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 Post subject: MPC: 2 on the floor.
PostPosted: Tue Feb 09, 2010 11:15 pm 
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Joined: Wed Feb 11, 2009 1:50 pm
Posts: 431
Location: Saint Louis
Warning: this is a "work in progress." It's not finished yet, but I'm a little excited about this one. I've been wanting to build this for a long, long time, and it's finally far enough along for you guys to get the idea...

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Right! Obviously, it's a dual MPC module host enclosure. Features:
- full bypass switching on both modules
- LED indicators on both modules
- separate inputs and outputs for each module
- series or parallel signal flow
- battery or adapter power

I recently finalized the general layout of the components. Still have to install some pots, do the wiring, and paint the box.

I'm particularly psyched about the series/parallel options:
1. Mono in > Module 1 > Module 2 in series to a single output (just like an MPC guitar).
2. Mono in > Module 1 > Module 2 in series, output from Mod 1, output from Mod 2.
3. Mono in feeding both modules in parallel, separate output from each module.
4. Stereo or "dual mono:" two signals in, two signals out (modules in parallel).

Ideas? Thoughts? Suggestions?

NOTE: I eventually sold this on ebay in Aug. 2012.


Last edited by ultra sonic on Thu Aug 23, 2012 8:02 am, edited 1 time in total.

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 Post subject: Re: MPC: 2 on the floor.
PostPosted: Wed Feb 10, 2010 7:07 am 
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Joined: Tue Dec 21, 2004 6:30 pm
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Location: Central Iowa
nice! how about a small plexi window so you can see which module is installed? or maybe one of these :) and just slip in a piece of paper...
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 Post subject: Re: MPC: 2 on the floor.
PostPosted: Wed Feb 10, 2010 7:13 am 
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That looks good. Nice idea with the switching options too. Mcbrat's idea of having some way to know which modules are in use is a good one.


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 Post subject: Re: MPC: 2 on the floor.
PostPosted: Wed Feb 10, 2010 7:21 am 
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Joined: Mon Jan 26, 2004 11:47 am
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Location: Amarillo, Texas USA
Interesting!

So you could actually use 2 in an MPC guitar and these 2 on the floor .......

or any number of these to utilize as many UPC module combinations that you might have.

RCSBlues :oops: :up:

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 Post subject: Re: MPC: 2 on the floor.
PostPosted: Wed Feb 10, 2010 9:54 am 
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Joined: Mon Oct 27, 2008 7:10 pm
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Location: Tifton, Ga USA
:up: I think this is a cool setup and I like the different output options. This would be great when used in conjunction with the 2 modules in the guitar and I also like the led indicators and the idea of a view port to ID the modules. Thanks for sharing this one with us. I would like to have something like this so if you decide to make them I am in for one. Thanks :up:

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 Post subject: Re: MPC: 2 on the floor.
PostPosted: Wed Feb 10, 2010 3:30 pm 
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Joined: Wed Feb 11, 2009 1:50 pm
Posts: 431
Location: Saint Louis
mcbrat wrote:
nice! how about a small plexi window so you can see which module is installed...


Windows would be cool! With LEDs inside to illuminate the modules, of course. Let me think about that...

One of the things that slowed me down starting this project was that I spent a lot of time trying to find a way to have the modules accessible from outside of the box, so they could be plugged in or removed easily. But there were simply some mechanical hurdles and compromises that I didn't like with every approach that I thought of. Finally, I just had to accept the compromises inherent with this layout, and I figured it was better to just get the project started than wait for a "perfect" solution that may never come along.

A weak point of every "socket" implementation I thought of was that they left the relatively fragile MPC boxes sticking out of the host enclosure. That's not too good for a pedal sitting on the floor. Especially where guitar players are going to be stepping on it. So in this case, the modules are hidden inside and a screwdriver is required to swap modules. But they are protected, and I wouldn't worry about using it on stage.

mortarman120gang11c wrote:
...
I would like to have something like this so if you decide to make them I am in for one.
...


As far as making these for other people... I don't know. I think it depends on how much time is involved and what anyone would be willing to pay for a box.

Let me get this prototype finished and we'll see how much time I've got in it. There is certainly enough public knowledge for anyone to build something like this. Either a copy or variation of what I'm doing, or someone else may have an entirely different approach.


