hmmm...remember kustom amps?

[wavley]

I find that I have to keep the perfect balance of caffeine in my system, not enough and I can't pay proper attention to detail, too much and it looks like an earthquake under the scope.

I think it also helps to be a tiny Indonesian lady with very small hands and slender fingers...or an industrial robot.

I guess I lean more to the caffeinated industrial robot side.  (at least that's how management and HR sees the technical staff)

[Electron Tornado]

Here's a 150 that's available:   http://www.ebay.com/itm/Kustom-150-Bass-Amp-Head-and-Kustom-2x12-Speaker-Cabinet-U53715-/360573456682?pt=LH_DefaultDomain_0&hash=item53f3da512a#

[pinkjimiphoton]

bass amps are nice, but they don't have the vib or reverb. very "flat" sounding, clean in a nice kinda transistor way.

my buddy tom guerra found a place in providence with a whole wall of kustoms i'm hoping to go visit soon.

[digi2t]

OK, while I'm waiting on the enclosure for the Infinitphase, I pulled out the breadboard, and threw the fuzz section from this schematic on it (lower half of circuit).



I started it at C38, and ended at the 10K pot. 2N5088's (as R.G. says, "When in doubt..."), and I adjusted the resistors to get the voltages spec'd since I'm dropping from 12V to 9V. I reduced the 3.3M B to C resistor to 2.2M. I found that 3.3M sounded too "saturated", making the fuzz muddy when hitting the strings hard. 2.2M gives me the right balance of fuzz and clarity. This is what I've got;



Well, I'm pleasantly surprised. It's got a nice "Suzie Q" kind of feel flat out, but what really impressed me was when I rolled the volume back on the guitar. With my Strat single coil neck pup, normally pretty mellow, I got some real Tele-type SPANK! But, the bridge humbucker, which is normally brighter, is now more mellow. WEIRD! I dunno, maybe a "treble-boosted Axis-face" is the best descriptor that I could paste on this one.

All in all, not bad, though it strikes me as a fuzz that would be better suited in front of a tube amp, rather than a SS amp. I think with the right tubes it could put out some cool mojo, but I wouldn't hesitate to use it with a SS amp either. 

[Gus]

Did the first collector voltage measure around 2.4VDC with a higher hfe 2n5088 and 2.2meg feedback/bias?

What is going on with the pickups is the added series resistance as you turn down the volume control, at 100% you have 250k to ground and no volume control series resistance as you turn it down you might have 50K series to the wiper and 200K from wiper to ground.  Part of the overall gain is the feedback resistance divided by what is connected to the input node(the guitar and cable).  This also changes the frequency response from having a bump at just below 1KHz volume control at max and tone at max treble(tele sim in a sim of the first stage) to being more flat.

You are also running the transistor more toward saturation with the 2.2meg instead of the 3.3meg the collector voltage is lower this also reduces the max closed loop gain (2.2meg vs 3.3meg).  This is a higher gain area of biasing a transistor (higher open loop gain).   IIRC there is something about this in "The Art of Electronics".

I noticed the offset at the emitter follower output this will be OK with the Ge clipping diodes but if you use with other higher voltage clipping diodes you might want to raise the emitter voltage by changing the input voltage divider resistors, however you need to keep in mind the RC filter change due to the resistor(s) change and also the hfe x the emitter resistor part of this.

sim of first stage moving the volume control wiper

green is max volume and max tone

[digi2t]

Did the first collector voltage measure around 2.4VDC with a higher hfe 2n5088 and 2.2meg feedback/bias?

Nope. Reducing the original 47K to 11K (using a trimmer) allowed me to adjust the voltage to the 3.2V spec'd on the schematic. I'm using my Geofex Spyder as the power supply, which gives me a nice stable 9.05V. I did the same for the B and E voltage on Q2, using trimmers to bring the voltages to what was spec'd, hence the weird 640K value on Q2 B leg.

