kay/rabb fuzztone vero...second set of eyes appreciated!!!

[pinkjimiphoton]

added pull down , led, and smoothing resistors, otherwise same as trabant's rabb fuzz i believe.
also added 1n34s in series with the 1n914 clipper diodes, i've had good luck with this in the past...you get the tone of the ge, and the boost of the si.
i'll socket them, anyways like i usually do.

i've gone over it 3 times, pretty sure i got it right, but historically i always seem to miss something, so someone else looking at it would be appreciated!!

first, the schematic:




now my vero:




i really appreciate the help!!!

EDIT:

i forgot to put it on the vero, but audio out is from the wiper of the pot.

EDIT 2: c5 is 10 u

see? this is why i ask for help!! lol

[IvIark]

There seems to be a few things to look at, and it's a bit more difficult to follow because you've used different component numbering.  I only had a quick look and haven't checked everything, but you'll need a cut on row F somewhere between C1 and R11, R12 should be connected to ground and you need a cut on row E somewhere between C8 and R19.

[pinkjimiphoton]

good eyes, ivlark!!

thank you!! will modify it accordingly...

[pinkjimiphoton]

repaired layout with ivlark's help...thanks brother!!

[pinkjimiphoton]

ok. it's built.

i do NOT believe the "rab fuzz" is the KAY FUZZTONE. i have a sneaking suspicion it's the KAY WAH.

i had both, and the tremolo back in the early 70's...they were some of my first toys.

this thing, works, but it's way too tame for the actual kay fuzztone. with ge 1n34's, it's close, but way below unity gain. to get it to a useable volume, i had to mess with the diode clipper...
left diode on my layout is di/d2 1n914 in series with a 1n34. the second clipper is a 1n914 feeding TWO 1n34's in series. that gets it up to unity gain, but the distortion changes. silicon diodes just don't cut it in this circuit.

it sounds more like a wahwah. for real. it may be the taper of the pot i'm using, (a 100k salvaged from the original rogue wah shell i used) at full heel down, it is one click above the absolute bottom of the pot's range, and gives a really nice sweep. very wah like, more than the original.

don't get me wrong, it doesn't sound bad...sounds like a really nice old fuzzwah!! but it doesn't have the "insects buzzing between your ears" rip your head off high end fuzz i remember.

with the ge diodes only? it's there. soon as ya add silicon, it's gone. i tried every silicon diode i had, from 1n4001 to led's, and the best was the 1n914...it seemed to let some of the ge fuzz come thru still. my advice? if ya want it bone stock, go for the ge.

if ya don't mind a slightly more modern fuzz, use a combo. if you don't really want a fuzztone but want a wah, use led's.

ok...now transistors....

it tried an assload of them. to my ears, an mpsa18 for q1, a 5088 for q2 another 18 for q3 and a 2n3904 for q1 seemed to work the best. higher the gain of q1, the better.

contrary to everything i read on the web, don't waste your time trying to match q3 and 4...the more mismatched, the better it sounds, and the more 2nd harmonic seems to be generated.

i will post voltages and stuff later, as i am suspecting that i may have something off...it WANTS to fuzz, but it just can't break over quite enough.

all in all tho, a nice sounding and potentially useful toy!

peace

[pinkjimiphoton]

i also suspect getting rid of c2 and c3 as shown on my VERO, not the schematic (they differ slightly) may get back some of the high end brutality this thing seems to be missing.

[pinkjimiphoton]

A full set of information about what you built

http://trabantland.wordpress.com/2010/03/27/rab-fuzz-project/

1.Name of the project:

rab fuzz (supposed to be kay fuzz)

2.Links to the source of the project web site with the schematic or project, layout and wiring diagram.

here in this thread:

http://www.diystompboxes.com/smfforum/index.php?topic=96905.0

3.Some candid admissions about how closely you followed the suggested layout, if any. If you just perfboarded it, say that, and if you can, include a picture of the board. Scanners do a GREAT job of making pictures of PCBs, by the way.

i built it on veroboard, layout and schematic here on this thread. i built it exactly as shown, with the following modifications:

4.Any parts substitutions or modifications you made to the original. If you didn't have any 10uF caps and used 22uF, say that. If you had to use a 2.7K resistor instead of a 2.2K, say that. If you used a BC109 instead of a 2N3904, say that. By the way, if you substituted any transistors, it's a sure bet that the first question you get asked will be "Did you check the pinout of that transistor?" Delight the questioner by saying (truthfullyâ€) "Yes, I did a google search on that part number and check the pinout against how I soldered it in." If you can't say that, chances are good that you've already found your problem, all by yourself.

