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Black box technology


Old King Log
Staff member
When I set up the "spot" for my group, a good part of the time is spent getting the sound system (used mostly for my wonderful group of vocalists) all lined up and ready to go. As this is an important factor when time is limited (try setting everything up twice in one day, with only two hours for the second set), I had been toying with simplifying this on more than one occasion.

Well, the recent doubled up experience was the last straw on this camel's back. After untangling the mare's nest of cables running from the precariously perched microphone receivers, I resolved to fix things up. And, so I was led to purchase a "big, (somewhat) bulky, black box" on wheels to start the process.

Rock folks are big on these things, two sided boxes on castors, with latching front, back and top. Built of heavy duty materials (mine is half inch Plywood), they are designed for rack mounting, the installation of electronic amplifiers and effects modules that bolt front and back to precisely sized strips of screw holes at front and rear. For the typical rock setup, heavy on signal processing, autotune and sechlike, this means a three foot stack of panels and the like.

Since there's no standard setup for this sort of thing, these units are sized by the number of panel slots, with each user installing their own mix of equipment. They aren't all that expensive, and the unit that I bought was even cheaper, as it is shipped in a knocked-down form.

There is one problem, however: with the sole exception of my sub-mixer board (which mounts in a pop-up fixture at the top of my "box", none of the stuff I want to install is designed to work with a rack mount system. What to do?

First off, I went and bought myself something I've wanted for a long time, a "contractor-style" table saw. With this precision tool (I hate sawing Plywood with a circular saw), a sheet of 1/2" Plywood, twenty linear feet of hardwood stock, and an assortment of nuts and bolts and electrical goods, I'm ready to go.

While the box itself remains to be built, I have my set of prints for all of the additions to the stock box already in hand. I plan to install a series of Plywood shelves within the box, both to give it rigidity and to mount my components. A lower shelf will hold the electrical power supplies (six for the mikes, plus three extra outlets for the mixer board, the PA head, and the LED lighting for the controls and connections front and back), and an electrical feed to the top of the unit for some utility outlets.

I'm planning on a twenty foot power supply pendant, coiled up and hung off of the back cover when it's all closed up. The LED lighting came from Ikea - four strips of red tinted LEDs, mounted on the underside of upper shelves so as to cast light on the controls of the PA head and the jacks on their back side. (I had to tint them myself, using some hobby paints in Candy Apple Red.) In the topmost shelf (hidden beneath the mixer board) will be two combination USB/single outlet outlets. The electrical power is for my lead alto's digital recording setup, while the USB outlets (four of them) are for two gooseneck USB computer keyboard utility lights (which will illuminate the mixer board).

When it's all done, there will still be some hooking up to do. When the mixer board is in the stored position, the XLR connectors into the head will still stick up too far to leave them in place. If I can't drop the mount for the board, I plan to address this by hanging them through a series of hook-eyes screwed to the back panel - they will drop down in connection order, ready to be pulled up and popped into place the next time that they are needed. But, the time saved just in setting up the components and wrestling them all into place will make that a minor annoyance at best.

These XLR cables will run the short distance down to the six microphone receivers, located on a shelf below. Semi-permanently installed, their setup consumed the greatest amount of time on previous occasions - now, they come "pre-installed", saving that amount of time automatically.

The bulky Peavey public address (or "PA" in the rock-based lingo) head, always an awkward item to handle and set up, will be cleated in place within the cabinet onto the third "shelf" of the unit. It just barely fits between the walls, so the hardwood cleats will firmly hold it in place while still allowing for its removal should it be necessary to take it out for maintenance.

All in all, it eliminates a whole series of small components than had to be moved separately and then custom hooked up at every job, unitizing them in a single, stable cabinet that has wheels and its own protective carrying case. Fifteen fewer cables to deploy and wind up, permanent lighting instead of easily lost flashlights, all of it on its own set of wheels, instead of in three cart loads. A little more space taken up in the trailer, but all in all it will be worth it.

Photos will follow when I start putting it all together. Now, all I have to do is to come up with the time and energy...


Staff member
Not sure how much clearance you have on the mixer, but you may want to check out right angle XLR connectors to see if they fit. I may have mentioned it before, but I really like Audiopile for cables. Nice selection, good quality and modest pricing compared to big box stores. They will also make custom lengths for you.


All that extra plywood weight may make this thing a gut buster to lift out of the trailer, up stairs, etc. You can also buy rack mount capable steel shelves, although I haven't seen any with four corner attachment, just front rail. Might be good for the light stuff like the wireless receivers.

Looking forward to seeing pictures.


