Crossover and Speaker matching

[centra]

Dear All,

What parameters are to be consider while matching 2 way active cinema crossover with Left , Center , Right cinema speakers selection. ( 5.1 surround)

Regards,
Centra

[wintermute]

Hi Centra, I'm not 100% sure what you mean...

I've read that ideally the same drivers and crossovers should be used for all three front channels to get a seamless sound, and that if possible the rear channels should also be matched for timbre (but that is less less important).

I'm a ludite and still listen to movies/tv with stereo which for me is more than adequate, but I did buy drivers with the thought that if I upgraded to a full surround system I could do so.

I just realised that maybe you are talking about crossing to the sub? Is it a question about getting good integration with the sub and the three front channels?

Tony.

[centra]

Hi Tony

Nice Photos..

What i am talking about Cinema Theater Surround system ,i which 2 way ( Hi / Low) crossover is used for Screen Left ,Right and Center speaker.

I am looking for parameters ( or technical sepcs points) of the crossover and speaker which are important to match with each other.

Best Regards,
Ceni

[rabbitz]

A HT speaker is no different to a music speaker and the crossover would be designed to suit the drivers. For HT you really want the LCR speakers to be the same drivers and crossover.... essentially 3 off the same speaker.

If I understand your question correctly, you have a HT system that has outputs for the LCR speakers and each of those has an active crossover for the high and low pass with a power amplifier for each. So each speaker is connected to the amp with 4 wires..... high pass +ve & -ve, low pass +ve & -ve.

If that's the case and if the active crossover is fixed, it would only be designed to work with the speakers that came with the system. If the active crossover is variable for crossover point, SPL, slopes then other drivers could be used but would still have to be designed the same as any speaker using an active crossover.

[sangram]

Usually the center speaker will have two midwoofers instead of one arranged as a horizontal MTM, so one can expect some of the parameters to be different from the regular MT anyway. The most important things are timbre matching so the sound does not change as it moves across the front stage, and level matching so that it remains fairly constant in volume.

Generally MTMs from the same line may have lower impedance and higher sensitivity than small mains, so some level matching may be required to be done in the electronics. In general timbre matching is easier to do when using speakers from the same manufacturer.

Since you are in a DIY forum, if you are looking to make your own speakers, a lot of advice here centers around not using a horizontal MTM layout due to dispersion issues, specially if the audience is more than one or two people. Do look up some threads pointing you in that direction. Generally, using similar drivers may be a good way to assure timbre matching. Unfortunately the crossovers for MT and MTM are different, and if you lay an MTM on its side vs standing up the results are slightly different too. I don't think there is a plug and play answer to your question.

[rabbitz]

Yes, the horizontal MTM is not the best way to go for the centre speaker and would suggest a TM the same as the LR.

The other option of course is not to use a centre speaker. My viewing is on axis so have deleted the front and rear centres to give me 4.1. I've found this arrangement better tonally and as well as better panning in my room than the 6.1. If viewing off axis then a centre is needed for sure.

[wintermute]

Originally Posted by centra

Hi Tony

Nice Photos..

What i am talking about Cinema Theater Surround system ,i which 2 way ( Hi / Low) crossover is used for Screen Left ,Right and Center speaker.

I am looking for parameters ( or technical sepcs points) of the crossover and speaker which are important to match with each other.

Best Regards,
Ceni

Hi Ceni,

Thanks

Another question, are you looking for information to help you choose some drivers to make the speakers, or do you already have some drivers and want to know the best freq to enter into your active crossover for those drivers?

If you are going fully active then (I think) the thing to look for (ideally) would be speakers that have flat freq response a reasonable way past either side of your crossover freq, and a smooth rolloff once they do start rolling off. This should make it easy to get a clean crossover.

for the tweeter also look at the resonant freq. You want to try and avoid having any meaningful output from the tweeter at the resonant freq. Look at the slopes of your crossover to work it out. The higher the order of the crossover, the closer to the resonant freq you will be able to cross.

Tony.