Tanabe.tv - Zenkudo

rousejeremy · Post by **rousejeremy** » 12 Sep 2009, 00:01

The Abalone on top could be Abalam, like this.
http://www.lmii.com/CartTwo/thirdproduc ... lam+Sheets

aflynt · Post by **aflynt** » 14 Feb 2011, 17:23

Sorry to dredge this up, but I'm just trying to understand what effect the changes to the original Zendrive circuit have. The selectable clipping diode changes aside, am I right in assuming that these are the only other effective changes to the circuit?

- The 1k resistor in series with the Drive pot has been increased to 10k effectively raising the amount of gain at it's minimum setting.
- A 10nf capacitor has been placed in series with the circuit input. This one I'm a bit confused about. Wouldn't that effectively just be series capacitance with the existing 470nf, thereby lowering the value to about 9.8nf? Why wouldn't he just use a 10nf instead of the 470nf in this case? Or does the 2.2Meg resistor somehow react with it?

The schematics for reference:

Zenkudo
members/soulsonic/schematic/Zenkudo.GIF

Zendrive
download/file.php?id=173&mode=view

-Aaron

Greg · Post by **Greg** » 15 Feb 2011, 02:11

Yes. the 10nf forms a filter due to being placed before R1.. although it's set well below any fundamental tones from a guitar.

Remember, there's always a good chance with a circuit like this that the "designer" has little technical knowledge, and is just trying things and convincing himself it sounds better.
Don't think that because it's commercial it's well designed.

aflynt · Post by **aflynt** » 15 Feb 2011, 02:45

Thanks. I'm pretty unknowledgeable myself, but I'm trying to learn. So this would be a high pass RC filter with a corner frequency of 7.2hz (assuming a low input impedance)? Could some high impedance input signals actually push the corner frequency up somewhere audible?

-Aaron

sjturbo · Post by **sjturbo** » 16 Feb 2011, 04:48

Any pcb or vero layout yet? I like the ytube clips I hear of the original. I think it will be a welcome addition to the ZDrive.

paulc · Post by **paulc** » 16 Feb 2011, 05:44

Greg_G wrote:Yes. the 10nf forms a filter due to being placed before R1.. although it's set well below any fundamental tones from a guitar.

Remember, there's always a good chance with a circuit like this that the "designer" has little technical knowledge, and is just trying things and convincing himself it sounds better.
Don't think that because it's commercial it's well designed.

You're forgetting the 470nf/470k 2nd pole. The 10nf is not isolated from these. Added up this would give you -3dB @ 41hz with the signal being down about -1dB @ 80hz. A small roll-off within the guitar range to tighten the bottom up a little. There's other ways of doing it (make the 470nf smaller for the roll-off while keeping the bleeder effect of the 2M2 resistor), but this is something you could hear.

Greg · Post by **Greg** » 16 Feb 2011, 08:01

paulc wrote:
Greg_G wrote:Yes. the 10nf forms a filter due to being placed before R1.. although it's set well below any fundamental tones from a guitar.

Remember, there's always a good chance with a circuit like this that the "designer" has little technical knowledge, and is just trying things and convincing himself it sounds better.
Don't think that because it's commercial it's well designed.

You're forgetting the 470nf/470k 2nd pole. The 10nf is not isolated from these. Added up this would give you -3dB @ 41hz with the signal being down about -1dB @ 80hz. A small roll-off within the guitar range to tighten the bottom up a little. There's other ways of doing it (make the 470nf smaller for the roll-off while keeping the bleeder effect of the 2M2 resistor), but this is something you could hear.

Thanks Paul.
I can see there's a 2nd filter there, but calculating the final result is beyond my abilities.