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 Post subject: Re: MPC: 2 on the floor.
PostPosted: Wed Feb 10, 2010 5:58 pm 
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Location: Tifton, Ga USA
Fair enough thanks and good luck. 8)

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 Post subject: Re: MPC: 2 on the floor.
PostPosted: Thu Feb 11, 2010 3:52 pm 
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Location: Ann Arbor, Michigan
Looks pretty slick, if you can keep 'production' costs down, I bet you could move them on the 'bay.

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 Post subject: Re: MPC: 2 on the floor.
PostPosted: Fri Feb 12, 2010 3:24 pm 
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Posts: 431
Location: Saint Louis
proendorser wrote:
Looks pretty slick, if you can keep 'production' costs down, I bet you could move them on the 'bay.


That's a good point.

I didn't build this thing with the specific idea of selling them, but it would be cool if the numbers would work out on both sides of the deal.

I've been working out of town most of the this week and last week, so I haven't made any progress on the internal wiring. Hopefully I can heat up the soldering iron over the next week.


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 Post subject: Re: MPC: 2 on the floor.
PostPosted: Tue Feb 16, 2010 9:43 am 
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Joined: Wed Feb 11, 2009 1:50 pm
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Location: Saint Louis
I have this (mostly) wired up to the prototype stage. Still outstanding are the following issues:
- test different pots (different values and tapers)
- AC adapter not wired (parts on order)
- paint or otherwise finish the enclosure
- LEDs not yet wired (wait until the box is painted)
- ultimately the modules should be secured to avoid possible damage

Here is what I've learned so far-- first, it takes quite a bit of time to hand wire this. Labor intensive!

Also, there is significant drop in signal when the modules are engaged, either from the module circuit loading the pickups, and/or bad gain structure in the modules. I have a suspicion that it is mostly loading. It's worse when the two modules are in parallel. I'll see if it works any better putting a modern pedal with a good buffer circuit between the guitar and the MPC modules. If that improves performance, the ideal solution would be to incorporate an input buffer into the box.


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 Post subject: Re: MPC: 2 on the floor.
PostPosted: Thu Feb 18, 2010 12:30 pm 
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Posts: 431
Location: Saint Louis
More photos showing the (almost complete) wiring...

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 Post subject: Re: MPC: 2 on the floor.
PostPosted: Thu Feb 18, 2010 4:39 pm 
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Location: Central Iowa
cool. I see you found some 150k pots...

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 Post subject: Re: MPC: 2 on the floor.
PostPosted: Thu Feb 18, 2010 5:27 pm 
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Location: Tifton, Ga USA
:up: :up: Looking pretty good so far. Thanks for the updates.

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 Post subject: Re: MPC: 2 on the floor.
PostPosted: Thu Feb 18, 2010 6:00 pm 
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Joined: Wed Feb 11, 2009 1:50 pm
Posts: 431
Location: Saint Louis
mcbrat wrote:
cool. I see you found some 150k pots...


Yeah, good Bournes conductive plastic! 150k can be difficult to find, and those particular pots are linear taper. Seems to work well enough, but I have a couple other options that I'm going to try. Audio taper 100k might work well enough, maybe with another resistor in series with one end of the pot. The strange thing is that different modules use the pot a little differently, so what is best for one may not be ideal for a different one.

mortarman120gang11c wrote:
Looking pretty good so far. Thanks for the updates.


Thanks. It's an interesting project. Hopefully it will result in some useful sounds at some point. I've shown a couple people the box- inevitably they give you the blank stare. Followed by ".... now, what is it?" And then I have to repeat the whole explanation again, more slowly!


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 Post subject: Re: MPC: 2 on the floor.
PostPosted: Fri Feb 19, 2010 7:36 am 
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Location: Southern Indiana
Nice neat job on the wiring. :) I am impressed. Yes, it take a LONG TIME to do a job THAT GOOD. Especially the first time! :up:

I am curious that you strayed - at least a little - from stock wiring. Do I see indicators and 4 input jacks, and different type switches? Is the loading down a result of these changes? Would it load it down less if you went with completely stock wiring from the guitar translated to the box? Trust me, I don't know (that is why I ask). But I know the regular modules in the guitar load down the circuit slightly, so some loading stands to reason. I find the phaser and flanger especially can load the circuit down a bit.

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