MXR - Flanger/Doubler ( M-126 )  [schematic]

Discussion regarding early stompbox technology: 1960-1975 Please keep discussion focused and contribute what info you have...
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Dirk_Hendrik
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Post by Dirk_Hendrik »

Mine suits the application. Thanks mr Tripps!
Sorry. Plain out of planes.

http://www.dirk-hendrik.com

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sadrew
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Post by sadrew »

i have one of this great sounding delays and unfortunately it has developed a noise issue

i can hear the effect flanging but there is a loud motorboating noise too

the noise disappears in bypass or when the mix knob is in dry position

i already recapped the unit with fresh electrolytics but the noise is still there

i tried to probe the circuit and the noise is pretty much everywhere. i can hear it in the +12V rail as well

on U10 pin 1 there is noise when the regen pot up is turned up. with regen at minimum there is no noise in that point of the circuit

i am trying to narrow the area where the noise builds up but this is a complex circuit for my skills and at the moment i can't figure out a solution

if anyone can help me understanding the schematic and how to nail the problem i would really appreciate

i re attach the schematics for reference

thanks !
Attachments
MXR_m126_flanger-doubler.JPG
MXR M126 Service Schematics.pdf
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kieganlenihan
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Post by kieganlenihan »

Hi everyone! I am new to this site and I apologize for kicking such an old topic. I have one of these units already, and I am absolutely loving it. The one problem with it is that it runs exclusively in Mono. I have two EVH 5150 III Stealth Amps with the same Mesa 4 x 12 Cab and the lead channel with some delay and the doubling effect from the MXR M-126cis simply beautiful. If I run this effect into my two amps, I don't really get true stereo, I just get dual mono. The reason for the long winded introduction is because I have read online the VC inputs are used as voltage control lines to connect two units in tandem. Does anyone have experience doing this? And if so how would I go about connecting these two units together so that they form 1 true stereo unit?

Thanks!

Kiegan

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kieganlenihan
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Post by kieganlenihan »

I have one of these units and cannot figure out what the CV controls on the back are used for. I am not an electrical engineer and I have been learning slowly what CV is used for in general but I am not sure how it applies to this unit. Over on the Universal Audio website, where they have a plugin for this unit, they say "While the original MXR Flanger/Doubler hardware was mono, CV controls in the rear of the unit allowed two units to operate in tandem." I want to see if I can buy another one of these units and operate it in stereo for my two amp units. That way I can get the flanging sweep effect to be more dramatic and physical.

Anyone have any clue how to go about this? I can't simply connect the CV in of one to CV out of the other and vice versa right? I imagine I would need some sort of controller.

Kiegan

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Fender3D
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Post by Fender3D »

kieganlenihan wrote:...If I run this effect into my two amps, I don't really get true stereo, I just get dual mono...
Welcome to FSB mate,

This effect IS mono, it has low and high sensitivity inputs and outputs but they carry the same signal (in different levels of course).
kieganlenihan wrote:...how would I go about connecting these two units together so that they form 1 true stereo unit?
...hmm I think unit1's CV out into unit2's CV in would work....

You might connect it from amp1's SEND to amp2's return;
setting the MIX control fully or almost fully WET you get pseudo-stereo sound when effect is engaged and dual mono when disengaged,

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