Boss Dimension C Build Question

[DiyFreaque]

It's coming

The idea of controlling the bypass gate voltage for intensity was rather a flop and has been discarded.  There's really not a lot of discernible change from the time the FET's come on, and the range where they're just coming on, but with high resistance sounds terrible!

Next up is how to best handle the regeneration.  The signal is tapped before de-emphasis, so it'll have to be, um, de-emphasized, but I'm trying to figure out if I want to run it through de-emphasis before the mixing/regeneration or after.  Things now are tilted a bit towards the treble end because of the pre-emphasis.  Guess I'll have to dig up the St. Croix article in Device and read up on regeneration technique.

And I suppose it'll take a bit of breadboard tinkering to figure it out.

Cheers,
Scot

[Mark Hammer]

I'm not sure what I'm more impressed with, the sounds you've managed to achieve, or that fact that in spite of having a family you manage to get something done almost every week! :lol:

[DiyFreaque]

Hi Mark,

   Well, once the thing gets on breadboard, it's pretty quick to switch things around, and the modular helps to patch rough ideas out sometimes without resorting to putting it to circuit.  I still find time to spend with the lab assistant outside the laboratory on projects he directs (technical details of stringing up Christmas lights, the occasional game of Duck Soup (don't ask), and of course the bedtime reading of technical treatises).  My wife's work hours are usually opposite of mine, so things come to a halt when she gets home.

Speaking of the lab assistant (my nearly 6 yr old son) did I mention the story of me soldering while listening to Tangerine Dream?  He came downstairs, listened for a second, and said "Daddy, that synthesizer sounds just like yours, only that one makes music."

I was thinking about the asymmetrical switch idea - the one about 'stopping' one of the BBD's.  I guess that would also serve to lengthen the apparent sweep time.  In the 'normal' mode, both delay lines are approaching, passing and receding from each other, so their relative 'speed' would be our auditory cue as to the sweep speed.  If one is stopped, then the perceived sweep speed would just be the one delay line.  I suppose it would analogous to cars approaching each other on a highway.  A car (hopefully) in the other lane will have a greater perceived velocity than a car (usually mine) broken down on the side of the road.

Well, at least I think so.....

Cheerio,
Scott

[Vsat]

Count 194 viewings of this thread since yesterday...looks like someone finds this thread interesting.. anyone care to join in  
Regards, Mike

[Ed Rembold]

Mike,
You already know what I think.
"take this baby off-line"

Nice work Scott, loved the samples,

Ed R.

[DiyFreaque]

Thanks Ed!

Hmmm, sorry, I'm a newbie to this forum, so I could be easily breaking protocol without being aware of it.  By 'take it offline', does that mean the thread has been extended too far?  

I didn't have much time to do anything tonight, but it was pretty easy just to remove the LFO input of one of the BBD's and inject a DC control signal into it to try out Mark/Mike's comparison of symmetrical and asymmetrical modulation for TZF.  I found the results to be pretty interesting.  

I used filtered noise for the signal on the samples (A) because it's easier to pick out the flanging effects and (B) I play noise better than anything musically interesting .

It's here

http://mypeoplepc.com/members/scottnoanh/slsdiy/id18.html

Under "06 December 2004"

Cheerio,
Scott

[Ed Rembold]

Scott,

You absolutely are Not "breaking protocol". You are doing just what we all used to do on this forum, posting "break-throughs" and "happy accidents".......
totally unaware of where those happy accidents were ending up
(commercial products).
Taking it "offline" doesn't mean the thread is too long.

Ed R.

[Mark Hammer]

1) Ed's comments mean "You've got something good there.  Maybe you ought to protect it."  It's a comment borne of respect rather than irritation (although I'd be a little irritated myself knowing that someone else thought of something that good!)

2) Definitely definitely prefer the asymmetrical to symmetrical sweep in your samples.  The asymmetrical just spends more "quality time" in the critical zone.  That doesn't mean the symmetrical HAS no earthly use, but as an effect appreciated simply for how it makes my ears feel tickled, I like one more than the other.

As noted in an earlier post, there is no reason why symmetrical sweep (complementary counterswept BBD's) could NOT be made to sound just as good.  The central problem is that most waveshaping tends to be all about the peaks/troughs of waves and not about what happens in the middle at the crossover point...which is where we need the sweep to be articulated a little more in this instance.  In effect, the LFO waveform needs to be sinusoidal around the middle and triangular at the peaks/troughs.  An LFO that knows how to be hypertriangular in both directions!!

I'll save RG a posting and suggest that maybe this is a job for a PIC, and a wavetable-based waveform that spends just the right amount of quality time around the through zero point.

[DiyFreaque]

Thanks Ed and Mark,

This forum has zoomed to the top of my list of favorites, and the last thing I want to do is muck things up (hence my question).  This forum has the right mix of knowledge, practical application and (just as importantly) *enthusiasm*.  

Mike discovered the TZF buried in the heart of the DC-2, Mark revealed symmetry and asymmetry, I'm just lucky enough to hear the ideas and plug'em in.  I guess it'll be interesting to see if any new TZF products pop up   .

