"1 Octave Down" pedal project

[swisher]

Hi guys!
I've got few questions I'm working on my special stompbox. It will be only 1 octave down (Boss OC-2 clone). I built two versions already (1% metal resistors & polyester film caps). First version was octaver only, but I know that analog octavers have tracking problems with lower notes so I decided to add compressor (CS-2 and Joyo mixed) before OC-2 in second version. In my opinion it didn't help, maybe tracking was even worst.

So there are questions:
1. Which compressor (with available schematic) could be the best to improve the tracking?
2. Which OP-amps will be the best for this project - something like: TL074, LM324 or LM358, TL072, or maybe TL022?
3. Compressor and octaver was connected on one PCB so I removed output buffer from compressor and input buffer from octaver. Do you think that octaver's buffer could change something with tracking?

Thanks for tips!
*Sorry for my English   

[EBK]

Best way I have found to improve tracking on this sort of thing is to use the neck pickup and roll back the tone knob a bit.  I doubt a compressor would be much help, actually.

I built an OC-2 once that worked pretty well.  I'll see if I can find my notes for it (it ended up getting recycled for reasons other than quality...).

[Plexi]

Welcome!

I'm not sure about the compressor to improve tracking.
I would think in some buffer, boosting a little bit. 

[amptramp]

1. I doubt you will find a compressor to be all that useful.  What you need is something to accentuate the fundamental of the input so you don't run into the problem of having the circuit lock onto a harmonic of the signal.  As EBK said, use the neck pickup (which has the highest content of fundamental) and roll off the tone control so you limit the upper harmonics.

2. The LM324 and TL022 (or TL062) are really not good enough for guitar-level audio.  The noise level is too high.  The others are OK but you may have a problem with dynamic range on the LM358.  Check to make sure the output doesn't reverse from positive to negative or vice versa when you exceed the common-mode range.

3. If you have an input buffer, you may be missing out on the treble cut you get from having a low input impedance driven by a pickup coil.  The coil has a typical inductance of 3 to 5 Henries and driving a low input resistance causes a rolloff of the input that emphasizes the fundamental.  To get this effect, the volume control on the guitar has to be maxxed.  Of course, it would be better to use a buffer and do the rolloff after the buffer so there is no difference in operation with any signal input.

You have to toggle a flip-flop to get the signal an octave down but this means you have to have some method of making sure you are toggling on the fundamental.  Suppressing the higher harmonics enables you to do this without getting wolf notes - notes that suddenly go up an octave.

[Quackzed]

you could put a boost or overdrive before it and experiment with boosting the signal into the oc2 also if it has a tone control you can turn down the treble before it, see what helps.

[swisher]

Thanks for all answers! (I didn't received notifications )
I'm almost sure I've got a solution for my problem - Q-boat designed by Merlin! I never found this project before because I always looked for some OC-2 schematics.
I've found 3 versions of this effect, but I think I will build my using Merlins PDF (2014) and TH Custom Effects version.

[duck_arse]

hey swisher, welcome to the forum. yer english is fine (where are you from?), carry on.

if you are interested, I've been working at a sub-octave with Ben Lyman, based on (the idea of) the shocktave. I think I've taken it as far as I can, it needs some more hands/breadboards/ears to say if it's any good. it will 'track' the wound strings (with a few warfs) ok when played with the thumb.

I did some fooling with adding a compressor to the circuit to improve tracking, but it doesn't work/help. as the others say, it's all down to suppressing what you don't want, the other harmonics. (I also tried the U-boat, couldn't get it to sink to my likings.)

[swisher]

Maybe compressor is working only as an idea and technically it doesn't work. I wanted to build prototypes of octaver and compressor and tested them together with some part's values etc. but I was to lazy for that.

I saw few videos on YT with "Q-boat" yesterday, and I hope now it can works. Here is really good tracking:

Shocktave looks really easy. Do you have some videos how it works?

BTW, I'm from poland

[Plexi]

Again...sorry my brutal sincerity...but I wouldn't waste my time on this [emoji16]
Go for a Ehx Pitch Fork...and save time/ lose one's temper with complicated and inneficients old schematics hahaha
Just MHO
[emoji16]

[jimilee]

Again...sorry my brutal sincerity...but I wouldn't waste my time on this [emoji16]
Go for a Ehx Pitch Fork...and save time/ lose one's temper with complicated and inneficients old schematics hahaha
Just MHO
[emoji16]

This logic makes this whole hobby null and void.

  I've used the tagboard layout to build an OC-2 and dalyk has a great OC2 layout in an a 1590b size.
You'll find many questions like the OP on this forum and others, all have resulted in a boost in front. I never cared for that answer myself, but I love THCustoms interpretation of the Uboat. It works well with high output pickups.
Good luck on your quest, I love octavers too.


Sent from my iPhone using Tapatalk

[Plexi]

Again...sorry my brutal sincerity...but I wouldn't waste my time on this [emoji16]
Go for a Ehx Pitch Fork...and save time/ lose one's temper with complicated and inneficients old schematics hahaha
Just MHO
[emoji16]

This logic makes this whole hobby null and void.

  I've used the tagboard layout to build an OC-2 and dalyk has a great OC2 layout in an a 1590b size.
You'll find many questions like the OP on this forum and others, all have resulted in a boost in front. I never cared for that answer myself, but I love THCustoms interpretation of the Uboat. It works well with high output pickups.
Good luck on your quest, I love octavers too.


