About to build a Tonebender MKI. Any advice?

[rousejeremy]

I've watched a couple demos of the D*A*M 1965 and they seem to gate on the decay. I'm finding with transistor swapping with hFe92 Q2 and hFe 123 in Q3 as D*A*M suggests it's either noisy hissy decay or gated.
Not sure what gain I should be aiming for in Q1 though. I'll keep swapping.

[Arcane Analog]

I agree with you. The DAM 1965, while certainly more refined, has that hint of gate which is a staple of the MKI sound - even in the full chords you can dial it in there. That gate mixed with the way the note decays and the ragged/earthy fuzz you get is what the MKI is all about. Primal and beastly. Even the Creepy Fingers demo that was posted has some gate on the decay. From my listening of the demo the only time there is alot of long sustain is when chords are hit hard on the Zonk. When only one is active you get that ragged fuzz with the sizzle on the decay which is obvious at the end of the demo. I do not hear alot of smooth fuzz going on there at all but I guess eveyone has their own definitions of sound. You can certainly get rid of all of the sizzle and gate if you want but that is some of the charm of the MKI.

Loads of long sustain is not really what the MKI is about. You can certainly have "ferocious" amounts of sustain without that sustain carrying on for a long time. that's what i think of when I think MKI. If you want loads of singing sustain you build a MKII. If you want that primal fuzz of the 60s like the Yardbirds or the Spiders you throw down the MKI. If you want 'Ziggy' Ronson you get the MKI and hit it with a Wah which pushes the fuzz and removes that gate and gets you more sustain. Lots of fun!

I have spent quite a bit of time on this circuit and built several pedals for different customers. I have developed a preference that mimics some of the preferences posted by several builders I very much respect (SonicVI, Creepy Fingers, DAM, etc). Mind you don't take that as me saying that I can build a MKI that rivals these builders at all. I simply like the vibe they have and try to get there myself. I have built a MKI that had more of a splatty gate on full chords yet still retained the agressive signature ragged fuzz tone. More extreme but kind of fun albiet a one trick pony.

You can use trimmers until you drive yourself crazy but if you pick the right leakage and HFE numbers for each transistor you can build one stock values wthout a lot of difficulty. You have to remember that even with HFE/uA values that are perfect for one set of transistors you can sound like garbage with another. I have found that when you approach the pedal from a transistor selection stand point over the "lets play with the bias" idea it becomes alot easier. The caveat here is that you need s decent amount of transistors to choose from.

For me it really boils down to transistor type and that individual transistor's properties. I really like 3 x OC75s (which were used in very early units) or a combination of OC75s and AC125s. I always seem to go back to an OC75s - I really like they way the circuit sounds with them. I have also had alot of success with AC128s. I seem to stick to lower gain transistors and usually find 60-100 is plenty. I do not recall ever reading Mr Main (DAM) suggesting specific HFE or leakage though. ia m curious - where did you read that?

Some folks like low leakage for Q1 while others dig a little leakage. Start at 60-80 HFE and 100uA and work up to see what you like. I usually like Q1 to have the lowest HFE but I also like 200+uA here.

Q2 determines the fuzz quality. Try around 80 HFE and 100-300 uA of leakage. I like Q2 to have the highest HFE. I find this one is most reposnsible for the texture and fuzz content.

Q3 seems to prefer lowish leakage for a quiet build - somewhere around 100uA is a good place to start. The gain of Q3 determines the treble content. Start in the 80s and work your way into the 120s and see what you like. Too much gain and/or too much leakage will get the sizzle going on the decay.

Bust out the breadboard, make a stock circuit and start experimenting. Leave yourself enough of room to swap transistors about.

[Arcane Analog]

Sorry for the typo/edits. I am on a difficult medium.

