As promised yesterday, here is the bass version of the overdrive pedal I posted yesterday. http://www.ssguitar.com/index.php?topic=2679.0

A few notes on the differences between these pedals. The bass version uses green 3mm led's instead of the reds I used in the guitar version, just for the slightly higher forward voltage of the greens. With the higher output from bass pups, I just figured it would keep things from being too harshly clipped. I also went to the 4558 op-amp instead of the LM1458 I used in the guitar version because while the 1458 produced the smooth grind I was looking for in my guitars, the 4558 has a bit more harshness on the guitar, but adds that nice bit of grit to the bass.

When I was first asked to do a bass version of the pedal, I took the easy way and just recalced the filters to drop them an octave. This, while somewhat pleasing, had the same problem as most bass OD pedals on the market, as you drop down the neck, the grind disappears on the lower register. So I went back and re- did things to drop two octaves, and when I saw on the scope that clipping started at 17 hz, I plugged in the Squire P-bass and liked what I heard. Boxed it up, demoed it and had to build 10 more. :cheesy: One of my bass friends described it (Aguilar SS bass head) as giving him back the sound of an Ampeg SVT that is severely ticked off. Both it and the guitar version are in a pair of local recording studios, so I think the sound came out ok.

The PNP is the same for both versions, I've never made a layout sheet for the bass version, just scribbled the values next to the guitar layout. I've never made an off board wiring guide for either, after making close to 30 OD's of these the wiring becomes automatic, so I need to take the time to throw one together. Promises, promises. Enjoy...

Bob

For those of you who are also putting together some old germ based effects, this simple device helps in determining leakage and hfe for germanium trannies. I built it one day when I was involved in testing and sorting a batch of a couple of hundred PNP and NPN germaniums I had acquired, and got to thinking about what I was doing, i.e. plug the transistor into the breadboard, power up, let it stabilize, take reading, hook the 2.2M resistor, take another reading, rinse and repeat etc. etc.

For the circuit I refer you to R.G.'s article on Geoefx about the tech of the Fuzz Face, his explanation is a lot more clear than I could manage in the space here. I had all the parts but the connectors in the parts stash, those came from Radio Shack.

For a quick explanation, the trim pot is a 5k set for 2.47k measured with my Fluke 8060a. Plug in the trannie, turn on the switch and let stabilize. The short leads plug into the meter. Labeling on the trace side shows orientation. Record the reading. The push button adds the 2.2M resistor into the circuit as per R.G.'s explanation. Take second reading, subtract the first and multiply by 100 for hfe. The circuit is normally set for PNP, for NPN reverse the battery and meter connections. It took me less than an hour to draw the traces with a sharpie, etch and then build the thing. I use a battery that is slightly used and measures 9.01 vdc, as R.G. says, close enough for our purposes. For purposes of illustration I have the battery in the PNP orientation and the meter leads in the NPN. It works like a charm and has been a time saver.

I guess I'm being a typical newbie with my first post asking for help/info...

For a little background, I have been playing / working on my (and others) gear for going on 5 decades now, I first got into electronics so I would not have to pay someone else to repair my amps. Spent better than 4 decades working for phone company and a major US railroad as an electronics tech, retiring three years ago. Got into pedal building a couple years back and do them from the ground up, etch my own boards, populate and troubleshoot them until working. Have and use a variety of test equipment including DVM, o-scope, sig generator and a Tracker 2000 for in circuit testing. Have a pretty good idea which end is the hot end on my soldering stations. :cheesy: I have no problem reading schemes and tracing signal through just about any kind of gear. Lately I've been reading through Teemu's excellent book, and enjoying the read, if that tells you what kind of geek I might be. Thanks Teemu.

I have a few amps in the collection currently, including a pair of old Fender BF Bandmasters that I've rebuilt, but also have and enjoy three Fender SS amps, a pair of Champion 30's and a Deluxe 90. How come Fender puts B taper pots on their volume controls in the SS amps? Doesn't really matter, log taper pots are going in the 90 (just picked it up a week ago) and are already in the Champs. I changed the caps in the tone stack of the Champs to reduce their icepick tendencies.

But to get back to the subject of this post, I am helping a local shop repair an old 60's vintage SS Toby GTR amp. Everything in it works except the tremolo. From what little I've been able to find about these, they were made in Ft Worth TX in the mid 60's to early 70's by a jazz bass player who now has a speaker company that makes high end speaker setups. (tobyspeaker.com) Gabor Szabo played through one of the guitar amps  for the last decade of his career back in the day. There were less than 100 made total, so info is a bit scarce, and most of what little I've found is on the bass amps. From contact with the company, the electronics were made by Ramco, and the enclosures and speakers by Toby. There are no schemes that I have been able to locate through google,  I am just starting to trace the board, I figure that will keep me busy for the next day or three, but I just thought I'd check here to see if anyone had heard of these or had any info they could pass on. Most of the trannies on the board appear to be obsolete germanium, of course, but I do have a smallish stash of germs I can probably match as far as Hfe etc. to substitute if needed. I've got a pretty good stash of passives from all the pedal building (40+ pedals so far) I just need to make or get a decent schematic and I think I can bring this beauty back to life. Have not done any board pics yet, but if anyone wants I can get some camera shots done.

Thanks, and howdy y'all.
Bob