Sent from my iPhone using Tapatalk

Don't get me wrong, that's why I say 'my humble opinion' 
Some people like the old octave monophonic tracking...and some people not.
BTW, I suggested the same upgrade as you.

[EBK]

This where I should confess that the E-H Pitchfork is partly what caused me to recycle my OC-2....

At the time I first saw/heard the pitchfork, I had just recently finished boxing up this:

It was an OC-2 in the same box with a Maestro Brassmaster.  I wired it up so I could feed the Brassmaster input with the dry signal or either of the two OC-2 octave signals, which was rather cool sounding.  Giant box. A 1590BBS, I believe.
I was quite pleased with it. Feeding a sub-octave into a Brassmaster made a powerful sound, which I could still freely mix with the OC-2 outputs (there's a third circuit board hiding under somewhere), making it sound as demonic as I pleased. 
But.... Once I saw/heard the Pitchfork, my pride was deflated.  I felt I had way too many parts in way too huge of a box, with much less agility than that tiny, less expensive commercial pedal.  Anyway, there's most of my OC-2 story.  I still love the Brassmaster though.

[Hatredman]

Again...sorry my brutal sincerity...but I wouldn't waste my time on this [emoji16]
Go for a Ehx Pitch Fork...and save time/ lose one's temper with complicated and inneficients old schematics hahaha
Just MHO
[emoji16]

The pitchfork is a digital effect and I believe at some point he said he wanted an all-analog approach.


--
Scarlett Johansson uses a Burst Box with her Telecaster.

[EBK]

Perhaps consider the Madbean Lowrider:
http://www.madbeanpedals.com/projects/LowRider/docs/Lowrider2015.pdf

[swisher]

Go for a Ehx Pitch Fork...and save time/ lose one's temper with complicated and inneficients old schematics

If anyone tought "go buy some" you would have nothing to buy

Here is my octave v1.5 (CS-2 + OC-2). As you can see it's Sabro layout but on designed PCB.




I want to build simple pedal. Only first octave down on 100%, mix pot only for adjust the sound, then replaced with resistors.

[duck_arse]

there is a thread, with some sounds, and some reading ......

http://www.diystompboxes.com/smfforum/index.php?topic=117811.0

[Plexi]

Again...sorry my brutal sincerity...but I wouldn't waste my time on this [emoji16]
Go for a Ehx Pitch Fork...and save time/ lose one's temper with complicated and inneficients old schematics hahaha
Just MHO
[emoji16]

The pitchfork is a digital effect and I believe at some point he said he wanted an all-analog approach.


--
Scarlett Johansson uses a Burst Box with her Telecaster.

I mean, its a personal case to the thread "f*ck it! I'll better purchase one" [emoji23]
Great looking builds here...but I havent the patient to that kind of stuff

[Hatredman]

Again...sorry my brutal sincerity...but I wouldn't waste my time on this [emoji16]
Go for a Ehx Pitch Fork...and save time/ lose one's temper with complicated and inneficients old schematics hahaha
Just MHO
[emoji16]

The pitchfork is a digital effect and I believe at some point he said he wanted an all-analog approach.


--
Scarlett Johansson uses a Burst Box with her Telecaster.

I mean, its a personal case to the thread "f*ck it! I'll better purchase one" [emoji23]
Great looking builds here...but I havent the patient to that kind of stuff

Yep. I can relate to that. Fuzzes are a more immediate Satisfaction


--
Scarlett Johansson uses a Burst Box with her Telecaster.

[Plexi]

Again...sorry my brutal sincerity...but I wouldn't waste my time on this [emoji16]
Go for a Ehx Pitch Fork...and save time/ lose one's temper with complicated and inneficients old schematics hahaha
Just MHO
[emoji16]

The pitchfork is a digital effect and I believe at some point he said he wanted an all-analog approach.


--
Scarlett Johansson uses a Burst Box with her Telecaster.

I mean, its a personal case to the thread "f*ck it! I'll better purchase one" [emoji23]
Great looking builds here...but I havent the patient to that kind of stuff

Yep. I can relate to that. Fuzzes are a more immediate Satisfaction


--
Scarlett Johansson uses a Burst Box with her Telecaster.

I would say: go for a Foxx TM...and instead of play the higher octaves to get the lowers...play the lowers and get the highers hahaha

[Mark Hammer]

One of the big hurdles in any octave divider that uses a flip-flop to divide the pitch by half is the intermediate zone where the signal level is sort of close enough to trigger the flip-flop, but not quite.  That's what produces the sputter that drives folks crazy about octave dividers.  A compressor can hold the  the signal level high and consistent enough to be above triggering threshold more of the time, but it also boosts parts of the signal that might not otherwise trigger the flip-flop into that sometimes-yes-sometimes-no zone.  So, less sputter, but not NO sputter.

In some respects, what can be better than a compressor at squelching the in-betweenies is a simple gate or comparator; something that forces the signal to be either clearly above or clearly below the triggering threshold.  One simple strategy is to stick back-to-back diodes in series with the signal at some point prior to the flip-flop so that unless the signal is clearly above the forward voltage of the diodes, there won't be any false triggering.  What sort, or how many diodes, would depend on the overall gain structure of the circuit, and the most sensible and effective spot to insert them.

Yes, this will produce crossover distortion, but I'm assuming the octave generated will either be very  square so you won't notice how much sideways clipping is produced, or the octave will be heavily filtered to make it sound more like a bass, which will soften the crossover distortion and make it less apparent.