A/DA Flanger does TZF?

[moosapotamus]

How long is a piece of string? How many North Vietnamese does it take to dig a hole? Yes folks it's North Vietnam joke time - don't theirmilitary wear silly hats!!!

I find their leader's hairdoo rather amusing. ~8{

[moosapotamus]

If the analog and digital circuits are powered of the same supply then you can't keep them entirely separate both analog and digital circuits need a ground.  Also if the analog and digital circuit interract at any point then the grounds of the two systems must connect.

In the nyquist aliaser circuit that JC Maillet presented, there is passive isolation between not only the audio and clock ground rails, but between the power rails, too. JC discusses it on his web page...
http://www.lynx.bc.ca/~jc/nyquistAliaser.html
... and, this is how I tried it...
http://moosapotamus.net/IDEAS/nyquist/NyquistENV2.gif

It seems to work well. But, maybe comparing the nyquist to the ADA is apples and oranges?

What you don't want to do is intermingle analog and digital grounds on the same tracks on the PCB.  You want to keep the tracks separate.

So, that's the deal with the star point in the ADA layout, right?

Thanks!
~ Charlie

[Gripp]

While on the subject of the ADA...

As I said before, I'm just trying to clean up the SAD1024 Mike I layout (the one based on the Bill B layout which is a rev3) and not do a complete redesign/relayout as I understand you guys are doing.

I have run into a problem here and could really use your help. Moosapotamus, you seem to have all the files and a good eye too. My problem is this, I can't find the coupling cap that comes straight off the clock null trim in the Mike I layout. In the Giles/Irwin schematic this one is 0.22u. In the original rev3 there is a coupling cap C13 (.1u) isolating the MN from the next op amp stage too. Have I just gone blind from staring at the files too much, is it truly missing from the Mike I layout or is it perhaps not needed at all due to some reason I can't think of??? Help!

Best!
Pelle G

[moosapotamus]

...I can't find the coupling cap that comes straight off the clock null trim in the Mike I layout. In the Giles/Irwin schematic this one is 0.22u.

I don't see it either, but I would add it.
But, you did see the note on the layout to add a 0.01 uF between SAD1024 pins 1 & 2, right?

As I said before, I'm just trying to clean up the SAD1024 Mike I layout (the one based on the Bill B layout which is a rev3) and not do a complete redesign/relayout as I understand you guys are doing.

Let's clear something up...
I am not really thinking about this as a re-design at all. I am working on a "stock" layout that incorporates the following...

• Mike Irwin's SAD1024 adaptation
• Rev3 diode limiter configuration
• Rev4 everything else
• Extra pads to make mods and experimentation easier

Aside from adding a few extra pads, I think that's more or less the same thing you are doing, Gripp... right?

This thing sounds like its getting complicated really fast!
What features have been agreed on?

Building it should only be as complicated as the person building it wants to make it.

Building it "stock" should be relatively straightforward. The mods you choose to add will be up to you, but there will be extra pads where needed to simplify any additional wiring that might be needed for whatever mods you choose to do.

A lot of the potential mods have been discussed in some detail here in this thread. I think the list of potential mods that I posted the other day still holds...

Here's my current list of potential mods, so far...

• TZF (second delay line TBD)
• True stereo outputs
• Additional direct/dry output (pseudo stereo with vibrato mod)
• Vibrato (switch to eliminate dry signal, or pot to control wet/dry mix)
• Foot pedal input jack for wet/dry mix
• Ultra slow/fast switch for LFO (dual, extended speed range)
• Bounce & Foldback (envelope controlled?)
  http://home.debitel.net/user/jhaible/jh_storm_tide_flanger.html
  http://img.photobucket.com/albums/v317/StephenGiles/bnce_clock.gif
• Variable cap(s) for 4047 timing capacitor
• Trim pots brought out as panel mounted controls

I think that's the first time I ever quoted myself.

There's been some discussion about using VCA's for some other mods, but I'm going to assume that those would need to be implemented in the same way as the TZF mod, on a small separate board that can be wired into the main PCB.

Any other potential mods to add to that list?

Thanks
~ Charlie

[Gripp]

...I can't find the coupling cap that comes straight off the clock null trim in the Mike I layout. In the Giles/Irwin schematic this one is 0.22u.

I don't see it either, but I would add it.
But, you did see the note on the layout to add a 0.01 uF between SAD1024 pins 1 & 2, right?

Thanks! Will add it. Yup, I saw that note fortunately.

Let's clear something up...
I am not really thinking about this as a re-design at all. I am working on a "stock" layout that incorporates the following...

• Mike Irwin's SAD1024 adaptation
• Rev3 diode limiter configuration
• Rev4 everything else
• Extra pads to make mods and experimentation easier

Aside from adding a few extra pads, I think that's more or less the same thing you are doing, Gripp... right?

Well, I'm just cleaning up the Mike I modded layout graphically because it was kind of low resolution, probably due to format conversion somewhere. I've tried a new (for me) method of doing this so it's an opportunity to learn too. Taking the gif to vector and edit in illustrator. So, I'm going to go with this, meaning using the rev3 (Bill B) for everything except clock, BBD and associated parts.
Are there any obvious advantages in using rev4 for everything else? I just haven't thought about rev4 since the Bill B layout is rev3.

