Dialing in a Mangler

[pryde]

Hello all,

I finished populating a mangler board and have it on the test rig. The circut works and sounds fuzzy!

Questions:

1. I built an NPN with CV7112 (OC140) trannies. I did not use the supplied resistors from SB and instead used what the build doc said (100k, 33k, 220R,470R). This is ok since there is a bias pot correct?

2. Speaking of which, my voltages are not negative (i.e. -4.5v) but are showing positive instead. Is this because of the NPN trannies/build or do I need to swap/change anything?

3. I used the red dot on the CV7112 as the collector. Is this correct? I have read different stories on this.

BTW: the pedal sounds pretty good (I think) but I have nothing to really reference against being a fuzz-face newbie.

 

[JakeFuzz]

1. Yes that is fine. I am betting Steve just has a box with a bunch of pots and tweaks the circuit values until he finds a good sound out of each set of transistors. But the most sensitive value is usually the bias resistor which the mangler has on a trimmer. I really like the feedback resistor on a trimmer as well (100K)

2. Yes, because the circuit is NPN you will get positive voltages. You don't need to change anything

3. I would test the gain using the dot as both the collector and emitter. Red dot is the way it is supposed to be but the device is symmetric (sort of like FET's are symmetric). I usually get lower gains backwards but once or twice I have gotten gains in the 200's! It was awesome.

Glad you went with the CV's. Those things sound huge and wonderful. Record us a demo 

[pryde]

Thanks for answering all my questions, I really appreciate it.

Edit: I looked up how to test gain and leakage but my DMM does not support it.

I gotta say I ran the circuit through my main rig and MAN does it sound good. I can't imagine it sounding much better. I also did the pregain mod which makes this thing way versatile. Got great sounds from a LP, Strat, Tele, and a P90-equipped tele. Stoked 

Gotta get this thing boxed up.

[add4]

really curious about these CV7112 trannies.. where do you source them? i haven't found anything on banzaimusic, musikding, and ebay.
are they similar to OC140 (that i can't source either :p )

i am asking that because jakefuzz's fuzz sound killer in the wheener way demo

[pryde]

Got the CV7112 from smallbear. They are the NPN "continental" fuzz-face set of 2.

[add4]

thanks!