Dr. Boogie, who's responsible for the sustain

[arma61]

Hi m8s

just finished my dr boogie ( as per gaussmarkov pdf), still needs some wire cleaning to avoid some oscillation, but is good enough atm, I mean I like how it sound but there's little sustain, the sound fade out almost immediately, just 2/3 secs. It's a good sound so I don't want to "touch" too much the trims, changing its behaving. I went through almost all link in this thread

http://www.diystompboxes.com/smfforum/index.php?topic=61391.msg481948#msg481948

but cannot find anything related to sustain, only Xavier is saying "it has sustain for days"

So which part is/are responsible for the sustain, I want to "put my hands" on it as little as possile!!

Thx m8s for help
Armando

[dschwartz]

definetly you have a misbiased fet...play with the trims....

[arma61]

thx Daniel,

they're all, but the last one,  biased to ~4.5v , anyone in particular to start with ? or I need to tweak all of them ?

[Ibanezfoo]

Are one of the FETs in backwards?  I did that on other pedals and had symptoms similar to what you describe.

[dschwartz]

~4.5V is just the ballpark..you need to tweak it by ear now, i do this:
- lower the gain pot to almost clean
- let the guitar strings ring
- start from the last fet to first searching for the loudest sound when turning the trimpot (loudest hiss/hum helps too)
- stop at the loudest position.
- put nail polish on the trims to fix the position (not necessary)


and voila!

[arma61]

thx m8s

I'm almost sure FETs are oriented in the right way, according to layout, schem, and pictures I saw of various DB made from the gaussmarkov layout, though another look is necessary before to start with Daniel's procedure.

I'll report back

thx again
Armando

[bancika]

that sounds weird, I've got mine set to 4.5V all the way and it sustains for days

[dschwartz]

well you´re lucky..fets vary a lot and 4.5v may be good for one fet, but not necessarily for the other..
i had even have builds that sounded ok not even turning the trims, sheer luck!.

[Minion]

Ive also had fets that simply would not Bias at all , actually a whole bunch of them , No matter were I set the Bias they would sound like crap and sometimes wouldn"t put out a sound at all , no matter at what bias they refused to turn on, that is why I hate fets , I now avoid them at all costs accept for mosfets .....

Cheers

[bancika]

I must have got a good batch, all of the first 5 I've got were easy to bias

[arma61]

hi there

got it working! thx Daniel your procedure worked very well!, not really sustain for "days" but for "hours"!! good enough, I had some trouble biasing the first FET, trim was behaving in a strange way, so changed the FET with an old one I had on another PCB(so different stock then the ones I'm using now) and voila easy to bias. Still I don't like how it sounds on the last two strings, E and B, they sound like they're out of tune,(playing the intro of ACDC's "Hard as a rock" sounds terrible), but the reason could be that at the moment I don't have the right pots value for Treble and Bass and Presence (close but smaller/bigger than required), so it's hard to get the right tone.

Thank very much again for help, now to get rid of the oscillations (on some settings it's looks like a nest of newborn baby birds!!), I wish I've used a bigger enclosure to place wires properly!!.

Armando

[dschwartz]

out of tune??
this pedal is great, but sadly will not be able to make an out of tune guitar sound tuned...

use fresh strings and tune your guitar properly..pot values and circuit variation will not make your guitar sound out of tune.. old strings, out of tune strings, bad fingering techiques can make it sound out of tune.

if you have a floating tremolo, the guitar may detune if the guitar is not 90 degrees respect with the floor due to whammy bar and tremolo weight..

[arma61]

out of tune??
this pedal is great, but sadly will not be able to make an out of tune guitar sound tuned...

use fresh strings and tune your guitar properly..pot values and circuit variation will not make your guitar sound out of tune.. old strings, out of tune strings, bad fingering techiques can make it sound out of tune.

if you have a floating tremolo, the guitar may detune if the guitar is not 90 degrees respect with the floor due to whammy bar and tremolo weight..

Daniel, you've got what I mean, floating tremolo that's it!, (oh language!!) specially when playing those 2 strings in that intro, with a BSIAB2 they play very well no tremolo at all, I don't have a whammy bar installed but I've used a crappy old strato clone, tuned but still crappy! (Vester, never hear?!), I'm gonna try tomorrow evening with my original strato American std and see if it'll improve.

Thx again for support.
Armando

[dschwartz]

it´s just that it have happened to me, when i play while twiddling with the circuits i bend over and the guitar goes out of tune..

[CynicalMan]

I get that on one of my guitars even though it has a trem-o-matic style bridge. It's because the neck is very easy to bend. It's great for vibrato and bends though.