[oldschoolanalog]

Any other potential mods to add to that list?

Thanks
~ Charlie
[/quote]


How about a switch to turn off the LFO? This would make it easier to use the voltage control pedal as a comb filter. Wouldn't have to reach down to adjust the range pot every time you wanted to use the comb filter function. Thank you!

[moosapotamus]

Are there any obvious advantages in using rev4 for everything else? I just haven't thought about rev4 since the Bill B layout is rev3.

I guess that's a good question that I don't really know the answer to. It looks like the main differences between all the rev's and Mike's version (Stephen's scheme) is the LFO... They are all slightly different. But, Mike's is very much like Rev4. The only difference I can see between the Rev4 LFO and Mike's version is R47 going from the junction of R60, R61 and the speed pot to ground. So, I'm leaning towards Rev4 LFO because it'll be easier to just leave R47 out if it runs better that way.

How about a switch to turn off the LFO? This would make it easier to use the voltage control pedal as a comb filter. Wouldn't have to reach down to adjust the range pot every time you wanted to use the comb filter function. Thank you!

Functionally, kind of like the filter matrix switch on the DEM? Sounds cool to me.

Thanks
~ Charlie

[moosapotamus]

Will it make any difference if the CMOS chips (4007, 4047, 4049) are buffered or unbuffered?

~ Charlie

[toneman]

hi Moose,   Usually....if U are going to use the CMOS digital chips in an "analog way",
then, U should use the unbuffered versions.
The bufferers are for digital drive called "fanout"; i.e. how many other gates it can drive.
When biased into the linear region, the buffers are not needed.
And, from most of what i've read, the buffers are detrimental to the analog useage.
Though, i've never done a side-by-side scope or sound comparason.
Maybe someone has 
Staybuiding
tone

[Rob Strand]

> It seems to work well. But, maybe comparing the nyquist to the ADA is apples and oranges?

That is a valid way to isolate, but it can only be applied in some instances.  There is a trade-off  with that circuit in that the ground resistors cause voltage drops between the ground.  On that circuit the ground drop can be accommodated.  On say a circuit using a BBD it's not so easy because the BBD chips don't have separated analog and digital grounds.   As you reduce the ground resistances the drops reduce, in the limit you end up with track resistances.  Most of the time it's good enough just to split the tracks and make sure each arm has good supply decoupling and that they connect back to a low impedance supply.

> So, that's the deal with the star point in the ADA layout, right?

I haven't seen it but I would say that is precisely the case - it's a very common practice.

[Gripp]

I'll do some guesswork here...
Isn't an LFO disable switch superfluous? Doesn't turning range to zero give full control to manual or CV jack?

Re buffered/unbuffered CMOS, my thinking is this (still guesswork).  All of the CMOS chips make up a high frequency CV controlled square wave bi phase clock, so the end result is in a way digital. The 4049 is there to make sure that there is good drive to the BBD in order to overcome gate capacitance so it wouldn't hurt to have this one buffered.
Somebody please correct me if I'm wrong.
/Pelle G

[StephenGiles]

LFO  - yes

CMOS - I used whatever I had - like I always do!!!!!!!

Grounds - I doubt if you hear the difference above a drum kit

[StephenGiles]

Our friends from Argentina/Chile of course will be using the subjunctive about all this because nothing is certain!!

Es importante que ADAmos

[Gripp]

Sorry oldschoolanalog, I read to quickly and didn't see the part about not having to adjust the range pot to get the static comb filter effect.
When done, my pedal will end up on a table close by for tweaking.
Best!
Pelle G

[moosapotamus]

Usually....if U are going to use the CMOS digital chips in an "analog way",
then, U should use the unbuffered versions.

Thanks, tone

Most of the time it's good enough just to split the tracks and make sure each arm has good supply decoupling and that they connect back to a low impedance supply.

Thanks, Rob

CMOS - I used whatever I had - like I always do!!!!!!!

Grounds - I doubt if you hear the difference above a drum kit

Well, I guess that sums it up nicely. Thanks, Stephen

~ Charlie

[sfr]

Here's a silly question - I'm watching this thread with much interest, as I kind of want a new flanger, and this seems like a it will be a fun, challenging build to try at some point in the future when layouts are done.   And everything I've heard about this flanger makes it sound super cool.

But it occurs to me, I've not exactly sure what flanger this is based on - but it occurs to me my friend has a rack-mount ADA flanger in his studio - is this the thing this is based on?  Is there a model # or something for this flanger?  Realizing that this may well be the same flanger he's been using just doubled my interest, because I loved that thing when I tried it out.

(I'm probably missing something in the beginging of this thread that answers my question, but I'm not seeing it)

[puretube]

moose has posted what he could gather in a "zip"...
you don`t even need the search-function - it`s all hidden in a link from this very thread 

have you read reply #23 thoroughly enough

[StephenGiles]

Nobody has mentioned power requirements - is this a consideration do you think?

[puretube]

no problem for a rack- mount unit...

[Horace]

or what about a step up regulator like http://cache.national.com/ds/LM/LM1577.pdf with a choice of wall wart or battery for a portable