Loudspeakers Crossover in monitors?

[SteveMcQueen]

Hi all. I have searches around and couldn't find anything. Maybe this is a terribly basic question, but I have some monitors, JBL array series 4890. I am trying to do this without a crossover. I have to make cables for them. On the back I says 1 LF, 3HF. Was wondering there is anyway to make these work full range. And if not, can I put the HF and LF ends of the cable into the same channel of the amp, with banana clips? Thanks

 

[Aman121]

If you do a google search, the first link will be the spec sheet for your speakers. Scroll down and you'll see the 4890.

It looks like they can only be run biamped. Running both highs and lows to one amp channel will simply lower the load impedance and the full range signals will likely blow out your tweeter. Your best bet is to pick up an electronic crossover, and using one crossover channel and one 2 channel amp per speaker, running highs through one channel of the amp and lows from the other channel. So the signal chain is send from mixer to one channel on the crossover and then the high and low outputs from the crossover to seperate amp channels and then the outputs of the high channel to the high input on the speaker and the output of the low channel to the low input on the speaker. Another option you may have is if you are using a digital amp like a crown itech, which can be programmed to act as a crossover, with one channel for highs and one for lows. In this setup, you would forget the electronic crossover and do everything at the amp. You'd still need to run 2 cables to the speaker. The recommended crossover points are on the spec sheet.
Hope this helps some.

 

[SteveMcQueen]

Yea it does. Thanks. Normally we do that. These amps are for the band, and the band will be in a different space for this show, so the amps aren't with are crossover, which we are using for the mains. So I have 3 bi amp speakers and 2 full range. And only 3 2 channel amps, and no extra crossover. I didn't think it could be done without a crossover, but I needed something to keep my hopes alive. Q

My plan now is to use the like larger studio speakers that were just donated that have a TRS in. So no cross over, no amp issues and less expensive cable. Yay. Win win win.

If this setup was not temporary, then I would get more crossovers and amps and cable, but this looks Ike it will just be for this one show, hopefully. We have the band in the gallery that over looks the stage, so problems galore with noise issues(city noise) since its an old building and the space has 3 thin windows fit out to a busy city street, and noise from the stage, since these is a huge window with no glass or anything that overlooks the stage. Yea, nightmares all around.
Thanks

 

[Footer]

It is possible to get a crossover built that would allow you to run this thing full range. Do some digging on ebay, you might be able to get one with the right frequency's. The LF driver rolling off at 500hz is pretty common so it should not be that hard to find.

 

[FMEng]

You might want to tell us what your "studio speakers" are. Taking your description literally, not all speakers in that category will tolerate that kind of use without rapid failure.

 

[Aman121]

It is possible to get a crossover built that would allow you to run this thing full range. Do some digging on ebay, you might be able to get one with the right frequency's. The LF driver rolling off at 500hz is pretty common so it should not be that hard to find.

If your going to do this, take note of power handling of the crossover and impedance of the tweeter and woofer. (all info can be found on the spec sheet)

 

[museav]

It is possible to get a crossover built that would allow you to run this thing full range. Do some digging on ebay, you might be able to get one with the right frequency's. The LF driver rolling off at 500hz is pretty common so it should not be that hard to find.

500Hz would be a rather low crossover point for most two way speakers and does not address all the relevant factors for a crossover such as filter type and slope and as Aman noted, if you are trying to do it with a passive crossover then the power handling and impedance are also important factors.

You might want to check out http://www.jblpro.com/BackOffice/ProductAttachments/DOC_476.pdf which shows JBL's recommended tunings for the 4890. They appear to recommend a 24dB/octave, Linkwitz-Riley crossover at 1kHz for the LF to HF crossover and that the high frequency signal needs to be attenuated by 8dB. Also note the recommended low frequency delay, low frequency high pass filter at 35.8Hz and +6dB shelving filters at 271Hz and 8kHz as well as two other recommended filters centered at 258Hz and 1.51kHz. If you ever want to use those speakers then I suggest separate amp channels for the LF and HF drivers along with a speaker processor that can provide the recommended processing.

You might want to tell us what your "studio speakers" are. Taking your description literally, not all speakers in that category will tolerate that kind of use without rapid failure.

Agreed, they may also be tuned for near field listening and have limited pattern control, thus not necessarily the best in terms of achieving gain before feedback. If they work that's great, but I would not be surprised if they are problematic as they simply are not designed for use as a stage monitor.

 

[TimmyP1955]

I think this is one of those tasks where if you have to ask, you should not try. Too much scope for poor performance and loudspeaker damage.