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

[mr_deadmaxxx]

 

[mr_deadmaxxx]

how do I adjust the trim pots?which should I bias first?
what does increasing the 2n2 feedback cap do?should I say I parallel it with a 3n3?will I get the airplane flanging with this?
is it really necessary to add the six 100nf filtering capacitors for the IC's?

[morales72]

Hi to all!

I finally tried it with the band this weekend and it worked great! Actually it inspired me in some The Cure like guitar lines (will try to upload later a bit of it since it was a long collective improv).

Thank you again T! Your work has been truly inspiring to me!

Regards,

Fernando.

[Thomeeque]

Hi to all!

I finally tried it with the band this weekend and it worked great! Actually it inspired me in some The Cure like guitar lines (will try to upload later a bit of it since it was a long collective improv).

Thank you again T! Your work has been truly inspiring to me!

Regards,

Fernando.

My pleasure, I'm really glad you like it! I'm looking forward to hear your samples Cheers, T.

[mr_deadmaxxx]

how do I adjust the trim pots?which should I bias first?
what does increasing the 2n2 feedback cap do?should I say I parallel it with a 3n3?will I get the airplane flanging with this?
is it really necessary to add the six 100nf filtering capacitors for the IC's?

can I substitute the 2N5087 with a 2n3906?

[Thomeeque]

how do I adjust the trim pots?which should I bias first?

This is exactly what "alignment procedure" is about, which I'm still too busy (or too lazy) to describe. But this is the Electric Mistress clone and there are zillions of guides how to align EM on-line, start e.g. here.

RT1 = FEEDBACK trim
RT2 = BIAS trim
RT3 = CLOCK trim

One hint: start with BIAS. Rough MN3207's DC bias (DC voltage measured at input pin 3) should be:

V_BIAS = 0.42 + 0.54*V_CC [V]

(approximation of V_BIAS -- V_DD graph from MN3207 datasheet).

Set this value and fine-tune later (following align guides).

what does increasing the 2n2 feedback cap do?should I say I parallel it with a 3n3?will I get the airplane flanging with this?

I doubt it, it will just have slightly different color - build it and try it.

is it really necessary to add the six 100nf filtering capacitors for the IC's?

No.

can I substitute the 2N5087 with a 2n3906?

Yes, but you may get slightly different sweep character (my advice is to stay as close as possible with parts around clock VCO = around Q2, IC4), on the other hand it shouldn't be fatal.

Btw. I won't answer any more questions if "thanks" and "please" keywords will be missing, this is not some sort of prepaid support service. When you are asking for favor you have to show respect.

T.

[12Bass]

Thanks Thomeeque. 

No questions.... just thanks...   

[oldschoolanalog]

Thanks Thomeeque. 
No questions.... just thanks...   

Amen. +1 .
Thanks!
And please too!
Just want to pay some gratitude forward...

[sugonidamaso]

Amen T! Thank you very much! Most especially your dedication to this forum! And yes " Please" too!

[Thomeeque]

Alright alright alright, it was meant for Don, but whatever You're welcome guys, my pleasure, amen T.

[mr_deadmaxxx]

Awts. My bad. Thanks...

Finally done building this and it worked right away I didn't even have to debug it. Though I substituted 2N5087 with another transistor, and even without the filter caps, I still got the flanging sound. Though the color pot starts to oscillate at midway up to fully clockwise and I can't seem to tell the difference of what the range pot can do. I just biased the parts by ear but I will try to bias this later following the above instructions.

And I apologize I forgot to say thanks. Will post photos once it's done.
Thanks.

[Thomeeque]

 Great, congrats! Apology accepted, looking forward for pics Cheers, T.

[mr_deadmaxxx]

This is what I can post for now. Crappy camera on a crappy phone.
Will post more once it's completely done. The fourth knob is a Gain knob replacing R5.



Uploaded with ImageShack.us

[Thomeeque]

This is what I can post for now. Crappy camera on a crappy phone.

