Burnski Buzzaroundski

[digi2t]

OK, I've been hunkered down with twin biggies of late, Tau Pipe Phaser, and the Ludwig clone, but due to having to wait for parts, I've come up for air. To kill time, I'm back on the Buzzaround circuit, which has been on standby, on the breadboard.

I've recently brought in some more Russian trannies, to keep my MP20B's company.



From left to right, 1T308B, GT402B, GT309E, MP16B, and some NPN GT311B's. I also have some NPN GT404G's on their way, The NPN's are for future consideration. As for the PNP's, I've found that a 150pF cap between B and C of Q1 is de rigeur to tame the high end fizziness that these trannies bring to the party. With that said, all performed well, with obvious differences between them. Some brighter, some darker, some woolier, some buzzier, and so on. Nothing bad, but for the reasonable prices that these transistor can be had for, you're sure to find a nice set for your ears, without having to remorgage your home.

Gain wise, I found that how you set the spread between the stages, can really affect how the circuit will behave. Even jumps between transistors, tends to yeild a, "managable", all purpose fuzz, for lack of better terms. But, if you stick a big jump between Q2 and Q3 (double, or more), you'll end up with a second order harmonics monster. Everything on you guitar that can, will vibrate, right down to the sub-atomic level. Even at very reasonable amp levels, stand in the right place, and whammy springs, un-potted pup wire, and even stray maple grain, will sing you a song. If you've never experienced the Leslie West "the guitar always feels like it's gonna just jump outta my hands" feeling, then this should get you there.

The ones that really stand out for me are the GT402B's though. With the circuit wide open, they seem to clean up best when you roll down the guitar volume. Now, by "clean up", I don't mean Fuzz Face super clean, I'm talking about a nice, mellow, edge of break up overdrive. Super sweet with the neck pup. The clip below demo's the 402's, with my multi meter giving me Q1=98, Q2=129, and Q3=223. Big jump to Q3, I know, but gives me a great roar, without losing control. Cheap Strat copy, breadboard, Ampeg G-212 with a touch of reverb. My apologies to Pete for messing up his song  ;

You can really hear the neck pup come in between 0:20, and 0:44. What do ya think boyz?

[pinkjimiphoton]

i'll take a half a dozen for the hotel room, please!!

THAT's what a fuzz should sound like...well done bro!!

[LucifersTrip]

I've found that a 150pF cap between B and C of Q1 is de rigeur to tame the high end fizziness that these trannies bring to the party. With that said, all performed well, with obvious differences between them. Some brighter, some darker, some woolier, some buzzier, and so on.
The clip below demo's the 402's, with my multi meter giving me Q1=98, Q2=129, and Q3=223.

sounds cool...

the biggest difference in tones you're getting is most likely just from your choice of Q3. As I noted earlier, Q3 is the big deal on this one and it's leakage that is a major factor. Most or all of the Russians have pretty damn low leakage.

remember, with a Darlington pair the leakage of the 1st is multiplied by the gain of the 2nd. Therefore, it's a great idea to just pick two medium to low gainers with the lowest possible leakage. The fact that you've chosen Q2 >100 is probably one of the reasons you need the BC resistor. For that Darlington pair, a super low leak 60/60 pair would suffice...and try different leakages of Q3 to see where it sets the collector voltage.

from past reports, measured gains I've seen from the original transistors are usually all < 100

edit:
http://transistor-spravochnik.ru/description/nkt213/48931

[digi2t]

i'll take a half a dozen for the hotel room, please!!

THAT's what a fuzz should sound like...well done bro!!

LOL... Yeah, I'm really taking a liking to these Russian trannies. The rejection rate has been real low so far (1 in 20, maybe 25?), and mixing and matching them turns into a buffet of tone. I could sit there all freekin' day and just plug in different trannies. Unless you're a real tone snob, sky's the limit with these.

BTW, Gemini III Dual fuzz generator is coming my way, so ya know what THAT means...

@ Luci; You're absolutely right on all counts. It's just that I find that when I use two same trannies in the Q1/Q2 slots, it just doesn't punch as much. I mean, I don't get that BARK when I really hit them hard. If I use a Q2 with about 20 - 25 more gain than Q1, I'm happier. That's why I prefer to cheat, and use the 150pF cap on Q1 B/C. If I really want to "Muff" it a tiny bit more, then I'll use a 220pf. It sounds great as well, although a tiny bit less bite on the top end.

