MN3007 ADA Flanger Clone Questions

[moosapotamus]

TR2 is near-full, btw, as per the calibration videos...

Calibration can have a big impact on how this circuit sounds.

Do you still have TR2 set near 100%? If so, I would back it off to at least 50% and see how TR6 behaves. There is a lot of interaction between TR2 and TR6. Looking at the scheme, TR6 adjusts the level of the wet signal, but it also affects the regeneration level. And adjusting the max regeneration via TR2 also affects the output volume because some of the regen signal gets added to the "dry" signal. So getting TR2/TR6 set is a little bit of a balancing act.

It would certainly make calibration easier if TR2 adjusted ONLY the max regeneration and TR6 adjusted ONLY the wet signal level. But, as I tried to describe, above, that's not the case.

~ Charlie

[LaceSensor]

Roger that it needs to be calibrated properly.
Get  a DMm with freq counter as minimum...

[Dave W]

Roger that it needs to be calibrated properly.
Get  a DMm with freq counter as minimum...

+1. a dmm with a decent f counter can be found for a very reasonable price. owning or having access to a 'scope is a major plus too….

[Fender3D]

It would certainly make calibration easier if TR2 adjusted ONLY the max regeneration and TR6 adjusted ONLY the wet signal level. But, as I tried to describe, above, that's not the case.

Calibration will come easier when you realize that the best flanging is when wet and dry are the same level.

Set T6 so that signal levels @ IC1's pins 7 and 8 are the same level (enhance fully CCW)... after that, set T2.

You'll find wet level depends on delay time, so you'll have to choose for "your" best compromise...

[MrStab]

Do you still have TR2 set near 100%? If so, I would back it off to at least 50% and see how TR6 behaves. There is a lot of interaction between TR2 and TR6. Looking at the scheme, TR6 adjusts the level of the wet signal, but it also affects the regeneration level. And adjusting the max regeneration via TR2 also affects the output volume because some of the regen signal gets added to the "dry" signal. So getting TR2/TR6 set is a little bit of a balancing act.

i figured out that they were interactive at some point, but not how exactly, and amidst my confusion i just kinda blindly went with what the calibration video set T2 to and tried to measure +3dB difference with T6. i'll need to reinstall Cubase or something to do so properly, as the freeware apps i found didn't have enough adjustable resolution on their meters. i've just been arbitrarily messing around with T6 since then, aware that it wasn't the preferred 50-50 mix, but just short on ideas for things to try.

i'm gonna be busy over the next few days, but i'll get back to this and try to apply this new info. thanks!

[MrStab]

just remembered: i think my TR4 pot may be damaged - it's a crappy one (even though i do have a couple of the more ideal multi-turn ones in there) and there's a sudden drop in the frequency at one point, as you turn it. i'll swap that out and see how it goes, unless that's expected behaviour.

[fpaul]

I hope someone can help me troubleshoot my ADA flanger clone.  I have the MN3007 Rev 1 board.  I finally got a meter with a frequency counter. When I try to set the frequency following Moose's video my circuit won't stop sweeping. I have the enhance, speed, and range at 0 and threshold, manual at 100% like the video says.  I've traced the manual and threshold pots and everything seems to be connected correctly. I have a jumper in place of C24 and have a 33uf in C25.  I hope someone can give me some ideas to try. I'd really like this circuit to work correctly.  I do get flanging but I'm sure something is off.

If it's not cool to post in this thread let me know and I can open a new one.

[johngreene]

I hope someone can help me troubleshoot my ADA flanger clone.  I have the MN3007 Rev 1 board.  I finally got a meter with a frequency counter. When I try to set the frequency following Moose's video my circuit won't stop sweeping. I have the enhance, speed, and range at 0 and threshold, manual at 100% like the video says.  I've traced the manual and threshold pots and everything seems to be connected correctly. I have a jumper in place of C24 and have a 33uf in C25.  I hope someone can give me some ideas to try. I'd really like this circuit to work correctly.  I do get flanging but I'm sure something is off.

If it's not cool to post in this thread let me know and I can open a new one.

