Circulator (Grand Orbiter) Build with boneyard mods

[Raspymcnasty]

I just boxed up the Circulator (Grand orbiter) with some of @Chuck D. Bones mods. I’ll list them below.

This pedal sounds pretty good, goes deep and wide.

From this Thread
“1. Increased R2 & R3 to 2.2M because I like my pedals to have a 1Meg input impedance. C1 was reduced to 47nF because it could be.
3. Replaced C8 with 390pF, cuts the high end above 40KHz.
4. Inserted 10K resistors (R103-R106) in series with pins 1 & 16 on IC1 & IC2. Pins 1 & 16 program the operating current and gain of each amplifier. The way EQD connected them all in parallel, there is no guarantee that they will share current equally. Putting those resistors in forces them to share. Should make for smoother phase sweep.
5. Changed the SWEEP pot to C100K, reduced R33 to 2.2K (to compensate for the 10K resistors I added in item 4) and reduced R34 to 10K. Gives the SWEEP pot more range and at the very bottom of the range, SWEEP acts like a Manual control.
7. Changed the RATE pot to C500K. Some not-so-good things happen when the RATE pot is above 500K. The sweep becomes asymmetric. There is a tendency for the LFO to stall or fail to start up.
8. Added a 3.3Meg resistor (R109) from pin 3 of the RATE pot to IC1 pin 3 (Vref). Along with item 9, ensures that the LFO will always start and never stall.
9. Added a 22K resistor (R107) from IC3 pin 8 to IC3 pin 6. Along with item 8, ensures that the LFO will always start and never stall. 8 & 9 must be done together.
10. Changed the RES (Resonance) pot to C100K and R23 to 33K. Makes for a much smoother adjustment.
11. Increased R27 to 33K. In the original design, the Circulator will break into oscillation when RES is dimed. “

 

[fig]

Very cool build! #s 8 & 9 are a fantastic addition!

 

[finebyfine]

Gorgeous build!!

 

[Paradox916]

Wow. Great job. I would love to hear it!

 

[Preverb]

Cool. With the mods, I wonder if this would cover the same ground as my old PT909 did (think they have the same # of stages).
Did you use one of the pre-drilled enclosures from Tayda?

This is one I would like to do in my second round of pedals. It is looking like 6-8 weeks for PCBs to get to Aus though...

 

[finebyfine]

Did you use one of the pre-drilled enclosures from Tayda?

I used a tayda predrilled 6 knob for my circulator build and just made sure ti have larger washers on hand for the toggles

 

[Preverb]

I think one of the mods was to remove the phaser/vibrato toggle. Do you find that you use the vibrato side at all?

 

[Barry]

Looks great!

 

[giovanni]

Love the graphics! Nice build!

 

[Raspymcnasty]

I think one of the mods was to remove the phaser/vibrato toggle. Do you find that you use the vibrato side at all?

I don’t but i haven’t played it enough

 

[Chuck D. Bones]

Looks great!

Buuuuuuut...
You have the 3.3M resistor connected to IC1-4 in the pic, should have been IC1-3. It will still work, but it's not the way I intended it.

 

[Coda]

Looks great!

Buuuuuuut...
You have the 3.3M resistor connected to IC1-4 in the pic, should have been IC1-3. It will still work, but it's not the way I intended it.

Maybe he works for JHS?…

 

[joelorigo]

Hello, I am about to start on a Circulatior and am going to do most of the mods earlier in this thread. I do have a couple of questions about a few of them however. Maybe @Chuck D. Bones himself will see this and answer!

On mod #1, what is the benefit of having the input impedance of 1M? And what is the benefit of reducing C1 to 47n?

For #2, are you saying that it doesn't matter if the listed value of C2 or a jumper is used, that it won't matter to the function of the final build? If that's the case I would most likely do a jumper and save the cap.

And for #3, this is more of a general confirmation, but it would be the first time I have actually done it; I can use a 120pf and a 270pf in parallel to add up to 390pf, right? Would that be inserting both caps into the PCB pads and soldering, or wrapping one's leads around the other?

 

[Chuck D. Bones]

1. I like high-impedance inputs to minimize loading the pickups. There is no benefit in lowering C1.
2. Yes. The circuit works the same either way.
3. The value of C8 is not critical. Just use the 270pF cap. Trying to fit two parts where there is only room for one can cause problems. Better to get the right parts in the first place.

 

[joelorigo]

Thank you @Chuck D. Bones! And I just realized I posted this in the wrong thread. I meant to ask the questions in your original modifications thread. Sorry for the hijacking @Raspymcnasty

 

[joelorigo]

Awesome build by the way. Did you ever form an opinion on the vibrato mode?