R1 as shown on the vero layout, 220r instead of 100.

R7 and R12 as shown on the vero are 2k subbed for 1.8k

used the following in diode clipper, as ge sounded great, but had significant volume drop:
(i think the silicon diodes involved with getting to unity gain may have f'd the tone up)

clipper left (as shown on vero) : 1n914 cathode up in series with 1n34a cathode up

clipper right : 1n914 cathode down in series with 1n34a cathode down in series with 1n34 (different type of 1n34) cathode down.

Q1 using mpsa 18 instead of 2n5088 gave more fuzz

Q2 is 5088...i believe this is where the problem lies

Q3 used mpsa 18 instead of 2n3904...improved second harmonic significantly

Q4 is stock 2n3904 (tried matched pair, didn't sound as good)

added a 1meg pulldown resistor on the input (r2 as shown on the vero..may be redundant because of r5 on vero? too much voltage drop or something?

used standard blue 3pdt switch, with true bypass grounding fx input in bypass:



added bypass led, fed by R20 as shown on vero...built inside a "rogue" plastic wah, standard stereo trs input, mono output with negative from power supply going to ring of input jack.

star ground sleeve connection of input jack, jumpered to output jack sleeve.

switch/pot case grounded.

and yes, i DID check the pinouts of the transistors both with google and my meter.

5.Whether or not it's a positive ground circuit like a PNP fuzz or a Rangemaster that has been hacked to work with negative ground. This is a special case, but a common one. "Positive ground" means that the positive/red lead of the battery clip is connected to signal ground. "Negative ground" means that the negative/black lead of the battery clip is connected to signal ground when the effect is operating.

it is an npn negative ground circuit.

6.What it does and does not do how it works; partially or not at all. For instance, if it lets no sound through; or if it makes a harsh, distorted sound only when you strum hard on the strings at full volume; or if everything is really, really low volume.

it sounds great as a wah...or a treble booster. not as much fuzz as it should have. if you put a fuzzface in FRONT of it, THEN it sounds like the original kay fuzztones sounded. without the extra fuzz, it's mostly a wah pedal. with just the ge diodes, it's fuzzier, but doesn't come close to unity gain. it's a very nice...wah. it should be a rude, compressed spitty almost super fuzz sound.

this ain't it.

i'm suspecting a problem with either the layout i created, or the schematic it's based on...as transistor voltages seem kind of weird, particularly on Q2.
when you have the guitar cranked and thrash on it, it WILL fuzz..if the guitar is cranked, and the amp almost off.

effect is being run by a 9volt wallwart

reading 9.7v @ the power supply jack, and at the ps side of r 1 approximately a 3v drop across resistor to 6.7v

Q1 mpsa18
C = 6.10
B = .82
E = 5.45

Q2 motorola 2n5088
C= 5.46
B= 6.10
E= 5.45

Q3 mpsa18
C = 7.80
B = .82
E = .26

Q4 2n3904
C= 7.80
B= .81
E= .26


i bet it's something dumb, knowing me...  

thanks for the help!!!

[pinkjimiphoton]

these are the best pics i could get with my lousy phone.

it's hard to see, but i made sure there's no cold solder, and no accidental shorts on the vero...and that continuity on the traces is right with the layout.

[pinkjimiphoton]

got it. had to add a 100k trimmer (set to about 63k...68 didn't work well enough, i tried just tacking a resistor on) in parallel

with R10 (on the vero). could then tune the fuzz in til it sounded right.

seriously have no idea what i did...or at least the math involved, but it worked...i guess divide 100,000 into 63.000 or something? i'm a hack.

final voltages were a lot better after this:

q1
e .25
b .83
c 5.45

q2
e 5.23
b 5.84
c  5.84

q3
e 1.40
b 1.93
c 2.03

q4
e 1.40
b .87
c 1.40

i don't know if these actually look better, but it sure sounds more like i remember it.

add an lfo to sweep the tone pot, and i bet you have the lost psychedelic machine. it doesn't sound like a wah as much as a phaser.

it's amazingly similar to some of jimi's mild fuzzed out univibe sounds ("gold and rose, the color of the dream i had")

i gotta gig tonite, will post a clip soon.

if dino or ian are paying attention, it's VERY mouthy, kinda like the mr multi a little...but fuzzier in a good way. a hint of formant.

anyways...thanks for looking. if i ever get around to it, i'll update the vero with a 100k trimmer.

if you attempt this, beware...the sweet spot between too clean "wah" and too fuzzy "fizz" is an extremely narrow window, between about 59k and 65. below or above either harsh distortion or way too clean.

peace