You are also running the transistor more toward saturation with the 2.2meg instead of the 3.3meg the collector voltage is lower this also reduces the max closed loop gain (2.2meg vs 3.3meg).  This is a higher gain area of biasing a transistor (higher open loop gain).   IIRC there is something about this in "The Art of Electronics".

Like my bro Jimi, I'm still pretty noobish at the tech aspect, but what you're saying makes sense to me (and my ears! ). To be honest, I didn't have a 3.3M resistor on hand, but I did have 2.7M, and 4.7M's. With the 4.7M, it's too fat and muddy, especially when hitting the strings hard. It was better with the 2.7M, but I liked the 2.2M the best. Again, having the trimmer on Q1C allowed me to tweak the voltage whenever I made changes. I did try some 2N3904's, and some BC108B's, but the 2N5088's sounded best to me. Using different transistors will require slightly different resistor values to bring the voltages to schematic spec.

I'm going to try a few other different transistors today, as well as some vintage Sylvania 1N450 diodes that I picked up from Goldmine recently. I try and shoot a Hen's Tooth video later today.

[Gus]

A little off topic.   
Look at the first stage of the BMP note the series 39K

First stage of a two transistor wha

FF like circuits the feedback/gain resistor/part of Q1 bias, is the resistor from Q2 emitter to Q1 base (think of it as a buffered  Q2 collector .6VDC or so lower, In R.G.s writeup) one reason the feedback resistor is a circuit adjusting point.  sometimes lower than 47k to 100k or even larger in one effect with a pinch control

The electra circuit

Note what any circuit with a C to B resistor has connected before it.

This can be part of the interactive control a guitar volume control has with an effect

What was the temperature you adjusted the collector to 3.2VDC have you looked at the voltage and checked the tone at different temperatures?

[pinkjimiphoton]

hmmm, shouldn't that have started off at R81 tho? seems to me like there should be a whole nother stage before it...i'd think input at the top of r81 maybe?

dino, you seem to have found that kustom fuzztone.. it does make your guitar sound like a tele with spank and a nice sustain.

guess i'm gonna get on this for shits n grins,  i realize it has a weird fet of some kind but thinking maybe just replace it with something more common?

shoot, maybe i'll just vero it up.

[digi2t]

hmmm, shouldn't that have started off at R81 tho? seems to me like there should be a whole nother stage before it...i'd think input at the top of r81 maybe?

Yeah bro, I thought about that, but I didn't feel like putting a pot at the front end. Ditto for C36 and R80. I just figured that the 0.047 would be a good front end. I don't think that the fets really contribute anything to the sound (I may be wrong), I think R.G. is correct on the switching duty call.

What was the temperature you adjusted the collector to 3.2VDC have you looked at the voltage and checked the tone at different temperatures?

Seeing as how the transistors are silicon, I never thought that temperature would be an issue, but I can check that. We've got the basement at 20 degrees Celcius, so that's what I got 3.2V at.

[pinkjimiphoton]

i've kinda liked the pot at the front end on some things, like the perc and the heathkit. even if i do tend to leave 'em pegged.

remember too, i believe this fuzz is after the preamp circuit, too, so maybe it's something to try in an effects loop? maybe i'm wrong, my printer is out of ink
and i can't get the whole schem on my puter at a size where i can see it all and still see what it says.

hey gus? i'm thinking you're cautioning us that temp extremes can mess with the silicon based circuits too?
is there any way to compensate for that effect? does it have to do with the actual biasing of the transistors, i mean, like is one bias range much more optimal,

boy...

i suck at this,

is that why you shoot for a bout 1/2 the power supply voltage to the fuzz's c, so you have the most margin for a stable circuit if temperature changes the circuit somehow?


boy. time to shut up, i'm sure this is a loaded question for which i should be flogged, but i still crawleth from the slimey nether regions of understanding the art of fuzzyness.

but i know what i like.


so, i'm gonna try and build one up too, but include a random fet of some kind as an initial booster and see what happens. i always liked the sound of kustoms anyways, so maybe it'll be something hip, or maleable enough to corrupt into a hopefully decent fuzz.

life is too short not to try every fuzz ever made, i tell you. too short.

