UMI Buzz Tone

[LucifersTrip]

I've built  numerous Buzz Tones and it's always been one of my favorite Fuzz Rite variants...

Here's the schematic that's been used by many:
http://tonebender.webs.com/UMI%20BUZZTONE.GIF

It doesn't sound like any of the many fuzzes I've built...It has a really tight sound that can pierce like a mother and can get some really heavy octave tones, especially down at the 12th fret and higher....buzzy, fuzzy, tight, etc...

I finally played through an original and it sounded very different than the ones I've built. It's a great sounding fuzz, but sounds really similar to a germanium Fuzz Rite, with an added tone control. The ge Fuzz Rite also has the .002's.

So, I quickly traced it and lo and behold, there's a couple friggin' errors in the circulating schematic. One makes a big difference...the other hardly does anything. The big one is the .0022uF. It comes off the .15uF/4.7K junction, not Q2 base.

The small one is the Buzz pot. I measured all pots in-circuit and they all measure between 75K and 100K, so the Buzz pot can't be 50K (resistance can't increase in parallel). The difference between 100K and 50K is barely noticable.

With the .0022uF corrected, the Buzz pot acts almost exactly like the Depth control in a ge Fuzz Rite. Full counter clockwise you hear mainly the clean tone with a hint of fuzz way in the background, and it slowly blends the fuzz in as you turn clockwise. The volume level is pretty consistent...and like a ge Fuzz Rite, there's no heavy octave tones.

In the incorrect version, there's almost no clean tone to blend and the Buzz pot almost works like another tone control. Therefore making it sound way tighter and thinner. Also, there is a severe increase in volume as you turn clockwise. I wrote that off as another goofball 60's design, but now I know...

The collector voltages were also a surprise. On my builds I usually hit the 6 - 7V range for the collectors. On the original, Q1's right around 4V and Q2 is .22V. With both voltages it actually sounds similar,  but with the original voltages it seems louder and fatter. I'll play through it a bunch more and really get to know it better soon... Funny, I've always said the Fuzz Rite variants are much better beginner fuzzes to build since you don't need to hit a really small voltage range on the collectors...like the common Fuzz Face where you need collector voltages and leakages in a small range to sounds great.

Anyway, the only way to get the voltages of the original is with some pretty damn high leakage...upwards of 400 - 500uA.  I chose a couple transistors to do just that and I got really close to the original tone.

Here's some board shots and the corrected schematic with original transistor numbers and collector voltages.

[pinkjimiphoton]

dave,
i love you, man.... awesome!! gonna revisit mine today if i get a chance, see if i can gussy it up a bit.
it's been close, but not "right".

thanks bro!!

[lowbrow]

I need to check my stock, I have quite a few RCA house number transistors. If I can shed some light on those two, I'll post the info.

[LucifersTrip]

dave,
i love you, man.... awesome!! gonna revisit mine today if i get a chance, see if i can gussy it up a bit.
it's been close, but not "right".

thanks bro!!

you'll be able to relive your 1st fuzz with one quick movement of a wire!

I have mixed feelings about this. Though I'm happy as hell to know what this one really sounds like, it's a little disappointing to know that there's no real vintage fuzz (so far) that sounds like the incorrect version...which is really, really cool and unique.

After playing through it a bit longer, it seems the higher leakage (and lower C voltages) will give it a looser feel, with possible spitting as the notes decay.

It sounds somewhere between the ge Fuzz Rite and a ge Orpheum...

have a blast!

[lowbrow]

Sadly, mist of mine are in the 35x range and I have nothing in the 40x range.

[pinkjimiphoton]

i had to re-do the old vero to make this thing right... on my build from the "mistake" schem, i'm gonna just tack on the .0022 cap however i need to make it right,
but this has it in the right place, and i know the rest works, as i've built it.

i never thought it was right.. it was close, but...

so i gotta wait til morning tho.. re-did my fuzzface tonite, and fixed a weird wah problem... the power jack was shorted, so the battery wouldn't work.. lol


anyways... from dave's schematic, to a pink jimi vero:

[LucifersTrip]

hey...

first, lowbrow...thanx for checkin. but, even though I have good working voltages on this one, I really don't know 100% that's what was intended for the design...until I see voltage readings from others. don't know how much leakage occurred in 40+ years.

jimi, if you're using this numbering system:


...then swap the outer lugs on "contour" and buzz". "contour"  goes from base to treble and "buzz" goes from mainly clean signal and mixes in the fuzz.

[mac]

Cool!
I'll breadboard it as soon as I can.

Any chance to trace the original PBC? 

The collector voltages were also a surprise. On my builds I usually hit the 6 - 7V range for the collectors. On the original, Q1's right around 4V and Q2 is .22V. With both voltages it actually sounds similar,  but with the original voltages it seems louder and fatter. I'll play through it a bunch more and really get to know it better soon... Funny, I've always said the Fuzz Rite variants are much better beginner fuzzes to build since you don't need to hit a really small voltage range on the collectors...like the common Fuzz Face where you need collector voltages and leakages in a small range to sounds great.

