BAZZ FUSS w/ Germanium Darlington Pair

[mac]

I breadboarded a Bazz Fuss using the darlington version and a silicon KSP13 darlington.
A 0.1uf at the input, a 1N4148 from base to collector, emiter to gnd, 0.1uf at the output, 100k volume pot, and a pot to set the right bias at the collector. Simple.

Nice sounding circuit. But I could not resist the temptation and replaced the si KSP13 with a couple of 2SA52 PNP Ge Toshiba, T1: hfe=52, leakage=20uA, T2: hfe=75, leakage=30uA. I thought that the second transistor would "amplify" the leakage so I put T1 first. Combined gain was around 3900 and surplisingly the bias point was about 12K. I expected a lower value because of the leakage but it seems that this Toshibas are fine for this project.
To set the bias I lowered the guitar volume and play the A string. Around 12K notes were into focus. Regardless what transistor you use, si or ge, USE A TRIMMER OR POT. With the KSP13 the suggested 10K in the original schematic made it sound like a green ringer or octave up.
The difference between the homemade Ge darlington and the KSP13 was big. And the oscar goes to ... Ge.

Pleased with ... no, wait, very very pleased with the result I went for a higher gain Ge darlington. I used a couple of Toshiba 2SA49,  T1: hfe=135, leakage=47uA, T2: hfe=168, leakage=60uA. In this case gain was 22680 but it seemed that a) the leakage is above the circuit's limit or b) the enormous gain amplified the leakage too much. What I'm saying is that I had to set the bias point near 3K, and since the voltage drop is 8.5V the current is 2.8mA, enough to kill a 9V batt fast.
Anyway I had a fat sounding fuzz with more final gain.

Finally I mixed transistors. A 2SA52 (T1) and a 2N3906, hfe=260. I had best result with the Ge first, and again the bias point was near 3K. And the sound is not far from the all Ge version.
When I have some free time I'll try with a Si  BC559 hfe=430 and some Ge AF106 PNP with hfe around 25 and leakage below 3uA. Maybe a triple Ge darlington? Also I will add a 50K pot at the input as in the Axis Face since the input impedance is low and HB does not sound good, and may help wahs.

I also added a third Ge at the front acting as boost, exactly the first Big Muff stage before Q2. It gaves a nice kick to the final gain and increase the brightness, but the bazz fuss spirit is lost. Anyway it deserves some experimentation.

Conclusion. If you have a very low leakage pair of Ge, say hfe=50-150 and leakage below 30-50uA you can improve your bazz fuss a lot. The only con is that leakage may be a problem.

Hope someone find this usefull.

mac

[Steben]

I breadboarded a Bazz Fuss using the darlington version and a silicon KSP13 darlington.
A 0.1uf at the input, a 1N4148 from base to collector, emiter to gnd, 0.1uf at the output, 100k volume pot, and a pot to set the right bias at the collector. Simple.

Nice sounding circuit. But I could not resist the temptation and replaced the si KSP13 with a couple of 2SA52 PNP Ge Toshiba, T1: hfe=52, leakage=20uA, T2: hfe=75, leakage=30uA. I thought that the second transistor would "amplify" the leakage so I put T1 first. Combined gain was around 3900 and surplisingly the bias point was about 12K. I expected a lower value because of the leakage but it seems that this Toshibas are fine for this project.
To set the bias I lowered the guitar volume and play the A string. Around 12K notes were into focus. Regardless what transistor you use, si or ge, USE A TRIMMER OR POT. With the KSP13 the suggested 10K in the original schematic made it sound like a green ringer or octave up.
The difference between the homemade Ge darlington and the KSP13 was big. And the oscar goes to ... Ge.

