Oh my... what a beauty. This is my dad's guitar that he bought and modified in the early 70's as a student at Berklee, on a seriously tight budget.
http://ghostsauce.net/random/pics/DadsTele-01.jpg
http://ghostsauce.net/random/pics/DadsTele-02.jpg
http://ghostsauce.net/random/pics/DadsTele-03.jpg
http://ghostsauce.net/random/pics/DadsTele-04.jpg
http://ghostsauce.net/random/pics/DadsTele-05.jpg
http://ghostsauce.net/random/pics/DadsTele-06.jpg
http://ghostsauce.net/random/pics/DadsTele-07.jpg
http://ghostsauce.net/random/pics/DadsTele-08.jpg
http://ghostsauce.net/random/pics/DadsTele-09.jpg
He put a Dimarzio super distortion in the bridge, a humbucker from an old Gibson les paul in the neck, and got another student to design a circuit that could make the sound in his head, and then he installed that into the guitar. And oh man, it's a good sound: http://ghostsauce.net/random/Dad's%2068%20FrankenTele.m4a
It's buzzy right now, I've got to give it fresh wires. In that clip I'm using the guitar into a Marshall Class 5, set crunchy. You'll hear the bridge pickup, then neck, then bridge + fuzz. The fuzz just swamps the amp's V1 in a beautiful way. :D I'm gonna trace out the fuzz circuit after all is said and done, but for now it's just a mystery to me. Any ideas what it could have been derived from?
Berklee or Berkeley?
Berklee college of music, Boston: http://www.berklee.edu/
Unless there's two in Boston.. idk
Familiar with it. Just wasn't sure if you were specifying the school you thought you were. Besides, you gotta admit, that IS the sort of guitar someone attending Berkeley in 1970 would have been playing.
I was wondering if you had managed to get Norman Greenbaum's Telecaster that had been modified with an on-board fuzz as used in "Spirit in the Sky". He eventually sold it but never knew what the circuit was that had been added in it, so it remains a mystery today.
Hah, neat. No, definitely not the same one though. The guitar was stock when dad got it, and with the money he had he turned it into the guitar he wanted. Dad and the guy who built the fuzz sat down and turned the circuit into the tone in dad's head. Just thought it'd be cool to figure out what it used to be and how far away it landed.
I may build one up in stompbox form sometime
Now listen. First of all I CONCUR that I almost did the same things to my TELE in the effort to make it better! OTOH, is there only one transistor there? If so, wouldn't that be a boost? I don't see diodes there at all.
Super Distortion? Your father has good taste! :-)
Looks like maybe 10 minutes of work to trace out the circuit.
Got good, clear photos of top and bottom sides?
That's the coolest Tele I've ever seen. What the hell do all those switches even do?
The stuff on the front are for different phase options, fuzz/boost on-off, battery on/off, tone knob for the fuzz/boost. There is one switch that needs replacing, and I think it is a coil split.
Idk, it's gotta be doing more than just boosting it... it gets this fuzzy clipping thing going on that I can't get out of my amp with a boost, and I've tried a lot through my class 5. And I can get it to do that with the amp clean.. Sounds like nothing I've ever heard. I'll be taking it apart and putting fresh wires throughout, and I'll trace it out then.
Took another clip - http://ghostsauce.net/random/Dad's%2068%20FrankenTele%202.m4a
Should've tuned.. in a rush for work. Bridge pickup used throughout. First the amp's setup very clean, played a few bars without the boost/fuzz engaged, then kicked it in. Definitely not a clean boost. Then I set the amp up dirty and did without/with once more.
That low-end "flatulence" is nice. Seriously.
Quote from: Mark Hammer on May 23, 2014, 08:19:22 AM
That low-end "flatulence" is nice. Seriously.
... almost like a mosfet!
To add a little to R.G.s post.
Post a picture of the trace side of the PCB. Someone could trace it from that with a good top and bottom side picture and part values.
#8 is a good start
Quote from: Mark Hammer on May 23, 2014, 08:19:22 AM
That low-end "flatulence" is nice. Seriously.
+1!
