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Re: The RMA drawing board/etc.

PostPosted: Mon Oct 21, 2019 4:08 pm
by Chankgeez
I really liked the version of the Stone Splitter that I played as part of the tourbox. :love: It can only get better. :snax:

Re: The RMA drawing board/etc.

PostPosted: Mon Oct 21, 2019 4:51 pm
by crochambeau
Chankgeez wrote:I really liked the version of the Stone Splitter that I played as part of the tourbox. :love: It can only get better. :snax:


Thanks!

Yeah, that was/is the third working prototype of that design. I've working some functional changes into it.. like being able to adjust the configuration of the two frequency divider sections from parallel to series (for that two octave down action) and more elbow room in the feedback configuration which affords some experimentation...

I settled on a wiring format for the 40 pin connector that I previously employed sloppily in the 1v4 Crustacean, so I'll start work on plug in modules that can do interesting things and ease some future ambitious ideas.

Re: The RMA drawing board/etc.

PostPosted: Mon Oct 21, 2019 5:20 pm
by frodog
So the Stone Splitter is still in development? I mean will there be a new, pre-built version available at some point? Same as Chank I liked that one as it was, but I fully get it if you want to improve/simplify the design somehow.

Re: The RMA drawing board/etc.

PostPosted: Mon Oct 21, 2019 6:36 pm
by crochambeau
frodog wrote:So the Stone Splitter is still in development? I mean will there be a new, pre-built version available at some point? Same as Chank I liked that one as it was, but I fully get it if you want to improve/simplify the design somehow.


I guess technically speaking the Stone Splitter is still in development, in that I have not fully fleshed out all the new additions I've worked into the design. The important stages are the same as already proven though, so bringing this up to the point at which I will have fully built units available for sale is not a formidable task. So, yes, there will be units available soonish (as measured in my time, FWIW). I'll be sure to let you know when they are available.

The 40 pin breakout connector is essentially horizon work at this point. As a hypothetical example, I could build a sub-circuit that would change the octave configuration, or other routing tricks based on input level or CV so you could essentially scramble the brains of the effect in a hands free manner; or, employ a daughterboard that connects to multiple complex effects to form up a more sophisticated Chimera, etc.. these things are in no way crucial to the normal operation of a build, I'm just punching in support for future efforts that may get interesting down the line.

For complex discrete transistor builds, I find it crucial in my own work to have an oscilloscope on hand. I can't expect that from the DIY crowd, so I'm super wary about presenting some of my designs in that form. Once I am satisfied with a split rail power solution I'm planning on ripping into some "budget" designs that will encapsulate some stages into IC topology for simplicity sake. That will not stop discrete transistor work, and those will probably be available to adventurous builders as well - once they've had some proper burn in time and I've run into as many pitfalls on the design as I can manage.

TL;DR I hope to have saleable units before year end.

Re: The RMA drawing board/etc.

PostPosted: Mon Oct 21, 2019 7:42 pm
by shikawkee
I'm sorry, I guess I missed it, what's the Stone Splitter all about?

Re: The RMA drawing board/etc.

PostPosted: Mon Oct 21, 2019 8:18 pm
by crochambeau
shikawkee wrote:I'm sorry, I guess I missed it, what's the Stone Splitter all about?


Octave down circuit. In the main mode your input signal splits into a dry path, a high pass filter, and a low pass filter - those latter two essentially forming a primitive crossover, and each component of the signal (minus dry) feeds its own octave divider. It's all discrete transistor instead of divider chips though (those sections are based on analog computer texts from the early 1960s). Each divided output feeds a waveshape section, and is then can be mixed back in with some dry signal to taste. There's an output each for both high and low frequency dividers, or the two are mixed to one output if a second plug is not inserted. (outer output jack is the combined output if inner output jack is not inserted)

Add in a feedback path or two to allow instability or re-triggering of the dividing flip-flop sections and it takes on a life of its own.

I'll certainly start a thread on in once I have them dialed and available.

Re: The RMA drawing board/etc.

PostPosted: Mon Oct 21, 2019 8:21 pm
by MrNovember
crochambeau wrote:
shikawkee wrote:I'm sorry, I guess I missed it, what's the Stone Splitter all about?


Octave down circuit. In the main mode your input signal splits into a dry path, a high pass filter, and a low pass filter - those latter two essentially forming a primitive crossover, and each component of the signal (minus dry) feeds its own octave divider. It's all discrete transistor instead of divider chips though (those sections are based on analog computer texts from the early 1960s). Each divided output feeds a waveshape section, and is then can be mixed back in with some dry signal to taste. There's an output each for both high and low frequency dividers, or the two are mixed to one output if a second plug is not inserted. (outer output jack is the combined output if inner output jack is not inserted)

Add in a feedback path or two to allow instability or re-triggering of the dividing flip-flop sections and it takes on a life of its own.

I'll certainly start a thread on in once I have them dialed and available.

Damn, that is right in line with what I've been gassing for lately. You need to stop making awesome stuff, because I can't afford it all

Re: The RMA drawing board/etc.

PostPosted: Mon Oct 21, 2019 8:37 pm
by ibarakishi
still hoping the preamp prototype is done by the end of the year

Re: The RMA drawing board/etc.

