Korg Mr. Multi clone build.

[pinkjimiphoton]

i already listed the green "chiklets" , all were 223. but on mine, they're on both sides of the chips. when i get a chance, i'll open it up and try to read the rest, and post pics.
pretty sure mine has different style caps in it in places...and get that reading to ground, too.

gimme a little bit...just getting on today..cold makes me slow.

[Ronan]

Thanks Jimi, I did see that reference to the chicklets but I have not heard of that term before. Chicklets? Spit peas? Or green chickens with 2 skinny legs?

I set bias about 3v5 by measuring at middle lug of trim pot to ground.

Thanks for that pravudh. Did you use four 0.1uF caps in the all-pass filter stages? Compared to other phasers, the value seems large, and 0.022 or 0.033uF values would seem more likely. But I guess the proof is in the pudding. How do you like the sound of it? I am about halfway through putting parts in the PCB and still waiting for other parts to arrive.

[Ronan]

Parts finally arrived, I bought some matched 2SK30 from tubeshunter (ebay), not cheap, and took a while to get here. They were matched for Idss, it says on the packet 4.86mA at 10V, but they seem to work fine, which was verified by resistance measurements in circuit with the oscillator set to a very slow sweep.

It turns out the positions of the switch on the schematic are indeed back to front. With a closer look, I don't think the author was actually trying to show the real switch positions. I just assumed...and you know what that leads too...

Anyway it sounds great, very close to Jimi's pedal in the double wah position, but Jimi's has the edge, with a touch more warmth and I think a slightly bigger swing from the LFO. It is a quite unique sound!

The tuning of the bias voltage and the 10K trimpot seems critical. Without enough bias voltage, there is not enough swing. I couldn't find the zeners I wanted locally so ended up using two LED's and a 1N4148 (where the zener would go), giving a 4.25V bias voltage. The voltage swing from the LFO is from 1.9V to 2.3V (measured at pad 9), and the resistance across the source to drain of the 2SK30's varies approx 1K to 5K with the LFO sweep. I am using 100n ceramics in the filters and 22n greencaps on the 2SK30's.

I will play with it some more, the outboard wiring is on a breadboard, and the 100n ceramics are in sockets, and the 2SK30's. The PCB worked fine, I guess you could call it verified, and the overlay. The PCB is missing a hole for the +9V batt wire, but I believe in the original the wire was just soldered flat to the copper. I admit I am a bit out of my depth in the understanding of this circuit, I understand most parts of it but am definitely having trouble seeing the "full picture". Just learning as I go. I really love this double wah sound   

[digi2t]

PHEW!!! I'm glad the PCB works. There was a trace that was out when I had originally gone over it, and corrected it.

Glad it worked out for you. Yeah, the double wah sound is really cool. Especially with a modded Uglyface 

It's got a kind of RATM, Bulls on Parade kinda feel to it. Sorta...

[Ronan]

PHEW!!! I'm glad the PCB works. There was a trace that was out when I had originally gone over it, and corrected it.

Yes I saw that correction, that would have been major. Thanks for fixing that.
Nice clip, wild stuff!
The phase is really nice too, I'll put this one in a box and just use the LFO, for now, wondering whether to have that 10K trimpot on the front of the box as a sort of depth control, with it wound down a bit you can get some really cool subtle sounds as well. Might be the go, nothing to lose.

[Ronan]

Just a clip of the double wah setting, clean and dirty. Sound level all over the place sorry.
mrmultisoundclip3.wav - 3.23MB

[Govmnt_Lacky]

Wondering about this scenario:

I want to use a matched set of 2N5952s (a la Phase 90) for this build.

Will this affect the bias voltage provided by the zener? Should I use the same zener required in the Phase 90 build? (5.1 or 4.7V)

Hmmm 

[Ronan]

I ended up with 3 x LED's which set the bias voltage to 5.3V, which resulted in the 10K trimpot needing to be set about halfway for full sweep. I *think* it sounded better this way, but I ran out of time to go back and try the former 4.25V bias to compare. It might be no different... The bias and trimpot are definitely worth tweaking to find the sweet spot.