Old King Log
Staff member
The Plywood amount comes out to about half a sheet - not terribly much for something on wheels. (It's made of the same dimension stock, by the way.) Two of the shelves will be of half length (mike receiver shelf and PA head shelf); only the top and the electrical box at the bottom will meet the full 19" x 20" dimensions ±. And, one of the full length ones will replace one already present, also made out of 1/2" Plywood.

(Metal shelves won't work, as I don't have the metalworking technology to make neat openings for the electrical gear.)

I will look into the right angle connectors though. However, they may not be necessary. I've got a full 1" clear now, but the "stop bolt" for the mixer mount can easily be lowered to allow for more. (I've just checked.) Right angle stuff will work for sure, but I might be able to get by with standard .

I'm still waiting for a couple of saw accessories before I start dicing up the wood. Zero clearance plates for the blade, plus feather-boards for both to the fence and to the table, and stuff like that. I have to make a run up to northwest Houston to get the stuff to fit my saw.

The saw is a nifty piece of work on its own. It's a contractor saw, which consists of the saw unit, plus a folding, substantial stand. Dead solid, holds angles and alignment well (I took the time to verify everything with the squares and measurement blocks). We here in Houston are cursed with no-basement homes, so everything has to either be compact enough to store in the (rather deep) garage, or in a separate storage unit. Since we're abandoning plans to buy a motorcycle style camper trailer, I've got more than enough space in the garage, but still...


Old King Log
Staff member
Well, I've got the right angle head XLR connectors either on order, or purchased. (It took a while to learn the secret of the things, but I've sorted that out now.) They are the only things that I have ever purchased that were made in Liechtenstein - weird. I'll just cut down mike cords to the proper length, then solder on the new connectors. With the connectors installed, the cover at the top of the box closes properly, but only just. I'm going to drop the two stop bolts down a couple of diameters, and that will provide all of the clearance in the world.

Also, I've finished fabricating the LED strips for lighting the mike receivers and the PA head, front and back. I took a standard Ikea item (their Dioder set) and tinted the clear housing of each strip of nine bright LEDs with Tamiya Candy Apple Red clear finish, creating four bright but very red light units. They'll be mounted beneath the third and fourth shelves, with the power supply leads being capable of being disconnected, and in aluminum channels to restrict and direct the light straight downwards.

The wiring for the power is mostly done as well. Two triple duplex outlets in the bottom plus space for the rather large sub mixer board power unit. Everything under the shelves is three conductor NM cable (Romex). The power supply pendant is the same heavy three wire flexible cord used for my light snakes, all run out of a custom designed strain relief fitting at the bottom of the unit. I've also designed in a flexible cord connection for the electric power to the pair of duplex outlet boxes at the top, with a plug and socket connection worked in so that I can break the wiring without destroying everything if I have to pull the PA head out for some reason.

I'm going to trim off all of the excess cord length for the mike power supplies, the cord to the PA head, and the cord to the transformer for the LED lights. Except for the PA head, all of the plugs are simple polarized two blade units.

Next, after a couple of days spent on my mother's estate (we just had two more mystery bank accounts crop up - I swear the woman had money stashed in every bank in Saint Louis), it's time to start fabricating the shelves. The bottom and top will be constructed with the fronts attached to the inside of the rack mount rails, with the shelves themselves as drop in (and screwed down) onto the cleats bolted to the side of the box. The other two will be shorter ones just mounted to the cleats themselves. I'll have to dig out the scroll saw to cut the outlet box holes - more heavy lifting as it's behind a veritable wall of book boxes.

One of the neat things about all of this is that I get to use all of the woodworking tools that have accumulated in my tool chest over the years. Of course, all of the nicely fitted woodwork (Plywood, but still) will be spray painted flat black once I'm done, but what can you do?

Upon reflection, I wish that I had been able to find a housing that was covered in black carpet, like the real musicians (i.e., rock 'n' rollers) use for all of their stuff. You can't have everything...
yep, You'll have stickers, chalk marks, stencils & orange spraypaint on that thing in no time :) Folks pay sound companies big bux for this kind of custom job , & you're a brave, brave, man for going at it yourself. 90% the problems you'll encounter have been met with roadworthy solutions: its only a (daunting) matter of finding the *exact* fix.

Just a suggestion, I have found that metal corner protectors, although expensive & heavy, are well worth it. Oh, and the carpet...naaah..it just starts to smell after a while. Stick with the paint.


Old King Log
Staff member
Got the corner protectors already installed. It did take me a while to figure out just how the doors with those corners were supposed to go, but trial and error (the drawing in the instruction was no help) got me there.

