Shavano Music Online

Speaker Wires and Connectors for stage cabinets

5/03 - Larry Mundy - http://www.colomar.com/Shavano/speaker_wiring.html


NOTE: This is a fairly basic primer on hooking amps and speaker cabinets together with various types of connectors and wiring - what to do, what to avoid and why.  I just figured that if you are starting out, it's better to read some of this stuff here than to learn it the hard way!  Be sure to also read the general information about cables on this site; while it has a broader outlook than just amp-speaker interconnection, it's full of excellent tips applicable to speakers and amps.

Most musical groups have an assortment of amps, microphones, speakers, instruments and assorted whatnot that all have to be hooked together for a performance – so they also have a bunch of wires, cables and connectors that do that.  Often these are jumbled in a big box or case, and during setup everyone pulls out what they want or think they need, and bustle around plugging things into each other.  Most of the time, the result works, everything makes sounds like it’s supposed to, but when it doesn’t, there’s a flurry of wire-tracing and cord-swapping that resembles the pits at an auto race.

This is not an article about keeping your cords and cables in neat little compartmented and labeled boxes (although frankly that can be a good idea) because basically you’re either anal and organized or you’re not, and most musicians are not, or they would have paid more attention in Accounting 101.  But this article is about keeping instrument cables and speaker cables separate, and not using one in place of the other, because that’s just inviting trouble in various forms.  Along the way we’ll talk about alternate (and usually, better) ways to connect amps and speakers.

The “phone plug” – the accepted standard.wpe1.jpg (2020 bytes)

The vast majority of instruments and speakers are interconnected with “phone” plugs and jacks, sometimes called “1/4 inch” connectors because that’s the diameter of the plug shaft.  Every electric guitar, every amp input, most speaker jacks, and all sorts of electronic equipment is designed to be interconnected with these.   They’re called “phone plugs” because they were first used many years ago when phones were manually connected at a central phone-company switch bank, by actual humans.  You would tell an “operator” who you wanted to call, and she would patch your phone to that other phone by physically plugging a wire from “your” jack to “theirs.” 

wpe2.jpg (1909 bytes)The “phone” plug was devised to be big enough to take a little abuse and for its shaft to be grabbed easily by operators and pushed and pulled in and out of jacks all day long, while still being skinny enough that a multitude of jacks could be placed on a big panel and connected to each other, and it worked great.  The same attributes make it the standard today for interconnection of electronic instruments – it’s big enough to grab, pops in and out easily, and the jack doesn’t take up a lot of “faceplate space” on an amplifier input.

Because the phone plug/jack combination came into early and universal use for electronically-amplified instruments, it “migrated” to other uses where it’s not as well suited, namely speaker interconnections.  In the early days of amplified instruments, most “amps” were amp/speaker combinations, just like the “combo amps” that many guitarists use today.  In a combo amp, everything’s in one box and the speaker is usually hard-wired to the output stages of the amp.  You plug the amp into a power source, plug your instrument into the amp with a cord having ” plugs on both ends, and you’re in business.

Then as amplifier power requirements grew, a couple things happened.  Musicians wanted to experiment with different combinations of amps and speakers, and the weight of larger “combo” amps became a problem.  Manufacturers started selling amplifiers and speakers separately, on the "hi-fi" model, with the speaker(s) in one box and the amp (what guitarists now call an “amp head”) in another.  This introduced great advantages in portability, convenience, and speaker placement, but it necessitated another connecting cord or cable from the “amp head” to the speaker cabinet.   Manufacturers had vast quantities of phone jacks lying around from their other products, and players had extra ” cables in their instrument cases, so the “phone plug” became the interconnection standard for instrument amps and speakers as well.  Today it’s difficult to buy a performance-speaker cabinet, other than a high-quality pro-audio cabinet or big subwoofer, that doesn’t have “phone jacks” in it for connection to an amp.  And most guitar-type speaker cabinets have only phone jacks.

At the same time, most performing groups came to realize that guitar-type amps, whether “combo” type or separate heads, did not have the power, proper preamps, or mixing capabilities to run a proper P.A. system, so they began buying and using “public-address” amplifiers that had been designed for more permanent installation in auditoriums, churches, studios, etc.  Because they weren’t designed for convenience and portability, they didn’t have phone jacks for speaker connections, and most of them still don’t, for reasons explained below.  So you ended up with speaker wires stolen from a home stereo or made out of a spool of Radio Shack wire, with whatever connector the amp used on one end, and a phone plug to go into the speaker on the other.