Quote from: amptramp on May 22, 2014, 02:26:41 PM
I was wondering if you had managed to get Norman Greenbaum's Telecaster that had been modified with an on-board fuzz as used in "Spirit in the Sky". He eventually sold it but never knew what the circuit was that had been added in it, so it remains a mystery today.
A little off topic, but Tim D made a simple 386 based fuzz that emulated N.G.'s fuzz. Actually, that might be the only tune you'd want to play through it. ;)
Build:
http://www.diystompboxes.com/smfforum/index.php?topic=99943.0
Sloppy Clip:
http://www.diystompboxes.com/smfforum/index.php?topic=103248.msg919082#msg919082
Any headway with this one? +1 for fuzz flatulence! It's my favorite part. 'Round these parts, we call that "Blurt", y'know that sputtery fighting compression before all the sound can get outta there? :icon_twisted: yea, that's the good stuff
Quote from: Brossman on May 26, 2014, 12:50:38 PM
+1 for fuzz flatulence! It's my favorite part. 'Round these parts, we call that "Blurt"
Oh I get it, like that guy with the segway
(http://www.wired.com/images_blogs/photos/uncategorized/2009/01/14/blartdragged250.jpg)
:D
Anyway, I put it back on the bench yesterday and started putting fresh wires through it. This could end up changing the strength of the fuzzboost, cause 2 or 3 of the wires connecting it were hanging by threads and actually fell off even though I was being very careful to avoid it. So we'll see if I got everything back together right, haha. I'm also shielding the fuzz cavity at least, and probably the whole thing while I'm at it, to help any noise issues. Getting a bunch of pics of the board and I'll try to get those up soon.
OK! So a lot of time has gone by, but I finally fixed up the guitar like I wanted. I kept the same vibe but dropped a new pickguard and bridge in so that everything lines up the way it should:
http://www.ghostsauce.net/random/pics/DadsTele-14.JPG
And now I am trying to duplicate the fuzzboost circuit and drop it into a pedal for my dad for Christmas. :D But I need help.. it works with the exception that it is too quiet. The output is quieter than the bypassed signal. I currently have it hardwired to some jacks and am using a true bypass looper to turn it on and off while I fiddle with it. I need you guys to help me make this thing work if you would.. so here's pics of the original circuit in the guitar, and a traced layout:
http://www.ghostsauce.net/random/pics/HC1.JPG
http://www.ghostsauce.net/random/pics/HC2.JPG
http://www.ghostsauce.net/random/pics/HarmonicClipper01.png --> original onboard circuit
http://www.ghostsauce.net/random/pics/HarmonicClipper02.png --> What I built
Dad had named it the harmonic clipper because of how it was chopping off the top n bottom of the wave. :D But anyways, what on earth did I do wrong? I thought maybe the gain of the 2n2925 I'm using was too low, so I tried my other two and same problem. I tried a 2n5088 too and it sounds the same.
I might have mixed up the input/output of the circuit, but I think I got it right. It sounds the same both ways though, haha. Actually, I did use a 100k trimpot instead of a 2k, but I think that's ok. At the furthest clockwise it there is no sound, then soon after you get sound and it slowly grows louder until you get to full counter-clockwise. Idk.. is this my problem?
Here's the schematic based on your layout. Can't tell if it's correct from your images unless you want to say what wire is going where.
(http://i246.photobucket.com/albums/gg114/mth5044/Harmonic_zps3avmksiy.png)
If only I remembered the 1000 times someone told me how to resize images.
EDIT: hang on, missed a part
Cool. The only two wires I didn't describe was the two red wires, and they just break the + connection to the battery via a switch. I guess they didn't think to use the output jack to disconnect the battery. :D
Hang on, missed a part. Alright, fixed.
The 100k is a problem, unless you are using a multiturn trimmer.
I simulated the schematic. As you go past the maximum of the trimmer that's supposed to be there, you continue to lose voltage/volume. At 5k, you get equal voltage swing compared to the input. After that, say 10k, you have already lost have the voltage swing. That's only 10% of your trimmer. With the normal trimmers, it's very hard to get the kind of accuracy that you'd need to keep in in the 2k range. If you have a pot of smaller value, 5k even, use that instead and put it on the outside of the enclosure.
