EM3207 (v1.1) - MN3207 based EHX Electric Mistress (9V) clone

[ricbox]

So, I finally trimmed vbias to 5.2 and did a new set of voltages. Now I can hear the flanging, but still distorts, and if I turn the Color pot, it distorts more.

IC3, pin 7 and 8 are SWAPPED IN THE IMAGE (sorry)

[oldschoolanalog]

Okay, you are close. Realize Vbias might not be exactly 5.2V. It often varies slightly from chip to chip. Try adjusting Vbias in small increments while checking your signal for distortion. You are probably just a bit off.

[ricbox]

Okay, you are close. Realize Vbias might not be exactly 5.2V. It often varies slightly from chip to chip. Try adjusting Vbias in small increments while checking your signal for distortion. You are probably just a bit off.

Listening again after trimming, it distorts just in the "feedback" trait. I mean, you can hear like a sea wave sound if you don't do anything. The "return to shore" is distorted, and it happens 1 sec later. It scratches.

I've recorded a clip to make you hear better.

http://soundcloud.com/riccardo-lomazzi/em3007-scratching

[DLC86]

http://soundcloud.com/dlc86/sample-mistress
here's a little sample i made to show the difference between wet level at 50% and on full. sorry for the poor quality but i recorded it with the pedalboard directly injected into the sound card. 
sound isn't quite the same when i plug into my hiwatt  but I hope this will give you an idea anyway...

[12Bass]

http://soundcloud.com/dlc86/sample-mistress
here's a little sample i made to show the difference between wet level at 50% and on full. sorry for the poor quality but i recorded it with the pedalboard directly injected into the sound card. 
sound isn't quite the same when i plug into my hiwatt  but I hope this will give you an idea anyway...

Glad you persevered.  There's definitely some flanging happening there, so that means the the circuit is working.  Seems like the flanger might have put your guitar a little out of tune...

Here's some info on how to find the optimal bias and wet/dry mix (for A/DA, but will also work for the EM):http://www.diystompboxes.com/smfforum/index.php?topic=96605.msg839822#msg839822

[DLC86]

Seems like the flanger might have put your guitar a little out of tune...

Shame on me!!   I've recorded that sample really "on the run" and with my old 50€ strat which has 1year old strings on
Thanks for the link, I'll give it a look as soon as I can

EDIT: mmm... maybe your message was for ricbox?

[12Bass]

EDIT: mmm... maybe your message was for ricbox?

Oops... sorry, it was.... didn't read closely enough.   

[ricbox]

EDIT: mmm... maybe your message was for ricbox?

Oops... sorry, it was.... didn't read closely enough.   

Damn, that's a sign I really broke some balls heheh
Thanks for the link, but I think it will become useful when I'll figure out what's wrong with that swoosh. I mean, you can tell it's like a feedback swoosh, so there must be something wrong with some components.

[Thomeeque]

http://soundcloud.com/dlc86/sample-mistress
here's a little sample i made to show the difference between wet level at 50% and on full. sorry for the poor quality but i recorded it with the pedalboard directly injected into the sound card.  
sound isn't quite the same when i plug into my hiwatt   but I hope this will give you an idea anyway...

Hi DLC86, thanks a lot for this demo, that is really interesting! Very delicate sound with those 50%, definitely to-be-considered feature for all us gilmourish!

Btw. hiwatt clone is on my TODO list, I just have to get right output transformer (for the reasonable price) which is not exactly easy here in Prague.

T.

[Thomeeque]

I've recorded a clip to make you hear better.

http://soundcloud.com/riccardo-lomazzi/em3007-scratching

Definitely sick sound, not only distortion but sweep (modulation) as well. Is it still true, that RT3 adjustment has no influence? Did you doublecheck C17 value?

Can you make those hi-res photos I have asked you already for? If you are too shy to show them here , send them to me via PM.

Btw. if you want to, you may pack your build with some beer money and money for post back and send it to me, I could probably fix it easily if I have it in my hands (if yes send me PM to tune-up details).

T.

[DLC86]

Hi DLC86, thanks a lot for this demo, that is really interesting! Very delicate sound with those 50%, definitely to-be-considered feature for all us gilmourish!

Btw. hiwatt clone is on my TODO list, I just have to get right output transformer (for the reasonable price) which is not exactly easy here in Prague.

T.

Yes, it's a very useful feature, previously i kept lowering the color pot & trim to obtain that sound but it wasn't quite the same. now it's perfect for me.
For the hiwatt trannie you can check this site, that's where i bought mine, he stopped his business but in that page he says he has the last set for a dr103 (PT+OT) for 118€. Maybe you can try to send him an email

[Thomeeque]

Maybe you can try to send him an email

I just did 118E would be nice price for set of both trannies! So thanks again! T.

[ricbox]

I've recorded a clip to make you hear better.

http://soundcloud.com/riccardo-lomazzi/em3007-scratching

Definitely sick sound, not only distortion but sweep (modulation) as well. Is it still true, that RT3 adjustment has no influence? Did you doublecheck C17 value?

Can you make those hi-res photos I have asked you already for? If you are too shy to show them here , send them to me via PM.

Btw. if you want to, you may pack your build with some beer money and money for post back and send it to me, I could probably fix it easily if I have it in my hands (if yes send me PM to tune-up details).

