Dirt Box Decay and Sustain

[claytushaywood]

I've built quite a few dirt boxes over my somewhat short time building pedals.  But I have not liked a LOT of them.  And this is due to some of the artifacts I'm getting that I dont hear in the stock versions of the pedals.  The attack and initial sustain always sounds good, but once i've been sustaining for a couple seconds I feel a lot of pedals have weird artifacts in the decay.  a LITTLE bit sputtery, crackley, not enough sustain, its really difficult to describe. I used to just think I didnt like LED clipping on opamp based overdrives, but I've had this problem on jfet amp in box pedals, a skreddy lunar module clone, a DAM 1966 clone (really that one just doesnt have enough sustain) and countless others. I measure and swap transistors forever, change clipping diodes, etc etc.  But I always start think i just dont like the circuit.  After getting full on thanksgiving feast I'm contemplating what I'm thankful for, and I'm thankful for this forum!  So I thought id call for help one more time. 

I know this isnt a very good description, but its really difficult to describe the sound and feel i'm talking about.  maybe I can post a sound clip of what I'm talking about.

what do you guys think

[Quackzed]

       I think that, yeah, theres a 'zone' or operating point for most devices where there are no artifacts. sometimes this zone is 'just' big enought to handle a guitars signal from loudest to quietest, sometimes not. a high gainer wont do great clean/slight od usually; and a low gain od wont do high gain well either generally. many circuits try to do 'too much' and consequently suffer some imperfections. but a well designed circuit should operate withing its design perameters without artifacts or fizzy decay or harsh attack artifacts.
        it may be a question of optimal biasing of specific devices, or possibly that the particular guitar signal you are feeding is bigger/smaller than expected and requires some tweaking of these circuits to keep it within the 'zone'. but these artifacts are usually not intended, but rather the result of the individual devices either being biased too hot (close to 9v) or too cold (too close to ground) or just getting too much or too little signal to do what they were designed to do.
       take heart, its definately not a case of 'all 9v pedals add crap to your signal'.

[nocentelli]

I've frequently encountered this with JFET-based circuits, and put it down to the natural variation  in characteristics due to the production methods of JFETs themselves: I assume it's related to bias, hence why so many JFET circuits suggest a trimmer on the drain. Likewise Ge transistors (I've never used them) usually require some tweaking of the bias or selection process (apparently).

I'm slightly suprised you had a problem with the Lunar module - One of the reasons I've made about half a dozen pedals based on this circuit is that it always sounds good with BC109c BJTs, no selection or bias alteration needed.

[anchovie]

that I dont hear in the stock versions of the pedals

Are these stock pedals that you own, someone you know owns, YouTube demos, etc.? To do a decent comparison of your circuit to a stock model, you'd need to have a similar setup for both.

Do you test your circuits through a loud amp or at bedroom volume? What's your guitar/pickups?

[claytushaywood]

yeh I know about tuning germaniums and certain fuzz circuits.  and surprisingly I usually do better with jfet circuits, but I spend a lot of time tuning them- I've had trouble with the wampler plexi drive recently though.  I can only get it to sound good at one on the gain knob- whatever position I bias it at.

that I dont hear in the stock versions of the pedals

Are these stock pedals that you own, someone you know owns, YouTube demos, etc.? To do a decent comparison of your circuit to a stock model, you'd need to have a similar setup for both.

Do you test your circuits through a loud amp or at bedroom volume? What's your guitar/pickups?

No I dont own the stock pedals.  But playing them at stores and whatnot I've not heard the artifacts I have in my builds.  Ive only had the chance to directly compare a few pedals- and its been pedals I've not had problems with unfortunately.  The wampler blackface 65 is one that sounded perfect. 

I'm using a strat with d allen pickups (somewhere around 5.7k or something like that- so pretty low output) and I'm using a little blackstar ht1 amp as of recently- I've been holding off on buying a new big amp because I'm not playing in a band at the moment and want to try out some more circuits before I decide on what to build or buy. 
I've been wondering if I should install a super low impedance buffer into my strat as I have a swimming pool route I could put a 9v in (btw- would putting a battery close to the pickups be a problem?) 

Like with this clone of the DAM 1966 I really dont find the fuzz knob to sound good anywhere but at 95% to 100%.  And I've never built a germanium fuzz face where I've liked turning the fuzz control down. 

I feel I should be more knowledgable about tuning some of the circuits I try to build.  I actually built a super hard on recently and it has the artifacts problem... which is something I didnt think I would encounter with that circuit.  Maybe I'm missing something.  Can someone point me to some articles regarding the biasing of transistor based dirt pedals?  I'd like to know more about the tonebender mk ii and the vox tonebender (dam 1966) i'm having trouble with.  What do you guys think? 

Much appreciated!

[Quackzed]

yeah, the more you know, the more you know! here are a few articles about biasing...
http://www.geofex.com/fxdebug/bias_prob.htm
http://www.geofex.com/fxdebug/trantest.htm
as well as a ff walkthrough, also applicable to the tonebender variants...
http://www.geofex.com/article_folders/fuzzface/fffram.htm
...i'd recommend just 'favorites' ize www.geofex.com and browse around, lots of helpfull insight into the hows and whys of effects circuits.
... also 5.7k is a bit low by todays standards, but right in the zone for vintage effects like fuzzes and benders; i wouldn't think that should be a problem for most effects...