Aha, ok.. figures. I do have a 2k here that I'll try. I just grabbed the wrong one by mistake when installing it, haha. I didn't think it was an issue... I'm gonna go try that now.
The only other tweak I made was to make the tone knob switchable by using a DPDT to simultaneously break the connection between C1 and Q1, and also C3 and R3. So when it is engaged it gives you the whole spectrum, which is pretty much just a standard boost, except it's still quiet because of the issue I'm having. I think it'll be nice to have the extra functionality when this is sorted, though.
Nope, I tried the 2K but it is even quieter now.
The original trimpot was a Helitrim, and had the markings 77PR2K. I assumed this is a 2K trimpot.. maybe it's more? I couldn't find a designation by googling.
Looking at eBay listings of Helitrim pots, the last number is indeed the value. You tried throughout the sweep of the trimmer? Got pics of your board? Or voltages?
Ok, here's some pics of my build. I socketed C6 and used two .02uf caps in series to give me .01uf. It also has the tone (stack?) bypass switch ike I mentioned above, which breaks connection between C1 and Q1, and also C3 and R3.
http://www.ghostsauce.net/random/pics/HC3.JPG
http://www.ghostsauce.net/random/pics/HC4.JPG
I can't post voltages tonight, but I can reserve some time for that tomorrow.
Yeah, idk. The more I think about it the more I wonder if it has something to do with the gain of the transistor.
Throw a 2N5088 in there.
x
Got it working. Two of the trannies legs are twisted in the original.
BTW it doesn't work with 2n5088 now that I have it working. It stays perfectly clean
Okay! Here's the original version that was mounted off a DPDT in dad's guitar, and a standalone pedal version. May your journey into gnarly fuzz be fortuitous!
Sound clip into a marshall class5. Amp set clean first, then dirty! --> http://www.ghostsauce.net/random/Dad's%2068%20FrankenTele%202.m4a
(http://www.ghostsauce.net/random/pics/HarmonicClipper01.png)
(http://www.ghostsauce.net/random/pics/HarmonicClipper02.png)
I still don't really understand what is going on in this circuit though. It seems like the + voltage off R3 mixes with the signal as it passes between R5 and R6. I don't think that's normal.. or am I wrong? I've never really tried to pick apart a circuit like this before, but I'd love to know.
Thanks for posting the circuit. I about to do a Mouser order and I'll add a couple of 2N2925's. :)
As for the circuit, there are others who know a whole lot more about this,
but I believe the circuit is an NPN Common-Emitter Amplifier with Feedback Biasing.
This is a well known circuit in the guitar pedal world.
The voltage from the power supply thru R3 is a DC voltage. The signal voltage is AC. The AC signal "rides" on top of the DC voltage.
Output Cap C5 blocks the DC voltage from the circuit output so that we're left with the AC signal.
( Fellow Forum members, please feel free to add/correct information :) )
This thing sounds amazing. I might try to breadboard it later and see if I can get anything from other trannies. Pretty certain I don't have any 2925's but I'm expecting some 2k trimmers in a delivery today, so if they arrive I'll take that as a sign that I was meant to do this. Any excuse really!
I wouldn't hold your breath, I don't expect to be able to get anything out of this without the specified parts, I'm probably not knowledgeable or skilled enough to really have any success where you haven't, especially considering you had no luck with a 5088.
I'll report back any unexpected victories and continue to follow this thread with intruige. Thanks for sharing this!
Cool! Try messing with R5, C4 and C5. C4 and C5 are the input and output caps, so they should change bass response in and out.. and I have no idea what R5 is doing, so changing that might have some usefulness. A 500k trimpot could find some cool things there.
I socketed the transistor in mine, so I'm gonna toss some others in myself. I have an old germanium can staring at me right now that could be amazing.
Matt, I redrew your schemo a little bit, and split it into 2 parts. Did that because I'm a moron and wanted to understand how it worked, not because there was anything wrong with yours.
Gain stage:
(http://i.imgur.com/KHZZW8Sl.jpg)
"Baxandall-ish" eq circuit:
(http://i.imgur.com/H1LIemMl.jpg)
It is surprising (for me at least) that the designer chose this approach instead of the more common tone stack, even placing it properly across the transistor's feedback network. This is kind of an engineer's decision - I guess the majority of guitarists-turned-into-electronic-hobbysts would go for a passive tone stack after the transistor. I, myself, love the Baxandall way of eq'ing things.