Carl H.

Distinguished Member
Distinguished Member
Oh, and the carpet...naaah..it just starts to smell after a while. Stick with the paint.
Exterior? I'd go with Duratex rather than paint. Much more durable.


Old King Log
Staff member
Today, I soldered up the Y-connector male plugs (for my stereo to mono connection running from the mixer board to the PA head.

The Y-connector that I have is a generic one (read cheap Chinese imported gear), but it has worked fine to date, so why buy another? I pulled the two ends of the Y (which plug into the stereo out outlets on the mixer board) and then desoldered the three terminals in each of them. Talk about your poor worksmanship (or, more likely, "Chinese teenaged girl worksmanship")?!?! Even though this item has always served me well over the years, two of the three solder joints were of the "cold joint" variety.

Compared to the generic fittings on the Chinese cord, the new fittings from Liechtenstein were a joy to deal with. Everything soldered up fine, even if the process was somewhat time consuming and required an extra pair of hands to hold everything still. (My fancy electronic soldering outfit was pirated by my son, so I had to improvise quite a bit.)

The Liechtenstein fittings have an additional feature in addition to turning a 90° turn right at the board's face. The heads on the fittings can be pivoted from side to side over 180°, and are then locked in place by a clever arrangement of the metal support fitting and lid. As a result, my two flattened out connection plugs also angle off to the side, making for a neater installation overall.

I also have to install six female 90° fittings on to six cut down microphone cords. Tedious work, but work that has to be done nonetheless.

If it weren't so hot down here right not, I'd have the shelves cut and fitted into the box already. But, the combination of torrid days (85° F at 7:00 AM, 100° by 1:00 PM) puts working in the garage with the saw out of reach.

Other than the shelving and the final installation, I've got most everything else done.


Old King Log
Staff member
Today, I started the final, "permanent" installation of everything back into the cabinet. Hot and dirty work, but I'm doing all of the fine detail finish work (routing wiring and cleaning up the back side of the cabinet) as I go, so it's worth it.

I had a tolerance problem with the cabinet sides spread out too far for the front and rear doors to clamp in place. This was caused by installing the shelves without having the two sides held to the final width of the cabinet. As a result, things keystoned a bit so that by the time I topped it out with the submixer board, it was about a tenth of an inch too wide for the doors.

For the final assembly, I bolted the two original 'flat plate' fibreboard plate at the top, then checked the fit of the doors and top, and only then started bolting the brackets, shelves, front and rear plates, and cleats back in, checking as each level was installed.

The biggest problem I had was with routing the wiring up into the upper levels. I have about a bazillion pounds of screws, fittings, clips and what have you, but almost all of it is packed up in the Pod, which is in storage awaiting our big move. (Also boxed up are all of my wire ties...)

However, I kept out a supply of Nylon loops, and rigged up appropriate fasteners to hold them in place with small screws and washers. Also a problem was the magnetic properties of the bit in the screw gun, which kept snatching the screws out of the screw hole. But, sweating like a pig, I got them all tied in.

All that remains is for me to replace one cross member that I had to cut apart to disassemble the test fit up. Then, after a test fit of the mixer head into the ever so slightly narrowed cavity (I shouldn't have to remake the spacers), it's time to re-install the threaded rods that trap the head in place, fit in the top shelf (the one with the outlets for the LED worms that will illuminate the top of the sub mixer board, glue some corner bead trim over the Plywood shelf joins, and then paint the remaining exposed woodwork in flat black.

I'll try to upload my photo series next.


Old King Log
Staff member

..except I see no "Font" icon or framed icon; all I see are some emoticons, and that's it. Can you show me an image of where this is located on the page?

Let me try this:

Nope; putting the img tags around the url just gives the blank image icon.


Brassica Oleracea
Staff member
You had the basic text editor set as your default. I've switched it on to "advanced."

The code for just inserting an image is
"Imagepath" has to be to a file ending in .jpg, .png, etc., which is why my text example doesn't work.


Using the Editor:

1. In the bar that looks like:



2. You'll have two choices:


Click on either "From Computer" or "From URL," depending on where your pic is. I'll do "URL."


and choose OK.



You can then double-click the pic to make formatting changes. Here's the dialog:



Brassica Oleracea
Staff member


Old King Log
Staff member
View attachment 2108

The "work in progress" cabinet. It spent considerable time this way, as I spent much of 2013 dealing with my mother's complicated estate. (Indeed, as this is being composed, it is still not completely resolved.)