PostPosted: Mon Oct 21, 2019 8:48 pm
by crochambeau
ibarakishi wrote:still hoping the preamp prototype is done by the end of the year


The bipolar power converter (RMA Boxer PCB depicted on page 7) is specifically ordered for the preamps, it just so happens it potentially solves other problems as well. My goal is to use the preamp circuit while recording demos, unless the character does not go neutral enough, then I'll just use them to blast things. So - yeah, that's on the short list, and you're first in line for the right of rejection. :lol:

Re: The RMA drawing board/etc.

PostPosted: Mon Oct 21, 2019 8:53 pm
by crochambeau
MrNovember wrote:You need to stop making awesome stuff, because I can't afford it all


:lol:

That's actually a big motivator behind my DIY considerations, as I wouldn't be able to afford all the shit I'm working on either. The Stone Splitter is nice to play, and with the fast and slow octaves with rounded waves and mix, it can be set in a relatively musical manner... in addition to ranging into mayhem.

Re: The RMA drawing board/etc.

PostPosted: Mon Oct 21, 2019 9:47 pm
by $harkToootth
Stone Splitter with the Polish CEM 3394 filter knock off?
EDIT: The Perogie Spliter

Re: The RMA drawing board/etc.

PostPosted: Mon Oct 21, 2019 10:53 pm
by shikawkee
Very cool idea. Dig it.

Re: The RMA drawing board/etc.

PostPosted: Mon Oct 21, 2019 10:55 pm
by crochambeau
$harkToootth wrote:Stone Splitter with the Polish CEM 3394 filter knock off?
EDIT: The Perogie Spliter


:lol:

Those AS3394 look pretty fucking cool, but it's not a drop in for the CEM parts I will probably need to revive my SCI Six Trak. The new part is 24 pin versus the CEM3394 in a 20 pin package. New aspects are 1) a separate output for triangle wave, 2) an output for the "mixed" waveform (originally this was internally routed), 3) an additional VCA input (aforementioned internal routing), and 4) a OSC trigger output. Looks like the filter section block is more or less unchanged. Who knows if they sound similar though.

I am remiss in working on learning code (for a different project), maybe some micro-controlled monosynth action is in order. Ambitious thoughts like this will take me years to get around to, hahaha. But they did break out points in the IC that can be of great benefit (and can also be ignored if I want to build a footprint converter, which would be a PITA since the SOIC-24 part is physically wider than the PDIP-20, demanding some foolishness).

Anyway, I can think of some RMA applications, but I'm needing to not dilute my focus too much, so progress in that realm will be organic and slow - but hopefully fast enough that I don't sleep through the production cycle. I expect poly-synths in the FIX ME pile will benefit my work down the road, eventually.

Anyway, this sort of thing is way more applicable to a ring mod, oscillating fuzz, or drone box/etc. Octave pedals benefit from relative simplicity.

Re: The RMA drawing board/etc.

PostPosted: Tue Oct 22, 2019 2:31 am
by ibarakishi
crochambeau wrote:
The bipolar power converter (RMA Boxer PCB depicted on page 7) is specifically ordered for the preamps, it just so happens it potentially solves other problems as well. My goal is to use the preamp circuit while recording demos, unless the character does not go neutral enough, then I'll just use them to blast things. So - yeah, that's on the short list, and you're first in line for the right of rejection. :lol:


this is what i like to hear. suuuuper excited for this, can't wait to see how it pans out and to finally get to try it out. currently what control/parameter set are you looking at including for knobs to adjust sound of the preamp (if im allowed to ask)?

Re: The RMA drawing board/etc.

PostPosted: Tue Oct 22, 2019 10:35 am
by crochambeau
ibarakishi wrote:
crochambeau wrote:
The bipolar power converter (RMA Boxer PCB depicted on page 7) is specifically ordered for the preamps, it just so happens it potentially solves other problems as well. My goal is to use the preamp circuit while recording demos, unless the character does not go neutral enough, then I'll just use them to blast things. So - yeah, that's on the short list, and you're first in line for the right of rejection. :lol:


this is what i like to hear. suuuuper excited for this, can't wait to see how it pans out and to finally get to try it out. currently what control/parameter set are you looking at including for knobs to adjust sound of the preamp (if im allowed to ask)?


You're allowed to ask (of course!) I just don't know if the answer will be that exciting.

There are provisions for a gain control, switches for input and output transformer ratio, polarity, and 1/4" and XLR inputs and outputs.

Image

The block in yellow is just a single operational amplifier stage, based on the 918 released to public domain in 1977 by Deane Jensen. The surrounding components are more or less also based on supporting components outlined in the published documentation.

Image

So, my elaborations are pretty much limited to adjusting transformer windings (ratio switches I mentioned above), choice of output transistor type, and choice of input transistor type (sloppy discrete or monolithic matched pair).

Any other embellishments one may expect to see in a stand alone preamp (EQ, etc) are separate circuits. Once I have everything working together I'll see what sort of phantom power situation I can dial, +24 will be easy, +48 might be challenging (without revising the PSU situation) because I don't want to put a voltage potential on the microphone shell.

Hopefully that didn't just dash your dreams, haha.