[sdiy] BBDs

[Scott Stites]

Anthony wrote:

> Heckuva flanger.  Don't forget JH's Dimension D project, too!  The
> Dimension
> D is what the Dimension C was based off of - same general concept, a bit

>Didn't forget! I just didn't want to dump too much info at once.

=0)

>I'm making something like a Dimension C with true stereo liek the D.
>(Because all I have is the C schematic.
>I've modded the circuit so much now that it's really my own design.

Cool!

>I didn't have any NE570's so I thought I'd use National's LM1894 Dynamic
>Noise Reduction chip. I have a whole bunch of these and they are very cool.
>The original gear I got 'em from used them /before/ the BBD which is kind
of
>silly.

This sounds very interesting to me, I'm totally unfamiliar with the LM1894.
Seems to me that I ran across them somewhere - I'm thinking it was the
dreaded Futurlec.

>I'm also using the CE-300 schematic. They're very similar and yet very
>differentAnd for my clocks I'm using the 4007/4047 combo. It's been hard
for
>me to keep this simple like the D & C were. I intend to use a knob to mix
>the two channels because I hear this can create a thru-zero flanging
effect.
>But other than that I plan to use just the four buttons (I'm just using
>regular push-on-push-off's so I'll actually have around 16 settings) and
>maybe some switches for range. But having CV inputs would be cool so I'm
>doing that. I want to try a multi-phase clock. I actually thought about
>using 3 BBD's instead of 2, but my goal is to use just ONE grid board
>(276-168B) from Radio-Shack!

Whew!  That's a lot to squeeze onto a board.  I bet you'll feel like a
qualified micro-surgeon after its done.

>This would not be possible if I didn't have a
>bunch of inline M5218's. I wish I had a lot more of those.

I was only able to find those in DIP package.

>I have 6 dual
>op-amps on there! (Along with everything else.) I'm using 2SC2240GR's for
>the LPF's, but I have some 2SC732BL's and a bucket-load of 2SC1815GR's...

I used the Japanese transistors mainly because I wanted to keep things in
the audio path as close to the original as possible.  I'd planned to (but
never did) sub in other transistors to see what worked out or not.

>I've overclocked an MN3207 to 1.5MHz without a buffer and it seemed to work
>OK. It falls off past that though. I totally forgot about that until now.
>The 3207 is in my Radio-Shack reverb which I've hacked and thrashed a lot.
>It has a li'l bank of 1/16th" jacks on the right side. These things
actually
>sound pretty good if you add some gain to the regen op-amp and put about a
>33KOhm resistor inline with the dry signal right between the blue wire and
>the op-amp on the right side. What? I know you guys all have one of these
>somewhere in a closet.

Mine disappeared years ago =-(.

>Yeah MN3006's overclock really well. Ganging a bunch of them up and mixing
>it with a 12-stage fixed phase shifter is way cool too (trying a 32-stage
>soon). This a lot like what's done on the Storm Tide but I wanted a bigtime
>"Theta Processor"

One of these days I'd like to try something like that out.

>I want to make something liek the STD. I want some MN3011's...
>I just found a schematic today.

That's my next big project - I'm laying the groundwork now.  I don't know if
I'd put 'STD' on a piece of gear, so I'll probably call it Variable Delay 1,
or VD-1 for short =-D.

I know you prefer to keep things to a small budget.  Having said that, Small
Bear has the MN3011, but it's not cheap - $15.95 apiece.  As expensive as
that sounds, I think it's actually less than they originally sold for.  It's
considerably less than I've seen advertised at places that claim to have
them (something like 60 pounds apiece over in the UK).

Or, you could keep your eyes peeled for a broken Scholz Rockman - they used
it for the reverb.

===

>Yeah so those lackluster flangers can actually be tweaked up good.. I
forgot
>about the 3207 having a spec'd higher clock rate. It has a lower S/N ratio
>though. I wonder how big of a deal that is? Like should I hold out for
>MN3005's or would MN3205's be fine? But that's another  project. (I thought
>having an analog delay that used 6 MN3005's would be cool. I want to out-do
>the Maxon units. I'd build it so that I could add them in piecemeal.)