Thanks anyway

..The fourth knob is a Gain knob replacing R5...

So, how does it work for you? Would you be able to measure value where you feel like it's in unity gain compared to bypass?

Cheers, T.

[Morocotopo]

Hi.

First things first: Thanks so much Thomas for the work you did and generously shared with us.

I built the MN3007 version from your files. Regarding your PCB:
- Man, you like to live in danger, don´t you? The jumper that goes between IC3´s legs is, hmm, a bold move! I actually made the jumper go around and "enter" below the chip from the top, not between legs. Seemed more safe to me.
- Some wires holes are very close to other parts, a bit difficult to get them in.
- The speed pot wiring left me a bit confused, I wondered why my LFO didn´t change speed ´till I looked at the PCB connections, was a little confused by a pic you posted. But an easy fix.
- In the layout file, the 3904 is reversed, should be the other way around.
- I actually modded your PCB, made the tracks thinner in places. Seemed to me that in some spots there were dangers of tracks bleeding into each other if you etched them with the iron a bit too hot.

About the build, I did some replacements:
- 2N5087 replaced with a BC559B. I tested the Hfe and it was around 430, so in spec with the 5087 Hfe range. A BC559C would be better, maybe. I think, as long as the transistor is in the original one´s Hfe range, it will work. Watch the pinouts!
- Some R´s: 30K for 33K, 14K for 15K
- The 4049 is a buffered one (4049B)
- For the Zener I used a 12V 1W one.
- For the 220 uF caps, the only ones that fit are 16V ones. 25V ones are too large to fit! Another trip to the store...

It works, flanges good. I´ve never heard an original, so I can´t compare sounds, but it´s nice as it is. Without the 100n caps to filter the chip´s power and with the thing lying on my desk, I get no ticking. Shielded input wire, though, just in case.  Well, now I´m gonna reread the thread to see if there´s any improvements to be made. I recall some
discussion about max clock frequency from my earlier read...

All in all, a good, nice, musical flanger. I made a 301 from tonepad´s site and, although I haven´t compared them side to side, this, in first impressions, is nicer.  If wanted, I can make sound samples/take measurements, whatever it´s needed. Tell me.

Thanks again Thomas!

P.D: Am I the first one to build the 3007 one on your PCB?

[Thomeeque]

Hi.

First things first: Thanks so much Thomas for the work you did and generously shared with us.

Hi, my pleasure, thanks for the report!

I built the MN3007 version from your files. Regarding your PCB:
- Man, you like to live in danger, don´t you? The jumper that goes between IC3´s legs is, hmm, a bold move! I actually made the jumper go around and "enter" below the chip from the top, not between legs. Seemed more safe to me.

I use it often, with properly shaped insulated solid core wire you are IMO safe.

- Some wires holes are very close to other parts, a bit difficult to get them in.

Bit difficult - OK, but you made it, right? IMO small price for compact layout.

- The speed pot wiring left me a bit confused, I wondered why my LFO didn´t change speed ´till I looked at the PCB connections, was a little confused by a pic you posted. But an easy fix.

Too sexy to read build instructions, huh?

- In the layout file, the 3904 is reversed, should be the other way around.

Oh, good catch, you're right - I've got or made wrong eagle symbol once and it still pops up time to time - thanks!

- I actually modded your PCB, made the tracks thinner in places. Seemed to me that in some spots there were dangers of tracks bleeding into each other if you etched them with the iron a bit too hot.

OK, I like'em fat And it can be advantage for toner transfer method too - at least my experiments with this method led to not very solid traces (as the toner did not cover 100%-ly) with lot of micro-holes which could even interrupt thin traces - but it may be just my hands.

One way or another I advice to carefully check PCB traces before soldering in build notes.

