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Bill Fitzmaurice Help me with my subs!
- Thread starter kringle77
- Start date
It's kind of early and Im feeling alittle slow. I can run 1+, 2+ out of channel one of the power amp to 1+, 1- of the cab and then diasy chain for 3200 watts at 4 ohms.
How do I wire the second cable if I want to run from amp channel two to the second cab instead? I really don't want to short something out or have to work on cables at the gig. Thanks in advance!
How do I wire the second cable if I want to run from amp channel two to the second cab instead? I really don't want to short something out or have to work on cables at the gig. Thanks in advance!
You still aren't getting this. You are not using Channel 1 OR Channel 2, you are using BOTH CHANNELS BRIDGED. Read my post again.
I really have no idea what the effects of running one speaker box off of both channels bridged and then another box just off of just channel 2 would be. I don't see any reason why it wouldn't make sound. I also don't see any reason why you would want to do such a thing, and intuitively it seems like it would blow something up eventually. Maybe not.
Best case I guess maybe you would just get half the voltage swing to box 2, and out of phase. Worst case something I'm not thinking of would cause the works to blow up.
With that amp, you cannot be running both speakon plugs from into the amp while in bridged mode. You need to connect the AMP END of one speakon to +1 and +2 in the speakon plug as below from the xti4000 manual:
Then you need to take the other speakon cable and leave it wired normally (+1/-1 to +1/-1) and daisy chain the subs.
Then you need to take the other speakon cable and leave it wired normally (+1/-1 to +1/-1) and daisy chain the subs.
You are correct on the first part. You are not using the Channel 2 output in bridged mode. That is what is messing you up.
No problem. Just be sure and clearly label that end of the Speakon cable that is wired differently. Nothing worse then trying to troubleshoot quickly right before a gig.
I hear ya. I'll bet that Im not the only one out there who has been doing this. I wrongly assumed that the internal dsp would configure the outputs for me.
Anyone have any comments on the new planned pa that I mentioned above?
Thanks again Bardley!
Anyone have any comments on the new planned pa that I mentioned above?
Thanks again Bardley!
This isn't going to turn into a flame war. Let's just say that you don't know how much or little experience I have with sound or gigging. You don't. I was just asking for advice, not jabs. I would welcome any advice that you have since you seem to know what your talking about. How would you you go about setting up a system? I mean it. I want to know.
I do know that most people who have spent the time bothering to research any of this would probably go with a pair of 15" subs with a pair of tops with 12's and horns. Sounds good. Been there. That doesn't even get the sound that we get doing it the wrong way now. With a pair of 12 or 15 tops, on top of 4 1x15 subs, we can get that sound. The three way system is an idea that I wanted to throw around at the suggestion of someone who knows better than 99% of the readers on this forum. Thats why this place is great. You can work through ideas with other guys in the same situations.
So maybe I'm a little grumpy today. Sorry bout that. But seriously, read that post again. Or if not that something else that will help you get a handle on what is actually happening when you bridge a power amp. If you have a understanding of what's actually going on both the wiring details and the reason you were having trouble before will be obvious.
Anyhoo.
Every separate driver, every crossover point, every different amp is an opportunity for phase and frequency response anomalies, as well as a place for something to go wrong in the physical installation. You are talking about building a system with the complexity of an arena line array rig.
Rent a good mid level triamped system for a show sometime and give that a listen. Something with a large format compression driver like the JBL PRX 2x12 or the Yorkville Elite 2x15. Put those on double 18 subs(the Wharfedale boxes are actually pretty OK, and cheap), triamped with something like a dbx Driverack unit. Way more simple, robust and clean sounding than what you are proposing. Just two crossover points(say 100 Hz and 1000 Hz or so) and three amps. You will not lack for clarity or punch, believe me.
The trick is the compression driver, you don't get in to the good stuff until you start to spend a little money, but for a rock band PA this is way cleaner sounding than cone midrange drivers and a 1" horn.
good luck.
Oh, by the way, I know how to bridge an amp but, I was thinking that since you select bridge mode on the crown via dsp controls, I was thinking that it would be done internally without any wiring changes on my part. Im an electrical tech for a power utility and pretty handy with gear. I know that it didn't appear that way though. 
