MXR Flanger redone

[Dave W]

Greg, Check out these MXR117 photos & descriptions...
http://s175.photobucket.com/home/oldschoolanalog

[slash_83]

Hi guys!

I ve the some problem of most of you, i ve a mxr flanger clone with a bad sad1024 probably. I ve decided after many years to' resuscitate it...i ve bought a mn3007 and i build a daughterboard following the layout founded here..


I ve seen the new Schematic to fill mn3007, but im not surehow to' link daughterboard to' mxr pcb...someone could explain it a little more simplified..?

Thank you in advance!

[omnitek]

Hi guys!

I ve the some problem of most of you, i ve a mxr flanger clone with a bad sad1024 probably. I ve decided after many years to' resuscitate it...i ve bought a mn3007 and i build a daughterboard following the layout founded here..


I ve seen the new Schematic to fill mn3007, but im not surehow to' link daughterboard to' mxr pcb...someone could explain it a little more simplified..?

Thank you in advance!

This is what I've done.
I removed the SAD1024 chip from the main board.
I compared the old schematics (SAD1024) with the new schematics (MN3007).
I installed the new components (MN3007, transistor, resistor) on the daughterboard.
I wired the daughterboard to the main board using the new schematics and cutted some traces on the main board when necessary.
I plugged the pedal and it worked.

After that I decided to install the MN3007 chip directly on the main board but that's a different story.

[pinio]

I have no more the etching PCB files 'cause the prototype pictured here http://www.diystompboxes.com/smfforum/index.php?topic=36392.msg655757#msg655757 was just that: a prototype,
I started modding and tweaking it as soon as I built it, so I redrawn pratically everything. [If you look carefully at the comp. picture you'll see there are pads for other parts not used (according to schematic), but since I was etching the board and I had to sell the pedal I wouldn't have any concern in case of missing components or misbiasing (I didn't breadborded it at the time, I did it few months ago, testing with different LFOs and dual BBDs)]. I build other units with other tweaks (such as a 3 transistors control for 4013 and just 2 knobs or a 4046 clock gen.), but all PCBs "on the fly".
 
There's a picture here http://www.diystompboxes.com/smfforum/index.php?topic=79154.msg652910#msg652910 of the schematic and comp. layout,
here you can find guts picture, you may trace it down eventually
.

Hello

In this forum, I'm new, but often browse. Sorry for my English. I support a translator.

Inspired by the quoted design, I decided to recreate PCB, you do not have the documentation. On the basis of shared images and layout, I allowed myself to torture in The Gimp. Not yet verified the correctness of the connections against the schema.

If anyone would be so wonderful and try to check and correct my work, I would be grateful.

Thank you and best regards!

[Fender3D]

You miss a track from U4's pin 1 and R21/R10/C5 and the U3's pins 7/8 junction.
Otherwise it seems ok

[pinio]

OK, Corrects zone and fill color. Does the TDA2107 view is the same as MN3007? Can I apply without modification, MN?

http://www.groupdiy.com/index.php?PHPSESSID=pkd2n8hlbkdkg7qmm3sq29brk6&topic=21694.msg258651#msg258651

YES

[pinio]

OK, I finished. Would Yoy check?

PS. How close to oryginal is Your version (sound)? Do You have finally version?

 

[Fender3D]

Hello, merry Christmas guys

@pinio:
it seems ok to me, etching time now...

I never owned an M117, therefore I don't know how much close my "clone" is. But, the owner has those VH flanging sounds at his feet now, definitely.
Filters are the same, 1024 BBD for both... I guess we're not so far  
Again, I trimmed the clock higher than MXR, since I found lower timing settings pretty unusable...

PS
Remember, if you mount Q1 and Tr3 you must avoid Tr2.
In my latest flangers I added ADA noise gate, all pots and jacks on PCB and LED away from footswitch.

[Fix_Metal2]

Hello, merry Christmas guys

@pinio:
it seems ok to me, etching time now...

I never owned an M117, therefore I don't know how much close my "clone" is. But, the owner has those VH flanging sounds at his feet now, definitely.
Filters are the same, 1024 BBD for both... I guess we're not so far  
Again, I trimmed the clock higher than MXR, since I found lower timing settings pretty unusable...

PS
Remember, if you mount Q1 and Tr3 you must avoid Tr2.
In my latest flangers I added ADA noise gate, all pots and jacks on PCB and LED away from footswitch.