To be honest, I have yet to do anything with the MN30XX devices (that's soon
to change), so I couldn't tell you from any experience of mine.  I'm not
sure what difference the S/N ratio would make, but I'd think BBD's need as
much as they can get.  Maybe that's a reason the MN3007 based flangers are
more prized than the later MN3207 incarnations.  The MN3207 does pretty well
in the Dim C.  But there's a lot of emphasis, de-emphasis, companding,
filtering and other histrionics to keep the clocks from hetereodyning, not
to mention the equalization/crossmixing, all of which play into the general
overall sound of the thing.

>I think a great way to make a boring flanger more interesting is to have
two
>of them and mix them. Two radically different ones would be choice.
Although
>the Infinite Flanger uses two very similar flanging units in the same
>package. I like Juergen Haible's idea of just having one and having a loop
>to mix another one in. I can't wait 'til I get my Storm Tide inspired
>flanger finished. I have an aluminum 19" rack for it to go in. The ears
were
>milled from billet. I also have some rad solid aluminum knobs (half of them
>are coaxial pots with pull switches - fun).

I'd make sure the signal you mix in has been companded and filtered
adequately, as well as the signal in your flanger at the mixing point.
Clock hetereodyning could get ugly otherwise.

>I thought about putting mine in a Geiger counter. Assembly of it is taking
a
>while. Mostly because of the need to find ways to artfully squeeze all of
>those parts on the small board. I have some cool large value polycarbonate
>caps that I'm using for the LFO. Also I'm also building a digital delay
(the
>badtz goodfortune one) with a psycho LFO built around a 74HCT14 which can
>either modulate the clock rate or the other, sane LFO. And of course a lot
>of time is being spent designing Synth-a-saurus Rex (mostly Ray Wilson and
>Ken Stone stuff).

Hmmm...I have an old Bounty Hunter metal detector that looks somewhat like a
Geiger counter chassis.  Hmmm....

>I have the Morely schematic. Mine's a little different. It uses an op-amp
>instead of the darlington and the 4007 is hooked up a bit differently.

It's a good clock setup, but as I understand it, won't hit the freq's a 4046
based clock will.

>I've thought about getting a CV flanger to track v/oct for some modeling.
>I've heard some examples and actually love that psychotic flute sound. I
>think a mixture of tracking short delay and fixed short delay with some
>phase-shifting would sound sweet. I think I'll add some modeling stuff on
>Synth-a-saurus. It's kind of small, but with a Dremel tool I'm sure I can
>get a lot in there. Including a stereo amp with speakers in the bottom for
>ballast.

I'd say you've got some good devices for that kind of stuff (the R5106's).
It'd be nice to have some 128 stage devices for that kind of thing, too.

>Oh yeah! You're the Birth of a Synth guy!

Yes, still gestating.  This water retention is killing me =-D

>Your page along with Juergen's was
>a big inspiration for my Dim C project. I call mine "Dimension ME". I
>never
>would have thought to do through zero flanging with the Dim C. I think
>having 2 BBD's obviates the need for fast clock speeds a little maybe. Well
>a single BBD even clocked really fast still can't go through zero. But
>clocking it really fast and making the delay really really short almost
>makes it. Making it sound better than run of the mill flangers. BF-1 vs
BF-2

I agree - generally the higher the clock rate the closer you get to T=0 and
how close a device can get to T=0 is one quality that distinguishes a very
good flanger from something rather ho-hum.  An added benefit to higher clock
rates is also higher bandwidth, which is good for chorusing and flanging,
but (IMO) not quite as vital for longer echo type delays, which sound a bit
more natural at lower bandwidth anyway.

>Am I the only one who uses Japanese transistors almost exclusively? I
>intuitively know which ones correspond to the Euro ones now. I get the best
>ones from tape decks from the 70's: 2SC1815GR/BL's, 2SC732BL's... I
>mentioned all this earlier I think...

I like'em.  Especially the Japanese dual trannies.

I should close this book - I heard a distinct groan emanating from the
Detroit region =-D.

Cheers,
Scott