Im re-thinking the new pa. I still want four pairs of light weight 15" subs. I can use a pair as subs and a pair as mids, or mix and match with other gear for different situations.
But, I think that I want to have a pair of horn tops built with JBL 2382a lenses and proper drivers to get down to 500-800hz. They would give me 120 degrees of horizontal dispersion down to 500hz. I could have them stacked vertically on top of each other in one spot, on in a small club and have all the coverage that I needed with no cancellation issues. They could be seperated in a bigger place with a pair of mids. Subs stay in one spot of course. What do you guys think of this?
But, I think that I want to have a pair of horn tops built with JBL 2382a lenses and proper drivers to get down to 500-800hz. They would give me 120 degrees of horizontal dispersion down to 500hz. I could have them stacked vertically on top of each other in one spot, on in a small club and have all the coverage that I needed with no cancellation issues. They could be seperated in a bigger place with a pair of mids. Subs stay in one spot of course. What do you guys think of this?
Correct me if Im wrong about two points.
1)If I was going to put the above mentioned pa in one spot, I could place the subs facing forward next to each other on the floor (100hz), the mids on top of those cross-firing (100-500hz) and the two horns on top of that, stack on top of each other (500hz - 16khz) This should be the proper way to do it in that setting.
2) The proper way to use this setup in a bigger room would be to place the subs together but seperate the mids and tops to each side of the room and face them inward slightly. The mid range drivers are very directional up to 45 degrees so that would be good but, the wide dispersion of the horns would cause some cancellations right?
Thanks guys.
1)If I was going to put the above mentioned pa in one spot, I could place the subs facing forward next to each other on the floor (100hz), the mids on top of those cross-firing (100-500hz) and the two horns on top of that, stack on top of each other (500hz - 16khz) This should be the proper way to do it in that setting.
2) The proper way to use this setup in a bigger room would be to place the subs together but seperate the mids and tops to each side of the room and face them inward slightly. The mid range drivers are very directional up to 45 degrees so that would be good but, the wide dispersion of the horns would cause some cancellations right?
Thanks guys.
Would a pair of horns that go down to 500-800hz with a 60 or 90 degree horizontal dispersion be a better ideal for most clubs?
No, you can't. Subs are subs. Sub woofer, infrasonic loudspeakers, sub-bass reproducing dynamic moving coil drivers, whatever you want to call them. They are not midrange drivers.
I think I know what you are trying to do. You are trying to get that BIG system sound in a smaller format?
I had luck with dual 18" reflex cabs, with a response to the low 30's. Then, full range cabinets. Not mid/hi boxes but full range cabinets. My favourite to my ears was a cabinet, not naming names, with a fifteen inch driver, a six inch driver and a four inch coil, two inch exit HF driver, all horn loaded. The arrangement was 1-on-2, so one full range cabinet to two subs. If I used a box per side, the low end would be four woofers. If I used 4 cabs per side, 16 woofers. Flexible, scalable and had great fidelity. The full range cabinets were tri-amplified and had time and phase corrected.
I prefere a cabinet with 60x40 or 40x40. If I want a larger field, I'll cluster.
Also, try not to bridge amplifiers. I am well aware that amplifiers can bridge, and some work quite well. However, bridging output stages puts a lot of stress on the unit, consumes more power to make power and can, in most circumstances, raise your noise floor and add distortion.
Cheers,
Mick
Thanks alot Mick. Some good info. After talking to LDS and the band guys, we came up with the same thing that you suggested. A pair of 3-ways (15,6.5,horn) with four 1x15 subs. Construction will start in the beginning of january. I can't wait.
From what I've been told, this may fly in the face of conventional wisdom when dealing with mono sub systems. Case in point:
I'm using (2) 8 ohm 18" subs (~300 watts) powered by a budget QSC RMX 1450 amp. If I were to run it in stereo (one side per sub), I'd only be seeing 280 watts per enclosure...less than adequate given the application. Instead, I bridge the amp and daisy-chain the subs which provides ~1400 watts into a 4 ohm load or 700 watts per enclosure. I use the 30 hz filters and run pink noise to establish gain structure / headroom. I've had no discernible increase in either noise or distortion.
In all fairness, I can make no claim as to whether a bridged power amp will suffer from premature wear. I am interested in hearing from others on this issue.
Riis
