A/DA Flanger does TZF?

[sfr]

Sorry to pull this thread back up again . . .

Pulled apart my A/DA to do some mods I've been mean meaning to do (mostly relay based stuff to enact some momentary switching, and to wire up a foot pedal for the expression input with another offboard on/off footswitch, yadda yadda . . . )

Anyway, figure I've actually got a working, proper scope and frequency generator now (yay!) I'd go through the calibration process for reals this time.  Not too much change in overall sound (confirming that yes, you *can* set this by ear hon') 

A couple of questions arise out of my tinkering with this thing today though:

1) How do I set the Clock Null (T6) trim?  I've tried pawing through this thread again (it's been a while) and haven't found anything - search is turning me up empty handed as well.  It looks like it's balancing two outputs (I'm assuming out of phase to cancel clock noise that makes it into the signal) Should I just probe the output on the scope, and try and set the thing so I get the least extraneous noise?  I can't hear much (if any) difference as I twist this trim, and I'm getting nervous because I used one of those junky Radio Shack trims that have a tendency to go bad on you if you mess with 'em too much.  I just set it at the center and left it.

2) Threshold seems to do very little for me - it's definetly doing something - but I've got a noisy rig in general - seems I can up the amount of attenuation (or however you word this) at the lower settings on the Threshold pot by decreasing the value for R27? (I'm just looking briefly at the schematic - I haven't figured out which way that pot is turning yet) I'll play around, but if anyone wants to point me in the right direction here, it'd be helpful.

Also - brief experiments in envelope control are revealing some cool sounds - I can't remember if that was brought up in this thread or not, but just plugging a quick and dirty envelope control on the breadboard into the footpedal input is resulting in fun.

Thanks,
-J.

[StephenGiles]

Can't help you much there as I set mine up by ear, but don't you see 2 waveforms on the wiper of the clock null trim, then adjust the trim until they converge - just guessing.

[sfr]

Can't help you much there as I set mine up by ear, but don't you see 2 waveforms on the wiper of the clock null trim, then adjust the trim until they converge - just guessing.

Yep, that's exactly it.  A little difficult to set the scope up to see it well, but that's spot on.  (And, yeah, it was pretty much where I had set it by ear - i.e. - the middle.)

Haven't gotten a chance to play with the threshold controls yet (hopefully tonight), nor sit down and look at the schematic in more detail,  but anyone got any insight on that front before I start plugging away at it?

[scottso]

I just finished my build and... OMG THIS THING IS AMAZING! The amount of incredible and different sounds you can get out of this thing are astounding.  Thanks for the board Charlie!

The board I got was marked Rev 03.  I had no serious issues at all in my build.  I just went down the BOM and bought all the odd caps and resistors I didn't have on hand, soldered them in and it worked right off.  Then I went through the calibration docs and I was all set.  The only two things I have questions about:

1) What the heck does TR1 do?  I have it maxed CCW.  If I turn it even a smidge CW it starts to distort the tone (sounds like massive clipping) and then about halfway the distortion goes away suddenly and the tone becomes crystal clear without any flange at all.  Then about 3/4 turn from the end it mutes the sound completely until the end of the range of the pot.

2) For TR2 I had no idea how to induce "self oscillation" so I just turn it up until the threshold knob at minimum gave me heavy flange and when I turn the threshold up it slowly reduces the flange effect.  I'm assuming thats right.

If you haven't built this yet, you should.

[sfr]

1) What the heck does TR1 do?  I have it maxed CCW.  If I turn it even a smidge CW it starts to distort the tone (sounds like massive clipping) and then about halfway the distortion goes away suddenly and the tone becomes crystal clear without any flange at all.  Then about 3/4 turn from the end it mutes the sound completely until the end of the range of the pot.

TR1 is a bias control - set it until it things sound the most "flangy" and you should be set.   Although your description of what the sweep of that pot does sounds a bit off from mine - my "sweet spot" is more in the middle, and sweeping to either side results distortion or no flange.

2) For TR2 I had no idea how to induce "self oscillation" so I just turn it up until the threshold knob at minimum gave me heavy flange and when I turn the threshold up it slowly reduces the flange effect.  I'm assuming thats right.

Do you mean threshold (which is sort of like a noise gate) or the "enhance" control, (which is more like the "regeneration" or "color" controls on other flangers) TR2 should ideally be interacting the most with the Enhance control - more enhance equals a more "flangy" sound, and that trimmer is basically setting the range of that pot - the setup instructions are basically turning all the controls (particularly the enhance control) all the way up, and setting that trim until they get out of control, and then turning it back to sane levels.   If you have that trim too high, with the enhance up all the way, hitting a note will basically start the thing making laser or whistle noises that continue even after you ground or remove the input.  So yeah, can't really go wrong with setting up that trim - it will just affect the usefulness of that pot.  (which looking at that schematic makes sense - it's simply a series resistance with the Enhance potentiometer)

[scottso]

1) What the heck does TR1 do?  I have it maxed CCW.  If I turn it even a smidge CW it starts to distort the tone (sounds like massive clipping) and then about halfway the distortion goes away suddenly and the tone becomes crystal clear without any flange at all.  Then about 3/4 turn from the end it mutes the sound completely until the end of the range of the pot.

TR1 is a bias control - set it until it things sound the most "flangy" and you should be set.   Although your description of what the sweep of that pot does sounds a bit off from mine - my "sweet spot" is more in the middle, and sweeping to either side results distortion or no flange.

Hrm you are making me think something is perhaps wrong on mine.  It only sounds "flangy" at all if I have it turn all the way down.  If I turn it up even the smallest bit I lose the flange.

