Zendrive 2

[digi2t]

Was an old request I came across in the requests folder. I used the information as per the request post. Breadboarded it, and it works. Actually sounds pretty damn good. Lots of even harmonic mojo happening.

Schematic;



C7 is a crapshoot. Use whatever sounds/works best for you. I used a 150pf. My tube is a JJ ECC803SS, but you can use whatever works best for you.

Layout (not verified);

See below.

[IvIark]

Nice job buddy

[digi2t]

Thanks. Unfortunately, while making up the new board yesterday, I discovered that a cut and jumper were in the wrong spots. Here is the corrected layout (my apologies to anyone that may have already cut a board);



Furthermore, reducing C3 also helps with any possible HF oscillation that may present itself. Even with the decreased C3/increased C5, there's still plenty of top end crunch on this sucker.

I rolled a few different tubes through this the other day. Some new JJ's, some older Tung Sol's, and old Mullard, GE, and RCA's as well. Each gives a slightly different edge to the top end, probably because of differences in the clipping knee. To date, I've only tested this through my little 15watter SS test amp. I'm anxious to see what this will do with a 100 watt OD channel.

Using a a TO-99 can (LM1458) for the op amp. I've used it before in another project, and it sounds as good as it looks.

Going to try and finish boxing this tonight.

[doxasound]

Awesome!

I'm a little bummed that it's just the original Zendrive with a few component changes and the 12AX7 replacing the diodes haha Even the power section is the same :P

But I guess I'm also not surprised either haha Was hoping for some 9v to 185v switch mode going on, so the tube is actually working, but meh...

Still, I'm excited to build this! Thanks for paving the way! *high five*

[Travis]

That’s a silly way to use a tube. I think marketing played a significant role here

[digi2t]

Damn, I missed a jumper. Layout is fixed now. It's verified too. Went with 22n and 220pF. Nice and crunchy.

[Frank_NH]

Nice one Digi2t!  Thanks for both sharing and verifying the layout.  I have a big tube collection and, well, why not try this out?  From old internet reviews of this pedal, it's supposed to sound "smoother" than the original Zendrive.   Looks like a relatively easy build so I may give it go.

[digi2t]

Tried it out this morning with an Egnater Tourmaster. The Tourmaster is running a custom set of preamp tubes from Doug's, aimed towards more headroom over gain. Power section likewise, running a quartet of 7581A's. Cab is a pair of 12" Texas Heats, running at 8 ohms, open back.

The 2 clean channels; Adds a nice crunch, accentuating the top end nicely. Increasing C3 would probably give even more top end, but I think it might make it too harsh. Then again, the breadboard isn't a great place to make final decisions, so socketing, along with C5, will be instrumental in final cap choices. Personally, 22n and 220pF work great for me.

The 2 OD channels; Wow. Gives the preamp tubes a real skelp in the bahooky. Increase gain for sure, but clarity as well, especially where upper frequencies are concerned. All without being obnoxious. The high gain OD channel really rips and screams, in a good way.

I have a regular Zendrive clone as well, and while it's excellent too, this version seems to have a little more... more... je ne sais quoi. Maybe the way the clipping knee is different because of the tube? Maybe the voice and gain stage cap changes? What the hell do I know. I'm old, and half deaf now, so take it for what it's worth. I'm happy. Neighbours... not so much.