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

[12Bass]

@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.

Have you noticed any difference in fidelity or high frequency response?  From what I understand, the SAD1024A is capable of much more extended high frequency response (>10 kHz) than the MN3007.  However, given that a lot of flangers employ low pass filtering, this may not be that audible in practice.  I've relaxed the filtering on my A/DA build and a delay path using the Reticon chip can definitely sound very clear if fed a full-range signal.

[jdub]

[quoteHowever, given that a lot of flangers employ low pass filtering, this may not be that audible in practice.][/quote]

I think this is the case.  I guess it depends on application: I didn't do a detailed comparison, as I don't own a scope, I just adjusted them on the bench and used them both at different times in a live setting, and to my ears they both had the same character- which admittedly is a subjective perception.  Of course, with the dueling frequencies bouncing around a live gig, it's tough to really zero in on the differences in high-frequency response between the two    In a controlled setting, though, I  think the SAD would certainly trump the 3007.  For me, though, the whole point is to be able to nail the vibe of the Mistress with a $10 chip as opposed to a $50+ chip, and the 3007 versions I think succeed admirably. 

[mr_deadmaxxx]

clear photos..








many thanks to T..

[12Bass]

I think this is the case.  I guess it depends on application: I didn't do a detailed comparison, as I don't own a scope, I just adjusted them on the bench and used them both at different times in a live setting, and to my ears they both had the same character- which admittedly is a subjective perception.  Of course, with the dueling frequencies bouncing around a live gig, it's tough to really zero in on the differences in high-frequency response between the two    In a controlled setting, though, I  think the SAD would certainly trump the 3007.  For me, though, the whole point is to be able to nail the vibe of the Mistress with a $10 chip as opposed to a $50+ chip, and the 3007 versions I think succeed admirably.

Thanks.

Sure... I wouldn't recommend using the SAD chips in a new build unless people already have one on hand.  I have a few MN3007s around and some time ago tried an MN3007 daughterboard with my SAD1024A A/DA.  In a brief test I heard output, but the sound was weak.  Didn't spend much time trying to fine tune the board for the new chip, so I'm not sure what to conclude.  I'm somewhat curious about using the MN3007 because they are supposed to have more headroom than the Reticon BBDs; my basses sometimes cause clipping in the BBD. 

[jdub]

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!

Bump? 

[oldschoolanalog]

Confusion. Ugh!

[Thomeeque]

 pads 1 (in ground), 4 (out ground) - you may want to use shielded wire for in & out, these pads can be used to ground it's shield

 pads 10 & 11 (CC) - build instructions, ADVICED MODS chapter, third bullet

 Good luck, T.

 EDIT:

@John: be careful about reversed Q1 (2N3904) layout on EM3007_v1.1_values_1200DPI.png and EM3007_v1.1_names_1200DPI.png, "belly" should go down not up..

 @all: Btw. thanks for all your posts, photos, samples, discussion, etc. I appreciate it, I just don't have time to answer properly

[jdub]

Thank you, Tomas.  Not sure how I missed the CC thing, since I've read over the build notes half a dozen times.  Argh!  Sorry to bother you with that... As for the input and output grounds, I suspected something like that but wanted to be sure.   Thanks again.

PS.  Apparently I missed the post in this enormous thread about the reversed 3904 (found it after the fact)...my fault really, I normally check transistor pinouts against the schem before soldering...but oh well, easily fixed...!   

[Thomeeque]

Thank you, Tomas.  Not sure how I missed the CC thing, since I've read over the build notes half a dozen times.  Argh!  Sorry to bother you with that... As for the input and output grounds, I suspected something like that but wanted to be sure.   Thanks again.

 No problem, you're welcome.

PS.  Apparently I missed the post in this enormous thread about the reversed 3904 (found it after the fact)...my fault really, I normally check transistor pinouts against the schem before soldering...but oh well, easily fixed...!   

 Yep, that's easy to be missed - I have updated original layouts with warning for the future builders

 T.

[nordine]

HOT DAMN!

First of all, i have to thank Tomas because of his incredible efforts sharing this amazing circuit, you're truly a bro  

Did MN3207 version,

Layout is so nice i had a blast populating the board, and guess what.... i needed only 5 minutes of debugging till this bad boy was running out of control... sounds so sweet, i had The Wall era Pink Floyd tones .... even Brixton Academy Faith no More's Bass flanging (cause im a bassman)

now, im curious about the trimpots

a) theres the 100k one, it regulates vref ...now, in every position it "sounds good" i just hear increments on volume ...whats the ideal voltage it should give off? 4.5?

b) color one, 10k trimpot.... it regulates the amount of feedback... i really like the metallic sound, but as said above, it turns into self oscillation pretty fast... id like to mantain the metallic timbre without getting into wailing area, is it possible?