The “phone plug,” wire sizes, and power-handling.

This connector mismatch was actually a Good Thing in many cases because it forced people to have dedicated, separate speaker wires and instrument cables.  The two functions require different types of wire, as explained below, and whatever connector was on the power amp usually provided a more secure connection, capable of conducting a stronger signal.   The problem with a phone plug/jack combination is that it was designed to carry very weak, unamplified or low level signals – either at the phone company or between an electric guitar and an amp.  So while the shaft of a phone plug (which is almost universally, the ground or “-“ connection) contacts the jack along its entire perimeter or “sleeve,” the little tip contacts the spring connection in the jack at only a very small point.  That’s enough to carry the sort of low-level or line-level signals put out by a guitar, keyboard, or preamp/mixer, but at high power levels, it’s not the best design for the much stronger, amplified signals going from your amp to your speakers.  But the biggest drawback is that it lets people use instrument cables as speaker cables and vice-versa, because they all have the same ” plugs on the ends.

Think of the flow of current from your amp to your speakers in terms of water being pumped through pipes.  Your amp puts out whatever “water pressure” it’s capable of – which is an awful lot, with many modern solid-state amps.  That pressure passes through a sort of “pipe joint” (the connector) and then along a pipe (the wire) to another connector, and finally to your speaker.  If you gradually reduced the size of the pipe joints or pipe in a plumbing system, you would restrict the flow of water to the other end more and more, until only a dribble came out.  Speaker wires work the same way.  Smaller-diameter connectors and wires, with smaller-diameter conductors, present greater electrical resistance (expressed in ohms) to the flow of signal, and waste energy in the form of heat.  And that’s amplifier power, which you paid so much for, being wasted.  So speaker wires should have large-diameter conductors to let the signal flow efficiently.

Also, speaker wires flow AC current, meaning that the polarity of the signal going through the wires changes according to the frequency of the signal – that’s what makes the speaker cone move back and forth.  So it stands to reason that both conductors in your speaker wires should be the same size, because they are alternatively carrying the same signal level, many times per second.  Speaker cables should have two identical-gauge insulated wires, big enough that they don’t unnecessarily impede the signal from the amp to the speaker.

Instrument-cable wire is not like that at all.  First, because it carries a relatively weak DC signal, it tends to have a smaller “+” conductor, usually 24 gauge or below (higher numbers mean smaller wire diameters).  And the “-“ conductor isn’t a “wire” at all, but a conductive “shield” that encircles the inner wire for its entire length.   Sometimes the shield is made of a braided-mesh wire, but more often it’s the literal equivalent of thin aluminum foil with a few wires passing through it.  If you have repaired a guitar cable you know what I mean.  Instrument cables need this “shield” to protect the weak signals in the inner wire from being bombarded by radio-frequency interference and stray magnetic fields, which can be strong enough relative to the weak instrument signals to add weird buzzing and interference noises (I have even heard a Stratocaster with a cheesy cable pick up a nearby radio station).   Your “coax” TV cable is built the same way, for the same reasons.  So an instrument cable has two different types of conductors in the wire, at least one of which tend to be pitifully small in diameter for flexibility, and because it only has to carry relatively weak signals.

zipcord.jpg (2453 bytes)rubberjacket.jpg (1733 bytes) Left: "zip-type" and rubber-jacketed speaker cable have two or more identical conductors.

shielded2.jpg (1438 bytes)shielded.jpg (1354 bytes)

 

Right: in a shielded or "coaxial" cable, a foil or wire-mesh outer "shield" surrounds a small central conductor.

What happens when you use an instrument cable as a speaker cable?  At low signal levels, it works OK.  At high power levels, the amp signal passes through a tiny connecting point at the phone jack, then through many feet of tiny wire, then to another tiny connecting point and on to the speaker; a significant amount of power is turned into heat and never reaches the speaker.  It’s a less-extreme example of the little wires inside a toaster, that carry so much current relative to their size that they glow red and toast bread.  The result is reduced speaker-output levels and perhaps actual distortion, as well as a reduction in something called "damping" that is esoteric enough that I will discuss it in a sort of footnote at the end of this article.  Cables can also mimic the components of crossover networks, rolling off low or high frequencies, in extreme lengths and/or small sizes.  In really extreme situations there can be a heat-related failure of the cable or connectors themselves.