About the build, I did some replacements:
- 2N5087 replaced with a BC559B. I tested the Hfe and it was around 430, so in spec with the 5087 Hfe range. A BC559C would be better, maybe. I think, as long as the transistor is in the original one´s Hfe range, it will work. Watch the pinouts!
- Some R´s: 30K for 33K, 14K for 15K
- The 4049 is a buffered one (4049B)

Not replacement actually, buffered logic chips are listed in the part list.

- For the Zener I used a 12V 1W one.
- For the 220 uF caps, the only ones that fit are 16V ones. 25V ones are too large to fit! Another trip to the store...

Again, price for the compact layout.

It works, flanges good. I´ve never heard an original, so I can´t compare sounds, but it´s nice as it is. Without the 100n caps to filter the chip´s power and with the thing lying on my desk, I get no ticking. Shielded input wire, though, just in case.  Well, now I´m gonna reread the thread to see if there´s any improvements to be made.

My advice would be to go thru the thread before the build, but..

I recall some discussion about max clock frequency from my earlier read...

All in all, a good, nice, musical flanger. I made a 301 from tonepad´s site and, although I haven´t compared them side to side, this, in first impressions, is nicer.  If wanted, I can make sound samples/take measurements, whatever it´s needed. Tell me.

Thanks again Thomas!

P.D: Am I the first one to build the 3007 one on your PCB?

Again, you are welcome, I'm glad you like the sound and as you probably really are the first one who at least admitted it here, I'd really appreciate sound samples and photos of your build!

Cheers, T.

[Morocotopo]

Errata:

It´s Tomas, not Thomas...  Repeat after me: Tomas, Tomas, Tomas...

Sorry about that!

Of course, most things I commented are what allow for a really small PCB, wich I think it´s great, I hate big pedals. I confess guilty of not reading thoroughly the build instructions...

After rereading the thread, I´ll try the 250K range pot and/or the 1K R34, to see what effect they have. I´ll take some measurements and do some audio samples, sure, no problem. As to the photos, I only have a crap cell phone camera, but I´ll see what I can do with that.

[Morocotopo]

OK, pictures:




Audio:

http://soundcloud.com/truemostro/eh-em-3007/s-g8s6I

P90 guitar>EM>computer. First at various settings, then in filter matrix mode playing with the range pot. The recording is a little saturated, not the circuit. Later I´ll take some measurements and do the mods posted earlier.

[JRM]

Hi,

I've just found this thread a couple of days ago when I was setting up the trimpots of my EM retrofitted with a MN3207. And after reading through it I'm a little bit confused: I thought that with the retrofit we'll be able to reach the same performance as with the SAD1024 (overclocking the 3207 to overcome the 512 vs 1024 stages, etc.) but after reading the first pages it seems that we don't, as the MN3207 can't deliever the same delay.
I'm not an expert at all, just a guy that likes diy, knows how to solder, use a multimeter and what an IC, a trannie, a resitor or a capacitor are, so:
Can someone PLEASE explain me if there's anything that I can/have to do get the sound of my EM clone as near as possible to the original (that I don't have/can't afford)?

P.S: In the beggining of my building project I have found a SAD1024 in a local shop for a very expensive €50! Maybe I should have bought it...

[jdub]

@JRM: Having tried both a 1024 and the mn3007 daughterboard retrofit in my EM, it seemed to me that with proper adjustment the 3007 version comes mighty close to the 1024.  However, I've never owned an original, so I can't say how close either of mine came to it...my impression, though, is that the 3007 retrofit does capture the character of the effect; as always, though, YMMV.  Sorry to not be much help with that one...

@Tomas: Thanks so much for this project, and all your others.  They've provided me with hours of fun and education.  Hats off to you, sir!

I do have a quick question about the EM3007 board, though, and apologize if it's a foolish one: What, exactly, are the purposes of pads 1 (in ground), 4 (out ground) and 10 & 11 (CC)?  Pads 1 & 4 already appear to be connected to circuit ground, so I'm puzzled, and while I know what Vcc is, CC is a new one for me.  I haven't run across these designations in other builds.  Can they be left unconnected?  Anyone?  Thanks!