c) this one is fun, 22k @ clock driver(?) ...used 50k anyways.... its kind of an offset control... i like it....now, if i turn it almost full to the left, i get more high offset, nearly sounding like TZF... but when its getting really there... it cuts abruptly the flanging, with a little "pop"... something like woooshhhhhhhh-pop-silence-pop-shhhhoooooo...... its like it falls out and deactivates... how to make it sound smooth?

well lots of questions, but this circuits really got me interested, good work!
will follow with pics and samples, cheers!

edit: toying more with the flanger, i got to clearly distinct clock noise... one thats too high in some settings to be usable..... its no oscillation, its clock noise, a digital(aliased?) kind of wooshing... like heterodyning.... somewhere i read that a proper way to cancel clock noise was to pick the two outs of the delay chip (in this case MN3207) and put a trimpot there ...so this could be replacing R12 and R13 for one 10k trimpot and tweaking it...... could it work??

[Thomeeque]

HOT DAMN!

First of all, i have to thank Tomas because of his incredible efforts sharing this amazing circuit, you're truly a bro  

Did MN3207 version,

Layout is so nice i had a blast populating the board, and guess what.... i needed only 5 minutes of debugging till this bad boy was running out of control... sounds so sweet, i had The Wall era Pink Floyd tones .... even Brixton Academy Faith no More's Bass flanging (cause im a bassman)

 Hello, congrats, I'm glad you like the result

now, im curious about the trimpots

a) theres the 100k one, it regulates vref ...now, in every position it "sounds good" i just hear increments on volume ...whats the ideal voltage it should give off? 4.5?

 Hmm, if it sounds good in every position then there is something wrong actually - are you sure you get flanging in it's whole range? Primary goal of RT2 is to adjust proper bias voltage for BBD chip and there is relatively thin area where is BBD biased properly (that's why I advice to use precise multi-turn type of trimmer here btw.), when misbiased it distorts passing signal or it does not pass signal at all..

 For more about RT2 read this post (Reply #245) or this one (Reply #131).

b) color one, 10k trimpot.... it regulates the amount of feedback... i really like the metallic sound, but as said above, it turns into self oscillation pretty fast... id like to mantain the metallic timbre without getting into wailing area, is it possible?

 Set COLOR pot to max and adjust RT1 before self-oscillation starts (or to any point you want your maximum of "color" to be).

c) this one is fun, 22k @ clock driver(?) ...used 50k anyways.... its kind of an offset control... i like it....now, if i turn it almost full to the left, i get more high offset, nearly sounding like TZF... but when its getting really there... it cuts abruptly the flanging, with a little "pop"... something like woooshhhhhhhh-pop-silence-pop-shhhhoooooo...... its like it falls out and deactivates... how to make it sound smooth?

 Frequency range of the clock is not infinite, at "pop" you reach it's maximum where clock stops. For more read "*" note in this post (Reply #94).

well lots of questions, but this circuits really got me interested, good work!
will follow with pics and samples, cheers!

 Looking forward to see&hear it

edit: toying more with the flanger, i got to clearly distinct clock noise... one thats too high in some settings to be usable..... its no oscillation, its clock noise, a digital(aliased?) kind of wooshing... like heterodyning.... somewhere i read that a proper way to cancel clock noise was to pick the two outs of the delay chip (in this case MN3207) and put a trimpot there ...so this could be replacing R12 and R13 for one 10k trimpot and tweaking it...... could it work??

 Maybe, it depends.. Describe your whole signal chain between guitar and amp (other effects, some digital or BBD based ones maybe?) and what PSU do you use (I know about one Mistress having similar issues with 1SPOT)..

 T.

[nordine]

I will try again that 100k trimpot, now that i remember, i set it when i had only the 4558 on board....maybe i biased it well just by accident, cause i dont hear any distortion in flanging

guitar is direct to effect, psu is transformer using hard filtering and 9v regulator

heres the video:



*rate pot is busted btw, needs changing

[Thomeeque]

I will try again that 100k trimpot, now that i remember, i set it when i had only the 4558 on board....

 Oh, in that case there was not much happening until you did reach one of the borders.

maybe i biased it well just by accident, cause i dont hear any distortion in flanging

 You probably did. Distortion depends on input signal amplitude as well, well biased BBD gives you biggest dynamic range before distortion starts.

guitar is direct to effect, psu is transformer using hard filtering and 9v regulator

 Hm, you may be picking something from the air then (even there is AM filter at the input it is not absolute).. maybe post audio sample of the heterodining you are getting.

 Anyway, trying to balance BBD outs for minimal clock noise may be interesting and valuable experiment, so if you don't mind to resolder it little for a while, please go ahead and try it.

heres the video:

 Sounds really good Very effective demo you have made (showing swiftly whole range of basic sounds), I like it!

 Cheers, T.

[nordine]

Thanks!

