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[lawrencemueller]

(I'm planning wiring for my LABhorns, figure my nice diagram will be helpful to others as soon as the design checks out as accurate and clear. See attached illustration.)

back story:

I'm having trouble finding information on how to wire my labhorns properly. Let me know if I'm asking this on the wrong part of the forum, or recommended places to search/search terms. I've tried many and came up with little or nothing.

I'm going to run 4 labhorns, 2 cabs per channel on a QSC Powerlight 3 PL380 (8000w). I want to wire this correctly, so I am assuming wiring in parallel (as 4 parallel speakers in a group) and running the amp at 4ohms would be correct for this setup, right?

I bought two-port speakon wall plates for the connections, because I think I should be able to connect one cable between two cabs (to complete the parallel circuit) and the next over to the amp, with jumper wires from the other speakon port.

I think that the one at the "end" should have a one-port speakon plate, because the current runs through the speakers and back out through two wires, but I am wondering - being a newbie - am I correctly seeing that the speakers will be firing towards each other in unison, as opposed to push/pull? (bad for lab12s)

[Nimrod Webber]

Welcome to the Lab/Horn place...

The Lab12 driver is 6 Ohm (nominal)
Four 6 Ohm drivers in parallel result to 1.5 Ohm.
I think your 'all parallel' wiring will overload the amp.

You should connect each two drivers (of one cab) in series.
From the Speakon's (1+) to #1 driver's (+),
from # 1 driver's (–) to #2 driver's (+)
and from #2 driver's (–) to the Speakon's (1-).
The two Speakons should be paralleled like before.

This will bring the impedance of a single cab to 12 Ohms
and when paralleled with a second cab will result to 6 Ohms per (amp.) channel.

I would also recommend installing double Speakon plates on all four Labs.
This will take one thing off your mind when setting up your system…

 

[lawrencemueller]

Thanks for the warm welcome!

So, treating each cabinet as speakers wired in parallel, while wiring the two speakers inside each cabinet in series. Attached to this post is the revised version of the diagram.

I guess there's no wiring configuration that would bring down impedance to 4 ohms?
What of the additional acoustic impedance that I hear about in LABhorns? Is that only half an ohm or so? That would increase impedance to near 7 ohm per channel.

[Al Limberg]

Yes, as with any horn, there is an 'acoustic' impedance to consider.  Just to make it more fun, there is a slight increase in the acoustic impedance each time you couple cabinets,i.e., two cabinets coupled physically will have a higher impedance than the two cabinets placed on opposite sides of the stage, and a cluster of four again will show a slight increase in impedance versus a pair clustered together.  The first four Labs I built have been in steady use since within about a week of the drivers becoming available.  On a regular basis they have been powered by a variety of Yamaha and QSC (and even Tapco!) power amps, probably most often with one Lab per side of  the stage and also per side of the amp.  On a very regular basis I have run a cluster of four at two per side from a QSC RMX5050 in parallel mode and even at one per amp off a bridged Tapco Juice 2500.  In the five or six years in question I have hade one power amp failure (in a 10+ year old Yamaha H7000 that at the time was running one Lab driver per channel.  From all indications, it was an amp channel failure as it also killed the attached 12" driver although this could be a 'chicken or egg' quandary.
Personally I see no point in wiring Labs in series.  It serves only to further enrich the power amp manufacturers, increase the weight of my amp racks, add to the size of my distro and shorten the lifespan of my back.

JMHO,
Al

[Alan Star]

One advantage I can see to wiring the drivers in series is that ... if one driver fails, it automatically shuts off the other driver and so you may save that other one from damage.

Also, I don't see how you would need more amps when driving them in series as you would bridge your amp to run 2 or 3 boxes. You can deliver the same output as if you wired them in parallel and used both channels on your amp.

ie : ... (and please feel free to correct me if i'm not right here but) ...in series, 2 drivers in a lab, in a stack of 4 to 6, will end up being a load of about  18 to 20 ohms, so parallel 2 cabinets and your bridged amp should be seeing around 9 ohms, stack on another cab and your amp will be seeing around 6 ohms(?) in bridged/mono.

[lawrencemueller]

There's a guy here named Josh Billings who said in another post, message #273555:

"I've been running mine 2 boxes per channel off of QSC Powerlight 9.0's. That's 2250w per box, or 1125w per driver. We've done some SERIOUSLY loud shows with this setup, and have only occasionally seen -10 lights on the amps. Usually they get run in blocks of 4 or more (usually 8 ) in this configuration. The only way I've killed them is with bad air seals on the rear chambers."

I want to get the same amp and run 4 labhorns on it, and I want to wire it correctly. It would be nice if I could find out how his is done, but I got no response from PM. However, sounds like this is a perfect example of what I want to do, I think...

Pardon my amateur-ity, we're just trying to set up a homegrown Drum-N-Bass backup-bass rig to take around town with us. Most of the clubs here just need more bass - they've got way too much highs and mids, and about half as much bass to support drum n bass sound. The (only) local sound equipment rental company doesn't carry anything like labhorns, just these mackie subs with built-in amplifiers (suck). I've got many of the necessary skills to build this thing right, but little experience with PA bass speakers - so I had to start asking questions...

[Kevin Pippen]

lawrencemueller wrote on Wed, 13 February 2008 15:18

There's a guy here named Josh Billings who said in another post, message #273555: "I've been running mine 2 boxes per channel off of QSC Powerlight 9.0's. That's 2250w per box, or 1125w per driver. We've done some SERIOUSLY loud shows with this setup, and have only occasionally seen -10 lights on the amps. Usually they get run in blocks of 4 or more (usually 8 ) in this configuration. The only way I've killed them is with bad air seals on the rear chambers."

Hi Lawrence,

I would think that he's running both the drivers and the cabinets in parallel...

Here's another thread that may interest you... Al Limberg makes a good point in regards to the acoustical impedance of the cab...

    http://srforums.prosoundweb.com/index.php/mv/msg/30530/0/0/2 0134/

Here's another thread...

http://srforums.prosoundweb.com/index.php/t/27136/20134/

Kev

[lawrencemueller]

Thanks, Kevin.

I'll (carefully) test this and the series speakers/parallel box configurations and come back with results and corresponding diagrams.

[lawrencemueller]

So, i just wanted to be sure that I have planned my wiring properly. The first diagram that I posted is what I think all-parallel wiring will look like in this configuration.

Does his look like proper parallel wiring???

[Kevin Pippen]

lawrencemueller wrote on Wed, 13 February 2008 15:40

So, i just wanted to be sure that I have planned my wiring properly. The first diagram that I posted is what I think all-parallel wiring will look like in this configuration. Does his look like proper parallel wiring???

Yes,...both the drivers and speakon connectors should be wired + to + and - to -...  

Kev