Korg Mr. Multi clone build.

[Ronan]

Done deal, it's in the mail, be good to see another one built!

[the3secondrule]

Done deal, it's in the mail, be good to see another one built!

Appreciate it, man - between this, and the phase II boards i've got on the way, i'm going to be totally sorted for weird modulation

[weadapt]

maybe i'm just a newb but i don't really understand where all the numbers on the vero layout lead to? or where the "off-board components" go?

[digi2t]

maybe i'm just a newb but i don't really understand where all the numbers on the vero layout lead to? or where the "off-board components" go?

You need to follow the schematic for that. The wire numbers on the vero correspond to the wire numbers on the schematic, and where they go. The off board components are soldered directly to the rotary switches, or pot.

Look in the layout gallery, under "Dino's Stuff", the schematic is there along side the vero layout. You need to use both, to cross reference the wiring. There was just too much to put all on a vero layout.

[weadapt]

trust me, i've been looking at this for a couple hours now, and i have that part, but what type of switches are needed for this, and do the numbers follow any specific pattern when matching the wires to the switches? i've never worked with rotaries before. thanks in advance

[digi2t]

trust me, i've been looking at this for a couple hours now, and i have that part, but what type of switches are needed for this, and do the numbers follow any specific pattern when matching the wires to the switches? i've never worked with rotaries before. thanks in advance

Looking at the schematic, you see the two rotary switches. One, is a 4 pole/3 throw, and the other is a 4 pole/2 throw.

I used this type of 4P3T rotary switch;



It has a special tabbed washer. You can set it to lock the amount of throws (positions) that you want. So, use one set to 2 positions, and another set to 3 positions.

As for the connections, looking at the bottom of the switch in the picture, you'll see the 4 poles in the center of the switch. These are labeled A/B/C/D. Each pole will have 3 throws associated to them. "A" will have 1, 2, and 3. "B" will be 4, 5, and 6, and so on. Using the schematic, take the wire number from the vero to the appropriate connection point on the switch. Although the throws aren't numbered on the schematic, the poles (A/B/C/D) are. Just number them from left to right, or top to bottom for the 2 throw.

As for the offboard resistors, and cap, these will mount directly to the switches, or pot.

Hope that helps,
Dino

[the3secondrule]

Anyone got a source for the 1m pot? I'm having trouble finding one locally (new zealand) with a long shaft *aaand* long enough bushing to mount in a crybaby shell. That's all i need to finish my clone...
would be eternally grateful if anyone had a spare they could part with?

Cheers, Jeremy

[pinkjimiphoton]

jeremy, what kind of pot do you need? i do have 1meg A's from radio shack, but it's a solid shaft, no splines or cutaway on it.

if that will help, pm me your addie and i'll go pick one up for ya today, get it in the mail!

[digi2t]

Get it at ABRA Electronics.

The PET pots fit perfect. Here's the web page;

http://www.abra-electronics.com/products/P2W1MEG%252dLS-2-Watt-Linear-Taper-Potentiometer-with-2-Inch-Shaft%252d-1MEG-Ohms.html

Then get the gear from Small Bear. The one with the flat, not the spline. Here;

http://www.smallbearelec.com/servlet/Detail?no=370

I can't find the circlip, but an auto-parts may have this. It clips into a groove on the shaft to keep the gear on.

Jig the pot in the shell, eyeball the pinion on the center of the rack, and mark the gear ends onto the shaft. You should have a couple of millimeters between the pinion and the pot bushing. On the free end of the shaft, add about 3 or 4mm extra length for the circlip. Cut your shaft down to size. Using a fine file, file the flat on the shaft. File from the end, to the inner mark where the pinion ended. You want to leave a couple of mm's space here, so the gear doesn't slide into the pot bushing. File slow, and check often, you won't need much. Try fitting often, and make it on the tight side, you don't want any slop here. Once you're done, with a Dremel cut-off blade gently score the shaft to fit the circlip. Go easy, you JUST need enough for the circlip to sit into, but make it so it will sit snug against the side of the gear. You should end up with this (you can't see the circlip, but it's there);



Trust me, it's worth the wait, the work, and the money. These pots are the best for this application.

[the3secondrule]

Get it at ABRA Electronics.
Trust me, it's worth the wait, the work, and the money. These pots are the best for this application.

thanks for the linky Dino - unfortunately Abra's minimum order for int'l orders is $75 :-/

is anyone able to pick one up and send it my way, if I arrange some paypay cash-monies?