What happens when you use a speaker cable as an instrument cable?  The big ol’ wire passes the signals just fine, but the lack of an outer conductive “shield” allows interference signals to enter the wire from fluorescent lights, amp power supplies, and even the AC power cords in the vicinity.  That low-frequency hum or buzz you associate with a certain guitar or cable, is probably the 60-cycle frequency of the alternating current of your AC power (at least, in the U.S.) leaking through unshielded or improperly shielded instrument cable, internal guitar wiring, amplifier wiring, or some combination of the three.   And your amp is dutifully amplifying that interference until it sounds like killer bees have mutated to the size of Buicks.  The low-level signal from an instrument needs to travel inside a grounded metal “shield” from the time it’s created, until it reaches the input stages of the amp.   Guitar “stompboxes” almost universally have metal cases, for just this reason.

So, if all your instrument, amp and speaker equipment is connected with ” jacks and plugs, you need to have two different types of cables – speaker cables and instrument cables – and you need to keep them separate and use them only for their intended purpose.  How do you best do that?  There are a number of ways.

There is no good reason, other than looks, why a speaker wire needs to be a round, black-jacketed cable that can get confused with instrument cables.  Any wire of sufficient size with two stranded conductors and some way of differentiating them by polarity will work, including the same type of “siamesed” two-conductor wire that’s used for plugging lamps into the wall socket (called, for obvious reasons, “lamp cord”, or sometimes "zip cord" because once you start to separate the insulators at the end, you can then just "zip" them apart).  If you make your own speaker wires, you can select wire and connectors separately.  You will probably need to go to an electronics store for connectors, but home centers and hardware stores generally stock two-conductor wire in various sizes, at prices much lower than electronics or music stores will charge you.

Wire is sold primarily by length (duh), by type and by conductor size.  As noted above, you need a larger size than the “24 gauge” that’s in most instrument cables, but how much larger?  That’s a function of power-handling capability and the length of the cable you need.  For short, low-power runs (from the back of a 100-watt amp head into the speaker cabinet it’s resting on, for example), 18-gauge wire is sufficient.   Happily, “lamp cord” is relatively easy to find in this gauge, for pennies a foot (again, lower “gauge” numbers mean larger connectors, and “gauge” is sometimes designated with the “number” symbol, like “#14,” and sometimes with the abbreviation “AWG,” like “16 AWG”).  You can buy clear-jacketed “speaker cable” which looks like lamp cord but with a clear insulator, so that you can see the stranded wire inside, which is usually silver- or copper-colored, but again check the wire gauge since most “speaker wire” is sold for low-power home stereo applications and tends to be small-gauge.  Or you can buy the round, rubber-jacketed type if you make sure it’s got two large conductors, and isn’t the shielded type.  And when you buy the connectors, make sure they accept a solder-joint wire and not just some microscopic little screw that you loop the wire around and tighten.  Screws are unreliable, and properly done, a solder joint is permanent, or at least as permanent as wire connections get.

For higher-power or heavy-bass use, use larger wire.   If you are transmitting a couple hundred watts over a couple dozen feet or more, use #16 or even #14.  If you are transmitting several hundred watts from one end of the stage to the other, as you might hooking up large PA mains and subwoofers, #12 is the way to go.  That’s about the highest practical limit for stranded wire that’s still relatively affordable – but it’s very difficult to attach #12 or #14 wire to the guts of a little phone plug, and that’s kind of like connecting a water main with a little hose fitting anyway.   For higher-power uses, I’d recommend something other than phone plugs, as discussed later.

Since length of the cable also determines its internal resistance, it's good to use the shortest cables you can get away with.  But of course, sometimes you're packed onto a tiny stage in the corner, and sometimes you're spread out over a huge stage, so it's sensible to have big, long cables that will accommodate either situation.   With sufficiently-large wire, this can work OK.  But if you find yourself playing small venues a lot, consider buying or making some shorter speaker wires just for this purpose.  It's not a huge expense, and you won't have to find a place behind your amp to coil up that 40 feet of extra large-diameter cable that's sitting there unused and diminishing your signal quality.

