Build Report: Burning Crunch (improved Krank D M)

[raulgrell]

Try a blackfire input stage... sounds rabid

May I also suggest a bit of a treble or high mid boost at this stage...

[dschwartz]

yes, i tried it boosted with a microamp, and sound incredible, very much like paul gilbert, extremely sensitive and clear...

[mensur]

Can somebody explain which are electrolytic capacitors(maybe this:220uF,1uF,10uF,47uF)?
This pedal is great,great sound, BRAVO DSM!!!

Thanks.

[tcio]

I got a little confused on that myself but I kind of used the original circuit to guide me. If you look at the PCB layout you'll notce the blue round caps. Those are electrolytic. I don't have or did I see a 220uF in the burning crunch schematics so I am still a little dumbfounded on that BUT.......

I just slapped this thing together on a bread board according to the schematics and Man-O-Man! IMO, other than the ones I custom built totally around all of my personal gear and amplification, this is the best heavy sounding circuit/concoction I have heard yet for a single standalone circuit (not one pedal driving another).

I am absolutely impressed. Other than changing the tone stack to my personal preferences, I doubt that I will alter anything else. Great work dschwartz!

[JeawJaw]

To dschwartz

How to scale down?

What is scaled down by factor 15?

You can show to calculate ?

Tutorial Please..

[fixr1984]

When you say "scaled down" do you mean that you just divide all the values by 15?  I read in an earlier post that there were some issues with the tonestack.  Does this cure the problem?

scaled down means lowering the resistance by a factor of 15 and increasing the caps by the same factor, such of the RC remains constant..

specifically, my tonestack has this parts:
- Slope resistor: 2.2K
- Treble cap: 4.7n
- mid cap: 330n
- low cap: 330n
- treble pot: 25k B (not exacly scaled by 15, but looks good on the tonestack calc)
- Bass pot: 250K A
- Mid pot: 2.2K B

This was posted earlier in the thread, dont know if it will help.

[dschwartz]

hi all..
i´m back now.. so..
let´s see..
first of all, please dpn´t think i´m the creator of the circuit..it still is a krank, i just made some mods and a pcb...
..
a scaled down thingy:
a frequency filter is defined by the multiplication of capacitance and resistance..that´s an RC filter..so, when you have X resistance and Y capacitance, the frequency corner is f= 1/2*PI*X*Y..

to scale down is to divide the resistance for a factor and multiply the capacitance for the same factor so the product of X*Y remains the same..BUT since there is less resistance, there is less impedance..

for example, i want to scale down to a factor of 10 a filter made of a 100K resistance and 10nF capacitance..
scaled down, the R is 10K and the capacitance is 100nF...the product of res and cap is the same...

[tcio]

please dpn´t think i´m the creator of the circuit..it still is a krank, i just made some mods and a pcb...

I knew that (he he) ....... BUT.......Although I found the original circuit to be one of the best sounding I have built (still somewhat of a beginner here), when I modded the Krank to your specs and played through it, I ended up playing for hours. I then brought the R6 47K down to 33K for more gain and played around with the tone stack a little. Ended up playing for about 4 hours straight and couldn't put the thing down until my fingers hurt so bad I had to LOL!

Yes, if you do the math I basically spent the whole day playing other than stuffing some food down here and there. Had a lot more noise due to the gain so I had to place a cap on the input to ground. Still learning this tone stack stuff so I have a little more reading and tweaking to do.

[dschwartz]

wow! that´s nice!!...

look at this video...http://es.youtube.com/watch?v=CO5aQuSdqZA

[tcio]

Alright!!!!! That is too cool!!!!!!!!! The "Burning Crunch" on You Tube! Good show. I haven't cased mine up yet but I know I am going to have to use a bigger enclosure to get the knobs further away from the stomp switch with my size 12-13 shoes LOL!

[snyder80]

Hi DSchwartz!

Your mods make this a very nice sounding pedal !
Before i mod my diy kdm to your specs i wonder if an "A" poti is NOT a log but a Liner pot in Chile as in the EU where i am from, otherwise a Reverse Linear pot doesent make any sense to me. The second question i have in mind is, about your asmples and the setting for recording. Was drive about 12 o clock till 14 o clock or was it already dimed to 16.30??

After all thx for sharing your mods and the schematic,

Greetings,
Snyder80

[dschwartz]

the heavy one is with gain at full..the bluesy ones with the gain at 12 or 13 o'clock, and using the guitar volume as a gain control (i tend to do that a lot)

[gigimarga]

i just builded one and no sound!!!
i test it after the 2n5088 and sounds ok 
on the pins of LM386 almost all tensions are 7.5-9V...isn't ok?
can anyone post some voltages here?
i used LM386N-1...i didn't found another type...this could be a problem?

[dschwartz]

did u use my layout?
maybe you missed one of the wire jumpers...

[gigimarga]

no...i didn't use your layout...i made myself one very tight:



my voltages, using a 9.30V fresh battery, are:

Q (BC549C instead of 2N5088):
   C=3.50V 
   B=0.70V 
   E=0.13V

IC (LM386N-1):
   Pin 1 = 8.25V
   Pin 2 = 7.53V
   Pin 3 = 7.60V
   Pin 4 = 7.53V
   Pin 5 = 8.50V
   Pin 6 = 9.30V
   Pin 7 = 8.20V
   Pin 8 = 8.25V

i think that i have big problems......thx a lot anyway!

[dschwartz]

did you use my schematic? remember that there´s a missing trace going to ground from the opamp..

those 7 volts on the IC looks wierd, 386 opamps have an internal voltage divider that bias the ic to 1/2 the Vcc..maybe youre shorting some Vcc to the IC through a resistor..

[gigimarga]

i used your schematic...it's good or something is missing in it?
i hope i can post my layout now:

[gigimarga]

i saw right now, on another site, that pins 2+4 must to go to the ground

[dschwartz]

and it worked?

[gigimarga]

yes...it's working now...and sounds very good...but i think i must change the tonestack a little...i like more a scooped sound!!!