Cheers,

J

[pinkjimiphoton]

minimum order here is 25....too broke right at the moment, i just did big orders from some other sources.

if nobody gets to it for ya before i get some cash (a couple weeks) i'll try and help ya out bro. 

[digi2t]

Get it at ABRA Electronics.
Trust me, it's worth the wait, the work, and the money. These pots are the best for this application.

thanks for the linky Dino - unfortunately Abra's minimum order for int'l orders is $75 :-/

is anyone able to pick one up and send it my way, if I arrange some paypay cash-monies?

Cheers,

J

Jeremy,

I could do that for you. I need to order some stuff for my Phase II project. Do you need the gear as well? If so, I could get one from SB at the same time, and then ship the lot to you. You can pay me through Paypal.

Like I said, for the external circlip, you can probably get that at an autoparts dealer. They usually have them in divider cases with all sorts of different sizes. Or, any industial supply shop (bearings and such) will have them as well. Another alternative to lock the gear onto the shaft, is to use a tiny spring pin. Just drill through the shaft, and drive one in snug against the gear. You leave it about 2mm longer on each side, and that gear`s not going anywhere.

Let me know what you need, and I`ll handle it for you. Just PM your address.

Yes Jimi, you heard right... I`m starting the Phase II. My Ring Stinger is done (EFFIN`AMAZING!!!... build report coming soon), and the Buzzaround is on hold while I await more Ruskie trannies to try. So... Luddies next on the workbench.

[pinkjimiphoton]

sweet...i'm repair/restoring a couple classic dod pedals, i just am now getting all my parts sorted out...

and after a couple building gigs (i'm actually being hired to build pedals by some friends, which is frikkin' awesome) i will order all the parts for the ludwig.

i gotta KILLER chrome-plated wah shell for the project..it'll really look nice. i may send the box for the guts out and get it chromed so it'll match.

and as for helping out our brother here...you da bomb, bro. righteous!

[the3secondrule]

Dino - PM'd 

Cheers all - looking forward to having this badboy up n running

J

[digi2t]

It's going to be worth the wait. It's a great pedal. Either it was severly under-rated, or a really well kept secret. Matching your FET's is the real key though. I used R.G.'s method, over at Geofex. It made a huge difference in the sound, between random FET's, and matched ones. The phase-wah setting is really nice.

and as for helping out our brother here...you da bomb, bro. righteous!

Life's a circle bro, you'll only ever get out, what you put in. That's been proven, since the dawn of time. 

[pinkjimiphoton]

[Ronan]

I recently read a post on this forum, no idea where it is, but the poster (God bless him) said to adjust the trimpot to get an even sweep of the LFO (referring to phazers in general from memory). Now I noticed my Korg Mr Multi wasn't quite even in the sweep, it sort of "hit the bottom" for a bit too long, so I adjusted the trimpot by ear to get it right, which was fairly close to where I had it. Just a heads up if anyone wants to try this. It may have been mentioned before in this thread, but I don't want to go back through the posts to find out...

Another thing I have noticed recently, is that a zener diode rated at say 5.1V needs around 20mA flowing before it regulates to the 5.1V. With stomp circuits, the currents we deal with are a lot lower than that, and a zener will regulate to a significantly lower voltage at lower current, like in this circuit. Therefore maybe the original circuit used a  5.1V zener (or higher) which regulated to 3.5V as stated on the circuit with approx 3.6mA flowing through the 1K5 resistor.

[digi2t]

Hi Ian,

I had written earlier in this thread;

Through trial and error, I also figured out how to set the trimmer. It sets the low end of the Q, suiting the frequency to the sweep of the pot. That way you don't have to fiddle with the pot position too much. A multi-turn trimmer is ideal here. In auto mode you can really hear the sweep.

Is that what you read? Maybe a little convoluted. I think you explained it better  . Especially the zener part, that was a bonus. Thanks man!

Cheers,
Dino

[Ronan]

In auto mode you can really hear the sweep.

That statement is the one 

[the3secondrule]

Anyone know if korg made any other pedal in the same treadle as the mr multi?

I just pick up a korg treadle pedal, on the basis of one photo, top down. It looks exactly like the mr multi, but I don't see the switches on the side - so I'm guessing its either a busted mr multi, or something else. Google didn't shed any light

For $20, I decided I'd take a gamble 

Thoughts, gentlemen?

And apologies for the necrobump, I figured this was the best place to ask.

J