Hello there. I've made up a layout from the M117 MN3007 schematic found here on the forum.
It works! Setup 69KHz clock (as ADA MN3007 project tells  ), fixed the TR1 value, which ought to be 20K I suppose. I setup TR1 for having the wave centered between the two threshold on the output of MN3007 (#7,#8) and TR3 to make the effect work without any feedback by regen.
Anyway I get a strange crackling noise whilst it sweeps the flanging effect. I can't get rid of it. I used 2N5088 and 2N4126 transistors and LF353N opamps. LM4562 for the LFO and the CD4013 buffered version.
I don't think it's opamps fault - those are JFET and the LM4562 has the higher slew rate @ low distortion I've ever seen on a datasheet.
I can't work it out. Hope you or somebody else will catch the prob.
This is the schematic:

p.s. Fender3D, are you italian?

[Fender3D]

Hello there. I've made up a layout from the M117 MN3007 schematic found here on the forum.
It works! Setup 69KHz clock (as ADA MN3007 project tells  ),

Main difference is that ADA uses a 512 stages BBD while MXR has a 1024, thus the double clock freq. to obtain the same delay time.
Said that, the best clock is more a matter of personal taste, unless you're looking for a "perfect" clone...

... fixed the TR1 value, which ought to be 20K I suppose.

By MN3007 datasheet:
Vgg (typ.) = VDD + 1V
Then you have 15V supply,
with a 100K + 7K5 voltage partitor you obtain ~ 1V at junction, which is what you need...

I setup TR1 for having the wave centered between the two threshold on the output of MN3007 (#7,#8) and TR3 to make the effect work without any feedback by regen.
Anyway I get a strange crackling noise whilst it sweeps the flanging effect. I can't get rid of it. I used 2N5088 and 2N4126 transistors and LF353N opamps. LM4562 for the LFO and the CD4013 buffered version.
I don't think it's opamps fault - those are JFET and the LM4562 has the higher slew rate @ low distortion I've ever seen on a datasheet.
I can't work it out. Hope you or somebody else will catch the prob.

TR1 adjusts MN's bias, I don't know what you mean by " having the wave centered between the two threshold on the output of MN3007 ", but if you watch your waveform with a scope you'll notice when and how it will distort... check this at different delay times (manual).
Again, I don't know if the crackling arises from wrong Vgg...
fix it first...

p.s. Fender3D, are you italian?

of course... 

[Fix_Metal2]

Main difference is that ADA uses a 512 stages BBD while MXR has a 1024, thus the double clock freq. to obtain the same delay time.
Said that, the best clock is more a matter of personal taste, unless you're looking for a "perfect" clone...

The ADA used the SAD1024 in a cascade configuration, didn't it? And so the MXR did.

By MN3007 datasheet:
Vgg (typ.) = VDD + 1V
Then you have 15V supply,
with a 100K + 7K5 voltage partitor you obtain ~ 1V at junction, which is what you need...

Right.
I changed the 100K over 20K because I mis-read some posts over this forum about the value. Will get back to 100K then.

TR1 adjusts MN's bias, I don't know what you mean by " having the wave centered between the two threshold on the output of MN3007 ", but if you watch your waveform with a scope you'll notice when and how it will distort... check this at different delay times (manual).
Again, I don't know if the crackling arises from wrong Vgg...
fix it first...

Input-ing 1Vpp 1KHz sin and probing @ #7 of the MN, I was getting the wave centered between max and min voltages - therefore yes, that's biasing. My bad about the explanation.
I had the same crackling problem with the 100K TR1, if I remember right. I'll start fixing it.

of course...

Anche io, scrivo normalmente sui forum diy italiani

[Fender3D]

The ADA used the SAD1024 in a cascade configuration, didn't it? And so the MXR did.

nope ADA uses parallel-multiplex configuration, it allows you to double the number of samples @ the same delay (better resolution)

Input-ing 1Vpp 1KHz sin and probing @ #7 of the MN, I was getting the wave centered between max and min voltages - therefore yes, that's biasing. My bad about the explanation.
I had the same crackling problem with the 100K TR1, if I remember right. I'll start fixing it.

I guess 1Vpp is a too much high voltage here (it's a guitar pedal). I usually raise the input signal 'till distortion, then trim.
(yeah I have to admit it easier with my Neutrik A1...)
If you're around 200mV you can safely assume it's allright,
Again, check this adjustment @ different "manual" values 'cause it will vary with delay time. Trim for the best compromise...