I recommend you make your own speaker wires, at least once, even if you have more money than you know what to do with, because I believe every musician performing with an electronic instrument needs to learn how to solder, and I know most musicians don’t have a clue.  We all know people that, when their cable breaks, they throw it away and get another one rather than fix it.  Then, when it happens at a Sunday gig in a little town, when the music stores would be closed except there aren’t any anyhow, and somehow the spare cables got left at home, there’s a panic.  If you are going to own and maintain electronic equipment, buy a small soldering iron and some rosin-core electrical solder (not acid-core, that’s for plumbers) and learn a little bit about how to use it.  Making your own -plug speaker cables is a great place to start, because it’s simple as dirt.  And throw it in your gear bag so you can repair stuff in the motel room before or after a gig, or behind the stage between sets (throw a flashlight in the gear bag too).

wpe3.jpg (2499 bytes)Here’s how easy it is: disassemble the connector plug – it will have a body or “barrel” of metal or plastic that screws onto the actual plug, and protects the wiring connections.  That has to slide onto the cable first.  If there is an inner plastic insulating sleeve, slide that on next.  Then separate the cable into two wires and strip the ends.  Figure out which one is “+”; that one will attach to the connector (probably the small one in the center) that goes to the tip of the plug.  Attach the stripped wires to whatever connectors are in the plug – sometimes there will be a hole to feed them through, other times a notch to wrap them around – and twist them around the connector or themselves until they’re fairly secure and cut off any excess.  Heat the soldering iron, and when it’s hot, hold it to the wire-connector joint for awhile, until you can touch the tip of a piece of solder to that joint and have it start to melt and flow.  The whole thing needs to be hot enough that the solder flows into the joint, and over the outside of the wires, and everywhere it needs to be, and ends up looking like a shiny silver raindrop.   There is a more detailed article on this site about the fine art of soldering.

After it all cools, the wire should not move relative to the connector; otherwise all you’ve done is soldered the wire to itself (the part of the connector where the wire attaches should not be shiny and slick, either; if it is, a wire brush, sandpaper or an “emery board” will rough it up).  There should be some sort of “strain relief” to keep any pulling force from pulling directly on the solder joint, usually in the form of a couple little “ears” near where the cable enters the body or barrel, that can be bent around the cable jacket with a pair of pliers.   Replace the insulating sleeve, if there is one (if there isn’t, a wrap with electrical tape isn’t a bad idea), screw the body or barrel back onto the jack, and you have a functional speaker cable.  Even better, you know what’s inside it and how to repair it if necessary.

Other types of connectors.

As noted above, PA-type power amps, and particularly high-powered ones, tend not to have ” connectors, because those are insufficient for the wattage they produce.  Most have either “binding post” connectors, “Speakon” connectors, or both.  Here's the output-connector section of a Crown amp:crownback.jpg (3024 bytes)

Top: Speakon connectors.

Bottom: binding-post connectors.

 

A “binding post” connector usually has two ways to connect wiring.  It will have pair of red and black little knurled knobs for each channel.  If you unscrew the knobs, you will find a little hole you can poke a bare wire through; then the knob is tightened on the wire and you have a very secure connection.  No one in his right mind wants to do this at every gig; this is primarily used for “fixed” installations (schools, churches) where the same speakers will be hooked to the same amp and untouched for years.  If you use bare wires and binding posts for a mobile installation, eventually you will tire of the hassle and your speaker wires will remain connected to your amp for months at a time, which is of course very inconvenient for storage and transport.  It’s good to know about this option, though, because if one of your connectors dies just before a gig, and you don't have a spare cable handy, you can always cut off the connector, strip the wire bare and use this method as a temporary fix.

banana.jpg (1607 bytes)In the center of the binding post is a little hole that accepts a “banana plug.”  It’s called this because the connector is a little fatter in the middle than on the end, like a banana.  Each wire of your speaker cable can terminate in a separate banana plug (they’re sold in red and black, so you can keep polarity straight), or you can buy “combo” banana plugs with two prongs on them, since the spacing between binding posts is pretty well standardized among manufacturers.  Banana connectors are also popular in hi-fi receivers and speakers, so you can buy them at audio stores as well as music and electronics outlets.

