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[Alan Star]

Have 2 subs built and am planning to build 2 more and then run all four with 1 crown itech 6000.

The amp delivers 3000watts per side into 4 ohm loads or bridged 6000 watts into 8 ohms.

Just wondering which would be the best way to wire up the 4 lab subs ?

At the moment I have the drivers in each cabinet wired in series so if each driver is 6ohms then that makes each cabinet 12ohms ?

If anyone has any recomendations would be great to hear them.

Thanks.

[Whit Hutchinson]

1.  Why are you running the drivers in series?  (Im sure there is a reason I just dont have the time to research the architecture of this sub).

Given each box is ~12 ohms (not going into specifics of horn loading charactericstcs and ohm load)would equate to:

Bridged on all cabs:  ~3 Ohms which is lower than the manufactures rating and is not worth risking a shutdown in the middle of a performance IMO.  (If it was a MA5002 VZ I would say try it since I have seen them run successfully at that load at near full output for an extended period but I am not familiar with the ITechs.

Stereo (Dual mono 2 per side):  ~1125 Watts per box.  Im not sure how this number falls into your driver specifications but it appears to be the better option given your wiring information.

...my $.02

[Jon McDowell]

I have 8 Labs with the drivers wired in parallel (actually each driver is independent: 1 to 1+/- the other to 2+/- on a Neutrik NL4) and run two cabs per channel on 2 PL6.0's with no problems. If they are paired up or you are using all four together, don't forget the impedance will increase somewhat. Also, the minimum impedance is only reached at about 30Hz and is higher above and below that frequency. If you do a search, you will find more in depth discussion about this by those wiser than myself .

[Alan Star]

Hi Whit, I am running the drivers in series because at the moment I am driving each cabinet with one mackie m1400 and I didnt want to risk overloading the amp. 6ohms + 6ohms in parallel gives an impedence of 3ohms, the mackie amp only goes down to 4ohms in bridged mode.

Interestingly also, each supplier quotes different impedences for this driver ?

Parts Express         - 6ohm
Orange County Speaker - 8ohm
Loudspeaker Plus Inc. - 4ohm

Are there different impedence versions of the driver or have two of these suppiers made a mistake ?

Also, if anyone knows who can ship some to me in Australia for less than $150 USD each (what 'parts express' and 'loudspeaker plus' have quoted me) that would be great. I am sure they would only cost $50 each by USPS ?

[Alan Star]

Well I've found someone to ship me drivers at $50 each (shipping only) Chris
Martin Sound Products.

So thats a bit better than parts express $150 each.

So still got to figure wiring option, funny thing with this crown amp is it puts 6000 watts bridged into 8ohms but only 5000 into 4ohms, usually its the other way round right, the lower the impedence the more power the amp delivers ?

http://www.crownaudio.com/amp_htm/itech.htm

New technology  

[Clive Milne]

Hi Al,
  It's been a while since I last looked at the info, but I believe that the impedance stated is a minimum value, from memory I believe Tom Danly suggested that for all intents and purposes you could consider it to be an 8 ohm box.
   The qualifier here is that the impedance value changes depending on how it is stacked....  bizarre as it might sound, the impedance of an individual box is HIGHLY dependent on how it's placed.  A cabinet on it's own is 3 - 4 ohms, if you provide an accoustic boundry for the horn exit such as firing it into a corner (or using it in a stack of four) its impedance will rise to more like 8 ohms, and it's power handling will double. This is a function of the sub actually starting to work like a proper horn, ie) as much power is being dissipated as accoustic energy as there is being dissipated as heat.
  As for wiring, I hadn't really thought about wiring them in series but it could be smart for one simple reason.  If one of the voice coils burns out and goes open circuit, it will automatically shut down the other driver which being unloaded, would otherwise tear itself to pieces operating on it's own.
Caveat: if one of the voice coils were to short circuit, the amp would instantly fry the other driver as well.
  I don't know, but gut feeling tells me that series wiring is more driver freindly, and better for minimising cable impedance losses.

 btw) did you end up selling the Mackies, or are you keeping them for the DR300's?

Cheers,
     ~C

[Alan Star]

hi clive, i've still got the sa1521's, had the woofers repaired, I thought they did a good job but one blew again the other day and I am sure it wasn't being pushed too hard, it was running on hi pass too, speaker repair guy said the coil was burnt and wouldnt repair it under warranty, ... so he is fixing that one but now I am too scared to use them in case it just goes again. Shame, I loved those speakers... dr300's, i know they probably go louder but how would they compare to the mackies in terms of sound quality ? I don't care what anyone says, sa1521's were a really nice sounding pair of speakers, at least thats what everyone on the dance floor thought and kept telling me all the time and thats what i thought too. Also you need 2 amps to run a pair of dr300's and I am not sure if I am up for building them, pretty complex woodwork. Hmmm, what to do ?

edit: hi clive I just realized you were talking about the mackie amps i thought you were talking about the speakers, i still have the 2 m1400's as well as the zpe800, i sold the qsc and am kinda wondering why i did ?

[Antone Atmarama Bajor]

     Sounds like your letting your amp clip a lot of you're burning your coils up Alan.

Antone-

[Alan Star]

Hi, thanks Antone but what i dont get is the sa1521's have built in limiters, in three years I had them I never burnt the coils out, the woofers eventually died because of continuous overdrive, but they werent burnt out, just worn out. Now the speaker repair guy is telling me this one that he repaired for me had a burnt voice coil, I only had it back like a month or so, I can't decide if he is just saying that so that he doesn't have to repair it under warranty ?

The original woofers in those boxers were 16ohm, the ones that he sent back to me had 8ohm voice coils in, do you think this may make a difference ? Would the amp and limiter in the back of the sa1521 cope as well with an 8ohm speaker as it would with a 16ohm speaker that it was designed to run with ?