Anche io, scrivo normalmente sui forum diy italiani

lol
too many "professors" over there...

[Fix_Metal2]

nope ADA uses parallel-multiplex configuration, it allows you to double the number of samples @ the same delay (better resolution)

Good to know. I made a layout of the AD/A MN3007 retrofit, but never worked. That's because I landed on the MXR - it's totally EVH, that's what I love.
Anyway I've got a fellow who made that AD/A layout work. My pcb wasn't that good because of bad uv exposure, that ought to be the problem.

I guess 1Vpp is a too much high voltage here (it's a guitar pedal). I usually raise the input signal 'till distortion, then trim.
(yeah I have to admit it easier with my Neutrik A1...)

Yea, I know, but it just didn't seem to clip or anything. There's 7,5Vpp dynamic in there!

lol
too many "professors" over there...

Oh well. You're right. Actually I had subscribed myself in here years ago. Activation e-mail never breaked through my gmail account, even after several resend attemps. I then  applied for this account using another e-mail address.

[Fix_Metal2]

Well I installed shielded cables on every connection and set it right.
After taking a read on the MN3007 datasheet, I've discovered a great graph: THD vs Vbias!  
That's saying that the lowest distortion is @ -8,1V bias (#3 ofc).
I've set clock ~69KHz and level in order to eliminate the regen feedback.
The pedal itself sounds good, but that crackling noise is still present. It is subtle, but it's there.
When I put the width at min, I get a little "speed" noise. More and more I turn the Width pot, whilst regen is not at minium, that crackling issue comes up.
Fender3D, I read that you installed the AD/A noise gate into the MXR. What's that all about?  
Actually I start to think it's a MN problem. This one comes from a lot of 5 I bought 2 years ago from ebay - Honk Kong.
1 of that lot was WAY distorting and throwed it. 1 is in my CE2 clone, another has gone in another CE2. 1 is this one I'm using and the last has been thrown in the bin just a few days ago because was dead! No signal on output!
Whatcha think?

[Fender3D]

Can you picture the noise with a scope?
I had no similar issues.
It may be some kind of op-amp's HF auto-oscillation or mis-biasing, I used TL072 and 5532...
ADA put a noise gate in their flanger, I did the same with this... http://www.adadepot.com/adagear/gearpages/stompboxes/ADA-Flanger.htm

[Fix_Metal2]

Can you picture the noise with a scope?
I had no similar issues.
It may be some kind of op-amp's HF auto-oscillation or mis-biasing, I used TL072 and 5532...
ADA put a noise gate in their flanger, I did the same with this... http://www.adadepot.com/adagear/gearpages/stompboxes/ADA-Flanger.htm

Well I'm going to swap the two MN and see what happens first.
I've got one of those DIY osc, will check with that.

[Fix_Metal2]

There was an error in my layout. Fixed and it works better now.
It seems like the noise it's just coming from the oscillator. I don't think the noise gate would bring any benefit because it's just a matter of proximity to the in/out cables.
I just wonder how to avoid this problem. I'm already using shielded cables for every connection, with just a star ground in the entire pedal!
Anyway, is there a better way to calibrate the level trimmer other "play-and-listen"?

[Fix_Metal2]

I just can't make it work properly.
I found a bad value in a cap in the LFO, but nothing more than that is wrong.
I swapped the opamps with TL072 and it seems more quiet than with LF353. THD is better with 072.
It starts to crackle when the man is not in CW position. It crackles more and more when it's in CCW.
When tweaking with the distortion trimmer, I get the thing very quiet when it's at minium. The bad thing is that it doesn't flange anymore, obviously.
I used shielded cables for input/output and the speed pot, with star ground in the pedal.
I don't think it's about the 2N5088 specifically, right?
Oh, I put a 10uF NP instead of the two-series 22uF caps!
The MN is well biased and it's ok. Even swapping it with another one I have won't change a thing.
Maybe it's all because of the 4013 buffered version? Should I use an unbuffered version?

[oldschoolanalog]

Are your shielded cable grounds hooked up at one end or both?

[Fender3D]

Look mum no shield...


lol joking...
I built it with tl072 and 5532, and BCs trannies also, and no cracking or else.
It might arise from power supply or layout...
LFO should be 1458, it won't draw too much current...
4013 is BCN in my picture above, I didn't care so much, just picked it up from my drawer (...trower  ).

PS
I must agree with Tomas on another thread here around:
do say thanks and give proper credit to author when posting on other forum please...