I had taken some "installed progress" photos, but I can't seem to find them right now. (I'll take some new ones of the almost finished cabinet (everything in place but the trim and the mixer board at the top) when I get the chance later this week.

The cabinet and the doors are all made of "real" Plywood, not composition or hard board. Some of the components were made of hardboard, however - not the best of choices for a permanent installation.

(The original intent was for most of the "structure" to be made up of the user-supplied rack mounted equipment, which would provide its own rigidity. My approach, with non-rack mounted equipment, had to provide panels to replace this rigidity.)

The Plywood panel at the top of the cabinet is a temporary one, installed there to stabilize the sides until some of the structure was in place.

View attachment 2110

This shows the general layout at the bottom of the cabinet. The box in the center is the connection point for the power pendant ("the power cord"). The cross-like thing to its right is the power brick for the Yamaha sub-mixer board, with the power cord and the cord to the mixer board issuing from it. The cross is made up of two pieces of plastic tie-down strapping, used to hold the mixer in place on the cabinet floor. This was done so that the brick can be removed and sold with the board should that occur at some time in the future.

View attachment 2113

A better view, showing the walls of the cabinet and their relationship to the stuff at the bottom. The two grey objects at the bottom edge of the cabinet are two five pound pigs of lead, installed there (after additional rough in work) by bolting them through the bottom of the cabinet. They are provided to help counterbalance the weight of the Peavey mixer later installed about a foot above the bottom of the cabinet (and on the other side, mounted all the way to the front). Regardless of these weights, I still have made it a rule that the cabinet is always dollied up and down ramps with the mixer side upslope.

The two pieces of light colored wood on either side of the cabinet are rails upon which the first shelf, carrying the power supply outlets and the PA head cutoff switch, will rest. Once in place, it is held there, like all the shelves in the cabinet, by two thin hardwood battens screwed to the sides of the cabinet. This allows for later disassembly should it be necessary.

All load bearing rails are through-bolted through the Plywood walls and floor of the cabinet. Most are made of 2" nominal hardwood; only the rails supporting the lightly loaded microphone receiver shelf are of smaller stock.

View attachment 2125

The L - O - N - G (20') power supply pendant for the cabinet. This is made of very heavy duty electrical cable, suitable for damp and wet service in coal mines (or for being trod upon by stiletto heels), the same stuff that I used to create my light snakes. (I had a friend in the mining industry pick me up a 100' reel of the stuff for next to nothing, and it has come in very handy over the years.)

Like them, this is designed to take a lot of abuse without significant damage. When the unit is packed up, the coiled pendant is hung from a hook through-bolted to the rear cabinet door, with the coil hanging in the large open space at the rear of the PA head.

View attachment 2115

The bottom of the "power shelf", the lowest shelf in the cabinet. Made of 1/2" Plywood, it has a single illuminated toggle switch installed in the blue box seen here at the top, and two triple sets of standard three pole duplex outlets, installed at the bottom. The electrical wiring is all three conductor, 12 AWG (either in NM cable or a separate wire for the switched leg of one outlet's circuit (the red wire seen leading to the switch box). The run of NM cable at the bottom of the photo is led to the box in the center of the bottom of the cabinet, from which is run the power supply pendant.

View attachment 2114

The assembled power supply plugs for the microphone receivers and the LED lighting system, here brought through the hole mentioned earlier. (When installed into the cabinet, these plugs would remain on the opposite side, there to be plugging into the outlets on the power shelf.

Also, note the rectangular outlines on the front of the shelf. These are Plywood "door skin" outlines, cut on the jig saw, that have been glued down to the top of the microphone receiver surface, on top of the microphone power supply shelf. They will serve to locate the six Shure wireless microphone receivers (in two stacks of three) once the cabinet is complete. Once the receivers are in place, a compressed high density polyethylene foam block will be wedged between the top of each receiver stack and the bottom of the PA head shelf located above. That way, the receivers can be temporarily removed should it be required, to be used with spare power supplies, for a smaller gig.

View attachment 2116

The bottom of the second shelf, the microphone receiver shelf. Mounted here are the six microphone receiver power supply transformers, with their power cables run through the hole at the bottom left of the photo. (They were moved there to clear up the photo; normally they would be hanging down from this shelf. Also mounted here is the power transformer for the Ikea LED light set; it's the light colored box on the right side of the photo. All of the output lines from these transformers are run through the hole at the center bottom of the photograph.


