Hi all,
I just dug up and re-read the Tonebender thread of awesomeness:
http://www.madbeanpedals.com/forum/index.php?topic=5623.0
My reason for doing so is that I just built up the following MkII variant, a Supafuzz to be exact:
http://tagboardeffects.blogspot.com/2012/02/marshall-supa-fuzz.html
So, my first impression is that it rocks--total Ron Asheton tones. I went with the Supafuzz specs because I thought the additional bass would complement my Mustang well. I just have a couple of questions:
1) Is there an ideal bias range for the Q3 collector? Are there any other bias points to check? I'm using 2n1305s of 74, 83, and 103 hfe for Q1, 2 and 3 respectively.
2) This one is a bit harder. The circuit initially didn't fire up--turned out the 10uf input cap I grabbed at work was bad; you could even see some residue at the base of the negative lead! I thought I had fried it on my test rig, even though I hooked it up with the test leads reversed for positive ground, etc. After changing that, it did fire up, but gradually, like no sound at first, then a clean-ish sound coming through, then the full fuzz. I hooked it up for the second time last night--kind of the same deal but it came to life much quicker.
Now, I know it's an unruly circuit, but is this normal? It was funny--the level of gain (or the bias?) almost seems to change on its own. Could the 47uf cap, which I believe is the power supply, be iffy? I initially had it in the wrong spot and had to move it, and it got pretty hot when I was soldering it to the place it's actually supposed to be. Then again, I was also testing it out of the box, during summer, in a room with a ceiling fan going. Too many variables, I know.
3) And lastly, how essential is it bump the 470r resistor up to 1k? I think I may be getting sub-unity output, but it's hard to tell without it hooked up to a switch to a/b it with the clean sound.
Thanks for all your help and for the research you undertook on the circuit last year!
Cheers,
Bret
Hmm its been a while since ive played around with the biasing in my MKII's but I could check the collector voltage on Q3. That last gain stage looks exactly like a fuzz face though and it has a coupling capacitor before Q2 so I would think Q3 is going to float around 4.5v like a FF. I have heard some people bumping it up though but I think I tried it once and it didn't help much.
That is really weird about the sound fading in. To me it almost sounds like a capacitor is charging up or something. It definitely doesn't sound right though. I would maybe go through and swap some of the electrolytic caps around the power supply and maybe that emitter bypass cap as well.
It is all up to your setup really whether or not you would like to change out that 470R. Note that it also adds some low midrange when you change that value. I swap that value out to beef up FF's some times. I would say play with it and see if you need more volume. With all the MKII's I've built though I never had to bump it up.
Also to get a more balanced bass sound (the MKII can be a treble monster!) I would slowly bump up the 10nF output cap and increase the value of the volume pot to 500K.
Thanks Paul, that is helpful. I think I'll at least change out the 47uf cap where the -9v comes in and see what that does. This is what I get for just digging for parts at work! I have no idea how old the electros are.
Also, I'll check out the bias tonight and just see where it is at the moment.
The MkII doesn't follow the Fuzzface biasing convention, while you may like it there in general vintage units measure around 7-8v on Q3s collector.
But yes I agree does sound like a bad or wrongly orientated electro charging up.
Thanks Scruffie--now I am wondering about an incorrectly oriented electro. I know I've got the big axial one right. But on the two radials, I had a hard time telling what was the negative side so I tried to look at the schematic to see. I think negative is the lighter-colored area on the ring that represents the electros' shells.
Would you mind looking at the layout I linked above and let me know if the negative side on those two radials should indeed be facing "north" i.e. the top of the board?
Quote from: Bret608 on July 31, 2013, 08:45:31 PM
Thanks Scruffie--now I am wondering about an incorrectly oriented electro. I know I've got the big axial one right. But on the two radials, I had a hard time telling what was the negative side so I tried to look at the schematic to see. I think negative is the lighter-colored area on the ring that represents the electros' shells.
Would you mind looking at the layout I linked above and let me know if the negative side on those two radials should indeed be facing "north" i.e. the top of the board?
Yup that's right :)
I tuned my mkii by ear then measured it@ 6.6 v sounded good.