If you look at a banana plug/jack combination, you see that the conductors make contact along the whole length of the plug, unlike the itty bitty tip of the phone-plug alternative.  That means they can carry much more power with much less resistance.   If your amp has only binding post/banana connectors, you just need a set of wires with banana jacks on one end and whatever connector your speakers require on the other.  And you will never, ever, mix these up with regular guitar cords, for obvious reasons.

But banana plugs and ” phone plugs share one distressing drawback.  Since they slide in easily, they slide out easily too, especially if someone moves the amp or steps on the cable.  Guitarists, you’ve stepped on your own cord and unplugged yourself, probably many times.  The same thing happens with speaker wires, and suddenly there is no sound from the speaker.  A solid-state amp doesn’t care if this happens; a tube amp can burn up if it turned up and suddenly there’s no output load from a speaker.  But the big problem is that your sound just died in mid-song, and then you scurry around looking for the problem (and looking like a total dweeb, onstage).  Sometimes you can spread the banana connector out a little (i.e. make the middle of the banana "fatter") with a tiny screwdriver or a pocketknife, to make it a bit more secure, but the fact remains that it won't take much force to pull it out.

All the objections to other types of connectors are overcome by the “Speakon” connector, which is absolutely the best solution for performance-speaker wiring, and perhaps one of the best inventions of the 20th century in my book.  They are big and strong; they lock together with a slight twist, and they won’t come out – you can probably topple your speaker or drag it around by the cable before a Speakon connector will pop loose.  But push a little button, give it a twist, and it pops right out.  It has very heavy-duty (and hence low-resistance) connections buried deep inside the barrel of the plug, and will handle pretty much any wire size.

speakons.jpg (2730 bytes)So what’s the catch?  They’re expensive.  Speakon connectors are patented and made by a company called “Neutrik” in Lichtenstein, which makes a vast assortment of high-quality electrical connectors.  It’s a high-quality product to begin with, manufactured to very close tolerances, and for those of us in the U.S.A., it’s like European cars or wines – you pay more because someone shipped it halfway around the world.  A Speakon plug or jack is about $5.00 mail order, and more than that at local retailers if you can even find them.  I happen to think that, for the quality of connection you get, it’s worth it, and pretty much mandatory for high-power systems like P.A. subs and mains hooked to megawatt amplifiers.  Also, Speakon jacks and plugs are designed and used for speaker connections, and speaker connections only.   You can’t get them mixed up with other types, which again is good during setup when time is short.

There are also a couple things they don’t tell you when you get a Speakon connector in its little plastic bag with no instructions.  One is that Speakons come in three flavors according to the number of connections – 2, 4, and 8.   I won’t discuss the 8-connector Speakons here, because if you have an application that requires 8 conductors to go to your speakers, you have a very complicated pro system waaaay beyond the scope of this article.  So let’s focus on the 2- and 4-connector models.  If you are running two wires from an amp to a single speaker, all you need is two conductors, right?  Well, usually yes, but I’d recommend you buy only the four-conductor jacks, and here’s why.  The two-conductor plug will fit in either a 2- or 4- conductor jack.  But the 4-conductor plug, which is far more widely used, will fit ONLY in a 4-conductor jack.  The Speakon jacks in many power amps and factory-made speakers are 4-conductor jacks.  If you make a 2-conductor-plug speaker cable, it will plug into these, and into any 2-conductor Speakon jack you might have used on a speaker.  But if you have a 4-conductor-plug cable (which many premade Speakon cables are, even if they only have 2-conductor wire and don’t use the other two contacts) it won’t fit in a 2-conductor plug.  Which means it may plug into your amp fine, but it won’t plug into the 2-conductor Speakon jack you put in your speaker.  If you put Speakon jacks in your speakers, use the 4-pole jacks only.  They cost only pennies more, and then every Speakon cable you have will connect to every Speakon-equipped amp and speaker.

