Univox superfuzz: Getting Similar voltages

[traktop]

I want to build an univox superfuzz with 2sc828s, (built a good one with averages, this is just a mojo build for a friend...), and want to get the voltages posted by fu-manchu bassist on this thread:
http://www.diystompboxes.com/smfforum/index.php?topic=64068.0
C B E
Q1 6.01 .66 .117
Q2 8.88 6.01 5.41
Q3 6.23 3.27 2.72
Q4 3.1 1.7 1.11
Q5 3.1 1.67 1.11
Q6 5.75 .98 .361

He stated: "I usually check the voltages and twiddle resistors around certain transistors to get it operating more like this one and it always helps.

I was wondering if I should shocket all resistors around trannies or maybe just collector ones...
I know this is a breadboard job, but still don´t have one, (it´s on the way), and need it for the next week.
Cheers, Gilberto.

[Frank_NH]

Perhaps the only way to get these voltages without using a breadboard is to use a simulation code like LTspice.  I may try making a model for the Superfuzz as it's my favorite fuzz and it's always interesting to see how these effects work, and if there are some cool mods that can be done.

[traktop]

I will take a look, thanks.
Is it hard to use?

[PMowdes]

Frank_NH wrote

Perhaps the only way to get these voltages without using a breadboard is to use a simulation code like LTspice.  I may try making a model for the Superfuzz as it's my favorite fuzz and it's always interesting to see how these effects work, and if there are some cool mods that can be done.

I've installed LTC spice but I cant seem to get it working (I haven't tried very hard to be honest).

Any tips??

[Frank_NH]

Hmmm.  Works fine for me.  I can run it on Windows 7 and 10 with no issues.  Note that the executable is scad3.exe.  Just double-click on that and away you go.

[PMowdes]

:)  What I should have said was the program works fine but I have no idea how to use it 

I've managed to figure out Eagle, I'm sure with a bit of time and a lot of Google I can figure this out.

[Frank_NH]

There are some YouTube videos you can watch, but the best approach (for me) is to start with a simple circuit and play around with the interface.  There is a learning curve, but once you get past that it's pretty easy to use.

 

[traktop]

Finally just changed some collector resistors. That did the trick.
Cheers, Gilberto.

[BassVD]

I assume you used the Univox Superfuzz layout from the site? Which resistors did you change (could you show it on the layout)?
I'm planning to build this as well :)

[PMowdes]

To continue on with this I've recently  put a superfuzz together with 2SC828 transistors and it is really gated.

I assume that this is a transistor biasing issue but my voltages aren't to dissimilar to the ones at the beginning of the thread.

Q1
C  5.13
B  0.67
E  0.1

Q2
C  8.07
B  5.19
E  4.65

Q3
C  5.43
B  3.00
E  2.6

Q4
C  3.37
B  1.41
E  0.84

Q5
C  3.38
B  1.42
E  0.84

Q6
C  3.82
B  1.02
E  0.42

Can anyone see an issue???  I'm going to go through with an audio probe once I have some spare time to see if I can identify which one of the buggers is giving me the trouble.

[Frank_NH]

I happen to have a model of the Univox Superfuzz for LTSpice so...

All your voltages are in the ballpark but the collector voltage for Q2 should be equal to the source voltage, and 8V is on the low side.   In fact, I changed the source voltage to 8V in my model, and pretty much got your transistor voltages bang on (my transistors are modeled as 2N2222s).   So, up your source voltage to 9V or more and see if that helps.

[PMowdes]

Thanks Frank.  I'll get a new battery on it tonight and check the voltages again.

[traktop]

BassVD wrote

I assume you used the Univox Superfuzz layout from the site? Which resistors did you change (could you show it on the layout)?
I'm planning to build this as well :)

I finally played with Q4/Q5 and Q6 base to ground resistors to get a little higher voltages on the collectors.