Help! Jordan Bosstone issues

[Ben Lyman]

here's the he schem I used, I had some weird oscillating feedback thing when turning the guitar volume off and the overall tone of the thing was weird, low octaves at random places around the fretboard and such. I added a small cap parallel to the .022 (circled in red) that goes to ground between the two 560k res, according to past threads on the subject, and it cured that but I still have one minor issue.

It sounds great with plenty of fuzz and sustain from the lowest end of the neck on every note until I get up around the 14th fret on the G string. It still sounds great but it loses sustain quickly, not a clipped kind of loss but a rapid fade out, then gone and no sweet feedback or sustain like everywhere else on the neck.

[Bishop Vogue]

I built the one at tagboardeffects and it works - didn't sound good enough to be a keeper though and ended up in my box o circuits. 

http://tagboardeffects.blogspot.ca/2012/01/jordan-bosstone.html

Probably faster to just build this than debug yours....

[aron]

Is that schematic much different than mine?

http://www.diystompboxes.com/pedals/bosstone.gif

[Quackzed]

i'd try a 10k instead of the 18k at q1's collector or just parallel another 18k over the existing 18k collector resistor there, if that doesnt work, or makes it worse try a bigger resistor there rather than smaller... next would be a 330 to 1k at the emitters of each tranny... gating is probably due to bias of the transistors, so fiddling with the collector and emitter resistors should move the bias point and get rid of it, though these npn /pnp type fuzzes tend to have weird behavior due to the opposing transistors fighting each other...

[Ben Lyman]

Thanks guys,

Bishop- I can't seem to make my brain understand tagboard layouts, but thanks.

Aron- yours does appear exactly the same, as does the other schem I had laying on my table at the time, it was a photocopy of something that looked old and original, it said 47pF where the others say 50pF but other than that, all the same.

Quackzed- Now that you mention it, I did add a small resistor to Q2 emitter (it's backwards, of course) in an attempt to get +4.5v and it does sound good. Maybe I went about biasing the wrong way, I'm new to this and I did not know about adjusting emitters as well as collectors on both trannys. I don't even know if 4.5v is right for this circuit or if it requires something different.

Overall, it sounds really good, tons of gain, so fuzzy it's over the top, no cleaning up with the guitar or attack knobs on this one, the range only goes from fat, crunchy OD to all out fuzz. It's just that one area up high on the neck where it loses some sustain. I dunno, maybe I'm just being picky because it does sound way better when my amp is cranked up anyway.

[mac]

Someone noted in an old post that oscillations and other issues might be caused by those three 0.022uf caps because they *look like* this oscillator,



If true, a gain of +29 is needed to start oscillations. Low gain transistors might help. 

mac

[blackieNYC]

I put a boost on the front end of my Jordan, to push it over the top, and, to actually bring out those subharmonics when I want to. You may have already eliminated these, but the boost could reintroduce them. My boost has a pot on it. I can get better sustain out of it as a result. I did however turn half the resistors into pots - 5 - which is silly. But try some cleanish adjustable boost in front. See if you get more sustain across the whole neck, and see if it introduces something you don't want.

[Ben Lyman]

Thanks Mac and Blackie, I will try the boost idea, EHX LPB-1 probably because it's the only thing I am familiar with. Is there a simpler way to put a boost in front of this with fewer parts?
The .022 caps do seem to create a pedal on the verge but I like it. I added a .047 cap in series at the input with a switchable jumper to toggle it in and out. The result is a nice but subtle tone change. 

[blackieNYC]

another pedal would do for a decent boost experiment.  got a cleanish boost function on something?

[Ben Lyman]

Ya I have a Phi 1.618 boost pedal but I prefer to build something into the Bosstone pedal to make it sound right on its own.

[blackieNYC]

Of course, but just to see if you like it, put the pedal in front. Look at the boosters at AMZ.  The simplest among them will probably do fine since you probably don't need to worry about a headroom. A little clipping in the pre-boost probably won't matter - you're boosting in order to hit the fuzz harder anyway. I'd give the booster an output level control - a "pre-drive"