2) For TR2 I had no idea how to induce "self oscillation" so I just turn it up until the threshold knob at minimum gave me heavy flange and when I turn the threshold up it slowly reduces the flange effect.  I'm assuming thats right.

Do you mean threshold (which is sort of like a noise gate) or the "enhance" control, (which is more like the "regeneration" or "color" controls on other flangers) TR2 should ideally be interacting the most with the Enhance control - more enhance equals a more "flangy" sound, and that trimmer is basically setting the range of that pot - the setup instructions are basically turning all the controls (particularly the enhance control) all the way up, and setting that trim until they get out of control, and then turning it back to sane levels.   If you have that trim too high, with the enhance up all the way, hitting a note will basically start the thing making laser or whistle noises that continue even after you ground or remove the input.  So yeah, can't really go wrong with setting up that trim - it will just affect the usefulness of that pot.  (which looking at that schematic makes sense - it's simply a series resistance with the Enhance potentiometer)

Sorry I meant enhance.  Through the range of that pot I can't make it hit that whistling noise you speak of.  It goes from heavy flange to almost no flange as I turn it up.  I guess its time to start  debugging? 

[sfr]

I might not be describing the noise quiet properly - basically, if you have TR2 too high, the effect is out of control with enhance all the way up - and high enough, and you it will continue to flange with no input.  There is a point on mine where scope shows oscillation, but it's not audible.  Like I said - TR2 is just setting the useful range of the Enhance pot.    If threshold is down, it should cut out a lot of the extraneous noise.  You want to set that control like the manual says, with all knobs full on.  But basically, if it sounds right to you, this trim is set.

I may be mis-remembering my experience setting TR1 - I do know that changing chips changed where that pot needed to be set, so things could very well be fine with your unit, even though you have to have that pot cranked all the way in one direction. I also built Rev 1 to your Rev 3 Couldn't hurt to check solder joints and values around that pot, but I'm tempted to say if it's working, leave well enough alone.  Who knows - the problem could be *my* unit!

I'm just relating *my* experiences - I'm not the most techie oriented person here.  Someone else is probably better versed to chime in with answers here than myself.

[oldschoolanalog]

Change R13 to 4k7 (instead of 10k). This will make TR1 behave the you want it to.

[scottso]

Thanks for that tip.  I'll give it a go tomorrow and see what happens.

[StephenGiles]

Change R13 to 4k7 (instead of 10k). This will make TR1 behave the you want it to.

If it's the one I'm thinking of, I had to do that.

[oldschoolanalog]

Change R13 to 4k7 (instead of 10k). This will make TR1 behave the you want it to.

If it's the one I'm thinking of, I had to do that.

Got that one from your nice circuit diagram Stephen! 
Just want to give credit where it's due and all that...
Thanks BTW!

[StephenGiles]

Change R13 to 4k7 (instead of 10k). This will make TR1 behave the you want it to.

If it's the one I'm thinking of, I had to do that.

Got that one from your nice circuit diagram Stephen! 
Just want to give credit where it's due and all that...
Thanks BTW!

And it may have been Mike Irwin who suggested that to me - where are you Mike???

[slacker]

I finally finished putting my rev 3 board together today and my TR1 behaves the same as Scott's. It biases up right at one end of the pot, I don't think this is a problem though so long as it works that's all that matters isn't it?

The only real issue I had with mine was that I couldn't set the sweep properly. Following Charlie's method from a few pages back I could set the lower end to 35Khz using TR4 but when I tried do do the upper end the lowest I could get was about 3.3Mhz no matter how much I adjusted TR4 and TR5. To get the upper end anywhere near 1.3Mhz I had  to reduce the low end so far that it went into audio frequencies which resulted in noticeable clock bleedthrough.
In the end I replaced TR5 with a 500k trim and then I was able to set it correctly. I had subbed a few resistors in a couple of places so that could have caused the problem but I thought it was worth mentioning in case anyone else has a similar problem.

[StephenGiles]

Change R13 to 4k7 (instead of 10k). This will make TR1 behave the you want it to.

Look at my drawing linked in post 7. The resistor is marked as 4k7 - was 10k!!!!!

If it's the one I'm thinking of, I had to do that.

Got that one from your nice circuit diagram Stephen! 
Just want to give credit where it's due and all that...
Thanks BTW!

And it may have been Mike Irwin who suggested that to me - where are you Mike???

[oldschoolanalog]

Just finished this one last night. 
http://i175.photobucket.com/albums/w121/oldschoolanalog/DSC00380.jpg

[Joe Kramer]

NICE WORK!   

[StephenGiles]

Sorry, I won't tolerate any competition (said in John Cleese tone!)

[oldschoolanalog]

NICE WORK!  

Thanks Joe!

Sorry, I won't tolerate any competition (said in John Cleese tone!)

Actually, the use of dual op amps (TL072 DIPs & 2904 SIPs) greatly simplified things. I made layouts for the individual "blocks" (audio, LFO, CV, gate, etc, first. Then I tied them together and came up w/what you see. Testing each section as it was built (Thanks Stephen!) resulted in it working right away (after calibration).
And yes, I did have fun doing this!
osa

[Joe Kramer]

Sorry, I won't tolerate any competition (said in John Cleese tone!)

Hey, there's plenty of love to go around, especially for you Stephen, one of the original ganstsas of the DIY A/DA flanger!   

BTW, my A/DA PCB still awaits attention, but JH's Tau phaser comes first. . . .

[scottso]

Changing R13 from a 10k to 4.7k did the trick.  The pedal sounds even better now that I could adjust TR1!  Thanks for the help!

Now my question is.. what do we do when you can't find the SAD1024 anymore?