[add4]

Is there a schematic of this sicko thing? i have an old way lying around, not used for a few years ..
i'd gladly rehouse something cool into it.. but i love to take every opportunities to learn to layout
THanks in advance

[pinkjimiphoton]

 
the search button is your friend.


(yah, schems, layouts, even originals for checking.)

and it IS  a sick pedal

[add4]

the search button is your friend.

i'll search again with better search terms then ^^

[Govmnt_Lacky]

Just wanted to chime in to say THANK YOU to all who contributed to this thread. Especially a huge thanks to Dino and Jimi for their contributions. I finally got this built and it sounds PHENOMENAL!!!

Posted pics in the Pictures thread if you wanna check 'em out 

http://www.diystompboxes.com/smfforum/index.php?topic=36392.msg822204#msg822204

[digi2t]

Just wanted to chime in to say THANK YOU to all who contributed to this thread. Especially a huge thanks to Dino and Jimi for their contributions. I finally got this built and it sounds PHENOMENAL!!!

Posted pics in the Pictures thread if you wanna check 'em out 

http://www.diystompboxes.com/smfforum/index.php?topic=36392.msg822204#msg822204

SHIT MAN!!! THAT LOOKS AMAZING!!!!

I love the chrome pedal. I'm really glad it worked out for you. I think I can speak for Jimi as well when I say that it's moments like this that make it all woth while. When a group effort culminates in success and happiness... that's what it's all about baby!

But... there's just one thing. The brotherhood requests a video, or at the very least, a sound clip miho. Chrome may walk the walk, but can this baby talk the talk? 

You made my day man, muchos gracias!

[Govmnt_Lacky]

But... there's just one thing. The brotherhood requests a video, or at the very least, a sound clip miho. Chrome may walk the walk, but can this baby talk the talk? 

Good at building excellent sounding Mr. Multi clones = YES

Good at shooting videos and uploading them WITH good playing = NOT REALLY 

I dont have a vid camera attached to my computer or even one around the house for that matter 

Looks like I will need to consult with Santa this year 

[Ronan]

Thanks for posting the pics! It is a cool pedal, its out there, thanks again to Dino and Jimi for digging these sicko gems out of the ground!  

Edit: Oh yeah, and to Dino, thanks for making them work (endless researching, breadboarding and resultant schematic corrections) which makes the difference between tears of joy and tears of frustration... 

[Ronan]

I finally got my PCB into a 125B box, just using the LFO, with rate and feedback controls, and it's permanently set in double wah mode. There's plenty of room for more switches/pots, I might get the urge to go further, but I'm very happy with it for now. The feedback pot is 25K and replaces the off-board 22K resistor. It works like a wet/dry mix control, which is what I was hoping for. I fitted the correct 100n input cap, up from the 10n, dunno why I had a 10n in there, and there's more bottom end now. But the 10n gives a bit of that "telephone freq response" that I often like in a distorted lead wah sound. Options...options...

[digi2t]

Beautiful build Ian.

Nice take, on a really nice circuit. Maybe an input cap blend pot is in order here? http://www.diystompboxes.com/smfforum/index.php?topic=95176.0

Great job man!

[the3secondrule]

any chance of getting an etched board for the Mr multi? 

between working fulltime, and having a 3 month old baby at home, I don't have the concentration to attack the vero layout ATM, and I don't have the means to etch my own 

help a brother out?

[Ronan]

I have a couple of spare PCB's, undrilled, quality not very good since my home etching skills aren't that good, but the one I just built was in the same batch. If you are happy to drill it, I'll send you one over, and you buy me a beer next time I see you, pm me your address.

[the3secondrule]

I have a couple of spare PCB's, undrilled, quality not very good since my home etching skills aren't that good, but the one I just built was in the same batch. If you are happy to drill it, I'll send you one over, and you buy me a beer next time I see you, pm me your address.

deal! if you are happy to post to New Zealand