It just so happens I am building a MK II too :) Just finished it last night - no sound :D
damnit. I measured almost perfect voltages, btw, when we are at it, what should be the voltages here? I am asking because voltages that I found on freestompboxes, home-wrecker, and general guitar gadgets are totally different. Although those on FSB and home-wrecker are in a similar ballpark. Pretty close.
I wonder why I get no sound...hm, gotta be a soldering error. Been on an error streak lately, I gotta take a vacation from this guys haha. Cheers
P.S. I found some excellent info about mk II tunning and a lot of other stuff thanks to you guys and the epic thread that Bret mentioned, great stuff!
P.S.2. How come that EVERYONE is frightened of doing an MK I? I mean, anywhere I go there's a person saying that doing a MK I is incredibly hard. And I am like, how harder that dialing a good sound of a fuzz face can it be, for example... What do you guys say?
P.S.3. And a question for you guys that made MK I and MK II, which one has more gain, which one has more bass, which one has a more focused sound, and which one has less spitty less gated-y sound? Thanks!
Quote from: Cortexturizer on August 01, 2013, 09:14:04 AM
It just so happens I am building a MK II too :) Just finished it last night - no sound :D
damnit. I measured almost perfect voltages, btw, when we are at it, what should be the voltages here? I am asking because voltages that I found on freestompboxes, home-wrecker, and general guitar gadgets are totally different. Although those on FSB and home-wrecker are in a similar ballpark. Pretty close.
I wonder why I get no sound...hm, gotta be a soldering error. Been on an error streak lately, I gotta take a vacation from this guys haha. Cheers
There were some vintage unit measurements on the D*A*M forum, seems I saved them;
OC75 MkII (10K on Q1 base, 47K on Q2 collector)
Battery -9.01
Q1 c -8.50 b -0.038 e 0
Q2 c -0.13 b -0.076 e 0
Q3 c -8.29 b -0.13 e -0.08
OC81D MkII #1 (100K on Q1 base, 100K on Q2 collector)
Battery -9.55
Q1 c -8.51 b -0.06 e 0
Q2 c -0.13 b -0.068 e 0
Q3 c -8.72 b -0.13 e -0.07
OC81D MkII #2 (100K on Q1 base, 100K on Q2 collector)
Battery -9.50
Q1 c -8.76 b -0.062 e 0
Q2 c -0.22 b -0.075 e 0
Q3 c -8.13 b -0.22 e -0.14
Fantastic, I'm gonna measure mine and post them asap.
Thanks Scruffie!
Please address my other questions as well, if you don't mind :D
And I have another one - what about leakage?
I read somewhere that the circuit needs leakage to even work properly. Some wrote it is for Q1, and others that you need leakage on Q3. I suppose the latter is right..
Glad to see more folks are joining the conversation and feeling the pain! :D Well, mine does more or less work at least, just not consistently.
For what it's worth, I measured the bias on the collector of Q3 last night. I'm getting 6.3 volts pretty consistently--it only varied from 6.31 to 6.34. I've got 10k on the Q1 base and 47k on the Q2 collector as in Scruffie's first example.
Let me know if this points in any particular direction!
I used a 2kb pot for fuzz like the mindbender specs with good results.fwiw
Sorry for the unceremonious bump! ;)
So for you folks with TB MkII/Supafuzz experience, does that 6.3v on the collector of Q3 sound suspect? If that is off, I most likely would suspect the 47uf power supply cap.
Cortexturizer, how is yours coming? To try and touch on your question about the difference between MkI and MkII sounds, I think the MkI tends to be more gated and temperamental, whereas the MkII wants to sustain forever. I think people get scared off of the MkI because the circuit is picky about transistors in a big way!
Quote from: Bret608 on August 02, 2013, 04:13:03 PM
Cortexturizer, how is yours coming? To try and touch on your question about the difference between MkI and MkII sounds, I think the MkI tends to be more gated and temperamental, whereas the MkII wants to sustain forever. I think people get scared off of the MkI because the circuit is picky about transistors in a big way!
Well, mine is behaving like a little biotch ;D Here I made a clip of it, it can have wonderfull sustain, but is either gated or absolutely oscillating like crazy!
