Author Topic: EQD Tentacle with Adjustable Octave  (Read 443 times)

HighSolstice

EQD Tentacle with Adjustable Octave
« on: January 19, 2021, 09:08:09 PM »
I would like to build just the Octave circuit with the potentiometer from the Parentheses Fuzz but I'm not sure how to go about removing it from the rest of the schematic.

https://www.pedalpcb.com/docs/Parentheses.pdf

GGBB

Re: EQD Tentacle with Adjustable Octave
« Reply #1 on: January 19, 2021, 09:58:58 PM »
The octave effect is the first section. Everything from "DIST_IN" to "OCT_2". It has an input buffer built around Q1 after which the signal splits to the octave circuit and C6. The OCTAVE pot is a blend control between clean from C6 and octave effect. You can either leave that in and take output from pin 2 of the OCTAVE pot, or you can drop C6 and connect pin 1 of the OCTAVE pot to ground to make it work as volume. If you leave the blend in, you might want to add an output buffer after "OCT_2" followed by a volume pot. The "OCT_1" connection is not used, as is "OCT_3" which is just the input to the distortion section.
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bartimaeus

Re: EQD Tentacle with Adjustable Octave
« Reply #2 on: January 20, 2021, 11:42:48 AM »
search for mods for the Dan Armstrong Green Ringer. that's the original name for the octave circuit, and you'll get more results searching that way.

Mark Hammer

Re: EQD Tentacle with Adjustable Octave
« Reply #3 on: January 20, 2021, 12:02:32 PM »
I find one of the single biggest weaknesses of the Green Ringer circuit is that it lacks any control over sensitivity.  I add a variable gain control to the front end of mine and it vastly improves the ability to generate audible octaves.  Remember that the octave doesn't really become all that immediately apparent amidst the harmonic haze at the start of the plucked note.  D1 and D2 are going to block the half-cycle they are intended to, but will also block the half-cycle they're supposed to pass unless it exceeds their forward voltage.  So if you want to actually hear that octave, you have to make sure they pass the desired half-cycle long enough for it to be heard.  If the note decays too quickly, you don't get much octaving to blend in.

The signal you feed the circuit might be strong enough to yield solid octaving...but it might not.  That's why I find having adjustable gain of the front end is useful.

HighSolstice

Re: EQD Tentacle with Adjustable Octave
« Reply #4 on: January 20, 2021, 12:31:52 PM »
I found a few different layouts, now I'm not certain which one I want to build.  Anyone tried the Groble layout?  Also, is that really a Green Ringer with a filter or is that a mislabeled Blend pot?  If it is a filter I might just have to build all three of these and decide which to keep.







Mark,
How is that achieved?  Is the variable gain control simply a potentiometer to ground at the input of the circuit or is there more to it?

Eb7+9

Re: EQD Tentacle with Adjustable Octave
« Reply #5 on: January 20, 2021, 01:55:44 PM »
I find one of the single biggest weaknesses of the Green Ringer circuit is that it lacks any control over sensitivity.  I add a variable gain control to the front end of mine and it vastly improves the ability to generate audible octaves. 

The signal you feed the circuit might be strong enough to yield solid octaving...but it might not.  That's why I find having adjustable gain of the front end is useful.

sure, Mark ...

https://www.diystompboxes.com/smfforum/index.php?topic=1440.msg1197087#msg1197087


Mark Hammer

Re: EQD Tentacle with Adjustable Octave
« Reply #6 on: January 20, 2021, 03:18:18 PM »
Which is pretty much what I do: make the emitter resistance to ground on that first transistor a pot, and connect an electro from the wiper to ground, "Fuzz Face style" to vary its gain.

HighSolstice

Re: EQD Tentacle with Adjustable Octave
« Reply #7 on: January 21, 2021, 03:35:48 AM »
What are the circular components near the labels Vi and Vo?

GGBB

Re: EQD Tentacle with Adjustable Octave
« Reply #8 on: January 21, 2021, 07:40:04 AM »
What are the circular components near the labels Vi and Vo?

Those are schematic symbols for the signal in and out - not components.
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