Octave down pedal

[aziltz]

I've wanted an octave down pedal for a while, i considered boss' oc-2, then they released the 0c-3 with the poly mode, but i hear it doesnt sound as good.  Has anyone seen a  good DIY/more contemporary brand that does a clean octave down?  Would a circuit like that be obtainable with analog easily? or is it better suited for digital?  I want to be able to play low clean/semi overdriven hammer-on type riffs on my tele with a and octave down on.  Any advice?

[Processaurus]

Nothings gonna beat a decent bass player.

All the analog ones that aren't very complex have trouble tracking anything but the neck pickup, and notes below the 5th fret on the low E string.  Also they don't reproduce any of the tonality of the guitar, its more of a filtered square wave.  Which can be very cool and desirable with its synthy-ness, but just isn't convincing as a bass guitar substitute if its mixed very prominently.  Of the DIY octave downs, I've heard good things about the Shocktave (simple and performs decently) and the Anderton Rocktave (more complex, but performs the best of what people commonly DIY).

Of the digital stuff the POG sounds fairly good (sounds great actually, compared to what else is out there), but its going to cost you.
Octavers have always been dissapointing, because none have that cool sound you get if you slow your guitar down to 1/2 speed on a 4 track.

[Connoisseur of Distortion]

whammy works well.

[jonathan perez]

yes indeed, my old WH1 does the trick mighty well...

[Paul Perry (Frostwave)]

Of the digital stuff the POG sounds fairly good (sounds great actually, compared to what else is out there), but its going to cost you.

I'll second that. Both the effect, and the expense.

[A.S.P.]

HOG

[trevize]

You can build also distorted octave down effect like the mxr blue box and then add a low pass filter in the end. 

The mxr is easy to build and the tracking is not bad.

[MartyMart]

The best sounding one I have is an old "Pearl OC7" octaver
Seems to track well and has a blend between natural 1 oct down and 2 oct down.

Still a kind of rounded off "square wave" tone though !!

Go buy a cheap bass .....

MM.

[DDD]

I've tried a lot of analog DIY octave down schematic, including pre- and post filtering, involved dividers, e.t.c.
And now I have to say analog octavers don't worth the efforts. They are nothing but a toy for very few moments.

[jim_inme]

You can build also distorted octave down effect like the mxr blue box and then add a low pass filter in the end. 

The mxr is easy to build and the tracking is not bad.

I second that  MXR pedals seem to be good all rounders

[dr]

....I split the signal and send one side to the regular effects and amp; the other I run through a volume control pedal>compressor>EBS Octabass> bass amp; then when I want bass I pick single note lines after I bring up the volume pedal-its the best thing I've found that works well. The compressor and the EBS are always on....

[Paul Perry (Frostwave)]

Of course, it depends whether you are using a single note or a chord!.

[Jaicen_solo]

I just did a bit of work on a DOD FX35 Octoplus pedal which might be worth a look. It uses the common flip/flop generator, but also includes what looks to me like a PLL, which greatly improves tracking on the lowest notes.
With a few modifications to the low-pass filtering and the tone controls, it sounds great. Definitely one to check out, especially as they can be had for £25 or so. You will want to add true bypass tho.

[jmusser]

If you do a search on this subject, you'll find about all the DIY info you'd ever want to read. Mark Hammer has several threads on the MXR Blue Box, as well as how the various octave down circuits work. I have built the Shoctave Harmonizer, and the MXR. Both of them still maintain their square wave synth type sound. The MXR doesn't track very well, and it's a two octave down. The Shoctave is one octave down, and tracks pretty well. One other circuit that has a good octave down similar to the Shocktave, is the Crash Sync, even though it's not really advertised for it's octave down function. None of these will do clean octave down. It's comes down to what you want to use it for, and how "clean" your ear has to have it. If it has to be clean you're probably not talking DIY.

[Mark Hammer]

Imagine you are on guard duty.  You have the night shift, and it's raining.  Your job is to keep an eye and ear out for anyone trying to sneak up.  Chances are pretty good you will respond to some things that really false alarms, and overlook other things that really ARE enemy.  Congratulations, you are now in the same position as the flip-flop in an octave-down box attempting to identify what is the note and what isn't.  They ALL track poorly unless the input signal and onboard electronics are a match made in heaven - sorta like having your shift changed from a rainy night to a mildly overcast (no sun to blind you) daytime shift.

