jt wrote:Goop_buster look a little closer to the uper left corner of that pcb layout.
There are two diodes in series standing each on one of their feet.
Oh bummer. I see it now. Thanks for the correction jt .
Btw Attention TMZ! I do not know if it was I that misslead you or if you just did the same misstake. D2 should be two diodes in series in your layout also
JHS wrote:The Mosferatu is a AMZ SoS-clone with a few altered values and MOSFETS instead of the diodes. The PCB for the Mosfertau and the part layout is the same on the ZD.
I think the only difference between those two is the clipping section and myabe a few part values.
JHS
i found this, search didnt bring it up so i'm posting it.
this is NOT the original Mosferatu! the original one is very similary to the ZD, the most difference is the Tone-stack (ts-like(220E +270n) with LP (1k/270nF) in front of it) symmetrical clipping in FB-loop (2n7000 + 1n34)
thats it...
that's just an old schem that Alf posted on aron's forum several years ago. IIRC, it was just a circuit he was experimenting with before the final mosferatu circuit.
bw
Sorry to beat a dead horse, what will be the number for D1 and D3, blue small glass diodes?
I have no experience with schottky diodes yet and couldn't find any useful information on the web.
Jun
Looking at the layout posted on page 2, is the gain pot wired correctly? It appears that D3 is in series with the pot. Is this correct? Normally, D3 would be in series with one of the diode/transistor pairs and the pot would be paralleled with the diodes across pins 1 and 2 of the IC.
Well, after following the discussion here and reading about the importance of the proper mosfets, I breadboarded it again using 2N7000's, 1N4454 diodes, a silver mica bypass cap (C4), and a TL082 op amp. WOW; I must have had something wired wrong before or maybe the mosfets make a huge difference. It sounds pretty darn good now, good enough to put on a perfboard. And this isn't even using a LF353 or RC4558. This circuit especially likes Strats, but does fine with humbuckers.
BTW I used the 1N4454's as Mouser had them listed as a sub for a 1N34A, but they seem far from that; 0.7V drop and looks like a 1N4148. But they sound good in this circuit so I'm gonna use 'em.
My first layout had one of the pots wired backwards - I think I changed it but not sure. Everything else IS verified. Next to a real Z Drive, it appears the Volume pot should be linear. Opamp choice does make a pretty noticable difference in this circuit. So far, I like a TL082 the best. I haven't tried different diodes. I did try reversing them per a previous suggestion in this thread with TERRIBLE results. Enjoy....
Do tube screamers have that 'congested' sound because they take so much highs and mids away before it hits the tone control and then try to add it back with the active tone control?
Ed G. wrote:Do tube screamers have that 'congested' sound because they take so much highs and mids away before it hits the tone control and then try to add it back with the active tone control?
Im not sure but congested is the only way I can describe it. I thought tube screamers had passive tone controls and the Bad Monkey was so popular because the tone controls were active.
hi there!
I tested yesterday a zendrive platform with different opamps. contrary to the belief that those hi-fi new ones are not for pedals, my favourite by far is the Burr-Brown OPA 2604 (I actually use it in buffers also and in my modded marshall JMP1 preamp). it has a very "guitaristic" quality in it and sounds and behaves very tube-like.
about the diodes, I tested some old germaniums and small zenners (tomorrow I will get some of those small blue metal bar shotkys and will report the results). the fact is that on this platform (with the mosfets already there) there are many combinations of diodes that all sound good, but different. but the point here is to make it sound as dumble-like as possible...
tryied today some ITT 600 small blue diodes and the result is very good! also tryied lots of zenners and germaniums but the combination of those small blue ones and one germanium works the best.
also tested again some IC's including 4558 and some old TL's. by far the best results I got with the OPA2604! the sound is very organic, has all the frequency spectrum and is very pick sensitive in a nice way. compared to it, the others sound like shit - always lacking something...
the picking response is tight, like the dumbles (solid state rectification), contrary to the one my BB Preamp has, which is a nice thing. the pedal is singing without having too much compression or distorsion.
I finished a perfboard version today, using 2N7000 mosfets and MBR040 schottkys. After playing with a bunch of op amps, the winner was an AD712; it had lots of life and character, the lows weren't muddy at all and the sound was very smooth even though it had lots of highs. It made a Strat sound more like a Strat if that makes any sense. The second place finisher was a TL082. This circuit seems to like fet input op amps. The RC4558 was too thick and dead sounding, while the fet input op amps had more life in the high end. Another interesting thing about the circuit is that with the gain all the way down and the output all the way up, after tweaking the tone and voice knobs, the bypassed and effect tone are almost indistinguishable. I plan to try a OPA2604 when I can get my hands on one. This one is definately going on the pedalboard.
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