T.

Doublechecked cap n. 17, it's a ceramic 22 pF with 1.01V passing through it ;-) .

I'm at my wits' end, and to celebrate it, let's put another clip online!
http://soundcloud.com/riccardo-lomazzi/em3007-plucking


Can you hear that "pluck" and the end of the wave? Its high volume makes it all strange to me.

Could I subtrack myself to public humiliation? Of course not! Ladies and gentleman, here's the ugly, clingy, mirrored version of the EM3007!

[Thomeeque]

Could I subtrack myself to public humiliation? Of course not! Ladies and gentleman, here's the ugly, clingy, mirrored version of the EM3007!

It's actually not that bad.

Scratches on the PCB are removed bridges between the traces? Did you check by DMM that bridges are removed (visual check is sometimes not good enough)?

Unfortunately you have gave us only one view of each area (I have asked for more angles), so I cannot check lot of the components and wiring. What I could check (most of the resistors and caps around LFO and clock, Q's orientation, pot wiring, mode switch wiring..) looks OK.

Soundclip sounds like some DC problem, what power source are you using? Can you try different one? You have not answered my question about RT3 either, there could be another lead to plucking issue (clock freeze above some frequency - but it sounds quite different IIRC).

About distortion one thing popped up in my head - you have mentioned that status LED does not work - is it still true? If yes maybe miswired LED hangs on the output and causes overdrive effect..?

T.

[Thomeeque]

..wrong button..

[ricbox]

Could I subtrack myself to public humiliation? Of course not! Ladies and gentleman, here's the ugly, clingy, mirrored version of the EM3007!

It's actually not that bad.

Scratches on the PCB are removed bridges between the traces? Did you check by DMM that bridges are removed (visual check is sometimes not good enough)?

Unfortunately you have gave us only one view of each area (I have asked for more angles), so I cannot check lot of the components and wiring. What I could check (most of the resistors and caps around LFO and clock, Q's orientation, pot wiring, mode switch wiring..) looks OK.

Soundclip sounds like some DC problem, what power source are you using? Can you try different one? You have not answered my question about RT3 either, there could be another lead to plucking issue (clock freeze above some frequency - but it sounds quite different IIRC).

About distortion one thing popped up in my head - you have mentioned that status LED does not work - is it still true? If yes maybe miswired LED hangs on the output and causes overdrive effect..?

T.

Ok, so, changing the Led's wiring made it work, but the sound's still popping like before.
About RT3, sorry for oversighting the question, if I turn the wheel to the max or to the min,  it starts whistling and my ears begin to explode.

The power source is a Regulated Universal Voltage Adapter by HQ Power, working at MAX 500mA and outputs values between 1,5 and 12 Vdc. Power is 6VA. It whistles a bit, but it works nonetheless.
The first smoke was totally a polarity problem.

I began to wonder, could it be the Diodes? I'm currently measuring 0.35V on D1, oscillating 0,00-0,42 on D2 and 8.03 on Zener D3 (yeah, it's a 15V).

I think we're close to the solution, apart from this popping problem it's a really fun pedal, do you know how much I searched it at good price to play a Rush song with a decent sound? And then I found this thread...I will surely reward you all with some Rush covers (yeeee)

..wrong button..

I hope you're not referring to the SPDT.

[ricbox]

I forgot about RT3: it pretty much works like it should do (at least I think), but the pops are always there when I turn the trimpot.

[juanjuin]

hello mr T
i have done build EM3207, but i have some question for you mr t
1. i put the pot offboard and the cable is about 10 cm, is that make my pedal didn't flanging?
2. i still understand about RT1, RT2, RT3, can you tell me with clock analogy?
3. i have put rt2 to the max the my pedal sound is distort like noise, and very little sound, is that wrong?

please mr T answer me, and sorry for my bad english. i'm Indonesian, sorry for my bad english.
thankyou
-juan-

[Thomeeque]

hello mr T
i have done build EM3207, but i have some question for you mr t
1. i put the pot offboard and the cable is about 10 cm, is that make my pedal didn't flanging?

Hello juan, no, this may introduce some (ticking) noise issues but it may not cause anything fatal, there must be some other problem.

Read this post (Reply #245), try to align your unit first.

2. i still understand about RT1, RT2, RT3, can you tell me with clock analogy?

RT1 = FEEDBACK trim, it's there to fine-tune COLOR pot range
RT2 = BIAS trim, sets proper bias voltage at the BBD chip
RT3 = CLOCK trim, it's there to fine-tune range of the clock frequency sweep

If you want more details start by learning how FLANGER effect works, how BBD works etc., use google..

3. i have put rt2 to the max the my pedal sound is distort like noise, and very little sound, is that wrong?

No, it's OK, you have moved bias voltage to the area where nothing can work properly..

please mr T answer me, and sorry for my bad english. i'm Indonesian, sorry for my bad english.
thankyou
-juan-

No problem mr. J , good luck, T.

[juanjuin]

it works mr T thankyou so much
but flanging sound is very small, i still can hear small flange
then i replace R5 with 10k but still small
for information i put RT1 half, RT2 4/10 (11 o'clock), and RT3 to the max
what should i do mr t?
sorry for my bad english
-juan-