The problem is around your range pot. One side of the pot should be DC the other side should be rising and falling in voltage. If the DC side is not connected then you will not be able to change, or turn off, the range.

[fpaul]

Thanks John. I finally got some time to look at this. With enhance, speed, and range at zero(CCW) and manual, threshold at 100 (CW) the range pot pin 1 is fluctuating from 4.6-11.3v and pin 3 is fluctuating from 5.0-13.9v. The test point frequency is sweeping from 90K-2.3M hz.

If I turn the manual to 0 I get a stable 58K hz. I can slowly turn the manual up and get a stable 165K but if I go any higher it starts sweeping.

My first post said I traced the threshold pot but I meant to say I checked the continuity of the range and manual pots and the circuit in those areas and every thing seemed to be okay.  Seems like something isn't but I'm hoping someone can point me to an area of the circuit I should focus my attention on.  Most of the circuit seems to be working okay other than not being able to stop the sweep.

[johngreene]

Thanks John. I finally got some time to look at this. With enhance, speed, and range at zero(CCW) and manual, threshold at 100 (CW) the range pot pin 1 is fluctuating from 4.6-11.3v and pin 3 is fluctuating from 5.0-13.9v. The test point frequency is sweeping from 90K-2.3M hz.

This isn't right. One pin of the range pot (that is connected to the output of the manual buffer) should always be a DC value. The other pin (1 or 3) that is connected to the sweep generator should be moving. That way the wiper pans between a DC value and a sweeping waveform.
Check the inputs to the manual buffer (pin 14 is connected to the range pot) and see if one of them is also sweeping. Both inputs should be DC.

[Govmnt_Lacky]

Pretty sure that I had this problem as well and... don't take it for gospel but, I think the instructions in the video had an error.

If you look at the original A/DA Flanger manual, there is a strange interaction between the Range, Width, and Speed pots.

http://www.adaamps.com/Media/Original%20FLNGMAN.pdf

I am "pretty sure" that one of those pots is supposed to be turned in the opposite direction to get the sweep to stop.

(Of course... I could be TOTALLY wrong ya' know  )

[johngreene]

Pretty sure that I had this problem as well and... don't take it for gospel but, I think the instructions in the video had an error.

If you look at the original A/DA Flanger manual, there is a strange interaction between the Range, Width, and Speed pots.

http://www.adaamps.com/Media/Original%20FLNGMAN.pdf

I am "pretty sure" that one of those pots is supposed to be turned in the opposite direction to get the sweep to stop.

(Of course... I could be TOTALLY wrong ya' know  )

The way I see it the interaction is the manual control sets the center point and the range sets the modulation above and below this center point. The range pot is a passive mixer that changes the ratio of mix between the two settings. So to get the actual modulation to stop, the range pot needs to be turned all the way down (I guess that means the manual side of the pot is pin 1) so the pot is shorted (0 ohms) to the manual side and max resistance to the sweep oscillator side. The opamp from the manual side should be low enough to stop any sweeping from being pushed back onto that pin. Unless the external manual sweep input jack isn't shorting the input to the internal pot as shown in the schematic. In that case the input to the opamp would be floating and would most likely want to follow the varying load on its output.

[fpaul]

voltage was stable at input pin 12 and fluctuating at input pin 13 and output 14. There weren't any solder bridges or anything so I finally realized the LM324 must be bad. I swapped it out and the circuit is holding stead now at 2.6M. Just need to finish calibrating.

I really appreciate the help John. I'm not sure I would have ever figured this out without your help. This forum rocks!

[tommycataus]

Sorry for bumping an old thread... I've just built this on vero and I'm having trouble with calibration and I think there is a mistake which is affecting the manual pot.

When setting the frequency I can get it to 2.6 Mhz, but if the frequency moves anywhere outside approx 1.8Mhz - 3.0Mhz range, the meter shows 0. The second problem is that as I turn the manual pot down, the frequency actually goes up (until it peaks at 3 Mhz and then zeros out). There is no problem with the DMM here, it's a circuit issue.

