Silicon Maestro FZ-1 Slow Attack

[mac]

Today I siliconized a Maestro FZ-1.
I used 2N2369A low hfe transistors, 70-90.
I tweaked the base resistors of Q2,3 to get a wide range of voltages.
A 100k instead of the 470k @ Q2, and I added a 47k from vcc to base, and a 25kB pot from base to gnd @ Q3.
To my surprise when both Q2,3 are near Vcc a nice slow attack effect is obtained.
I quickly replaced the silicons for very low leakage 2N388 germs, but the effect was way more subtle.
It seems it's the higher Vbe of silicons that *interacts better* with the 22u caps... 

Paula was passing by and recorded with my cell phone while I was playing some stuff from Oldfield, Yes and Rush... my apologies to them :-)

Booster to Breadboard to Boss DD3 to clean Epi Valve Jr 8" speaker.

mac

[ljudsystem]

That sounds really cool. I've been breadboarding this fuzz and I got the swell effect to but not this consistent. Gonna have to try with silicon transistors.

Do you have a a schematic?

[BluffChill]

I did this one by mistake by putting the transistors in the wrong way round  cool sound.

[Mark Hammer]

That sounds really nice.

[ljudsystem]

On the low notes it makes a pretty convincing cello sound.

It would be cool to be able to control the amount off attack with a pot or a switch.

[mac]

It would be cool to be able to control the amount off attack with a pot or a switch.

It's what I did.
The standard "attack" pot controls Q2 collector voltage. I set Q2C very close to Vcc.
Q3 needs a resistor to feed the base, so I added a 47k from Vcc to base, and instead of the fixed 10k from base to gnd I used a pot to control Q3 collector.
Both collectors are up.

Let's say I have two "attack" pots. With the second pot one can dial "satisfaction" tones easily.

The booster runs at 9v and it's needed to have a decent amount of signal to ignite Q2,3. The 22u's do the rest.

mac

[mac]

I simplified things a bit.
Instead of using a Maestro FZ-1 and a booster, I tweaked a TB MKI which is very similar but at 9v.

I replaced the input buffer with a BMP first stage, 100n input cap, and 100kA level pot to 22u before Q2.
22u between Q2 and Q3. 3n3 and 50kA at the output, like the FZ-1.

Very similar response.

I'm thinking of adding another variable stage.

mac

[mac]

Schematic



mac

[ljudsystem]

I forgot the fuzz pot is called "attack" on the Fz-1. Guess it would be pretty confusing having two "attack" pots...

Thanks for the schematic. I'm gonna order some 2n2369As and try this one out.

[mac]

I'm gonna order some 2n2369As and try this one out.

Any Si in the range 70-90.
MPSA42, some BD139 or BD237, TIPxx, 2N2218.

Biasing is *tricky*.
Adjust R8 and R10 to get a useful voltage range with the attack pots. These could be even 10kB with a minimum fixed resistor in series to have less sensitivity.

mac

[Gus]

Sounds good.

Have you tried selecting a fixed value for the base to ground resistors and adjust the base to VCC resistors value?
This should keep the input resistance of the two stages above a minimum value.

[mac]

Sounds good.

Have you tried selecting a fixed value for the base to ground resistors and adjust the base to VCC resistors value?
This should keep the input resistance of the two stages above a minimum value.

Thanks Gus,

I tried this in the last stage, but went Q2 way.
It sounds the same as long as the // base resistance is similar.

You can use 50kB pots at the bases, pin1 to Vcc, pin2 to base, pin3 to gnd.
You'll have higher sensitivity when adjusting the base voltage.

mac

[moterrac]

Really interested in this, been experimenting with siliconizing a MKI with mixed results, going to stick the FZ-1 on the breadboard and see how it goes!

[moterrac]

Been playing with this on a breadboard today, can get the effect working but sadly no swell effect on the note attack. I haven't changed the 47k resistors to base on q1/2 yet so I will try that and report back. Using 2n2369as for this.

[pacealot]

Apologies for another necro-bump, but I wanted to report that I have had very good results with Mac's schematic above (in reply #7) using BD237s rather than 2N2369As for the three FZ-1 trannies. The swell effect is touchy, yes, and challenging to control with one's picking at times, but it is definitely there, and it's no harder to work with than, say, the Anthony Leo "swell" section of the Experience pedal.

I've found that setting the 25K pot at the base of Q3 to around 2K-ish and adjusting the Q2B 25K to taste around the middle of its throw gets me in the swell/slow attack ballpark consistently, provided that the boost at the front of the circuit is all the way up. I put a 1.8K minimum resistor on that Q3B pot just to make it a little easier to dial it in. When it's all set up just right, it works well enough that I've temporarily set aside the Morley Sync Attack circuit that I'd been playing with previously to try to achieve a similar effect...

[mac]

using BD237s rather than 2N2369As

C4 & C6 could be omitted because those BD237s have high internal capacitance.

When it's all set up just right, it works well enough that I've temporarily set aside the Morley Sync Attack

mac

[pacealot]

C4 & C6 could be omitted because those BD237s have high internal capacitance.

Thanks for the tip, Mac — I've played around with the values of those a little bit, and I might consider keeping one on Q3 purely for tone-shaping, but I will also try omitting them to see how it sounds...