Author Topic: Best gains for buzzaround  (Read 13414 times)

Colonel Angus

Best gains for buzzaround
« on: June 23, 2012, 06:01:19 PM »
Any suggestions? I have a buzzaround from the Andrew Carrell schematic on breadboard (toast-board and jam?) and would like some advice on gains to try. I got a ever-loving sack of low leakage Russian GE's with gains from 25-150.

Thanks!
Why should you not have 90o angles? Do the electrons bunch up in the corners?

LucifersTrip

Re: Best gains for buzzaround
« Reply #1 on: June 23, 2012, 06:19:33 PM »
there's a bunch of discussions on this forum...biggest thing is not to expect 4.5 on Q3C

here's my final version after alot of experimentation. it is actually one of my favorites:



As I noted on the other threads, any low leakage (since darlington pair) for Q1/2 is cool...just something in the 50-75 hfe range is good enough. you can try even lower (remember the gains are multiplied)

Q3 is the only one you need to experiment with since it is LEAKAGE that will give you different Q3C voltages, tones, timbre sweeps, etc. A very low leakage Russian, for me, was not great in Q3...but is perfect for Q1/2

I altered the 43K from 10K to give me a better (less volume change than the original) timbre sweep.

« Last Edit: June 23, 2012, 06:21:23 PM by LucifersTrip »
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Pyr0

Re: Best gains for buzzaround
« Reply #2 on: June 23, 2012, 11:28:14 PM »
LT,  How much is "medium" leakage ? 150uA or higher ?

I suppose with that voltage on collector of Q3 it must have a leakage of approx 165uA.

LucifersTrip

Re: Best gains for buzzaround
« Reply #3 on: June 24, 2012, 03:40:05 AM »
LT,  How much is "medium" leakage ? 150uA or higher ?

I suppose with that voltage on collector of Q3 it must have a leakage of approx 165uA.


It was just a general note to myself. For me, low leakage is under 200uA, so I'd guess I hit around 200-300uA for medium.

According to RG, "More than 300uA means the device is suspicious, and more than 500uA I would say is bad."

I usually consider >300uA high...


Edit: just checked my notes. Q3 leakage was ~ 300uA.
« Last Edit: June 24, 2012, 10:18:18 PM by LucifersTrip »
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mordechai

Re: Best gains for buzzaround
« Reply #4 on: June 24, 2012, 10:24:54 AM »
What purpose does the Ge diode to ground before Q3 serve in this circuit?

Colonel Angus

Re: Best gains for buzzaround
« Reply #5 on: June 24, 2012, 04:38:49 PM »
Thanks a lot ! That clears things up a good bit. Sorry if the answer was already posted, I was having no joy and no luck finding a buzzaround thread that was specific with transistor gains. Hopefully I'll get to play with it some more tonight. We'll see though, we rented some neve 1081s for the weekend and we are trying to squeeze every bit of time out.

Thanks again LucifersTrip! :)
Why should you not have 90o angles? Do the electrons bunch up in the corners?

rutabaga bob

Re: Best gains for buzzaround
« Reply #6 on: June 24, 2012, 05:10:16 PM »
According to Paul (PRR), the diode is to combat blocking distortion.  Other threads to check are the Burnski Buzzaroundski and the Buzztain, although the buzztain is an npn modified buzzaround.  At guitarpcb.com, look at the Fuzzy Bee.   Larry
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chromesphere

Re: Best gains for buzzaround
« Reply #7 on: June 24, 2012, 08:15:55 PM »
I was playing around with a few different sets of transistors in my madbean bumblebee (which is a buzzaround) and recorded a few quick clips using different gains.  Too be honest, the different was actually pretty minimal.  Some difference, but i fear if i was in a dark room and someone was swapping them, i wouldnt be able to tell.  Heres the clip, also, a clip of the final product.

Paul



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LucifersTrip

Re: Best gains for buzzaround
« Reply #8 on: June 24, 2012, 09:40:48 PM »
I was playing around with a few different sets of transistors in my madbean bumblebee (which is a buzzaround) and recorded a few quick clips using different gains.  Too be honest, the different was actually pretty minimal.

did you make notes of the leakages and voltages? you'll see that the voltage (and tone and timbre sweep) varies greatly with different leakages...again, it's the leakage more than the gain that matters!  ...and Q1/Q2 have the least effect...They're nothing more that a darlington pair.

If I remember correctly, I was getting >1V on Q3 collector until I threw in a higher leakage one there, then the voltage dropped below 1V and everything improved

edit: in your vid, you mention using a tonebender transistor set....that would be for a MKIII, if any.
Especially in the 1st vid, it seems you're getting much more of a quick, semi-fizzed decay than I got...but it all sounds cool!
« Last Edit: June 24, 2012, 10:33:15 PM by LucifersTrip »
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chromesphere

Re: Best gains for buzzaround
« Reply #9 on: June 25, 2012, 02:25:07 AM »
Hey Lucifer,

Pretty sure q3 would be around 100-150 leakage, which is pretty low i guess?  Your probably right with regard to the leakage of Q3. It probably makes more difference then the actual HFE of the transistor, because like i said in the video the differnce was slight.  Might also explain why the high HFE for Q3 sounded marginally better, as it had a higher leakage then any of the other combinations.

You'll have to forgive me if the info isn't totally accurate, i'm quite new to germ fuzzes.  "Tonebender set" i just meant, 50-75 for Q1 & Q2, and high HFE for q3 (100+).

Paul
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LucifersTrip

Re: Best gains for buzzaround
« Reply #10 on: June 25, 2012, 02:39:49 AM »
Hey Lucifer,

Pretty sure q3 would be around 100-150 leakage, which is pretty low i guess? 

yes...pretty low...excellent for Q1/Q2

Quote
Your probably right with regard to the leakage of Q3. It probably makes more difference then the actual HFE of the transistor, because like i said in the video the differnce was slight.  Might also explain why the high HFE for Q3 sounded marginally better, as it had a higher leakage then any of the other combinations.

yep...very possible..

Quote
You'll have to forgive me if the info isn't totally accurate, i'm quite new to germ fuzzes.  "Tonebender set" i just meant, 50-75 for Q1 & Q2, and high HFE for q3 (100+).

Paul

One of the hardest thing about germ fuzzes is actually getting a variety of transistors with different gains AND leakages. It's that extra factor that makes em so much more fun for me.

The "Tonebender set" would seem to work well for the Buzzaround, except Q3 might need higher leakage (but again, just my preference...you may like the sound with low leak better)

one last note: The leakage/noise of Q1 is multiplied by the gain of Q2 in a darlington pair, so put the lower leakage one in Q1.

always think outside the box

chromesphere

Re: Best gains for buzzaround
« Reply #11 on: June 25, 2012, 09:22:54 AM »
Good info Lucifer! Gotta say, sounds pretty dam nice as it is, but might have to try a leaky Q3 i think!
Paul
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