Anyway, the only way to get the voltages of the original is with some pretty damn high leakage...upwards of 400 - 500uA.  I chose a couple transistors to do just that and I got really close to the original tone.

My calculation says that Q1 voltage is in the range (6.5v - 4v) <--> (non leaky - 500ua), no problem here.
and Q2C goes to gnd as soon as the leakage gets close to 9v/100k=0.09ua, unless the reverse diode is so leaky to shunt excess Q2 leakage to gnd sending the collector a bit up.
I think in that days 0.09ua was not common, so it is very likely that it was designed to work near gnd.
If you want to steal leakage from Q2, add a 100k pot from B to gnd to fine tune Q2C, as in the Tonebender MKI.

mac

[pinkjimiphoton]

ok, dave, here ya go:



i don't ever trust pots as shown... seems like it's always wrong, or at least i get it wrong 50% of the time.

i look at pots like this...

just like in a schematic... from top to bottom, from side view with shaft to the right, 1, 2, 3 usually. i've had pots with the lugs numbered completely contradict each other, so i just play it by ear, and if somethings backwards, i just reverse the two outer lugs.

[pinkjimiphoton]

real quick... i did the modification,
and yep, nite and day tonally. suddenly it sounds like 1968 in here, and the vol expander works and makes sense..
very thick, chewey, germanium fuzz... don't have to peg the buzz control anymore, it sounds great with the buzz only half way up.

i will take pics and voltages shortly, gotta go run out to tcob real quick..

anyways... dave... man... you are godlyke. when the flashback hit, the world got much fuzzier sounding. awesome.   

[pinkjimiphoton]

i ended up swapping out the transistors i'd had in it (russian mp16b) for a pair of russian mn256 (b?) each with a gain of around 120 according to my meter (yah i know) but that did the trick...
thick as mud fuzzy goodness... contour and buzz controls work great, the boost function too sounds as i remember it.
i got to re-play some stuff from my youth and get the same kinda tone i had back then...

thick and buzzy with killer sustain, no wonder i ended up being such a big muff pi head later in life.

anyways...
voltages (which stayed the same irregardless of what transistors i used) with a fresh 9volt battery, reading 9.65v

q1
c 6.73
b .15
e 0

q2
c  7.33
b  .04
e  0

i also tried some silicon transistors around 120-140 hfe and it sounded real good too, a little more ragged and octavey.
i am impressed... thanks again dave, i'm gonna take this thing and rock it tonite with Smokin' Herb

[LucifersTrip]

Excellent!  one small change and you're back to the 60's....looking forward to In-A-Gadda in your SPT vid. I think Iron Butterfly used a Fuzz Rite.

Your voltages are exactly what I'd expect with low leak transistors. It should give you a tighter sound.

I think as a possibly mod, I may try to vary the 4.7K between-stage resistor.

Btw, I numbered pot lugs in the schematic.

crank it up

[pinkjimiphoton]

will do... right now i'm finishing my kay vanguard 700 that just came in, i did all the electros in it and got the hum gone.

totally germanium amp... sounds really sweet. i can't wait to pump some FUZZ  into it!!

the buzz sounded GREAT with leaky low gain ge's too, but the background noise when the guitar was off made it unusable... that's why i tried the other transistors.

i will try and get a SPT tomorrow if i can. this is awesome!

rock on!!

[LucifersTrip]

...just did four tests of the extremes...

I used four transistors...Two with higher leakage (~400uA) which gave me very close to the sound of the original (-4.8V, -.1V on Q1C, Q2C respectively) and two "zero" (less than 50uA) leak Russians  (-7.2V, -9V on Q1C, Q2C respectively), with 9.6V supply.

^, v = high, low leak respectively

1) Q1^Q2^ = nearly same tone as the original, rich single notes on high strings
2) Q1^Q2v = tighter. sharper when contour is CCW compared to (1). way too trebly single notes on high strings
3) Q1vQ2^ = tighter. "clean" tone is way less prominent, not as rich single high notes as (1), but still cool
4) Q1vQ2v = tighter. sharper when contour is CCW compared to (1). way too trebly single notes on high strings. "clean" tone way less prominent

It's exactly as expected. Q1 is more responsible for the clean and Q2 for the fuzz. You can get away with a low leak Q1, but not in Q2 if you want a richer tone like the original for single note solos on the high strings. It's night and day. The only thing slightly better with Q2 low leak was some added clarity when the contour is full CCW.  The higher leak ones generally make it sound fuller & richer louder.  

The original and all my tests above are quiet, like almost all Fuzz Rite variants I've built.

A couple extra notes if you're trying to get close to the original. With buzz 100% and contour 50%: Volume) There's a slow increase in volume up to around 30%, then a quicker jump at around 40% and unity at around 50%. Then a slow increase until max.

The contour is similar. With buzz at 0%, contour has hardly any effect. With buzz at 100%: Contour) There's a slow increase for about 25%, then a quicker jump right after that, then slow increase until max.