The other thing they don’t tell you is how to wire the plugs.  The 4-pole jacks have little “1+“, “1-“, ”2+” and “2-“ notations on them, but when you disassemble the plugs, there are just four unmarked holes.   Here’s the code: At the “top” of each plug is a little (usually metal) press-tab used to release the connector, and a wider little raised area that ensures the plug only goes into the jack one way.   Looking at the back of the plug when disassembled, there are four places to connect wires, and the “1” wires (often the only ones you’ll use) are on the left and top.  The “+” wire goes to the top hole, nearest the center of the connector.   The “-“ wire goes to the leftmost hole, which is at about 8 o'clock.  As of this writing, Crown Audio has a little how-to file on their site that hopefully clarifies this, at http://www.crownaudio.com/pdf/amps/126986.pdf.

For most applications, you only need to use “1+” and “1-“.  If your power amp has Speakon connections, it’s probably wired that way too.  So are the vast majority of premade Speakon cables.  The “2-“ and “2+” connections are for more exotic applicatons, like when you want to run all 4 connectors from a biamped (subwoofer + mains) system in a single cable.  That’s fancy, but it requires complementary wiring of your speaker cabinets and amp hookups and huge-diameter wiring and violates my fundamental KISS (Keep It Simple, Stupid) principle for stage wiring.  So my advice is, use 4-connector Speakons, and resign yourself that you will only use 2 of the internal connectors, so everything will be “pluggable” to everything else and each cable is carrying only one signal and all your Speakon cables will be interchangeable.

Note: many power amps have a central Speakon connector for running the amp in “mono bridge” mode, and this may require a different wire-connector setup, which probably means a whole separate cable for this purpose.  You need to know what your amp expects if you use a Speakon in bridge mode; your amp manual should spell this out.

Retrofitting cabinets.

Let’s say your mongo power amp has Speakon outputs, but your speakers only have phone jacks – a common situation.   The simplest solution is to get or make a cable that has a Speakon connector on one end, and an ” plug on the other; these are readily available and/or simple to make (the same is true of a banana-plug – to ” cable).  Or, there are Speakon-to-1/4” adaptors available that allow you to use your existing, ” – to – ” speaker cables.  For low-to-medium-power applications, that’s the way to go, so long as your cables are nice and heavy-gauge and all the other stuff we talked about before. 

The only drawback of this situation is that you have a big, heavy Speakon connector from the amp, a big, heavy-gauge cable, and you’re pumping all that wattage through that tiny contact point in the ” jack of your speaker, creating a bottleneck at that point and a “weakest link” situation at your speaker jack – which is buried under a plate, probably, inside your speaker box, and hard to access in mid-performance if anything goes wrong.  Most reputable speaker manufacturers who use only ” jacks in their cabinets will at least give you two of them side-by-side, ostensibly so you can “daisy-chain” speakers together in parallel with additional cables, but also because that gives you a spare jack that probably works, if one of them breaks.

If you’re really particular, or your speaker is handling vast amounts of power, you can retrofit a Speakon jack into your cabinet in addition to the ” jacks that are already there.  In fact, I would not build a new, powerful PA cabinet that didn’t have both types of jacks, because you never know what connection scheme you’ll want or what cables will fail, and the more options, the better.  The PA main speakers in one of my previous articles each have two ’ jacks and two Speakon jacks.  At any given time we only use one of the four, but this setup gives both flexibility and redundancy.  If you will never need to “daisy-chain” speakers to each other, you can get by with just one Speakon jack, because the chances of its failure are very, very slim.