Endless hours of fun!!

[digi2t]

Alrighty then... I decided to stick a fork in this sucker... FINALLY!!! I've had the bag of parts sitting around for long enough me thinks.

I decided to stay true to the Russian angle, finally settling upon two MP16B's for Q1 and Q2, with a nice phat GT402B in the Q3 slot. As an added bonus, I did a bit of free-cycling, using the majority of the components (including the shielded wire) from a Farfisa organ that I gutted last year. I could have used the 1N695 diode that was in the organ too, but I elected to run with a 1N450 Sylvania instead. Doesn't make any diff audio-wise, but it does look like it can out of some 1960's nuclear power plant. Naturally, I had to redo the vero, since these parts were not exactly, ahem... small. Also, since I was removing them from another board, the lead length was very limited, so I had to work around that as well. In the end, it wasn't anything that couldn't be handled with a digital vernier, and everything fit nicely into the BB enclosure.

Tone section resistor is 39K. Couldn't find a 43K on the Farfisa boards, and I was adamant to use what was in there.

Measured with a Peak DCA55 meter, room temperature (20 deg. C) the transistor gains/leakage re as follows;
Q1 - 61 / 0.04mA
Q2 - 64 / 0.06mA
Q3 - 112 / 0.12mA

My final voltages are as follows. Guitar plugged in, with guitars volume at zero, pedal plugged into the amp, all pedal controls at maximum;

Supply voltage = 9.08v

Q1
E - 1.472v
B - 1.535v
C - 4.90v

Q2
E - 1.366v
B - 1.472v
C - 4.90v

Q3
E - 0.0mV
B - 26.3mV
C - 2.265v

Here's the bigger vero;



Pics of the guts;











External. Not crazy about the knobs, but I'll find something funky later;



And of course, the customary Hen's Tooth Café video. Complete with halo backlight 

[garcho]

"My apologies to any Polish people out there..."

Ha!

[Foxbat]

What are the actual Leak values on those transistors?

OK, I've been hunkered down with twin biggies of late, Tau Pipe Phaser, and the Ludwig clone, but due to having to wait for parts, I've come up for air. To kill time, I'm back on the Buzzaround circuit, which has been on standby, on the breadboard.

I've recently brought in some more Russian trannies, to keep my MP20B's company.



From left to right, 1T308B, GT402B, GT309E, MP16B, and some NPN GT311B's. I also have some NPN GT404G's on their way, The NPN's are for future consideration. As for the PNP's, I've found that a 150pF cap between B and C of Q1 is de rigeur to tame the high end fizziness that these trannies bring to the party. With that said, all performed well, with obvious differences between them. Some brighter, some darker, some woolier, some buzzier, and so on. Nothing bad, but for the reasonable prices that these transistor can be had for, you're sure to find a nice set for your ears, without having to remorgage your home.

Gain wise, I found that how you set the spread between the stages, can really affect how the circuit will behave. Even jumps between transistors, tends to yeild a, "managable", all purpose fuzz, for lack of better terms. But, if you stick a big jump between Q2 and Q3 (double, or more), you'll end up with a second order harmonics monster. Everything on you guitar that can, will vibrate, right down to the sub-atomic level. Even at very reasonable amp levels, stand in the right place, and whammy springs, un-potted pup wire, and even stray maple grain, will sing you a song. If you've never experienced the Leslie West "the guitar always feels like it's gonna just jump outta my hands" feeling, then this should get you there.

The ones that really stand out for me are the GT402B's though. With the circuit wide open, they seem to clean up best when you roll down the guitar volume. Now, by "clean up", I don't mean Fuzz Face super clean, I'm talking about a nice, mellow, edge of break up overdrive. Super sweet with the neck pup. The clip below demo's the 402's, with my multi meter giving me Q1=98, Q2=129, and Q3=223. Big jump to Q3, I know, but gives me a great roar, without losing control. Cheap Strat copy, breadboard, Ampeg G-212 with a touch of reverb. My apologies to Pete for messing up his song  ;

You can really hear the neck pup come in between 0:20, and 0:44. What do ya think boyz?

[ElectricDruid]

What are the actual Leak values on those transistors?

We'll see if anyone turns up with an answer, but it's a decade-old thread...

[antonis]

After 11 years of leakage, no current left availiable..

[Rob Strand]

Posts #22 and #24 have some leakage info.