I can change the trim pots to get a sort of phasing sound, but the wet signal clicks loudly and there is no proper flanging. It's not possible to calibrate as I am certain that I've made an error somewhere.

I have triple checked the following:
No solder bridges
trace cuts are good
reseated/replaced ICs and JFET
component orientation
Offboard wiring
trimpot values

I've even gone over the whole layout and checked each component.


I'm using a charge pump via testing breadboard to generate 18v so I'm not sure if that is the problem, but it doesn't explain the manual pot travel and frequency issue.

Any ideas which part of the circuit could be causing the issue?  Pics to follow

[tommycataus]

[Ed22]

Hi,

Years ago, i built the MN3007 version from moosapotamus.
I've found this flanger to be fantastic. But since calibrations time, I've always had an issue with my build. If i set the flange in the correct area (more or less), the flange sounds fantastic (as it should  )) but there is an "electronic" sound we can clearly hear when the wave of the LFO is in the low part. It's like a sweeping sound in the mid/high frequency range. In different settings it can be loud (not as loud as the audio of the guitar but it's here and annoying). If the LFO is set at high speed, it can produce something like a police car if you see what I mean . It's not hum (the flange is really quiet apart from that). Maybe some clock signal that bleeds into the audio part or something like this. I can get rid of this buy setting higher the maximum frequency (turning CW T4 trimpot) but then the flange sound is way too high and it does'nt sound as good.
I've never really used it because of this. It's a BIG shame since it's a project that needed time to be done. And of course, I do love the sound of this flange. It's so lush and beautiful.
But I've plugged it a few days ago and said to myself it was time to fix it.

So does anybody have any ideas to start with to help me getting rid of this issue?

thanks,

all the best,

Ed.

[StephenGiles]

I expect it's a too low clock speed. Do you have the correct value capacitor connected between pins 1 and 3 of the 4047? I think I put a variable cap their when I built it.

[Rob Strand]

If the unit has feedback  that can often promote a whine.

But following StephenGiles' line of thinking, a low clock frequency can promote that as well.

One point is it seems OK at higher LFO settings.   So one way you can get a low clock frequency at low LFO speeds but not high LFO speeds is when the filtering on the LFO (usually a cap to ground) is too heavy.   When the LFO is at high speed the LFO filter limits the swing of the LFO that in turn prevents it modulating the clock down too far.  But at low LFO speeds the LFO filter lets the full level of the sweep through and that in turn causes the clock to modulate down to a lower frequency.  Beyond that the slower LFO might just be letting it stay in the lower clock frequencies long enough to be annoying.

[Rob Strand]

One point is it seems OK at higher LFO settings.   So one way you can get a low clock frequency at low LFO speeds but not high LFO speeds is when the filtering on the LFO (usually a cap to ground) is too heavy.   When the LFO is at high speed the LFO filter limits the swing of the LFO that in turn prevents it modulating the clock down too far.  But at low LFO speeds the LFO filter lets the full level of the sweep through and that in turn causes the clock to modulate down to a lower frequency.  Beyond that the slower LFO might just be letting it stay in the lower clock frequencies long enough to be annoying.

So if this is the ckt.
http://moosapotamus.net/files/ADA-MN3007-rev5-Jan2010-Documentation-rev20120225.pdf
The LFO filter is R66 and C28.  The cut-off doesn't look low enough to cause the effect I mentioned. 
C23 can also cause similar effects but that looks too small as well.

So it's got to be something else.

[Ed22]

Hello Stephen and Rob,

thanks for your help.
The issue is not linked to the speed of the LFO. That sound occurs at low or high lfo levels. But it dissapears when I change the calibration range (69.6 KHz to 2.6 MHz for MN3007 version) : if I set it higher than 2,6 MHz (can't tell how much but it's quite big, maybe 5 or 6MHz), I don't hear it anymore but on the other hand, it changes the sound of the flanger in a drastic way : to get a decent sound, I have to put Range and  Manual pots at the minimum, and i loose plenty of the possibilities this circuit offers.
I also suspect something in the clock timing section, since it is linked to the frequency range of calibration.
I'll check C29 value and let you know.

thanks,

Ed.