Doctor Q mods.

[aron]

I was looking for the threads for mods to the Doctor Q, but most of the links are dead.

Does anyone have a summary of the mods that can be done. I traded for a Doctor Q and it came in but now I know why they traded it :-)

Aron

[B Tremblay]

I used a bunch of them when I cobbled together the Nurse Quacky: http://home-wrecker.com/nurse-quacky.html

[aron]

I just gave up. I'm going to give it away.

I hate this pedal, it's junk to me. I think my bass player likes it.

Aron

[MarcoMike]

I didn't like this pedal at all, but I found it to be great after some mistaken mods. It was my first built, I was not very skilled in soldering and so on. it had a weak joint (which failed) at one of the LEDs and I didn't have the right transistor for Q1 (or Q2?). anyway, I fixed it by shorting the LED (or disconnecting one lug, now I don't  remember) and changing the transistor to a ... mumble mumble... I guess 2N5457 with two of its lugs "crossed" (central to "left" and left to center, dont remember the orientation  ). the result is some kind of ultra distorted wah-ish ring modulator. it only works in front of some pedals or amps, not all of them. I guess it is because of its really high output, it drives into distortion what you put after it and not everything is happy with it...

sorry for the sloppyness of my description, but I'm not at home and the pedal has been boxed and never opened since long. I'll check it as soon as I can, because I really think it is a cool effect now. and actually I was thinking to re-box it together with my old Park 15Watts preamp. that's where it sounds best!

[Mark Hammer]

1) Variable attack and decay...the usual way.  Time and experience tell me that variable decay is the less problematic and provides the most noticeable change in feel for the least effort.  Just stick a 250k or 500k pot in variable resistor mode in parallel with the 10uf time constant cap.

2) Range shift.  Sub a pair of .01uf caps in series for the stock .0047uf caps.  Wire up a DPDT toggle or slide switch to shunt one of the caps in each pair to shift filter range up/down an octave.  Alternatively, move the trimpot on the board to a panel-mount pot.  Just note that not ALL the rotation of that pot will be useful.  You may want to replace the trimpot with a 10k panel mount, supplemented by suitable fixed resistors on each outside lug such that the pot only covers the usable range of adjustments.

3) Variable Q.  Not the greatest mod but the Seamoon Funk Machine makes use of it.  Replace the 470k feedback resistor in the filter with a 330k fixed resistor and 1M pot.  Higher resistance gets you a more focussed filter and a little more output.  It also has the property of shifting the sweep range downwards a bit.  Interesting.

4) Since the filter gain mod introduces more volume, this calls for an output level pot.  Sub the output terminating resistor for a pot of the same value.

5) Cure undersignalitis by replacing the stock 2.2m feedback resistor with 2.7m or even 3.3m.

[tiges_ tendres]

Me too! I hated this pedal when I tried it out.

[MarcoMike]

mh, I made a kind of mistake. mine is a Dr Quack, not DoctorQ.  Q1 has been replaced by a 2N4402 (no specific reason, it was there in my drawer...) GSD->BCE. The LED closer to the OPAMP (the one at the input reference of the OPAMP) has been removed.
I beg forgiveness for this blasphemy....

[petemoore]

  I had lovehate with Nurse Quacky.
  Sounded real cool sometimes, but had many limitations and requirments of other circuits..to be 'tuned around' NQ, or not used.
  Either a plain guitar or compressor to input seemed to work good, when carefully adjusted, of course any pre-boosting or volume controlling at guitar throws the Env. detector off, as does playing single treble notes to loud bassy chords.
  Tuning the NQ or DQ to be a stand alone [with other circuits carefully chosen and adjusted to work well] would be the option I'd consider if I wanted to be able to use this Env filter more.

[oldrocker]

I like both the Nurse Quacky and the Dr. Quack but only as stand alone effects playing clean.  I just built the Phuncgnosis but the filtering seems to be very much in the treble frequencies so it's my least favorite although I like the wah up effect that it has..   My favorite auto wah is the FSH-1 in the envelope filter mode.  It's very adjustable and it sounds like you're using a pedal at times.  Nice wide and deep wah sweeps with a lot of control not including you get a sample and hold mode with it.  It has a wah up setting too.

[Mark Hammer]

In 1979-80, our keyboard player wanted to spice things up in his tone so we went to a music store and I coached him through buying a few pedals.  He got a Dr. Q and a Small Stone for somewhere in the vicinity of $29.99 or $34.99 each ($Cdn plus applicable taxes), and we thought they were the bees' knees and cat's pajamas (a few decades too early for the real shiznazz, I'm afraid! ).  Both great value for the money.  I still liked my MXR Envelope Filter better, though, even then.