?
http://rapidriotboxes.blogspot.com/2009/03/sansamp-gt-2-and-bddi-3-band-eq.html#comment-form

[screamersusa]

I actually had and liked a TRI-AC for what it was.
wonder if we can move the mids around a little with another pot.