ADA Flanger Calibration Videos

[moosapotamus]

Check 'em out on my YouTube channel, here...

http://www.youtube.com/moosapotamus

Just me rambling about what all those trim pots do and how how to set them up.

~ Charlie

[Mark Hammer]

Excellent!  Good on ya.

[StephenGiles]

Excellent - I may set up my "other one" properly!

[12Bass]

Nice!  Should be very helpful.

A few suggestions which might assist those who are interested in even more fine tuning: 

For setting the bias voltage, I found it easier to audition the delay path by itself and adjust for minimum distortion.  In order to find the absolute maximum clean input level, I sent a sine wave test tone into the flanger with the signal level set to the onset of clipping, then carefully adjusted the BBD bias until the clipping went away, then increased the level slightly and readjusted the bias.  After a few times through this process, the optimal bias voltage should be found.  This can be done by ear or by using a real time analyzer or oscilloscope (which indicates the presences of harmonics generated by clipping).  A high resolution RTA will show the presence of increased harmonics before they begin to produce nasty audible clipping.  Note that the optimal bias voltage will vary somewhat with clock frequency, so it will have to be set at a happy medium, somewhere between the two extremes of the delay range.

For fine tuning the mix, those with access to a real time analyzer can use it to calibrate T6 by adjusting for the deepest possible notches when the dry and delay paths are combined.  For this procedure I set the flanger to a static delay time and fed in pink noise.  The response notches generated by the flanger are clearly displayed in the RTA.  Although my A/DA clone circuit uses the SAD1024A, and did not originally have a mix adjustment, I added a T6 for setting the optimal wet/dry mix.  Due to the nature of BBDs, there is once again a variation as clock speed changes; in this case gain goes down a little, perhaps a couple of dB, as the clock frequency nears the top of the range.  Thus, the wet/dry mix will vary somewhat between the two extremes of the delay range.  I set mine for maximum cancellation (biggest notches) in the mid part of the sweep, where the "swoosh" is most prominent.  After calibration, I'm seeing roughly 34 - 35 dB notches at maximum cancellation (without added regeneration).     

[oldschoolanalog]

Just watched all 4. Nice job Charlie!

[moosapotamus]

Thanks, guys!

12Bass - Thanks for the additional info!

Good to have some confirmation that I didn't say/do anything wrong.

I actually consider the four of you to be some of the most knowledgeable folks around here when it comes to clocking delay lines in flanger/chorus/delay circuits. So I really do appreciate the feedback.

I hope others find the videos helpful.

Thanks for watching!
~ Charlie

[Valoosj]

Just watched the first vid (will watch the rest later) and I immediately thought 'why not calculate the difference between min and max range, set that up first and then move the range to the correct values?' That way you could work one trimmer at a time. Or does this not make sense? Haven't tried it, so I'm just shouting out stuff

[moosapotamus]

Just watched the first vid (will watch the rest later) and I immediately thought 'why not calculate the difference between min and max range, set that up first and then move the range to the correct values?' That way you could work one trimmer at a time. Or does this not make sense? Haven't tried it, so I'm just shouting out stuff

Give it a try! In the video I describe T4 and T5 as acting like the MANUAL and RANGE controls, respectively. But I guess I did not go much into how, un-like the MANUAL and RANGE controls, they interact with each other in some sort of non-linear way, such that when you set one of them, it affects the setting of the other.

But anyway, there's always more than one way to skin a cat. And what works for one person is not always the easiest way for someone else. So I say, give it a try. I'm curious to know how it works for you.

Thanks
~ Charlie

[12Bass]

On my SAD1024A A/DA build, I set T4 and T5 for a range which sounds good.  The stock range is fine, but people shouldn't be hesitant to experiment, IMO.  As I recall, I think the range is around 14 ms to 0.2 ms, which means that it sweeps a bit higher than the stock MN3007 version.  Because I don't have a frequency counter, I used my Boss DD-20 to calibrate the low end by setting the DD-20 for 14 ms with high regeneration and matching the resulting metallic resonant frequency with the A/DA (also with high regeneration).  To set the top end, I just found the point where the sweep was no longer proving to be musically useful.

[moosapotamus]

On my SAD1024A A/DA build, I set T4 and T5 for a range which sounds good.  The stock range is fine, but people shouldn't be hesitant to experiment, IMO...

Totally agree! There's some good sounds to be found "outside the boundaries".

~ Charlie

[Govmnt_Lacky]

Excellent video tutorial Charlie!

Didn't see any mentions about the Threshold portion of the circuit. I was hoping to see something about the pot change (10K to 100K) and something about the threshold transistor issues.

All in all it was a good watch 

[moosapotamus]

Thanks! I added a note about using 100K for the Threshold pot in the updated documentation and decided to leave it at that. Not sure what you mean about "the threshold transistor issues". Sourcing the LS4393 (or 2N4393) is the only issue I've heard about, and I've had no trouble at all getting them from mouser.

~ Charlie

[Govmnt_Lacky]

Thanks! I added a note about using 100K for the Threshold pot in the updated documentation and decided to leave it at that. Not sure what you mean about "the threshold transistor issues". Sourcing the LS4393 (or 2N4393) is the only issue I've heard about, and I've had no trouble at all getting them from mouser.

~ Charlie

I saw the update in the documentation. I was just surprised that you did not show what to look for according to the factory set up. (4B)

As for the "transistor issues," I was referring to substitutions. I have seen a lot of questions about sub-ing for another tranny.

All of this is clearly addressed in the documentation however, I was just surprised it was not addressed in the video.

[moosapotamus]

All of this is clearly addressed in the documentation however, I was just surprised it was not addressed in the video.

Sorry, man. I made the videos to expand on what's in the documentation, not to repeat it.

~ Charlie