EVERY octave divider needs to bring the level of the input up to some critical threshold where the flip-flop will respond to rising edges of a given amplitude. The majority will provide a preset boost to do that.  Of course, that boost may be insufficient to assure triggering/dividing of every note that needs to be divided, or so much that even finger glisses on the strings or dying notes produceunintended octave divisions.

Regrettably, it is rare that an octave divider has a sensitivity adjust control to optimize tha match between what the circuit needs and what the guitar supplies.  No reason why YOU couldn't provide that, though.  For instance, look at the Tonepad Blue Box layout ( http://www.tonepad.com/getFile.asp?id=73 ).  IC1a provides preliminary boost and also sends a feed to a sidechain (envelope follower) which controls the gating action of the two control transistors Q2/Q3.  These transistors are intended to turn off just before the note might get sputtery.  IC1b provides additional gain to both produce a fuzz for one of the two blended signals and also a signal high enough for the flip-flop to respond to.

You can reduce the drive in stage 2 (IC1b) to offset too hot an input by increasing the value of R23, or decrease it to offset too weak an input (both are sources of mistracking).  Indeed, it might be a great idea to redesign the board to accommodate a 10k trimpot to put in series with a 6k8 fixed resistor.  This would give stage 2 gains adjustable between 60 and 148.  Similarly, replacing R8 in stage 1 (470k) with a 250k trimpot and 390k fixed resistor in series, and R5 with a 1k2 resistor would yield gains adjustable between 326 and 534 (a current stock value of x471) to produce gating action that is optimally suited to the input signal properties.

Since what the flip-flop sees is a function of the IC1a gain multiplied by the IC1b gain, adjusting stage 1 gain would likely necessitate upping stage 2 gain.  However, one ought to be able to get, in theory anyways, a better-behaved Blue Box and better octave tracking.

Other units, like the PAiA Rocktave, use a compander to produce a more reliable signal level to the flip-flop, regardless of what the input might be like.  These units have, in my view, superior tracking, if one chooses to define such tracking as the ability to handle whatever you feed it.  I'm certain that any o the units mentioned earlier in this thread can do a terrific job, but they may be very picky about what you feed them.  Use of a compander allows the flip-flop to survive on whatever you feed it.

In any event, though, all octave dividers will oblige you to adjust your playing style to let them do their work.

[phaeton]

Nothings gonna beat a decent bass player.

Does ROG have any FET-adapted schematics for a "decent bass player"?  I want one with a blend pot so I can pan between Glenn Cornick and Geezer Butler, maybe with a Jack Bruce switch on it.


Seriousry-
IIRC I read R.G. state that for the most part any analog octave shift is going to be:

1) distorted
2) synth-like

to varying degrees.  Fine if that's what you want, but if you want pure pitch shifting that's clean and sounds like cassette tape a alternate speeds, you have to get into microcontroller/DSP type stuff (please see appropriate forum).  It's attainable, and it's doable, but it's kind of a completely different sack of monkeys than your average analog effect.

[Stompin Tom]

Although it sounds like you want something digital, you might want to try this:

http://www.musiciansfriend.com/product/Guitar/Effects?sku=150512

I haven't a/b tested it with the oc-2 yet, but it seems to compare and is super cheap. If you don't like it, well, you're only out a few bucks.

[jmusser]

I think the MOC-1 is one of the better two octave down pedals at any price myself. It has great tracking, and good separation between one or two octaves down, as well as the fundamental. It's still a little synthy sounding, but filtered pretty well.

[aziltz]

methinks line 6 will probably add a digital (of course) version to their tonecore series eventually.

[StephenGiles]

The EH deluxe Octave Multiplexer must be considered. Once again, this contained the front end fundamental generator of the EH Guitar Synthesiser, designed by Howard Davis (was it?) and almost guarantees a clean octave down. By clean of course I mean free of octave jumping..............uses a couple of CA 3094s though, but I dare say there is a workaround.