The buzz is a nice, even blend from start to finish. At about 10-20%, it sounds very similar to a Contrafuzz.

If you're playing through the "volume expander" part of the circuit, then step down to engage the fuzz with buzz and contour at 0%, the volume & sound is very close. The fuzz may be a little lower in vol and of course has the slightest bit of fuzz way in the background.

I subbed a pot for that 4.7K between the two Q's. Very simply, it controls the prominence of the "clean" part of the mix. Raise it and the "clean" is higher in the mix and the overall sound is louder. That explains why #3 above is lower in volume. Lower the resistance and the "clean" mix slowly diminishes until zero, where, you guessed it...you have something very similar to the errored version.  With no "clean" tone battling in the mix, the octaves come out much heavier and the sound is more compressed...

[Henry89789]

Hello Pink Jimi Photon:

I want to build that vero board version of the buzz rite that you put up.  Here is a quote from one of your posts:

real quick... i did the modification,
and yep, nite and day tonally. suddenly it sounds like 1968 in here, and the vol expander works and makes sense..
very thick, chewey, germanium fuzz... don't have to peg the buzz control anymore, it sounds great with the buzz only half way up.

Is that a confirmation that you have built the vero board buzzrite and that it works? thanks.   

[pinkjimiphoton]

if you mean the umi buzzTONE, yep, built it on vero and it does indeed work.
one of my favorite fuzzes, in fact. very creamy with long sustain depending on how ya set it.
kinda like a nice cross between a big muff and a fuzzface.

the vero above is not the one i built, but should be fine, as i just took the one i did build and added power supply filtering to the board and moved that one capacitor.

check it to the schematic before ya build of course!!

parts not on the schematic are:

f2 - j2, 1meg pulldown resistor
a5-e5 220p cap to help keep down rfi
a3-e3 100u filter cap (help quiets it if run on power supply)
a4-j4 1n4001 reverse polarity protection


you can leave these parts out if you want to, they don't affect the sound of the pedal, but will help eliminate switching transients and line noise.

this vero tho, should be good to go.

[LucifersTrip]

hey jimi!

I really hate to be contrary (or a downer), but are you 100% sure you built it correctly...It  has a completely different topology and sound than a Fuzz Face or Big Muff, so I'm having a hard time seeing how you're making that comparison. 

It's a blend Fuzz/Buzz where the fuzz should slowly blend into a semi-distorted clean tone (similar to when the volume expander is on) . When the Buzz is turned up, you should get closer to this...

[pinkjimiphoton]

that sounds nothing like the umi buzztone i had from 78-83 when it was stolen.
that sounds more like a buzzaround, almost kay-y to my ear.

the one i used back in the day (in a southern rock/heavy blues band called horseful carriage) was way closer to a big muff tonally..
crazy sustain, and very smooth sounding... a lot of cream. it depended on how overdriven the amp was... into my deluxe, it sounded great..very warm and loud... into my vox it sounded a lot fuzzier (the vox was a 2x12 bass combo, solid state)

i spent a couple hours playing with this after you posted the "fix" dave, and went thru pretty much every pnp in the house (a bunch, i've been on a jag buying low-gain everything i can find to try) and what i ended up with is just a hair fuzzier than my original, but real close to the same kind of tone on my original one.

the only diffs between mine and the original is the power supply filtering, being true bypassed, and missing the battery meter.

i'll try and shoot a clip in a little bit and post it so you can hear... what i've got is pretty close to the original one i had.. but again, it depends on settings (i like mine pretty much pegged) and how much dirt the amp has to begin with i think.

variations in transistors could account for it a bit too... interesting!! stay tuned bro!!

[Roger Martin]

that sounds nothing like the umi buzztone i had from 78-83 when it was stolen.
that sounds more like a buzzaround, almost kay-y to my ear.

the one i used back in the day (in a southern rock/heavy blues band called horseful carriage) was way closer to a big muff tonally..
crazy sustain, and very smooth sounding... a lot of cream. it depended on how overdriven the amp was... into my deluxe, it sounded great..very warm and loud... into my vox it sounded a lot fuzzier (the vox was a 2x12 bass combo, solid state)

i spent a couple hours playing with this after you posted the "fix" dave, and went thru pretty much every pnp in the house (a bunch, i've been on a jag buying low-gain everything i can find to try) and what i ended up with is just a hair fuzzier than my original, but real close to the same kind of tone on my original one.

the only diffs between mine and the original is the power supply filtering, being true bypassed, and missing the battery meter.

i'll try and shoot a clip in a little bit and post it so you can hear... what i've got is pretty close to the original one i had.. but again, it depends on settings (i like mine pretty much pegged) and how much dirt the amp has to begin with i think.

variations in transistors could account for it a bit too... interesting!! stay tuned bro!!

"Crazy Sustain".....wow interesting, Jimi   
I hope this is the sustainer i've been looking for, maybe some mods will suit my taste.

[pinkjimiphoton]

i really like this pedal... if it cleaned up better with my guitar knob, it would probably be on my live board permanently.