Crunch IT ! - My small contribution.

[rocket]

Are you looking at the pdf samy has posted? there is a voltage divider of 2 22k resistors, creating a virtual ground (4.5V). that is used for biasing both opamps.

[mac]

The wiring of VR1 is nice, when it goes to zero not only the gain of the opamp is reduced but the signal is lowered by VR1 itself.
With two gain stages of about 100X, the dist+ has only one of 200x, I wonder why it is called crunch it.  

mac

[bean]

It looks like R10 (for Vr) is listed as 10k instead of 22k on the PCB layout. Also, I noticed in the schem that R3 is 1k, but is 1M on the PCB.

I have a close up shot of the guts of the orginal on my home computer. I can upload it if anyone is curious.

[Samy]

It looks like R10 (for Vr) is listed as 10k instead of 22k on the PCB layout. Also, I noticed in the schem that R3 is 1k, but is 1M on the PCB.

I have a close up shot of the guts of the orginal on my home computer. I can upload it if anyone is curious.

Yes, i have found that error also but i didn´t have time to upload the new files. The schem is correct, the error is in the pcb, sometimes by doing some copy/paste we forget to correct the values... sorry.
I have used the TL072 in the schematics because the PCB Wizard didn´t have the LM833, i think any regular dual opamp with the same pinout will work.
If you have the original fotos, can you check the Drive pot ?


Thanks.

[powerplayj]

I have the commercial version and have subbed many chips but the LM833 is by far my favorite in this circuit. 

[bean]

I have used the TL072 in the schematics because the PCB Wizard didn´t have the LM833, i think any regular dual opamp with the same pinout will work.
If you have the original fotos, can you check the Drive pot ?

Here it is:
Crunch It!

[stm]

I have the commercial version and have subbed many chips but the LM833 is by far my favorite in this circuit. 

Have you tried the CMOS opamps like TLC2262 / TLC2272?

[powerplayj]

I have the commercial version and have subbed many chips but the LM833 is by far my favorite in this circuit. 

Have you tried the CMOS opamps like TLC2262 / TLC2272?

just duals like LM1458, JRC2043DD, NJM2043, TL072, LM358, Burr Brown (don't recall the number...the $4.50 one), LM833, JRC4558.  Haven you tried those you mentioned?

[mattpocket]

The reviews on HC sound good, how would you say it is?

What styles does it suit? Metal? Fuzz?

Matt

[stm]

Have you tried the CMOS opamps like TLC2262 / TLC2272?

just duals like LM1458, JRC2043DD, NJM2043, TL072, LM358, Burr Brown (don't recall the number...the $4.50 one), LM833, JRC4558.  Haven you tried those you mentioned?

No, I haven't tried the circuit. My question arised because the opamps I mentioned are used for direct clipping by several NYC Tech 21 pedals, such as the Sansamp GT-2. In this pedal the TLC2262 makes a sonic improvement in comparison to other opamps like TL072.

[bean]

I've got a stripboard layout of this one going. Hopefully, I will have time to put it together this weekend 

[BoostAddict]

Mine arrives monday!

I'm going to build another one anyways 

[powerplayj]

The reviews on HC sound good, how would you say it is?

What styles does it suit? Metal? Fuzz?

Matt

To me, I would say a Marshall Super Lead meets a JCM/Jubilee.  From the lowest amount of gain you're in Trower territory and at half gain EVH.  Anything beyond that is G'nR and 80's hair metal (Ratt, Dokken, etc) depending upon where you set the tone control.   Probably the most notable thing about it to me is the clarity at higher gain and how well the pedal as a whole sounds with single coils.

[Samy]

Updated files :


Here's the pcb in pdf:
Download CrunchIT.pdf

PCB Wizard 3 file:
Download CrunchIT.pcb
I don't know how the program will behave because the 16mm pot was created by me, if you don't have it in your libraries it's possible that one error might occur.

[Meanderthal]

What's up with that tone control? Am I missing something?

(heh- quoting myself) This was buggin' me... looked familiar, yet I couldn't place it... til I remembered this:

http://hammer.ampage.org/files/SWTC.gif



(the rat tonestack on the right...)

[stm]

According to the schem the tone control is wired RAT style, not SWTC style.  It could be improved to the latter kind.

Also, there seems to be a high end adjusting trimpot in the newer version of the pedal, which I bet it is just a 20k trimpot that replaces resistor R9 (4.7k).

[Samy]

...
Also, there seems to be a high end adjusting trimpot in the newer version of the pedal, which I bet it is just a 20k trimpot that replaces resistor R9 (4.7k).

Can anyone confirm that ? It´s very easy to mod the pcb to use the resistor or the trimmer.

Thanks.

[WGTP]

Looks good.  Thanks.  The op amp layout is similar to the Blues Breaker, but the LED's to ground rather than Diodes in the loop, is more like the Shred Master or other Marshal pedal.  The tone control is like the Rat, except it is 10K rather than 100K.  The last RC network is similar to what I've been using lately on the breadboard and it is really cool for adding bottom end and boody by reducing the High's and upper Mid's.  Should work in lots of similar pedals.  I would guess the output isn't hugh, but for SS amps it usually doesn't matter.  It's in line for the next available breadboard.   Hmmm and there is that extra unused op amp in the YJM308.   

[bean]

I've got a trimmer in place but haven't had a chance to experiment with it. I've completed the stripboard layout for this, as well, if anyone wants it. Too bad I screwed up the sealing on my box...now I have to re-sand and start over 

[WGTP]

If the trimmer doesn't replace the 4.7K resistor, it should.  Very valuable control that would work well on the outside of the box.  You could also do a switch and use .047uf - .1uf caps for a very tunable EQ.