[digi2t]

i believe this fuzz is after the preamp circuit,

Effectively bro, so the input signal might be boosted. I'm also wondering if Q10 is switching or boosting? I'm looking at different types of mosfet boosters right now, trying to figure it out.

[R.G.]

i believe this fuzz is after the preamp circuit,

Effectively bro, so the input signal might be boosted. I'm also wondering if Q10 is switching or boosting? I'm looking at different types of mosfet boosters right now, trying to figure it out.

In studying the circuits preparatory to an assault, I believe the dual-gate MOSFETs are all used as semiconductor switches.

I believe that the structure of these much older MOSFETs may not have the inherent body diode of modern vertical or lateral MOSFETs. There's not much info on this available, and it may come down to setting some up in test fixture and trying them.

[pinkjimiphoton]

i sensed a calm before the storm....

go, rg!! can't wait to see what comes of it!!

dino, any chance you can try the breadboarded fuzz thru an fx loop?
maybe it will offer a glimpse at what they intended?

seems to me, what you describe sounds pretty good!!

[digi2t]

dino, any chance you can try the breadboarded fuzz thru an fx loop?

Hmmm....

Plugged a Rangemaster type circuit in front of it. Not bad. Gives the fuzz more pop, but then again, a Rangemaster in front of a fuzz generally always does. Tried an Omega booster in front, again, similar result to the Rangemaster.

I plugged my Gemini III Dual Fuzz in front of it, and all I can say is,

NASTY!

A real synthy type of fuzz with the GIII running maxed out in front. What's really neat is running the neck pup with the tone at 0. It gets really synthy, with incredible sustain. By "sustain", I mean real sustain, not feedback. I'm running through my little practice amp, and I've got the headphones plugged in, so feedback is a non-issue. Just really fat and synthy. Fuzz on steroids. Not great for chords, but single note passages are PHAT!!

I would be really tempted to run this circuit after any of my fav fuzz pedals, and kick it on for solos. Really juices things up. 

[pinkjimiphoton]

suzy q my ass!!

i'm on it!!

[pinkjimiphoton]

http://www.freepatentsonline.com/3812278.pdf

look what i found.

the fuzz circuit is from q8 on. i swiped a screen shot from the pdf, which i couldn't download... but it makes it clearer for breaking this thing up!

[R.G.]

Ok, that clears things up a bit! 

[pinkjimiphoton]

sweet.

RG, you may glean more from the link there... the patent goes into great detail, way above my pay grade tho.

[analogguru]

So now we know that the "invention" of this Fuzz circuit was filed on Feb 1, 1972.  The nearly identical Sam Ash Fuzzz Boxx already existed in 1967.  And here the "inventor" tells us, that he doesn´t have any clue of this fuzz circuit:

The clipped output waveform is amplified by the transistor follower Q-12.....

Sorry, but a buffer is only a buffer and doesn´t "amplify" anything.....

Enjoy building a Sam Ash Fuzzz Boxx (Astro Amp - Astrotone).

analogguru

[digi2t]

http://www.freepatentsonline.com/3812278.pdf

look what i found.

the fuzz circuit is from q8 on. i swiped a screen shot from the pdf, which i couldn't download... but it makes it clearer for breaking this thing up!

Nice find bro! You got WAY too much time on your hands.

Page 9 gives the lay of the land for the fuzz section. All the FET's (Q8, Q9, Q10) are for switching. The fuzz circuit begins at C36 (take out Q10, that's for switching). The signal being sent here is preamplified, so clean boost in front to some degree would be desirable, hence the input (EFFECT) pot too. Maybe try a SHO, or mosfet booster in front?

EDIT:

So now we know that the "invention" of this Fuzz circuit was filed on Feb 1, 1972.  The nearly identical Sam Ash Fuzzz Boxx already existed in 1967.  And here the "inventor" tells us, that he doesn´t have any clue of this fuzz circuit:

Yeah, I read that too!    Then again, if you look at the history of Kustom, their ownership, and why they went under, the aforementioned claim is, ahem... understandable.