Here's the clip
[soundcloud]https://soundcloud.com/kuato-design-stompboxes/problematic-bender-behavior[/soundcloud]
FIrst I play with the bias trimpot and the Attack pot, and you will hear some really crazy sounds and oscillations. Then I bias it somewhere [hadn't looked] and play with the Attack pot, it sounds great but has all sorts of oscillating sounds underneath.
Then I put the Attack on zero, and things become better. It can have crazy sustain and is pretty gainy, but as soon I even touch the Attack pot it becomes absolutely unpredictable and really starts to struggle with me playing :) [a great example of this is at the end of the clip, I am having the attack on zero and then suddenly start turning it from zero to max in equal increments and it sounds like I am playing a synth]
It's crazy that I like it the way it sounds now ;D
but of course, I wanna make it sound as it should.
This on the clip is just like 15 different sounds concatenated, after every sound I changed something.
Hey Cortexurizer,
Thanks for sharing--I had a chance to play with mine a bit more this weekend. I don't have an adjustable bias, so I wasn't getting as crazy of a sound as you, but the "normal" sounds are very similar. I have a quick question:
How do you find the volume knob interacts with the circuit? Mine cleans up very nicely, but there are some scratchy sounds as I'm actually turning the pot. I'm not sure if this is normal for the circuit or not.
I'm happy to report I'm not having the "charging up" issue any longer. The circuit is behaving a bit more stable and as expected. I wonder if, after I changed out the bad input cap, the new one was maybe a little old and had to "burn in" a bit at first?
Also, for what it's worth, I changed Q3 to one with the same hfe but slightly more leakage. After doing so, the collector on Q3 gets much closer to 7v (6.8 or so). To my ears, this did give a slightly improved sound.
Cheers and good luck,
Bret
Sorry, late to the party! Glad to hear it is working out for you. My best MKII tips are to put a small 220-470 ohm resistor in series with the -9v power going to the board, this can help quiet down a noisy build and make sure to filter the power too, lower gain in Q1 is good, and a little more leakage is ok in Q3, and sometimes helpful as you described. FWIW I didn't have to do anything special to get the nice 1590a MKII stomptown (Jon) is selling to work great, see my comments in his FS ad here.
100, 0.04
74, 0.03
56, 0.121
102, 0.032
128, almost no leakage?
I measured the Ge trannies that I have left, and the clip was recorded with this combination
56, 0.121
102, 0.032
128, ...
I tried other combiantions but they either produced no sound, or sounded pathetic.
I feel like I end up writing this once a month, probably because there's so much misinformation out there about biasing a Tone Bender MKII compared to a Fuzz Face:
David Main (of D*A*M) measured vintages ones and said he found between 7.9-8.6 volts on Q3's collector.
Thanks Scruffie for posting those measurements with the other transistors too!
Quote from: timbo_93631 on August 06, 2013, 03:35:09 AM
Sorry, late to the party! Glad to hear it is working out for you. My best MKII tips are to put a small 220-470 ohm resistor in series with the -9v power going to the board, this can help quiet down a noisy build and make sure to filter the power too, lower gain in Q1 is good, and a little more leakage is ok in Q3, and sometimes helpful as you described. FWIW I didn't have to do anything special to get the nice 1590a MKII stomptown (Jon) is selling to work great, see my comments in his FS ad here.
Thanks Tim! Based on the tone you were getting in the clip you posted, his board is worth picking up. I've about got my build squared away but for a little extra noise and static when I play with the volume pot. I think I have enough trannies to do another though if the mood strikes me! :)
@Cortexturizer
now here's a just a 'random' thought...
did you happen to wonder that you are dealing with temperature unstable semiconductors and the fact that you are working in extreme temperatures of 40°C/104°F got something to do with it!?!
try to cool it down and see what 'll happen. 8)
[soundcloud]https://soundcloud.com/kuato-design-stompboxes/tb-mkii-professional-first[/soundcloud]
So i started from scratch, made another one, and this one is killer. It is incredibly quiet, still unboxed.
