Baldwin Burns Buzzaround

[Brushthrower]

Hey,

I've just built a Buzzaround clone based on this schematic and layout:

http://4.bp.blogspot.com/_y4AYtND8Hz8/SO00F9q9iJI/AAAAAAAAAMw/hRP5dCXBmA8/s1600-h/Buzzaround_vero.png

http://3.bp.blogspot.com/_y4AYtND8Hz8/SO00F7to5oI/AAAAAAAAAMo/zK5PHOBMnYY/s1600-h/BURNS+BUZZAROUND.GIF

I used a matched set of GE trans I purchased from Small Bear (for the Tonebender MKII). When I installed them according to the layout they worked, but the sound was flat and lifeless. The trans are a 2SB77 in the Q1 position and two generics in Q2 and Q3. I tried swaping the trans around in different positions and then eventually reversing them (so that the collector was were the emitter should be, etc.) when I did that with the 2SB77 in Q1 it really came to life! Sounds great now.

Any thoughts on this? Why would the 2SB77 work better reversed? Will this cause problems with the circuit? Will I ruin the trans?

Thanks!

[danielzink]

I went through the same thing on a recent Buzzaround build - have you looked the datasheet for a 2SB ? the marking are a little different than normal - what you think is "reversed" may actually be normal.



Dan

[Brushthrower]

Thanks for the reply Dan. Yeah, I checked the specs of the 2SB77 before I started switching the trans around. Oh well, I guess if it works, it works. 

[smallbearelec]

The Buzz around circuit is more similar to the 3-knob TB than to the TB Pro MKII. In all three cases, the biasing is different. When you reversed the 2SB77, you effectively changed the bias such that the circuit is happier. So the result is not surprising, though I would have looked to get it by setting the circuit up on solderless breadboard, wiring normally and tweaking bias resistors. That is actually what we do when lining up sets, but we don't have a test setup for the Buzzaround. At some point I'll ask Adriano, the assistant who does the testing, to build one so that we can sell sets and guarantee performance right off the rip.

Regards
SD

[Brushthrower]

Hey Steve,

Thanks for the response. So will the reversed trans eventually be problematic? R3 is the biasing resistor for Q1, correct? I might just put a 10k trimpot in its place so I can tweak it to where the trans is happy.

[smallbearelec]

So will the reversed trans eventually be problematic?

Probably not.

R3 is the biasing resistor for Q1, correct?

R3 is collector load. Yea, tweaking that or the 470K base resistor might help. Again, I would be doing this on breadboard first.

[mac]

I hope this helps, although it is about Tonebender 3K,

http://www.diystompboxes.com/smfforum/index.php?topic=64677.msg512877#msg512877

mac