How to extend installed speaker cables that are too short?

[mjl5007]

Lately I've been doing a lot of work tidying and improving things in our tech booth, which a lot of the time involves rolling the 4-poster rack that has most of our equipment in it out away from the wall so I can get behind it. The power amplifiers for our house speakers are in the bottom of this rack, and the speaker cables run into a hole in the wall directly behind the rack. Unfortunately, there is only about 4 or 5 feet of speaker cable sticking out of the wall, and I can barely get the rack out far enough to squeeze behind it without pulling the speaker cables taut and, occasionally, having the speaker cables pull out of their binding post connections on the back of the amps. So, I'd like to do something to:

A) extend the cables a bit longer so that I can pull the rack all the way out and have plenty of room to get behind it, without pulling the cables taut and risking them getting disconnected
B) the power amps have Speak-On output connections as well as the binding posts, so if possible I'd like to connect the wires using Speak-On connectors since they're locking, thereby further reducing the risk that the cables can get accidentally unplugged.

I'm sure I could buy Speak-On connectors to wire onto the bare ends of the speaker cables, but I'm not sure how to go about extending the cables themselves. One option I thought might work would be to put in a wall plate with female Speak-On jacks and wire the speaker wires to the back, and then just get some 6'-10' Speak-On cables to go from the amps to the wall jacks. I could also do something similar but use 1/4" jacks in the wall, and asymmetric cables between the amps and wall, with Speak-On on one end and 1/4" on the other, but then I lose the locking function of the Speak-On connectors at the wall (which could be a good or a bad thing; maybe it would be better to have the connectors at the wall able to pull out if someone pulls the rack too far, or trips/catches one of the speaker cables and yanks on it, to provide some strain relief?)

I'm sure there are all kinds of other ways to accomplish this goal, so I'm all ears to whatever you folks would suggest.

Thanks!

[cmchamp]

You can also purchase cable-mount female, however, I would be more apt to use the option you mention.
Wall mount an electrical box(s) for the size face plate you need, remembering that you can use an NL4 (4 post) or NL8 (8 post) jack/plug as an option to having a lot of jacks/plugs on the wall. Labeling 1 or two jacks leaves less room for error.
One comment, you should never be running cables of any sort where traffic could possibly trip and pull, that's a safety hazard.

So, here's my recommendation:
1: Wall boxes/jacks with locking style connectors that are labeled.
2: mount/route cables along the wall, or bottom of the work table, etc. with some sort of bungie/spring extending strain relief so that slack is off the floor, but you can move the rack safely without pulling/straining the connectors.

[mjl5007]

Thanks for the quick response!

I just took a look at the literature for our amps (2 x QSC RMX 2450, 1 x QSC RMX 1850), and it turns out that one of the Speakon outputs is an NL4 with Ch. 1 on +1/-1, and Ch. 2 on +2/-2. We are running all of the amps in stereo/2-channel mode, no mono bridge or bi-amping. That means for each amp I could put a single NL4MP jack in a wallplate, wire both speaker wires to the back, and run a single 4-wire cable with NL4FC connectors on each end from the two-channel Speakon output on the amp to the jack in the wallplate, correct?

Regarding the traffic/trip-hazard, we aren't doing that; the rack is usually pushed back in the corner and all cables are behind/under it, so no hazard. It's only when the rack is pulled out that the cables are lying ont he floor and could be tripped over (particularly in the current situation where they're pulled taut and about 2' off the ground, which what I'm trying to remedy).

[Brad Weber]

Another option would be to run the existing cables to a terminal strip in a screw cover wall mount box, then on the other side of the terminal strip tie in whatever length cables you need to the rack. No chance of someone unplugging the cables at the wall plate but they're accessible if needed.

If you use SpeakOn connectors then in the rack you might want to tie wrap the cable to a lacing bar, the rack rail or a tie wrap mount firmly attached to the rack, that way if someone does pull on the cable the stress would be on the cable and tie wrap rather than on the connector or rear panel of the amp.

[cmchamp]

Yes, 4 conductor speaker cable would work.

[Frank DeWitt]

Probably not possible for this install (You mention that the rack is in a corner) but worth thinking about for the future. I finally realized that the back of a audio rack should not be in back! The side should be in back. I turned our rack so one side is against the wall. Now controls AND wiring are easy to get to.

Frank

[Frank DeWitt]

Originally Posted by mjl5007

That means for each amp I could put a single NL4MP jack in a wallplate, wire both speaker wires to the back, and run a single 4-wire cable with NL4FC connectors on each end from the two-channel Speakon output on the amp to the jack in the wallplate, correct?

