9V Electric Mistress retrofit with MN3007

[Thomeeque]

 Hello!

I'm helping to juancra with development of an MN3007 based daughter-board replacement of SAD1024 for markusw/gaussmarkov 9V Electric Mistress clone - same concept as an original oldschoolanalog's A/DA Flanger retrofit with MN3007.

Based on info extracted here and there (some of you may recognize fragments of their work, so thanks to all of you! ) and on some of my previous expreriences (gained mostly on my TDA1022 based EM9V clone) I did came up with following daughter-board schemo:



Changes on (and connections to) the EM main-board (tonepad's schemo used) would look like this:



(plus 47pF capacitor in the clock circuitry /between ground and pin 3 of LM311 comparator/ would be halved to 22pF to double base clock frequency).

• Base MN3007 circuitry is I'd say essential, almost same as in AD/A retrofit
• Clock buffer (A/DA extract as well, approved to do the job) is added to support doubled sampling frequency - it seems to be necessary here, because frequencies may go above MN3007 specs
• Output buffer made by common-collector Q1 voltage follower is added to compensate (approx. 5 times) bigger output impedance of MN3007 compared to SAD1024 - it seems to be necessary here, because following EM's passive feedback/output network creates relatively big load to BBD output (contrary to A/DA).
• C3 makes output LPF and replaces original 3.3nF capacitor (value is 5 times smaller due to bigger output impedance of MN3007 again)
• V_CC (and GND maybe?) should be taken from main-board as close to source as possible (not from the pin of SAD1024's socket), to get most effective R1+C1 & R5+C4 filtering.

So, what you say? Do you see some catches?

What I'm probably most scared about is doubling of the base clock generator frequency - will it still tick? Did somebody experimented with EM's clock circuitry this way, did somebody tried already to replace that 47pF cap by 22pF to double it's frequency?

Any comments and thoughts are welcome!

Thanks, T.

[juancra]

Hi tom!

I Think we were not so lucky with this post! Maybe we just go and build it and see what happens! I'll give it a try next thursday, after a final exam I must pass. Thanks a lot for all your hard work!

[juancra]

Moderators, Please delete this post!

[bluesdevil]

I just received a SAD1024 for an Electric Mistress build, but I also have a MN3007 handy... looking forward to your results!!

[quarara]

it's incredible that this post was at third page with just a couple of replies!
guys, i'm looking forward for your results too, thanks for your work.

[mudmen]

What about 18V Mistress? Will this mod fit this circuit too?

[Auke Haarsma]

Keep it up guys! I'll keep a close watch on this thread. Good stuff, very good stuff!

[Thomeeque]

What about 18V Mistress? Will this mod fit this circuit too?

I'm not sure, which one is it exactly - could you post (link to) schematic here, please?

Thanks, T.

[WLS]

Tom,

I think he is speaking of GGG's DEM. On his site it is referred to as a 18 Volt version running off a transformer with filterring. Their are other differences in the layout. Mostly from what I can tell it incorporates one more IC a TL-071 in the beginning of the signal path.

My thoughts on this is even if it might be a pin for pin swap AND WOULD NOT TRUST MY SKILL LEVEL TO DETERMINE THAT. The capacitors and restore values would have to change simply due to that the curcit is running in the 15 volt range instead of 9.


My two cents

Bill

[Thomeeque]

 OK, thanks guys for your interest - I did made just two small changes to original schematic (renamed to v1.0a now), schemo above should be now actualised (v0.1, 10.8.2009 - you may need to refresh this page to overrule your browser cache). 1st change is about separating of V_CC for BBD part and clock buffer part (to allow bi-wiring or other approaches for better power filtering), 2nd is about R3 value set from 13k9 to 14k (it's the best value for this resistor and good suplier should have it in stock, it's E48 standard). I did created PCB layout based on this updated schemo, and juancra is about to verify it - right, Seb? How did exam go?