I used this combo
56, 0.121 [unknown transistor from smallbear purchased ages ago]
74, 0.03 [gt308V]
100, 0.04 [gt308V]
What you can hear in the clip is the new circuit with Attack maxed and playing with the volume pot. I start with the tele deluxe bridge pickup rolled back to almost zero, you can hear how nice this thing cleans up. And the bias was set by ear, and when I measured it it was 4.5V! Ha! I tried higher values of course but I am undecided whether I like em. Haven't even tried this on an amp.
I did the following mods:
replaced 470R resistor with 1k5 for lots of volume and that low mid thing
put a 100K trimpot in series with a 10K resistor as Q1's base resistor [this is great for fine tunning]
put a 100R resistor from the emiter of Q3 to Attack pot [probably should put a liiiiiiitle more cause there's still a slight buzz when Attack maxed]
25K as a Q3 biasing trimpot
220n PIO instead of the 100n cap on schematics
Pretty satisfied.
@ummagumma
Haha de si matoriiiiiii :D
Ma nesto sam zeznuo pri samoj izradi...prihvatio sam tvoj savet od odavno...bolje napraviti novo nego provesti vecnost gledajuci gde je greska. A vec sam pola vecnosti trazio gresku...no sad odlucih da ga napravim opet i radi uber i neverovatno je tih, ne mogu da verujem koliko. Pozdrav care :)
That sounds great! I played through mine again this morning and am now extremely pleased. I wish I had a way to record so I could share too, but then again unleashing my poor playing on you all may not be too friendly!
I was not getting any extraneous noise or crackle when I tweaked my guitar's volume pot. Two things that may have made the difference: first, I dialed back the volume knob to where it was just above unity rather than utterly slamming the amp's front end. Also, it was a bit cooler here this morning than it was last time I played with the circuit. This ties back to what ummagumma said--I think any perceived instability in the circuit on my part is an artifact of playing it unboxed in a warm house in the summer.
Okay I think I got this mastered now. Here's a clip
[soundcloud]https://soundcloud.com/kuato-design-stompboxes/wooz[/soundcloud]
Attack close to max, and playing with the volume knob. It has the most sustain ever.
I biased it by ear. For the Q1 base resistor now I have a 100k and a 100k trimpot in series. Still a 25K trimpot for the Q3 collector. I biased the two by ear and this is what came out.
I am absolutely satisfied with the sound now.
Oh, and I put the cap that goes from Q1 to Q2, normally a 100n, well I put it to be a 10n. I made it for a friend and we felt it had too much bass, so I decided to cut some there.
What do you think guys?
And I suddenly realised that I just used a battery that measured 6.14V!!!
I had two of them, exactly alike, on my desk, and I thought I got a brand new one, but no, what I got is the old one which was standing there for months.
So go figure...What an incredible improvement in sound. From a dead battery.
Oh to hell with this, I'm done for tonight.
No, I am not done.
I just tried the brand new battery and it behaves the same, just has a buzzier sound, which is to be expected, since the bias is higher.
So, with my battery being 6.4V, I got 2.8V on Q3 collector and 0.16V on Q1 base.
With the battery on 9.3V, I got 4.9V on the Q3 collector, and 0.16V on Q1 base.
I prefer the first sound. Did Hendrix used to give batteries to his rodey and get em when they were way down? Heh.
Hey cortex,
Maybe you could throw a voltage sag potentiometer into the circuit.
I know the zygote has one built into the circuit..... Have not tried it, but it could be set up to give you your preferred dead battery sound.;)
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Quote from: Cortexturizer on August 08, 2013, 11:55:28 PMI prefer the first sound. Did Hendrix used to give batteries to his rodey and get em when they were way down? Heh.
The Fuzz Face clone on my board has external voltage and bias. I regularly run it closer to 5V. Also, the Selmer Buzz Tone ran on a 3v battery. (I think the Maestro did, too?)
If you were using an adapter, I'd tell you to just order a 6V regulator (those exist), but in this case, a 10-25K pot in series with the -9v source is probably less wasteful (electronically). It's not like there's a danger of overheating. Or you can just use a trimmer or -- best -- a fixed resistor that drops the voltage however much you need.