Chances are your existing jack plate or dish (the metal thing your phone jacks are attached to on the rear of the cabinet) is too small to fit another jack, particularly a relatively large one like a Speakon.  Plus, it tends to be difficult to drill holes (and especially big holes) in a thick metal plate, and you will need big holes.  One form of 4-pole Speakon jack, designated NL4MP, fits in a hole which is also the standard panel-jack diameter of a Canon-style “XLR” connector – the three-pronged connector used for various balanced line-level connections such a microphone inputs.  Another type, the NL4MPR, has a larger flange and barrel and fits in a larger hole.   You can buy jack plates with these holes prepunched for one or two connectors, making sure you get the right jack plate for the connector type, and saber-saw another jack-plate hole somewhere in the back of your cabinet.  The “1+” and “1-“ poles of the Speakon jack can then just be wired to the “+” (tip) and “-“ (sleeve) connectors of your existing phone jack(s), and you’re in business.  The NL4MPR, with its larger flange, may even be mountable directly in an appropriate hole bored in the wooden back of a speaker cabinet, but I’ve never tried this.  One other note: the NL4MP and NL4MPR jacks have closely-spaced lugs on the back that will accept either a soldered wire (a hassle) or a female crimp-on, slip-on connector of the type used to connect many speakers, as well as auto wiring and anything else that requires a solid but removable connection – the package may refer to them as “quick-disconnects.”  You can find these pretty much everywhere in ” (.250) wide size, for various wire diameters.  However, the NL4MP series (and other Speakon panel connectors too, I think) use a smaller,  .187 (3/16”) slip-on connector, which is a little harder to find at the hardware store or even Radio Shack.  You want to use the right-sized connector, both for a firm connection and because the wider .250 ones may contact each other and cause a short in the cramped space on the back of a Speakon jack.   If you mail-order some Speakon stuff, order a few of these as well.  And you will need two #4 screws and nuts (four, for the NL4MPR) to secure each jack into the metal plate.   I’d recommend buying “stop” or aircraft-type nuts if you can find them; these are highly resistant to loosening even under vibration and will help keep your jack secure for a long time.

nl4mp.jpg (3640 bytes)nl4mpcup.jpg (1793 bytes)                                   nl4mprcup.jpg (3041 bytes)nl4mpr.jpg (3315 bytes)

NL4MP and terminal cup                                                 NL4MPR and terminal cup

Or, let’s say you don’t want to add another terminal plate to the back of your speaker, but would rather put another, bigger one where your existing terminal plate is, to hold both Speakon and ” jacks all together.  You can get a plate, Parts Express #262-322, that holds two NL4MP’s and two ” jacks.  Or, if you aren’t into daisy-chaining speakers and just want one of each type, Neutrik also makes a ” mono phone jack that fits in the “D”-sized hole you will find on a “dual-D” terminal plate or cup like the one pictured on the left above.  It’s called the NJ3FP6C, and it has another advantage over the standard ” jack: it has a little latch designed to resist removal of the ” plug unless you push the latch.  It only comes in “stereo” (i.e. 3-conductor),  but it works fine with just two wires connected (tip and sleeve).  It’s not a secure as a Speakon, but sure beats a regular ” jack (which was designed for easy plug removal, remember?) when someone steps on a speaker cable by mistake.

          nj3fp6c.jpg (3910 bytes)          qdterm.jpg (3003 bytes)          qdtermins.jpg (1688 bytes)

Left to right: FJ3FP6C locking 1/4" jack, female "quick-disconnect" terminal, fully-insulated quick-disconnect terminals.  I like the fully-insulated type but you will have to search a little to find them in .187 size.

What’s inside.

Okay, you have a secure connection at both ends, and a large-diameter wire between the two.  You’ve optimized your speaker connection.  But if you take the back or jackplate off the speaker cabinet to retrofit a jack, or even remove a woofer to clean out that hive of bees that flew in the speaker port and nested on your tweeter, take a look at the internal cabinet wiring.  Some manufacturers skimp on this, and use wire more suitable for hooking up doorbells or flossing your teeth.  Again, it makes no sense to have a huge cable leading to your speaker, and tiny wiring inside the cabinet.  If your internal wiring looks awfully small, there are two things you can do.  One is, obviously, to replace it with thicker wire.  Another, sometimes easier, method is to simply run another wire right alongside the existing one, at least from the jack or crossover (if there is one) to the woofer(s), which is the path most of the powerful signals take.  For our purposes, two smaller wires equal one larger one (i.e. less resistance) and you will not have to disturb your existing wiring.  In fact, your existing wiring remains in place as a template for stringing the new ones alongside it.  Twist the new wire around the old one as you go, and it will be easier to trace what goes where, later.  If your speakers are connected with push-on, quick-disconnect terminals, and you need to crimp two wires into one connector, you will likely need .025-size (1/4”) inch connectors which are pretty universally available (in a pinch, try an auto-parts store).  A “crimping tool” is a help, too.  Combination crimper-stripper tools, which look like big flat pliers full of holes, are fairly cheap at home centers, electronics or hardware stores.  Put that in the gear bag with the soldering iron and solder.

