Double your pleasure, double your fun

[Mark Hammer]

Rather than continue to butt into Dino/digi2t's thread about the Ibanez Standard Fuzz, I'll start a new one here.

The Roland Double Beat is another fuzz-wah from the golden era.  It's a very aggressive-sounding fuzz, situated ahead of a wah circuit in its original form.  While the wah allows it to do even more interesting things, the fuzz on its own is pretty decent.  These folks here cloned the fuzz part and boxed it up.

The origina provides for 3 very distinct tones, which I guess gave it 50% more tonal variety than its competition: the Superfuzz, that had only two tone settings.  The three tone settings are shown below, and you can see they are very simple filters for two of the settings, and a mere level-adjusting fixed resistor for the 3rd.  The 150k/250pf (I used 270pf) yields a thin reedy sound, and the 150k/ 2 x 6800pf network yields a rounder smoother tone.

I decided to use a 6-position switch and add some more presets to mine.  For the 4th setting, I used a 100k resistor and silicon diode pair to ground, in parallel with a 6800pf cap, to achieve a little more grind with some smoothing.  The 5th setting, I ran a 150k into a back to back Ge pair in series with the resistor, to produce some crossover distortion (which always sounds better on a bridge pickup).  The 6th setting is waiting, but will be a midscoop, similar to the Superfuzz category, but I have to work out the values first.

The AD-50 selects using a single-pole switch.  I decided to minimize interaction by using a DP6T rotary switch, so that only one network is inserted ahead of the volume pot at a time.  Lotsa variety.  Worth building.  I used 2SC828s with hfe in the high 200's.  More than enough gain. 

[RickL]

I don't think the first position (with the 330k) is just level adjusted. the 150k/0.0068uF bit is always in the circuit for all three switch positions, so there is going to be a little bit of treble cut from that section for all three selections. I haven't done the math, so the cut-off may be so high that you can't actually hear it, but it's there. Effectively, the first position is a low pass and the second two positions are band pass, with the second allowing more lows through.

I think.

But your version, with the dp6t switch, will actually cut that part out, so the first and second positions won't have any treble cut.

I made a stand alone version of this fuzz too, but I kept to the original three selections.

[Mark Hammer]

Hey Rick!

You're right, the 6800pf treble bleed remains in place at all times, which is precisely why, when I started thinking about other filters/voices to add that may use connections to ground, I thought it best to simply lift everything else, so that only one filter is in effect at any given time.

(BTW, my last day as public servant is Oct. 2.  Let the building begin!)

[sergiomr706]

I was taking a look at that circuit again and remembered I had seen one double beat modified with some of Mark Hammer suggestions.

http://guitar-fx-layouts.42897.x6.nabble.com/Roland-Double-Beat-fuzz-section-td7287i20.html

[Mark Hammer]

I had forgotten all about that.  Thanks for the link and reminder!