Has anyone done a silicon Buzzaround?

[mac]

The general idea out there is that Tonebenders can't be replicated with Silicon Transistors. I haven't succeeded in making a good one yet, but I'm glad people haven't given up.

IMHO the key points are the transistor's internal capacitance and its gain. I had very good results using power transistors like BD175 or BD137. Some TIPxxx can work too.
Hfe should be below 100.

Even with germaniums there are big differences. If you try some Toshiba 2sa49/53 they sound as trebly and harsh as silicons.

mac

[Gus]

I would use a power transistor at the 2nd stage like mac posted. 

[digi2t]

I'm a bit confused right now. Probably some basic transistor theory that I haven't learned yet. I have an NPN version on the board right now, and the voltages are no where near the PNP version.

Why is that?

It actually sounds fairly decent, but for instance, Q3 collector is running around 8 volts. Should I list all the voltages I have now, or can someone give me the quick and dirty as to where all my voltages are different?

I'm such a noob.   Had the meter leads the wrong way around. 

EDIT:
Here is my NPN version that's on the board right now. Piggybacking Q3/Q4 is the only way I can get smoothness out of it. If I go with just 3 transistors, it's a real Velcro machine. Nasty. Of course, this could be a switch option, simply disconnecting E and B for the Velcro effect. Right now, it sounds close to the PNP version I posted earlier. Still needs some fine tuning.



I actually have some BD transistors on hand from my Ludwig build. I'll try that tomorrow solo as Q3, see if I can get away from the piggyback deal.

[mac]

I actually have some BD transistors on hand

NOt all BDxxx are low freq devices. BD139 is one of them.

mac

[digi2t]

I actually have some BD transistors on hand

NOt all BDxxx are low freq devices. BD139 is one of them.

mac

I'll check it out today. I do believe they're 139's.

[digi2t]

Here is the recording. Balance is at max, Timbre at 1 o'clock. Same set up as before, straight into a BR-600, JC-120 amp setting, slight reverb.

It starts with the Sustain at 9 o'clock, then noon, and finally at max. At each stage, I vary between single coil bridge, bridge/middle (for a humbucker feel), and single coil neck.

http://www.soundclick.com/player/single_player.cfm?songid=13075245&q=hi

or download at;

http://www.soundclick.com/util/downloadSong.cfm?ID=13075245

This is almost the same layout as the PNP version. The transistors are 2N2219A in Q1/Q2, and 2N2218A in Q3/Q4. Slight changes in resistances, no cap parallel to the diode. No cap makes it a bit buzzier, especially at max sustain. With the cap, it's got more of a Muff growl. Placing a rotary switch with several caps here could be an option for several textures. Disconnecting the piggybacked transistor adds another dimension as well. Easily incorporated into a vero.  :thumb:

I tried the BD139 angle, but it wasn't that great. It was hard to get decent sustain, and I didn't like the texture rolling off the guitar volume. I have yet to find a 3 transistor layout that beats the performance of the piggyback layout. With the trimmers set just so, I can mange to get some really cool harmonic overtones.

[Arcane Analog]

The timbre pot is not really wide ranging tone-wise, but neither was the original. The real tone controls are the sustain and balance knobs. The timbre pot only adds a bit more top end..

I have made many, many Buzzarounds. If you select transistors properly there is a wide range to be had with the Timbre control.

I have made a silicon version as well but I ended up changing quite a few components.

[Gus]

Why did you remove the collector resistor in the 2nd stage?

[digi2t]

Why did you remove the collector resistor in the 2nd stage?

I didn't. I removed the 120K resistor that I had between B and C (parallel with the 220p cap). I found that it didn't really do much sound-wise, so I could justify leaving it there. Sorry if I didn't come across right with that.

I've played with the voltages some more, and as soon as I can wrestle my computer from my son's grip, I'll post the latest schematic, and maybe a vero too.

All in all, I'm really liking the final product. No, it's not a Buzzaround per se, but using the Buzzaround as a platform, with a sprinkle of imagination, and some Jimi Photon spirit, I think I've conjured up something that I would build. Running flat out, there's quite a bit of harmonic content that waves through the decay, even through headphones. I imagine through a cracked amp, it should be quite interesting. Toned down, it can give a nice bluesy overdrive crunch.

Post what I have later today...

[Arcane Analog]

No, it's not a Buzzaround per se, but using the Buzzaround as a platform, with a sprinkle of imagination, and some Jimi Photon spirit, I think I've conjured up something that I would build.

This is what I found. Directly substituting silicon with only minor tweaks is not all that pleasing. With modification you get something nice but not the same.

[mac]

The balance and sustain pots change bias. Because of leakage Ge are always on, and that pots are going to react in a different way when you use silicons.
For example, with sustain near zero silicons are almost off, but germs are still on.

mac

[Gus]

When I posted "Why did you remove the collector resistor in the 2nd stage?"  I meant the 2nd gain stage 15k collector resistor I see in the schematic of the buzzaround I found on the web.  You have the collector going direct to the voltage divider the original has a 15k to the divider

The Burns Buzzaround is a Darlington input gain stage to a reduced voltage clipping stage the 22k or  27k from the +9VDC to the 5k or 10k potentiometer depend on what you see on posted schematics.  The wiper of the potentiometer goes to the 15K collector.  So the collector load is combination of the 15k, 27k and balance control along with the timbre network and what is after the fuzz

The collector direct to the voltage divider(balance) changes the collector resistance and collector current

Also a single high beta/hfe Silicon mpsa18 etc. transistor will be closer the the two Vbe drops of the original two Ge Darlington first stage.

[digi2t]

Ah...

Well, when I initially started this adventure, I pulled the ge transistors, and simply swapped in silicons.Of course... it didn't work. From there, I started reading up on swapping ge for si, and I came across this web site;

http://www.hawestv.com/transistorize/germanium1.htm

I just started pulling/replacing/tweaking until I could get it to work, using the web site as a guide, and then made finer adjustments to get better performance out of it. The 15K was a victim of this "experimentation". The fuzz was just really weak and gatey with it in there. When I pulled it, it roared to life.

Not very scientific, I know. Sorry. 

[Arcane Analog]

Not very scientific, I know. Sorry. 

You cannot argue with results, though. Breadboaring "accidents" have provided great results for me from time to time.

[thehallofshields]

It looks like DAM made a Silicon Tone Bender a while back that sounded great. Not sure how this one flew under my radar, but the sound is pretty impressive. FSB has a thread, but some component values are a ?.

DAM GB-83
http://www.stompboxes.co.uk/greaser.html
Soundclip: http://stompboxes.co.uk/downloads/Greasebox%20GB-83%20mp3.mp3

[mac]

A few monts later, mid 2015, I made my own version,

http://www.diystompboxes.com/smfforum/index.php?topic=111831.0

mac