But, also, it is not a proper, text-book Baxandall (something like this, found somewhere else):
(http://img.bhs4.com/c8/5/c85c07713bcd506244f6a72179bf15d1ed8e5fa1_large.jpg)
Anyway, as presented, Dan's dad circuit is a simple enough circuit to provide hours and hours of tinkering fun.
That's really interesting!
As the story goes, the circuit was the result of tinkering by two students living on a very small budget, without much knowledge of how then modern day guitar effects manufacturers were doing these things. More of a 'read a couple books, tinker until you get something that sounds cool' kinda deal. No google back then!
Wow thanks for that! Delivery didn't show and I'd forgot both my BBs are occupied. This gives me some reading for the weekend.
I'm guessing then there is nothing overly special about that 2n2925 and that the unconventional tone stage is more responsible for the most of that sound then?
Amazing what you can do with EQ and gain.
When I removed the tone stage via a DPDT like I mentioned before, it was still fuzzy but yeah it sounded like a normal guitar signal fuzzed up. I liked it like that as well, but I couldn't get it to not buzz terribly when bypassed. I think if I use shielded wires and had it been inside the enclosure it would have fared better. I will be attempting that at some point before boxing it up.
I love the fatness of the tone stage though. In dad's words, trying to control the thing "is like a mouse trying to control an elephant on a leash".
Where's this thing getting it's fuzz from, anyways? Without a second transistor or diodes, shouldn't it be only a boost like aron was saying? I first thought maybe it was the bias of the 2n2925, but I'd think it would sound gated if it just wasn't getting enough voltage, and the 5088 is just purely clean.
> it is not a proper, text-book Baxandall
I don't see any relation to a Bax or James tone-control.
It is a Twin-Tee. You find Twin-Ts in older Gibsons, sometimes sprinkled like salt, rarely variable.
Bass passes through R1 R2.
Treble passes through C2 C3. (C1 is just a coupling cap and may have nothing to do with tone shape.)
It can be sensitive to source and load impedance.
Twin Ts usually give a mid-range dip, though many alignments are possible, and with heavy loading a small mid-boost is possible.
Mid-dip is characteristic of the classic Fender X-Face amplifiers for many settings of the B M and T knobs.
However this Twin-T is inserted in the feedback path? Then mid-dip becomes mid-cut, all is backward. If the forward amplifier had infinite gain, you could study the Twin-T abstractly. But 1-transistor is far from infinite gain, and you have to consider them (and R4 and other stuff) together.
I can well believe this wasn't "designed", but "just happened". Schemes like this are incredibly painful to design by hand. It was done for RADAR and some Bell Labs projects, but they had 'computers' (low-pay workers with adding machines and log tables).
Thanks Paul. I'm really looking forward to getting to play with this and try to get my head around how it works.
Very neat, PRR, thanks. Any suggestions on where else to place the twin T for different effects? Adding a mid boost might be nice.. maybe even as a second tone control or something funky like that.
Quote from: PRR on December 05, 2015, 05:25:51 PM
> it is not a proper, text-book Baxandall
I don't see any relation to a Bax or James tone-control.
It is a Twin-Tee. You find Twin-Ts in older Gibsons, sometimes sprinkled like salt, rarely variable.
Yes, you're right. I didn't know how to call it, so as it resembles a Bax a tiny bit I called it "Bax-ish". Never knew its proper name.
So, I'm looking at R5 (470K) right now and wondering. Is this the input impedance? If so, putting it to 1M would probably be more useable and roll off less highs as you adjust the guitar volume, right?
EDIT: hmm, after doing a little more research it may not mean anything on it's own.
Not real sure which schematic you are looking at.
The input is not R5. That is primarily DC bias. Also R5 is levered-down by transistor voltage gain to present a lower impedance to the guitar.
It all gets even messier with the Twin-Tee wrapped around.
Leave it alone for now. The circuit apparently DID work. Pre-thinking is folly. It is not faultless, and maybe is not a sound you want all the time, but it promises to be good for something.
Gotcha, thanks for the info.