Seen here is the completed PA head shelf. A piece of 1/2" Plywood, with a wood strip through bolted to the front edge, it is a tight fit atop two runners bolted to either side of the cabinet. Once in place atop the supports, the PA head is snugged into place atop the shelf, and then held in position by four 1/4" threaded metal rods, through bolted through the cabinet walls to the rear of the PA head, and over the top of the PA head. The ends of the rods are capped with stainless steel acorn nuts installed with Loctite applied to the end of the threaded rod. Thus secured, the PA head isn't going anywhere any time soon.

On the bottom of this shelf are mounted two LED strips and aluminum channels which are illuminated whenever the cabinet is plugged in.

The shelf is set atop a pair of 2" hardwood cross members, which are set into two notched side rails, through bolted to the sides of the cabinet. Getting this shelf to come out level in all directions was one of the hardest things of the whole project. It took the two of us, holding and leveling the shelf, to get it in place, following which I marked the side rail locating with a silver marking pen. Only then could the holes be drilled and the side rails mounted. When it was all set in place, the two rails were level end to end, and the two cross members level side to side - a real accomplishment, as the cabinet was "rather poorly put together" by the manufacturer.

Also seen in the photo is one of my grey work shirts (former office attire) and a pair of my red "water shorts", de rigueur summer work attire in hotter than hell Texas. When we set up at a venue, I work in shorts and T shirt, following which I take a shower, and only then change into formal wear for the performance. Today, shaded thermometer readings in our area were in the mid-100° F range, with humidity up above 80%. However, the winters are nice...

View attachment 2124

Another view of an installed LED strip and channel. This shows the bottom of the front edge of the PA head shelf. The bolts seen here pass through a strip of hardwood that helps keep the PA head in place on the front of the shelf.

View attachment 2123

The four LED strips are all backed up with right angle aluminum channels, both to serve as a mounting for the flimsy mounting clips and the incredibly small screws that the Swedes expect you to use to mount them, and as a reflector to direct the light from the strips onto the equipment and not out of the cabinet. Two are mounted on the bottom of the recording equipment shelf, and two on the bottom of the PA head shelf. The two upper LED strips (front and back) are switched through two toggle switches (mounted front and back), while the two lower ones are on at all times while the cabinet is powered up.

View attachment 2121

The front of my Peavey model XR684F public address head (PA head). It has six channels for microphones, four duplex channels for other equipment, effects like reverb, and all sorts of bells and whistles for injecting and take offs and the like. Other than the standard stuff found on such equipment, there is also an automatic feedback reduction system, very nice for dealing with touchy halls and venues. This is the core element of the system, with all other feeds directed through it and out to the front of house speaker cabinets (FOH), the powered monitors, and the recording equipment. There is also a provision for headphones to monitor the output from the head instead of from FOH.

One thing not present on the XR684F is compression. However, our vocal microphones are all run through a Yamaha sub mixer board that provides compression for the four primary vocal mikes, so we've got that covered.

View attachment 2122

This is an end on view of the PA head's cabinet. I took off the carrying handle, leaving the head more or less clean on each end. It's a snug fit into the cabinet, and the handle would have made it impossible to be contained within any cabinet that I was able to find.

View attachment 2120

The top of the topmost shelf, the recording deck shelf. The two outlet boxes are set through the rear end of the shelf. Each has a single outlet (ungrounded) together with two USB powered outlets. The outlet is for our recording equipment, allowing the feeds from the back of the microphone receivers and other outputs on the equipment to be brought directly into the recording decks. The USB outlets are for powering four LED goosenecks, with the lenses tinted red, like the rest of the lighting. These goosenecks are threaded around the upward tilted sub mixer panel so as to shine on the controls.

The round dot in front of the righthand outlet is a toggle switch for the "trouble light" LED strip, located above the rear of the PA head. This is provided to switch on the light (normally kept off) if a fuse has to be changed or a connection visited. (A separate LED strip, placed above the rear of the microphone receivers, is kept in "on" condition whenever the master power plug is in an outlet.)

View attachment 2119

The bottom of the recording equipment shelf, showing the two outlet boxes for the power outlets on the shelf, the piece of cord connecting them, and (partially obscured) the male plug that connects the upper outlets with the rest of the electrical system in the lower portions of the cabinet. Also seen here (upper righthand corner) is the bottom of the toggle switch for the upper rear LED strip (mounted along the upper edge.

View attachment 2117

The switch on the bottom of the receiver shelf. At the right is seen the end of one of the aluminum angle/LED strip combinations, screwed to the bottom of the shelf. Here, the wiring has been temporarily connected to the switch to test the arrangement of the lighting.

I'm doing the final fitting and adjustments to the cabinet now, and will take photos of the rest once it is all ready to go (minus only some trim). Stay tuned...
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