Anyway, I agree - the symmetrical and asymmetrical apps both have their appeal.  It's not terribly difficult to have both as it sits now - a two position switch labeled "Cake" and "Eat it, too".  Any PIC programs I will gladly leave up to RG - zero PIC experience here, though it certainly would be in my (and anyone's) interest to learn about them.  They certainly do get their share of app's.

Take care,
Scott

[puretube]

An LFO that knows how to be hypertriangular in both directions!!

remember puretube asking a while back, whether anybody has analyzed the SS 2-OTA LFO closer?...


:wink:  :wink:  :wink:

---silence---

[Vsat]

Scott, Ed, Mark -
Just thought it was instructive that this thread has received close to 350 viewings in the past couple of days, with relatively few active participants. The "EH Microsynth" thread is the next runner-up... and the grand prize winner gets... a TZF!!

If I was concerned about other companies/individuals making commercial use of  my designs or research results I simply won't make that info available on the net. However, some neat goodies need to be put into the public domain every now and then to keep interest up. Most people will appreciate it, a few will want to use it in actual products. Whether the originator of the idea and eventual design is credited is a different story.

The DC-2 is a more evolved version of Roland's earlier "vibrato-free" chorus designs (and there was a patent, perhaps it is still active). The Roland JP-4, Juno 6, 60, JX-3P, JX-8P are all capable of producing TZF sounds. With the DC-2 a more "natural" sound was desired, along with better S/N. Also, some  of the old string synths have a "slow" chorus mode that produces mono TZF.... a Siel stringer (from 1980) I recently fixed is one of them.
Regards, Mike

[puretube]

free information block:

[DiyFreaque]

Thanks, that's a real treasure trove of information!  

It'll be interesting to study them to see what is different from application to application.  I've seen the ensemble chorus patents filed by Norlin and also the system used in the ARP Omni(?) and know what differences there are there (one uses two triphase and the other uses separate LFO's for each BBD line IIRC), but (at first glance) a few of these use a couple of tri-phase LFO's.  Seems to me somewhere around here I've got the Solina patent.  I'm wondering if anyone knows the patent number of the two BBD system in the Dimensions C and D (and the other synths Mike has mentioned).  Guess it might be here - I haven't read closely enough yet.

To deviate from the thread a bit, I've often wondered if someone has made a stompbox from particular other synth-originated modules.  At the forefront of my mind is the Korg PS series resonator (resurrected and improved upon by MaM, among others) - I've put one of these together, and it's not nearly as complicated as the Dim C, and I think a guitar would sound awesome through one.  I think it'd be fittable into a stompbox.  

Another one I've thought about is the Wave Multiplier from the Serge Modular (redone to great success by Ken Stone) - again I think a Strat through that (at least single notes) would be the bee's knees.

But, I digress.  Thanks mucho for the links!

Cheers,
Scott

[puretube]

free information block:

[Mark Hammer]

Korg resonator.....

Doesn't Paul Perry (Frostwave) make one of those?

[DiyFreaque]

Hi Mark,

No - it's a different device.  What Paul has done is put the absolutely wild S-K filter from the Korg MS-20 synth into a box - a brilliant idea.  If ever a synth design screamed 'guitar', it was that one.

The PS series resonator is a unit that is made up of three parallel bandpass filters.  The initial center frequency of each bandpass filter is individually adjustable, and they can all be swept in tandem.  The result can range from a gorgeous phase shifter-like effect to formant tones to other things that are a bit hard to describe.  The first time I heard one was at Jeff Pontius' house - I literally went weak in the knees when I heard his Prophet 5 run through his MaM resonator.

The MaM is an improvement over the original resonator, because it adds more modulation capability, and very, very cool stereo.  What's more, it's based on Vactrols (VTL5C3's is what I used) and is whisper quiet.

A very good write-up on the MaM can be found here:

http://www.midiwall.com/gear/rs3.html

Cheers,
Scott

[DiyFreaque]

Here's a sample I dug up on my website of the (PS style) resonator in action - hope the link fits.  The file's around 3.5 MB:

http://mypeoplepc.com/members/scottnoanh/sitebuildercontent/sitebuilderfiles/3notebass_snippet.mp3

The phase-shiftery effect is the resonator.
I just had the resonator mono, and did a track right and a track left for stereo.  

Towards the end there's a little bit where just noise is tracked through and it's controlled with an EG percussively - it has that sort of formanty quality the circuit is capable of.  It ends with a sequenced bass that has no resonator (it's going through a filter I was working with, derived from two cascaded sections of the Buchla 291 low pass gate).

The schematic for the original PS resonator (which I used) is somewhere out there - I can't remember where I found it....

Cheerio and off track (sorry),
Scott

[Vsat]

Here's the Roland patent....

US4205579

Describes a ramp-based technique.. actually easier to implement using triangles, which Roland used in  their commercial fx.
Regards, Mike

[Vsat]

Here's the Roland patent....

US4205579

Describes a ramp-based technique.. actually easier to implement using triangles, which Roland used in  their commercial fx.
Regards, Mike

[DiyFreaque]

Once again, thank you Mike!

You guys have supplied me with some study material to last me quite some time.

Cheers,
Scott