Now you’re getting the best your amp and speaker have to deliver.  The same holds true for other speaker installations such as your home stereo.  Audio stores make tons of money selling large-diameter, “oxygen-free” cables under the “Monster” brand name and others.  This is undoubtedly good stuff, but it’s pricey.  The most important attribute of anything you use for speaker wire is its gauge or diameter, and fat cheap stuff works better than thin expensive stuff every time.  For producing music, fat expensive stuff is generally unnecessary unless you’re making so much money that you can care about a “brand name” on your speaker wire. 

Get in the habit of coiling and storing your cables in a sensible way, that's both easy on the internal wires and connectors, and easy to uncoil during setup.  Basically this means a storage method that avoids sharp bends in the cable.  Little Velcro strips can help keep your coils looking somewhat round, but you will probably need more than one of them around the perimeter of the coil.    If you're handy with a sewing machine or know someone who is, you can make your own cable straps.    Never, ever remove a plug from a jack by pulling on the cable from 3 feet away, and never throw your cables uncoiled into a big, tangled mess in a box - not only because it's a pain to untangle them, but also because the process of untangling can put real stress on cords and connectors.  Treat cables right and they'll reciprocate, for the most part.


NOTE: We do not work on Home or Car Audio. We work only with Pro-Audio applications. We cannot help you with Home or Car Audio questions.

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Footnote: you may have noticed that your shiny new PA amp touts its high "damping factor."  This is a measurement that describes a type of potential "control" over unwanted speaker-cone movement.  A speaker, like any permanent-magnet "motor," acts as a motor when current is applied, moving back and forth, and as a generator creating current when the cone is pushed around.  It's the same motor/generator process utilized in diesel-electric locomotives and those eco-friendly new "hybrid" cars.  No sane person will push a speaker cone in and out just to create a microscopic current, but when a big, heavy speaker cone is driven with a quick, transient sound, it doesn't always stop when the signal does, due to the momentum of the moving cone - a phenomenon known popularly as "over-ring" because on those rare occasions when it's audible, it can have a slight bell-ringing quality to it.  For that brief microsecond when the speaker cone keeps moving with no input signal, it is producing current (i.e. its own "signal") rather than consuming it.  "Damping" or "damping factor" refers to the ability of the amp's output stages to counteract "over-ring" by applying a sort of "electronic brake" to the moving cone.  It's a complex topic electronicaly, but basically effective "damping" is a function of the relative resistance/impedance of the amp and speaker.  The lower the output impedance of the amp, the higher that relative proportion, the product of which is expressed as the claimed "damping factor" of the amp, usually into a standard 8-ohm speaker load.  It's not unusual for a high-quality amp to have a theoretical "damping factor" of 200, 300 or even more.

The problem is (and this long-winded discussion is tacked to the end of this article because) the resistance/impedance of the wiring between the amp and speaker can change the damping factor quite a bit - sometimes by a factor of 10 or more in extreme cases.   All of the resistance between the amp and the speaker counts in the equation, and speaker-wiring resistance both inhibits damping, and is avoidable to some degree by using larger-conductor wire, shorter runs, or both.

How critical is the "damping factor?"  In my experience, not very critical, much of the time.  To begin with, the motion of the speaker cone is already "damped" to a great extent by the resistance of its cone surround and spider, as well as the resistance of the air the speaker is pushing around both in front of its cabinet, and inside the cabinet itself.  Higher-frequency speakers (tweeters, for example) have such low-mass cones or diaphragms (they have to, to vibrate at the frequencies they do) that their susceptibility to over-ring from cone momentum is effectively negligible.  Damping is most important at low frequencies, when the cone excursion or in-and-out movement is greatest, and with heavy-coned speakers, which are of course most likely to be used for low frequencies and high power levels in the first place.  So I'd only be concerned with electrical speaker damping for high-powered, low-frequency amp/speaker combinations.  And these are precisely the amp/speaker combinations that should be connected with large, low-resistance wiring anyhow, because they are transmitting the most powerful signals and are most prone to the sort of heating and resistance described in the main article.  Give powerful amps and heavy bass speakers large-diameter wiring and secure connectors, and the "damping" will take care of itself in the bargain.

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