Octave Down?

[nathan Dodd]

Hello! another newbie with another question:

is there any sutch thing as a pedal that produces an octive or so down?

thanks in advance!

Nathan.

[Mark Hammer]

Yes, plenty.

By consensus, the most comfortable-to-use unit out there in the all-analog category is the PAiA "Rocktave", designed by Craig Anderton some 22 years ago, which PAiA still sells in inexpensive kit form.  If you are a dyed in the wool DIY-er, the plans and board layout can be found at www.generalguitargadgets.com and the original Guitar Player project article can be found at hammer.ampage.org.

Many folks have been pleased with the simpler design and rawer sound of the MXR Blue Box, a clone of which can be found at www.tonepad.com

Please note that ALL analog octave down boxes can only provide an octave or two below a single note at a time.  If you attempt to play chord into them, you will be either displeased or frightened by the results.  Tracking of notes has always been a tricky matter for such boxes.  The Rocktave has enjoyed a good reputation because of what it does to improve tracking and eliminate the parts where tracking would normally go wacky.

At this time, Electro-Harmonix has released a polyphonic octave box that will let you play chords instead of just one note at a time.  I suspect it is pretty much all digital since I can't figure a way that it could track 6 separate notes in analog mode.

It's been said a zillion times here and elsewhere but needs to be mentioned again now and then that in the analog world, octave up and octave down are produced with different technology/designs.  You cannot simply convert one to the other.  They each have their own unique designs and unique problems/attributes.

In the digital domain, an octave down can be easily produced with a Harmonizer (I think the E-H "POG" is a simple harmonizer).  True harmonizers have a different tone than an analog octave-down box.

[jmusser]

Absolutely! I have an Arion MOC-1 Octave pedal, that gives two octaves down, and allows you to mix the original guitar signal with either or both of thes octaves. It makes your guitar sound a lot like a bass, and is an absolutely awesome tone when mixed with something like a Fuzz Face. I use mine through Joe Gagan's Easy Face. Be warned, that this is a single note type effect. You cannot play chords with these things, or it will turn to pure mud! Somebody may know of a good octave down circuit to build yourself, but most of them are way to complex for the average Joe to build. Since I am not an electronics guru like a lot of thes guys, I'm not sure what electronic gymnastics are needed to flip the signal wave down off the reference signal as opposed to up like an Octavia. I love this effect, and most always just use the lowest octave selection, with barely any original or first octave down. I'm sure Boss, DOD and Danelectro make this effect. Probably others do too. Personally, I'd buy this one instead of make it.

[puretube]

yep, the POG is digital...
(anyone heard its sound in the HC NAMM videoclip?        )

[nathan Dodd]

Thanks for the help people   fantastically quick response! It’s nice to meet people with a passion. The tonepad MXR Blue Box sounds most like my 'Cup of tea'. I have an age old MXR pedal - it's a stereo chorus - bright yellow. It’s got a couple a 4558's in it that are going to be scavenged. It packed up about 8 years ago and it wasn't really a strong enough effect for me so. Please stop me if I’m sacrificing a vintage - it was a friend's of mine, he's had it years he bought it from a pawn shop in the first place. He’s also got a Guild S-90 that he picked up for £20 - these things just fall into the hands of some people. Anyway i digress... thanks again all!!

[RDV]

Joe D.'s Shoctave is a fun little circuit, somewhat akin to a Bluebox. Octave down mixed with a lite fuzz circuit.

RDV

[Marcos - Munky]

If I was you, I didn't sacrifice the stereo chorus. You can buy the ICs for cheap in common stores, and maybe you can trade it for some pedal. There's a way to generate octave down if you transform the guitar signal to square wave, then use it to drive a flip flop. With two CMOS ICs, a transistor and a few caps and resistors you can get a square wave fuzz with no octave, octave up or octave down options.

[Mike Burgundy]

Mark:
We've talked a bit about this before (some time ago - mainly about getting the rocktave to go lower) and I've mucked about a little bit on breadboards to test some principles, but I found I really had to go all the way (probably) to really test this. I might make some modules or something someday so I can switch different bits of circuitry.
What's your take on this: (I hope this makes at leats some sense the third time you read it )
inputs, buffers, sure. This is also where the straight signal is tapped.
Next up: a compressor/compander to muck with dynamics, which in turn will have a profound effect on envelope detection.

Split into the sound stage and the envelope stage (this can also be before the compander - I'd like to find out what the dis-/advantages are) Optional: see below.

Next up : Simple octave UP. Either this does the octave to all of the signal (so no split in the above sentence) OR does it in a side-chain. Clip to almost-square, perhaps filter (combined with the , and then detect the octave's frequency in the normale way. Use this to go:
a) (one signal chain) two octaves down from the octave up to yield an octave down from original, or
b) (parallel chain) two octaves down from the original signal *using the more stable (?) control signal from the octave up chain*

Intuition sais a) is probably best, plus it gives you the possibly cool addition of a synthesised unisono note. I have no idea why my intuition thinks (um...) this though.