You may want to keep each speaker on a separate jack. Some day one of your amps will fail. If it is the amp feeding the mains and it fails 20 minutes before the service you will want max versatility in routing another amp or amps to your mains. Ben there, done that. That experence is what lead me to relocate the rack with it's side to the wall a few monts later.

Frank

[mjl5007]

Originally Posted by Frank DeWitt

You may want to keep each speaker on a separate jack. Some day one of your amps will fail. If it is the amp feeding the mains and it fails 20 minutes before the service you will want max versatility in routing another amp or amps to your mains. Ben there, done that. That experence is what lead me to relocate the rack with it's side to the wall a few monts later.

Good point; I'll go with individual jacks/cables for each speaker channel.

For the wallplates, I could buy the pre-made ones from Pro Co (http://www.parts-express.com/pe/show...number=248-148 or similar), but $16+ each? I can buy the NL4MP panel mount jacks for $2 a piece, and the metal plate can't cost more than $1, so that's $10 markup, per plate! I'd rather make them myself and save the money (almost $30 since I'll need 6 jacks total), only problem is I don't know where I'd find wall plates with correctly-sized holes for the panel-mount jacks, or how to attach the jacks to the plates. Maybe I could just buy blank solid plates (metal or the super-cheap off-white nylon ones) and drill the holes myself? What kind of drill... spade bit? Step bit? Anybody else have ideas on how I'd make plates like that myself?

Or, what about a stage floor box, but mounted in the wall instead? Can you get those with empty holes that take standard panel-mount jacks?

[cmchamp]

I've used standard issue plastic or wood blanks, a round hole saw and screw holes - done. I'll have to look at what size I've used.

[mjl5007]

I thought that might work, but feel much better hearing that it worked for you.

According to Neutrik's schematics for the NL4MP panel mount connectors, the round portion of the connector that sticks back through the panel is 24mm (~0.945") in diameter, so a 1" hole should be perfect. Slip the connector in the hole, drill a couple of 3mm mounting holes through the blank plate using the mounting holes in the connector as guides, and add a set of M3 nuts and bolts and it should work out just fine.

[Brad Weber]

Originally Posted by mjl5007

For the wallplates, I could buy the pre-made ones from Pro Co (http://www.parts-express.com/pe/show...number=248-148 or similar), but $16+ each? I can buy the NL4MP panel mount jacks for $2 a piece, and the metal plate can't cost more than $1, so that's $10 markup, per plate!

You work for free? The hardware components are not the major cost on an item like that. Seriously, besides two jacks and a plate you have the labor to order/receive/stock/track the connectors and plates, the labor and equipment to punch the plate, the labor and equipment to mount the connectors and so on. You probably can do it cheaper - if you don't account for the cost of the associated tools and labor.

Originally Posted by mjl5007

I'd rather make them myself and save the money (almost $30 since I'll need 6 jacks total), only problem is I don't know where I'd find wall plates with correctly-sized holes for the panel-mount jacks, or how to attach the jacks to the plates. Maybe I could just buy blank solid plates (metal or the super-cheap off-white nylon ones) and drill the holes myself? What kind of drill... spade bit? Step bit? Anybody else have ideas on how I'd make plates like that myself?

Now you're getting into the time and tools involved. There may also be other costs associated with buying components and putting them together yourself. Here's a wall plate for two NL4MP connectors, http://www.google.com/products/catal...ed=0CDYQ8wIwAA for $1-$2, but with shipping it's more like $7 to $12 and if you bought it and the connectors separately you'd be paying shipping on both rather than for one assembly.

Originally Posted by mjl5007

Or, what about a stage floor box, but mounted in the wall instead? Can you get those with empty holes that take standard panel-mount jacks?

Yes, you can get stage boxes with standard holes and do that, but they're going to cost considerably more than a wall plate.

[mjl5007]

Originally Posted by Brad Weber

You work for free?...

True enough, but in this case yes, I do work for free (being a volunteer and all). But, I'm an engineer and this kind of thing (figuring out all the parts I need, then putting them together to build something) is highly enjoyable to me, so it's a win-win for everyone

Originally Posted by Brad Weber

Here's a wall plate for two NL4MP connectors, http://www.google.com/products/catal...ed=0CDYQ8wIwAA for $1-$2, but with shipping it's more like $7 to $12 and if you bought it and the connectors separately you'd be paying shipping on both rather than for one assembly.

Hmm... what would I mount those to? I gather that they won't mount to a standard 2-gang electrical box, since the screw holes are in the corners and not above and below where the switches/receptacles would be. Those would be ideal if they can be easily mounted to a cheap wall box, because I was already planning to order the cable ends, panel connectors and speaker wire from Parts Express, and adding 3 of those doesn't change the shipping costs.

If not, I'll still plan to DIY my own from blank wall plates.