any multiple mn3008 suggestions?

[pinkjimiphoton]

i was reading mark hammer's bbd article and got to thinking where he said you could use one clock to drive multiple bbd chips in series..
so i guess what i;'m wondering is could you use one clock to drive, say 4- 6 mn3008 chips and get a fairly decent fidelity diy delay with a fair amount of useable delay time too out of what's still a reasonably easy to find chip? i've still got a sleeve of them from years ago, and would love to put them to a good use.

are there any projects out there i haven't found that use this kind of approach? is it even feasible to think about for a vero guy like me to do?

cuz it seems if all you'd have to do would be put the chips in series (i assume that means just the inputs and outputs of the delay itself) and give each whatever support peripherals you need to and drive it from one clock circuit,  it really wouldn't be much harder than making a single "stage" version.

or am i like wayyyyyy off base like usual? pipe dreams.... but sometimes they pan out into interesting things

please educate me if you can, thanks!

[Scruffie]

I wouldn't try and do it on vero but madbeans Total Recall project is a Deluxe Memory Man that can use 4 x MN3008 with an expansion board.

[armdnrdy]

Maxon AD-900 Build doc on page 2.

http://www.diystompboxes.com/smfforum/index.php?topic=109774.0

[Mark Hammer]

1) Kudos to Larry for the build document.  Kudos to you for being adventurous.  Government Lacky's build is impressive.

2) Aiming for more than 8192 stages of delay demands a more complex circuit, in order to buffer the clock pulses against the input capacitance of all those pins 2 and 5 ( can't see the build document from here, but assume it's using an MN3101 clock driver).  The equivalent of two MN3005s will get you 600ms delay with decent bandwidth.  If you are willing to sacrifice a bit of bandwidth, you could aim for 800msec.

3) Some manufacturers take the gamble and provide a single bias voltage to all BBD chips used.  That can work, but makers of other desirable pedals tend to stick a DC-blocking cap between BBDs, and rebias each BBD individually (e.g., Maxon AD-999, Memory Man).  Essentially, the more BBDs one uses, the more you want to fine-tune each BBD individually.  Larry has wisely adopted that approach, and also provides output balance trimmers for maximum cancellation of clock noise.

4) Vero?  If it were a chorus with a single puny 8-pin BBD, I'd say sure, have at it.  But the prospect of running clock lines to 4 BBDs seems to invite clock noise potential, where proper layout becomes paramount.  It'll work, but you'll kvetch about the noise.  Etch Larry's layout.

[pinkjimiphoton]

thanks for the sobering advice on the vero.

i forgot what a PIA it can be in some circuits. i know dino could probably do it, but...

also thanks for the info as always.

i am gonna check larry's link as soon as i gotta free minute to digest more information

looking at jack orman's modbox distortion from the may 97 electronics now! pdf looks fun

i was just curious if it could be as easy as stacking a bunch of bbd's on top of each other like ya can with some dual ic's in all honesty.

i often wonder more than i think i should

peace!

[armdnrdy]

If you choose to build this beast....I came up with a mod for it after the fact.

Greg (Government Lacky) and I added this mod to our builds.

The "stock" AD900 is sort of a dark sounding delay.

The mod incudes adding a bright switch to...well....brighten up the delay. 

There is a daughter board which contains a SPDT switch, and a couple of caps, and a couple of resistors.
This switches between stock filtering and brighter filtering.

The delay become much more versatile with sounds ranging from Sabbath (Heaven and Hell) to U2.

[pinkjimiphoton]

awesome larry, thanks for the heads up.

i just made another huge parts order... believe it or not, them ruby doobies (the ones on vero) are selling.
some shizoid face fuzzes too. what's wrong with people? beats me.

would love to see a schem or layout for the daughterboard.

but this is gonna be a ways off, i have a tau phaser build que'd up next after i finish jc's paradigm. just waiting for the proper time...

you know, the old "we will sell no wine before you buy it" thing or something like that.

gonna have to bite the bullet and get some pcb etching supplies.

i convinced my girl a laser printer was a good thing to have