Simple Delay Schem?

[Peter Snowberg]

Thanks to people like Steve at Small Bear Electronics, the PT2399 is available to everyone around the world. He has top notch customer service too.

It takes a lot of circuitry to make a delay. I just don't understand the endless quest for simple circuits. I'm more of a fan of the quest for useful circuits, regardless of how simple or complex they are on the outside.

[Seljer]

Could you theoretically make your own BBD line out an truckload of the invidiual delay stages (with the FETs + capacitor thing thats going on inside a BBD chip)?

[Mark Hammer]

The thing to keep in mind about delay circuits is that, because of the constant risk of objectionable noise, it takes a lot to make them liveable/tolerable.  This stands in contrast to many distortion and other circuits where it takes more to make them flexible but very little to make them tolerable.  I think a lot of folks who maybe start out building fuzzboxes mistakenly assume that all the "complicated stuff" in delay circuits is simply bells and whistles that can be reduced if you don't want them.

In general, the difference between delay and distortion circuits is like the difference between packing for a trip for a 4 month-old infant vs a 19 year old guy.  One simply requires a lot more absolutes than the other does in order to avoid sure disaster.

[Nasse]

I think I have readen somewhere that doing discrete bucket brigade line would end on bad noise and loss/attenuation problems

[Mark Hammer]

Could you theoretically make your own BBD line out an truckload of the invidiual delay stages (with the FETs + capacitor thing thats going on inside a BBD chip)?

Yes, and the odds are that it could have much greater fidelity, too, since one of the constraining factors in BBD ICs is the leakiness of the caps.  You can't really "freeze" audio samples for very long in a BBD the way you can "freeze" sampled voltages in a conventional synth S&H unit.  That's one of the reasons why audio quality declines with long delay times and multiple repeats - essentially each repeat adds error to already erroneous or misrepresentative voltages.

Of course, you're not going to be able to fit that sort of all-discrete circuit into anything smaller than a 1-U rack unit, and even there it would probably require fairly high-density boards and be miles away from cost effective, relative to even higher-end digital units.

I think I have readen somewhere that doing discrete bucket brigade line would end on bad noise and loss/attenuation problems

I don't know about attenuation, but I suppose there would be some risk of clock signal leakage since an all-discrete circuit would necessitate clock lines running all over the place.

[Seljer]

it'd be like the ultimate-mojo delay pedal if it were possible, and there'd have to be some rich guitarist out there that would buy it on their quest for the ultimate tone 

[Rafa]

Hi:
What about the K.I.S Delay?? Looks not so complex.
I have another question, is it theorically possible to design a chorus with commonly available parts, which is not extrmely big, its not important that it is too versatile, just a chorus??
Thankssssss
Rafa 

[Seljer]

err, KIS Delay?

and a chorus is essentially just a (shorter) delay with and LFO controlling the delay time

[Rafa]

Yup KIS
Take a look:

Rafa

[BDuguay]

I trust that the mention of B.Y.O.C. here will not offend anyone in anyway but, as the builder of the B.Y.O.C pre-build orders, I can tell you that they're PT2399 based Delay kit is a very low part count circuit assembly. Having said that, I don't know if that means the actual circuit itself is simple but, I do know I can assemble one of those kits in less than 2 hours.
"short post from Hammer" now that's funny!
B.

[Seljer]

Its basically just an analog delay, the 3201 generates the clock, there are three 3208 BBD delay chips. Theres that SA571 compander at the start and then theres a a couple of filters and mixers.
When you look at the amount of parts in there theres much more than in one of the PT2399 ones.

[puretube]

that schemo is
TOO BIG
to be simple...

[Rafa]

JAJAJAJAJAJAJAJAJAJAJAJ
Its small compared to commercial delays as the pt2399 is not available here
Rafa

[Seljer]

Its been mentiomed that guys like Steve from Smallbear will happily ship to prettymuch anywhere. I dont think I'd be able to find a PT2399 here either, and I'd just as much luck trying to find BBD chips at a local store.

[Mark Hammer]

"short post from Hammer" now that's funny!
B.

That's it, Brian. You are hereby cut off.  NO SCONES FOR YOU!!

Seriously, though, there are many things I've been able to build in under 2hrs using perfboard, for pete's sake, but ONLY AFTER I'VE ALREADY BUILT THEM 3 OR 4 TIMES ALREADY.  Indeed, there are plenty of 10-chip projects that could come easy to lotsa people here, but the thing is that they already take most construction best practices for granted and do them without even having to think about it.  As a result, the number of degrees of freedom for error are considerably reduced, and even 100-part projects fly the first time they are launched.

When someone says to me "I want a simple circuit for....", I treat "simple" as a code word implying that the requester has not got all that much construction experience under their belt and that the step up from a Distortion+ to a Tone Machine is more than likely a big leap in complexity for them.  Here, "simple" sort of means "please don't hurt me with a circuit that will cost me $50 in parts and will NEVER ever work".  I don't mean to insult anyone.  It's just that what feels "easy" after building for 10 or 15 years is qualitatively different than what feels easy after building for 9 months.

The AD3208 and PT-80 projects (and thank you again, Scott) ARE relatively straightforward designs that use available parts for a reasonable total price.  But, there are a couple of dozen IC pins that can accidentally get tucked under the chip during insertion, plus there are all those electrolytic caps that can be installed the wrong way, and all those other things that make it....complicated.  "Simple" also means "I'll know where to look/test/measure if'n it DON'T fly at first launch".

PT2399-based delays are a walk in the park compared to the design I saw for a digital delay in a 1980 issue of POLYPHONY.  There, we were talking an outlay of at least $100-150 for less delay time with less bandwidth/quality and probably at least 20x the build time and 0x the debug time.  Yup, a walk in the park for those whose memory goes that far back.  But compared to a Tweak-O or Bazz Fuss, it IS complicated.

[Rafa]

Hi:
Mark you are toatlly right, Simple= little expirence sometimes or maybe cheap, but I think that maybe some peolpe like me mean that to design a pcb for the boss ac-2, build it and get it working is hard. Maybe its fear to those hughe build, but maybe with some more expirence and with a boss ce-2 for example, wouldnt be  a problem.
Well tahats my point of view, and maybe I didnt expressed myself right its hard for me and even more difficult in english.
Rafa

[dano12]

Its basically just an analog delay, the 3201 generates the clock, there are three 3208 BBD delay chips. Theres that SA571 compander at the start and then theres a a couple of filters and mixers.
When you look at the amount of parts in there theres much more than in one of the PT2399 ones.

Seems like most of those parts are in the SmallBear catalog. However, what's the 3201 DIP in there? Couldn't find anything on Google...

[dano12]

Its basically just an analog delay, the 3201 generates the clock, there are three 3208 BBD delay chips. Theres that SA571 compander at the start and then theres a a couple of filters and mixers.
When you look at the amount of parts in there theres much more than in one of the PT2399 ones.

sorry/double-post

[Seljer]

err, MN3102, swapped around the numbers 

[dano12]

err, MN3102, swapped around the numbers 

Doh! Thank very much you