Well, i messed again with the bias trimmer and, since its multiturn, it takes a lots of turns to "fall out of bias", and there i heard distortion and no flanging... but anyways, it works as suppossed

will do the balance thing in my next EM, this one is eager to be played with 

while boxing it, and after listening to a youtube demo of an old electric misstress (vertical box, green letters), i saw that it has HUGE range... unlike this one (EM9v)... so then i put a 250k pot instead of the 100k it has... the range was maximized, but it got "bird chirping", clock issues i think? much like john holli's ultraflanger (a good flanger but plagued with noises that rendered it useless)... any ideas on how to expand range without getting the "chirp"? ...will post samples of all the noises im talking about, cheers!

[Thomeeque]

Thanks!

Well, i messed again with the bias trimmer and, since its multiturn, it takes a lots of turns to "fall out of bias", and there i heard distortion and no flanging... but anyways, it works as suppossed

 When adjusting BBD bias "properly" using sinus signal generator at the input and oscilloscope at the BBD output you'd find that there is basically one sweet spot (even this sweet spot actually moves little bit with the clock frequency so the chosen value is sort of compromise anyway) and that you loose it rapidly during small fragment of one turn of the bias multi-turn trimmer. On the other hand it is adjusted for relatively big input signal amplitude and with guitar you are usually significantly lower (with bass it may be different) and mainly: you probably don't mind little bit of distortion there (it just affects wet path, clear signal is still clear) anyway, it may be even interesting (we are not hi-fi purists here, quite opposite ).

will do the balance thing in my next EM, this one is eager to be played with  

 

while boxing it, and after listening to a youtube demo of an old electric misstress (vertical box, green letters), i saw that it has HUGE range... unlike this one (EM9v)...

 This demo by any chance?

 This old EM had very different clock circuitry (including the way it's frequency is swept). When I saw this demo for the first time I was surprised by it's HUGE range too and I was getting bit jealous, but later I did realize that extended range moves it mostly to the areas where it sounds already too crazy and unpleasant for my ears and that I'm quite happy with EM9V range (maybe just placebo but it works ).

so then i put a 250k pot instead of the 100k it has... the range was maximized, but it got "bird chirping", clock issues i think? much like john holli's ultraflanger (a good flanger but plagued with noises that rendered it useless)... any ideas on how to expand range without getting the "chirp"? ...will post samples of all the noises im talking about, cheers!

 If it's caused by the clock you cannot fix it by different way of clock range expansion unless you would move the range away from critical frequency. Definitely post sample first, "chirp" is too abstract for me .

 T.

[12Bass]

When adjusting BBD bias "properly" using sinus signal generator at the input and oscilloscope at the BBD output you'd find that there is basically one sweet spot (even this sweet spot actually moves little bit with the clock frequency so the chosen value is sort of compromise anyway) and that you loose it rapidly during small fragment of one turn of the bias multi-turn trimmer. On the other hand it is adjusted for relatively big input signal amplitude and with guitar you are usually significantly lower (with bass it may be different) and mainly: you probably don't mind little bit of distortion there (it just affects wet path, clear signal is still clear) anyway, it may be even interesting (we are not hi-fi purists here, quite opposite ).

Hmmm... I might be a bit of an exception.  Though I use effects with bass more than guitar.  A clipped BBD does not sound very pleasant with bass, so I try to set the BBD bias as optimally as possible to maximize clean headroom.  What you say above is true - the bias voltage "sweet spot" varies slightly with clock frequency, so a "happy medium" must be chosen.  At a given clock frequency, however, the lowest distortion occurs at a very narrow point in the adjustment range.  What I do is send the circuit a sine wave (say 100 Hz) and keep increasing the amplitude and readjusting the bias until the maximum amount of clean signal through the BBD has been attained.

[ricbox]

Got a question for the EM3007 version: what kind of switch do I have to wire up for the Filter? 3PDT? SPDT?  

EDIT: Nevermind, got it.

[ricbox]

I've got trouble on the DPDT wiring.

I've got the rear pad like this.

 1  -
 -   -
 -   -

How should I wire it following the scheme?

[Thomeeque]

How should I wire it following the scheme?

 Probably like this:

 

 For more precise answer I'd have to know exact pinout of your switch (it can be derived from the datasheet of the switch or determined by ohm-metter).

 T.

[ricbox]

How should I wire it following the scheme?

 Probably like this:

 

 For more precise answer I'd have to know exact pinout of your switch (it can be derived from the datasheet of the switch or determined by ohm-metter).

 T.

Thanks, I inverted SWa3/b1.
But now I've got a new problem: in the EM3007 I can't understand where pin 1 of the IC2 goes to. Is it VCC or GND? Because the PCB board I made from this image http://thmq.mysteria.cz/em3207/build/EM3007_v1.1/EM3007_v1.1_PCB_mirror_1200DPI.png
shows that pin 1 is connected to...nothing.
And the schematic shows it connected to...GND? Shouldn't this create a short?

I can hear the sound the guitar, a little whistle when turning the color pot, but it doesn't flange.