Pleased with ... no, wait, very very pleased with the result I went for a higher gain Ge darlington. I used a couple of Toshiba 2SA49,  T1: hfe=135, leakage=47uA, T2: hfe=168, leakage=60uA. In this case gain was 22680 but it seemed that a) the leakage is above the circuit's limit or b) the enormous gain amplified the leakage too much. What I'm saying is that I had to set the bias point near 3K, and since the voltage drop is 8.5V the current is 2.8mA, enough to kill a 9V batt fast.
Anyway I had a fat sounding fuzz with more final gain.

Finally I mixed transistors. A 2SA52 (T1) and a 2N3906, hfe=260. I had best result with the Ge first, and again the bias point was near 3K. And the sound is not far from the all Ge version.
When I have some free time I'll try with a Si  BC559 hfe=430 and some Ge AF106 PNP with hfe around 25 and leakage below 3uA. Maybe a triple Ge darlington? Also I will add a 50K pot at the input as in the Axis Face since the input impedance is low and HB does not sound good, and may help wahs.

I also added a third Ge at the front acting as boost, exactly the first Big Muff stage before Q2. It gaves a nice kick to the final gain and increase the brightness, but the bazz fuss spirit is lost. Anyway it deserves some experimentation.

Conclusion. If you have a very low leakage pair of Ge, say hfe=50-150 and leakage below 30-50uA you can improve your bazz fuss a lot. The only con is that leakage may be a problem.

Hope someone find this usefull.

mac

What do you mean with the darlington version?

[mac]

Steben, there are two version, one that uses a single med to high gain transistor, and another which makes use of a darlington transistor. The darlington can be a 2n3904 and a 2n5088, NPN in this case. See this link:

http://home-wrecker.com/bazz.html

The only difference is that I used different caps and the circuit is PNP positive gnd. I did not try PNP neg gnd.

mac

[mac]

I forgot to mention a little fact... collector voltage varies with temperature... 

mac

[JimRayden]

Love the idea. I'll be breadboarding that and reporting back.

--------
Jimbo

[caress]

i did something similar with a fuzz face recently and found the same - the ge/si hybrid outshines the all ge or all si.  you can get the ge warmth with the si gain without some of the downfalls of either individual transistor type. 
great bredboard report!

[mac]

REMEMBER to use a trimpot and very very low leakage Ge, less than 20 - 30uA or you'll have lots of mA draining your battery soon.
Today I breadboarded NPN version with 2SD352 Matsushita (50, 110uA; 70 150uA). The collector resistor dropped to less about 1K, ad voltage drop was 8.5V. Ic=8.5mA!! But it sounded terrific.

mac

[sfx1999]

How about a clip?

[mac]

Bad rec system, add mp3 conversion...

mac

[Steben]

Bad rec system, add mp3 conversion...

mac

To me MP3 conversion seems unimportant these days, unless you have VERY BAD software.
You could simply connect the signal to the computer and do some software EQ similar to the speaker tone.

[JEPorter]

What value would you guys recommend for the bias pot on the germanium pump version?
Thank you, long time no see,
Jeff

[bushidov]

How about a Sziklai pair? That should defeat the leakage if the NPN in the pair is silicon and it would remove any need of a 1044 style charge pump IC.

For the RB trim, 100K. It will probably settle around 62K, but the 100K should cover that.

[tubegeek]

(Note: 12 year-old thread)

[Ben N]

(Note: 12 year-old thread)

Seems like only yesterday...

[mac]

How about a Sziklai pair?

12 years...

mac

[tubegeek]

12 years...

mac

Nice work on the archiving, to be sure! Did it turn out to be a good idea? Do you remember how it sounded? Do you still have it?

[Ben N]

Nine parts--worth a breadboard, I'd say.

[tubegeek]

Nine parts--worth a breadboard, I'd say.

Not sure if I have both flavors of Ge in the house....

[Ben N]

I meant the Sziklai - 3904 + 3906, easy peasy.

[tubegeek]

I meant the Sziklai - 3904 + 3906, easy peasy.

OH! I thought the latest schem was still Ge...didn't click that those were Si numbers. Right, got it.