Point is: electronics have a hard time making anything out of the really morphing signal a guitar or bass string produces. Plus, it takes at least one cycle for an octaver to catch on to what frequency is being played, so maybe this could work? Doubling is easy.

I've been grinding this through the back of my head for some time and have a very sincere but annoying feeling I'm missing something here. I actually feel like some guy thinking he invented flight because he saw a feather float on hot air. Where's the catch? Or should I just try to take up a couple of weeks holiday and build the damn thing?

[toneman]

dividing is easy.

multiplying....now, that's more difficult.

U know,
if U put 2 sine waves into a balancedmodulator,
one into the "carrier", other into "modulation",
same amplitude, same phase,
U get a sine of DoubleE the frequency......
Probably could do something to the GonkuLator....(?)

why would U want lower than divide-by-4???
(assuming U mean divide-by-8 and NOT divide-by-6, or 7, or 5)
yes, it *can* B done, grasshopper.
afn
T

[R.G.]

Maybe the simplest octave up/down is to do an octave divider, then phase lock a frequency multiplier to it. You can get several octaves up, or better, use resistive weighting on the divider outputs to shape a sawtooth wave.

[Mike Burgundy]

I'm thinking more along lines of doing an octave down quick and reliable. Recitifying the original, and clippping the crap out of it yields a somewhat asymmetrical square wave - if you trigger on positive zero-crossings, this should if anything be twice as fast as regular. That was the basic idea. I'm not looking for a CLEAN octave up, I'm looking for a fast and steady oct. down.

[toneman]

R.G. wrote:
>>Maybe the simplest octave up/down is to do an octave divider, then phase >>lock a frequency multiplier to it. You can get several octaves up, or better, >>use resistive weighting on the divider outputs to shape a sawtooth wave.

EML did a similar technique with the "Polybox".
Used a PhaseLockedLoop(PLL) to get the (way)upper (hi)freq,
then divided it down for the PLL to get locked on.  Then used
4 TopOctave Generators to get several octaves of square waves.
All notes (3octaves) available simutaneously(polyphonic)!!
Plus, it remembered the "chord" U played.
Every one note in, U got 3notes out.  
1 note enters.....3notes leave.........
Some things U gotta do  *easy*,
others, U got to do them *rough*!!
playon grasspicker~
tone

[Ben N]

It's been said a zillion times here and elsewhere but needs to be mentioned again now and then that in the analog world, octave up and octave down are produced with different technology/designs.  You cannot simply convert one to the other.  They each have their own unique designs and unique problems/attributes.

True, but a lot of the "helping" circuitry--square wave generator, LP filter, buffer, mixer--can be shared, so a multi-octave box ought to be quite doable, at least in theory.  It'd be a bitch to build, though.

Ben

[nathan Dodd]

It may turn out knob-heavy but you could build a box with a seperate octive up and octive down - 2 stomp switches - one bypass and one changer - rig a bi-coloured LED. you could even print both seperate circuits on the same PCB.

that is, you could do that if you weren't proficient enough in circuit design (like me) to design it yourself. a quick fix if you like.

my 2 cents

[Mark Hammer]

Check out the Super Octaver at hammer.ampage.org

You'll need to scroll down a few pages to get to it.

[vanhansen]

The one I'm most familiar with (mass production wise) is the BOSS Octaver.  I don't know if they still make it though.  Had 2 knobs on it.  I think it's been replaced with the Super Octave.  I haven't tried the MXR box but heard good things about it.

This looks like a fun project.

[gez]

Dano chilli dog is an excellent octave down for the price.  It's all surface mount but the number and type of ICs suggest that it's a Boss clone.  I love it, though it's prone to the same tracking problems as the Boss.

[puretube]

from almost 60 years ago:
http://www.pat2pdf.org/patents/pat2561349.pdf

[travissk]

vanhansen - I think those pedals are the OC-2 and OC-3 respectively. I think the OC-3 supposedly tracks better and makes an attempt at tracking multiple notes.

I sometimes use a Whammy IV or the Boss GT-6 to do an octave down in front of some distortion. Both of them get the job done, but there is a little bit of latency that is noticable. And of course, both are DSP-based so a DIY clone route isn't possible. I've played through an MXR blue box, and it's crazy.

The POG sounds really cool (just like the rest of EH's line ) and, from the video seems to track better than any other pedal I've heard. Latency seems extremely low as well. Very impressive. Here's the video from last year's NAMM. The POG is featured a little bit in the 16-second delay demo, and then in more detail at the 8 minute mark.
http://trio.harmony-central.com/ramgen/SNAMM04/EH-Pedals.rm

[hank reynolds 3rd]

I did a clone of the mutron octaver...Pretty meaty and theres a switch to stop the 'burbling' sound some octavers produce...I think Munky was hosting it at his site...The layout i did was on two boards ,1 for logic,the other audio...


Cheers

Sam