Hardwiring individual circuits and shielding questions...

[cmloeffler]

I know it gets mentioned a lot on different forums, and I think that I'm finally in a position to try this out.  I've got four individual effects circuits that I've taken out of their housing and am going to rehouse in a single box, hardwire the circuits together, and place and internal powersupply in.  I've already got a pretty good handle on the box I will need that is the proper dimensions.  My questions are:

1. Is there a way I can hardwire the individual circuits inputs and outputs together to save space and avoid using a 1/4" connector plug between them?  How would I go about it, and are there and potential noise/crossover issues?

2. Can these four circuits coexist in a single enclosure (properly secured) without adding additional line noise?

3. Can a cheapo powerline be daisychained in the box without adding noise (note that I'd be using a wall wart to keep the transformer away from the circuits).

4. Anyone modded an Arion SOD1, SAD3, MOC1, of SFL1?  

I think that's all I have at the moment... what do you think?  I know that there isn't that much of a space difference between rehousing, but I'd love to have an integrated ghetto box and it would keep me busy for a little while.  Fire away!!!

[cmloeffler]

Let me add to the post that if possible, it'd be fun to swap the cheapo switches into 3D3T switches.  Any suggestions on this?

[Mark Hammer]

1. Is there a way I can hardwire the individual circuits inputs and outputs together to save space and avoid using a 1/4" connector plug between them?  How would I go about it, and are there and potential noise/crossover issues?

Modular synths from the 70's used somethng called "normallized" patching.  A default set of connections was set up so that A went to B, C to D, etc., without the user having to do anything.  HOWEVER, a panel of jacks was available such that one could interrupt the "normal" connections and reassign them, simply by plugging in.  In fact this is identical to what happens with wallwart adapter jacks on pedals.  If there is nothing plugged in then they switch to the "default" power supply, which is the battery inside.  Plug in the adapter, and the battery is disabled.

So, if you had an enclosure with room for all the effects, the smart thing to do would be to have something like that on the back, with a mono closed-circuit jack for each in and each out.  The closed circuit jacks are wired up such that if nothing is plugged in, it is as if you have a patch cord going from A to B, B to C, C to D, etc, except that the "cord" is simply a wire between the jacks on the inside.

Why is this "better"?  Because it allows you the freedom to reassign the order of things.  Because it allows you the freedom to substitute something in place of one of the effects.  Because it allows you the freedom to run things in parallel.  Because it allows you the freedom to nest other effects, or even series of them within each of these send-receive loops available.

2. Can these four circuits coexist in a single enclosure (properly secured) without adding additional line noise?

Yes, just make sure that the distances you have to run leads to be able to fit all the controls and switches in the box do not risk acquiring nosie or oscillation by passing near places where they shouldn't.  Typically ins shouldn't be right near outs, things carrying audio should be shielded and short, and things carrying audio shouldn't be too close to high frequency clocks.[/quote]

3. Can a cheapo powerline be daisychained in the box without adding noise (note that I'd be using a wall wart to keep the transformer away from the circuits).

Imagine you build a mixer board that requires 40 dual op-amps for the 8 channels it contains.  Okay, now stick each channel in its own box, 5 dual op-amps to a box.  Does the amount of current needed change, simply by virtue of physically separating them?  Could you use the same master power supply and run power lines to those 8 boxes?  Yes.  Just note that each power line needs to be decoupled from the others connected to the same source, so that momentary changes in current draw fromone effect don't impact on the others.  A 100 ohm resistor and 10uf cap to ground between the wallwat and the point where the power connects to the effect board is probably sufficient.

[cmloeffler]

Hmmm... I'm familiar with the modular patching system (I've got an Ibanez UE400 that does it) but am quite a ways away from feeling confident enough to do that.  As for hardwiring the circuits together,are you saying there's no way I could lay them touching side-by-side?  How would I go about shielding them?  Is there a way I could simply remove the input and output jacks and solder the connections between the circuits together, making the four circuits for all intents and purposes a physically single unit?

[RedHouse]

I have done this but instead of decoupling the power supply with resitors as Mark suggested, I chose to implement an LM78L0x regulator (LM78L09=9v/100mA, LM78L12=12v/100mA etc) for each board. A single 1A wall wart powers the box, but inside there is a small circuit board with 5 regulators and their supporting caps. It's a little more work, and a few more parts, but it works VERY well and is robust and quiet.

If you use regulators be aware they are low impedance so if you drop a Fuzzface board into your new multi-board stompbox you might use an LM78L12 and place a 1.5k -or- 2k resistor in series with the power supply line (after the regulator, before the FF) and something like a 10uF cap (after the resistor) to ground as the Fuzzface like some impedance for best tone. It's not ideal but better than nothing, the  battery impedance is said to affect the tone of a FF.
(I just run mine straight and feel my FF sounds great, but that's just me)

Note; if one needs more current than the 100mA of the LM78Lxx (maybe you need 4 or 5 LED's too) use the LM780x (no "L") as opposed to the LM317 regulators folks normally design their power supply circuits around. The TO-220 package has a big heatsink that can be bolted directly to the chassis on the LM780x series where the LM317 series needs insulating spacers and heatsink compound yaddayaddayadda.
(and if you need bi-polar suppy's use LM780x and LN790x both can be bolted directly to the chassis which is normally at ground)

[Mark Hammer]

Hmmm... I'm familiar with the modular patching system (I've got an Ibanez UE400 that does it) but am quite a ways away from feeling confident enough to do that.  As for hardwiring the circuits together,are you saying there's no way I could lay them touching side-by-side?  How would I go about shielding them?  Is there a way I could simply remove the input and output jacks and solder the connections between the circuits together, making the four circuits for all intents and purposes a physically single unit?

You certainly CAN do this, and in fact I have a chassis I bought 2nd hand from a music store where someone had actually done this with his BOSS pedals.  But you lose the option to place the pedals in a different sequence or stick something in between.  In other words, you would be committing yourself to something you may want to change in future.  If that works for you, go with it.  Personally, I try to keep as much flexibility as I can.

Take a look at the sloped front chassis that Hammond makes (http://www.hammondmfg.com/dwg16Steel.htm).  These are a nice fit for what you want and not all that expensive.  They will provide all the shielding you need.  In some instances, you may be able to install your power transformer inside and a power cord socket on the outside like what you see on computer PS's, so you can coil the cord up and tuck it away neatly.