About GGG DEM: this retrofit should fit there nicely as well (MN3007 should even profit from those 15 volts there). No values have to be changed, only 15+ volts capacitors have to be used - connections would be:

GGG/DEM	Retrofit
A	VCCb
B	VCCa
C	CLK+ (or CLK-)
D	CLK- (or CLK+)
IC3, pin 2 or 15	IN
IC3, pin 6 or 12	OUT
GND	GND

Only change necessary on GGG board would be halving clock capacitor C17 and of course proper bias and gain adjustment (bias adjustment remains principially same, for gain adjustment divider made by R12 and R13 could be used*).

Only change on retrofit board would be not loading of C3 (there's no LPF applied directly to SAD's output on GGG's DEM, so retrofit should not do it either).

Anybody willing to try?

T.

* if the unity gain (R12=min, R13=max) was not enough, lowering of R14 would allow to achieve required boost.

[Thomeeque]

 There's one thing I did overlooked about GGG's DEM: To be able to dial whole DC bias range stated by MN3007's d/s (5 to 10V) by bias adjust trimmer (R7), the R6 should be lowered to cca 5k (5k1). But it may not be necessary (original GGG's DEM range with R6=8k2 is approximately 0 to 8.24 volts, it may be sufficient for typical MN3007 chip..?).

T.

[kupervaser]

Awesome, who will try this first?

[oldschoolanalog]

Awesome, who will try this first?

Hmm...
Who indeed?

[mudmen]

I think he is speaking of GGG's DEM. On his site it is referred to as a 18 Volt version running off a transformer with filterring. Their are other differences in the layout. Mostly from what I can tell it incorporates one more IC a TL-071 in the beginning of the signal path.

No, I thought about NON-DELUXE, 18V version. Here's how it looks:
http://www.pink-floyd.es/imagenes/sonido/ElectricMistress.jpg

And links to schematics:
http://img210.imageshack.us/img210/9172/18vmistressschmhr5.gif
http://img357.imageshack.us/img357/5590/ehelectricmistressukhq5.jpg

[Thomeeque]

 For the most impatient ones:

PCB_v0_1_1200DPI.png
PCB_v0_1_1200DPI_mirror.png
PCB_v0_1_layout_1200DPI.png



Good luck, T.

[Thomeeque]

I think he is speaking of GGG's DEM. On his site it is referred to as a 18 Volt version running off a transformer with filterring. Their are other differences in the layout. Mostly from what I can tell it incorporates one more IC a TL-071 in the beginning of the signal path.

No, I thought about NON-DELUXE, 18V version. Here's how it looks:
http://www.pink-floyd.es/imagenes/sonido/ElectricMistress.jpg

And links to schematics:
http://img210.imageshack.us/img210/9172/18vmistressschmhr5.gif
http://img357.imageshack.us/img357/5590/ehelectricmistressukhq5.jpg

OK!

From the BBD point-of-view it's almost identical as an 9V version, so same applies here as in original post - only thing to worry about is the DC bias adjust range (from 0 only to approx. 6.1-6.7V depending on version /black versus green values on 18vmistressschmhr5.gif/), which maybe not sufficient. And it would be bit more complicated to extend this range here, since the bias adjust trimmer is part of voltage stabilizer circuitry..

From the clock point-of-view it's question, how to double base frequency here - will halving of that 470pF cap do it? Somebody would have to try..

T.

[oldschoolanalog]

Awesome, who will try this first?

Here you go:
http://i175.photobucket.com/albums/w121/oldschoolanalog/DSC01233.jpg
http://i175.photobucket.com/albums/w121/oldschoolanalog/DSC01234.jpg
Works/sounds great.
More later...

[quarara]

i miss the times in which there weren't projects for flangers... now i have to build them all...

[Thomeeque]

Awesome, who will try this first?

Here you go:
http://i175.photobucket.com/albums/w121/oldschoolanalog/DSC01233.jpg
http://i175.photobucket.com/albums/w121/oldschoolanalog/DSC01234.jpg
Works/sounds great.
More later...

Ho hooo, good news everyone!





Nice, Dave, congrats and thanks for sharing!!

T.

[oldschoolanalog]

If anybody is interested in the changes done to make this work let me know.
If not, I won't waste my time posting info that is of no interest.