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Vintage threads from the first ten years

Re: FZ-1S Schematic

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12/9/1999 2:22 PM
R.G.	Re: FZ-1S Schematic There's yet another version I traced that is a four transistor version, kind of mid way between the earlier germanium three transistor versions with AA batteries and the later FZ-1S. I don't care for the distortion of any of them, but that's only my ears.

12/9/1999 2:27 PM

Do Q5 and Q6 need to be matched in some manner?

The title says it all. I, too, don't really understand how the section around Q5/Q6 works. Are they being used as diodes? What does make sense is the mid-cut section after Q5/Q6 (switchable by S2). In some respects, the overall design is not unlike the Roland Bee-Baa, in terms of having a booster+overdrive in one pedal (I'm assuming that each half of R1 is wired opposite - which makes it linear - and when the balance is all the way to one side, Q2 forms a straightforward booster/buffer section).

12/9/1999 5:16 PM
JD Sleep	Mark, I don't understand the transistors either. They are 2N5133 transistors, the data sheet inside the box calls for 8393 transistors. All other transistors are 2N5088s. You're right about the balance control on both counts, they are wired opposite and with the balance on zero, it is a clean buffer/booster (not much of a boost), on 10 it is pure fuzz.

12/9/1999 6:03 PM
GFR	Mark a transistor has two PN juctions so it's like this: C---\|<----B----->\|-----E Then what you have is on this schematic is a diode clipper. Q5 gives you two diodes in parallel with both anodes to ground, Q6 gives you two diodes in parallel with both cathodes to ground. You only need matching if you want perfectly symmetric clipping.

12/9/1999 9:20 PM
Mark Hammer	AHA!! So my hunch was right. They ARE being used as diodes. In which case, do you think the schematic "makes sense"? If it does, can you think of any reason why the transistors would HAVE to be the ones listed? Could one even just swap the transistors for appropriately chosen diodes?

12/9/1999 11:57 PM

I understand that the clipping properties of the transistors in that circuit are dependent upon the proper aging of the transistors. What they did was to take the unselected "raw" transistors and clean them up, then give them an initial annealing bake at 170F for two hours, air-cool to room temperature, then allow residual stresses to dissipate by leaving them to "rest" in a dark environment for two weeks.

After this preconditioning, the devices are sorted by gain and case coloration (as the bake slightly oxidizes the exterior) into batches, and then go into the primary aging pit. The transistors are hand-laid in layers between layers of banana peels up to eight deep and then buried for two months at a depth of two feet. This allows the primary oil in the banana peels to diffuse into the pins and cases, so you can get that smooth, slippery feel to lead passages.

After aging, the devices are again tested for fallouts and batched by slipperiness. The best grades are vapor degreased and placed in a vacuum chamber to allow all the volatiles to evaporate, then inserted into the PCB's. Only indium-based solders are used as they have a much lower melting point. The high temperatures involved in normal soldering can adversely affect the sinuous quality of the sound that the aging process gives the devices.

12/10/1999 8:46 AM
Aron	I'm pretty sure they salt the banana peels before they use them. If have heard of some companies re-using the throw-aways by using of all things, olive oil, to add more slipperiness. Pretty weird, I tell you. Aron

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