[rousejeremy]

I'm thinking shielded wire would help a bit with the noise. Hopefully. I have the board all wired up and everything, but the noise is unbearable. I'm going to box it up and do the transistor swapping with it boxed up, just to eliminate the RF.
Thanks for the info about your transistor preference. I have a couple OC81's I yanked out of an old radio and a bunch of 2N404's and 2SBXXX's so I'll probably get something workable. This pedal is for a customer who wants that early Yardbirds "Roger the Engineer" sound. It's been quite fun though, I have been learning some of Becks weird licks to compare tones.

[Arcane Analog]

Edit: Damn typos.

I always build them with sheilded wire on the in/out to the board and the in/out to the jacks - absolutely makes a big difference.

[Arcane Analog]

My last one - just finished it a while ago for a Ronson fan.

[rousejeremy]

Nice enclosure! Make it yourself?

[Arcane Analog]

That is a Peadalenclosures Jorgan. Extremely durable box and powdercoat.

[rousejeremy]

I think I found the right combo. Minimal noise and crackliness, somewhat smooth decay.

[Arcane Analog]

Nice. For what it is worth, I usually end up auditioning about 5-10 transistors for each position.

[rousejeremy]

That's probably what I had to do. I was hoping there was a trick like the Fuzz Face trimpot to get bias on this pedal. Looks like you just gotta go for it. No wonder reproductions are so expensive.
I think if I have to do this again I'll get that enclosure you have and have some decals made up to make a true tribute pedal. Oh, and PTP construction of course. Looks classy.

[Arcane Analog]

I like tagboard. Not true PTP but it is very durable - much more so than a PCB in my books. Damn near bullet proof. I have built them with the plain drilled phenlonic board as well but I am much more of a tagboard fan.

I 100% agree on going for it. In the end the trimmers really are just extra work you do not need to do.

[mac]

Jeremy, can you post transistors data and voltages please?

mac

[rousejeremy]

Q1-2N404 hFE 57 E-0.05 B- 0.10 C- 9.03
Q2-2SB186 hFE 123 E- 0.00 B- 0.16 C- 3.66
Q3-Unmarked hFE 93 E-0.00 B- 0.03 C- 8.44

All these voltages are with the attack pot dimed. I don't know the exact leakage of these transistors but they are all under 300.

[Arcane Analog]

I have found that the higher you go with the HFE the more apt you are to get that 'snap, crackle and pop' staccato sound and the subsequent gate/sizzle on the fade. Then again, the random nature of germanium can toss you for a loop. I would wager that this one has higher gain transistors than the 'normal' ranges (60-100) most people use. Understandably, Mr Main keeps his specific preferences under his hat.

My guess is that this one has lower gain transistors. Less chop, splat and sizzle than the previous example but I would bet you could definitely dial in more if you wanted - the demo did not really cover that end of things. Note the decay is alot smoother too. 

Of course it also depends on what type of rig and how you are running it in combination with your playing technique. Pickup slection is a big factor. There are definitely big differences in the variants and even in pedals by the same builders due to transistor selection but getting some amount of that gate/sizzle/splat in with the ragged fuzz/sustain is pretty key to getting a MKI sound in my books. I do not think the sustain lasting along time is nearly important as getting those signature MKI aspects. If not you just get something that sounds like another type of Bender.

[rousejeremy]

I checked out both of those vids before building and they just confused me. The GMD demo sounded great, but those were humbuckers and he didn't really let the notes decay naturally.
The other demo, man that pedal does not sound good IMO.

[Arcane Analog]

I think they both sound great! Haha.

The GMD video really does not help with learning about the decay - only in a few spots. It is a pretty generic sounding - still great though. Devin's box sounds amazing to me. Nothing else sounds like that - just the MKI. There are folks who will pay a truck load of cash to get that sound. I like it somewhere in between. This one by SonicVI is great middle ground.

[rousejeremy]

Here it is. I think I need to make more adjustments to get a little more sustain out of the thing.

[Arcane Analog]

Trim pots and such adjustments really will not get you where you want to be. Subbing transistors until you get three you like is the only way to go.

[rousejeremy]

I have three transistors that got me in the ballpark. The trimpots are actually helping a bit, that or I'm just reaching the acceptance stage of grief.