Both wonderful ideas, and I can't believe I haven't thought of the voltage sag thing and I've known about it forever.
And yeah, Maestro did run on 3V.
I'm gonna put a trimmer inside definitely.
How do you like the sound guys?
I think it sounds great! I love that a few changes to the part values lend such possibilities for tailoring the sound and response to your particular setup.
I can never even see the sound clip links on my mobile device.....grrr. It just looks like empty space in the post
Sent from my PG86100 using Tapatalk 2
ummm..... I don't thing we got a good enough sound clip. Need to dial up on the volume and a pinch of gain and run some (lots) of zeppelin through that bad boy ! LOL
Beautiful sound / build sir ! bravo
Quote from: Cortexturizer on August 08, 2013, 11:38:27 PM
Okay I think I got this mastered now. Here's a clip
[soundcloud]https://soundcloud.com/kuato-design-stompboxes/wooz[/soundcloud]
Attack close to max, and playing with the volume knob. It has the most sustain ever.
I biased it by ear. For the Q1 base resistor now I have a 100k and a 100k trimpot in series. Still a 25K trimpot for the Q3 collector. I biased the two by ear and this is what came out.
I am absolutely satisfied with the sound now.
Oh, and I put the cap that goes from Q1 to Q2, normally a 100n, well I put it to be a 10n. I made it for a friend and we felt it had too much bass, so I decided to cut some there.
What do you think guys?
This sounds great man! Like it a lot! What kind of amp and axe are you using in the clip?
Thank you pedalman and jrod!
Yeah, sounds awesome now, expect a build report veeeeery soon :-)
As to the setup being used it's a Fender Roadworn Tele Deluxe bridge pickup ran through Line 6 UX1 and into POD Farm and it's fantastic vox ac30 sim. So unfortunatelly, no amp here,but I am glad I got you fooled :-D
Midwayfair and chinaski, I put a 10k trimpot (all I got) in series with -9v and as soon as I turn it just a tad,i get some sort of ticking which becomes harder and harder as I turn more. i can play the bender but if i hit the strings really really hard the sound disappears for a moment and then gets back...i don't understand this behavior
Hmmm....uh, Jon? Paging Mr Patton.....
I'm bit unsure, as I've not incorporated the sag pot into mine yet. And I'm out and about.
Maybe I'll look at the way it's set up on the zygote....
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Cortex, is the trim pot set up before or after the electro cap coming off the supply?
I think it should be after....
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It's before. Hm...
Ok, got it boxed and tuned, [the voltage sag problem remains, but will solve it later].
I won Elle magazine's local photo competition with one of my pictures taken from the Greek island of Paxos, and they awarded me with Samsung WB250F camera, yay, so expect some videos of my pedals in the future.
It's funny though, I made the picture with my Minolta analog camera which I intend to continue using exclusively [or some other analog camera] and they gave me a brand new digital camera, haha. Of course I am satisfied with the gift, it will be used mainly for HD sized video though. Here's one of my Bender MK II:
The amp was the loudest I could get it in an apartment and not woory about the neighbours, but I intend to record a new video once I post a build report which I hope will be better...this one is just to get the feel of the sound and pedal behavior and way it reacts to the volume knob.
The settings were Volume and Attack halfway up.
Battery 6.4V or lower.
That was half up on controls? This thing must really scream!
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Yep, it does!
Although, I don't know why my voltage sag thing doesn't work, I cut one of the outer legs of the trimpot and connected let's say lug 2 and 3 in series with the -9V rail and it just behaves bad. Makes a choppy tremolo effect and the sound is disappearing on me if I only touch the sag trimpot. Any ideas guys?
What kind of trim pot style do you have? Some styles have metal under the spot where you adjust them, and using a metal screwdriver to adjust it causes a connection.
Have you checked the voltage after the trimmer?
Take a look at the zygote schematic, it has the voltage sag control
hi I built a MKII with Marshall spects, it sounds great but the vulume is low... too low compared with a fuzz face. do you know any trick to fix this?.
http://fuzzcentral.ssguitar.com/mkII/supafuzzschematic.gif
Change the 470R resistor to 1K5. I did it to mine. It's very loud.
thx man.....