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Author Topic: Finding trhe perfect x-over point  (Read 9393 times)

AllenDeneau

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Finding trhe perfect x-over point
« on: August 01, 2015, 04:35:28 pm »

I've got a rare weekend to myself and my mind is running wild with questions and one I've begun to really ponder is, what's the best way to find the right x-over point for your subs?

I don't have a SMAART system so I can't use measurement system to determine it. I have factory specs and my ear and I am pretty happy with the x-over points I end up with in various deployments but, is there a quicker, more scientific way?

I have Peavey SP2G's over Peavey SP118's powered by a side of a PLX 3402 per box. My usual setup, if possible, is to have the main sitting right on top of the sub if that'll get the horns over the audience's heads.

Here are the speaker specs.
SP2G -3dB is 65Hz and box tuning frequency is 55Hz
SP118 -3dB is -10dB is 38Hz and box tuning frequency is 36Hz minimum x-over point recommended is 90Hz at 18dB per octave

I've been pretty happy with crossing them over at 80-90Hz by using my ear but shouldn't I be able to sue the info above and maybe the frequency response charts and get it about right?

Thanks to all who chimed in on my other posts about tuning the subs, they have sounded great with good low end, for what they are.

Anyway, I'm always looking to learn more of the "science" of our industry and I think this is certainly something I can improve upon.

Thanks.
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Allen D.
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Keith Broughton

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Re: Finding trhe perfect x-over point
« Reply #1 on: August 01, 2015, 05:41:46 pm »

I've got a rare weekend to myself and my mind is running wild with questions and one I've begun to really ponder is, what's the best way to find the right x-over point for your subs?

I don't have a SMAART system so I can't use measurement system to determine it. I have factory specs and my ear and I am pretty happy with the x-over points I end up with in various deployments but, is there a quicker, more scientific way?

I have Peavey SP2G's over Peavey SP118's powered by a side of a PLX 3402 per box. My usual setup, if possible, is to have the main sitting right on top of the sub if that'll get the horns over the audience's heads.

Here are the speaker specs.
SP2G -3dB is 65Hz and box tuning frequency is 55Hz
SP118 -3dB is -10dB is 38Hz and box tuning frequency is 36Hz minimum x-over point recommended is 90Hz at 18dB per octave

I've been pretty happy with crossing them over at 80-90Hz by using my ear but shouldn't I be able to sue the info above and maybe the frequency response charts and get it about right?

Thanks to all who chimed in on my other posts about tuning the subs, they have sounded great with good low end, for what they are.

Anyway, I'm always looking to learn more of the "science" of our industry and I think this is certainly something I can improve upon.

Thanks.
I would suggest that unless you can get access to a SMAART (or similar) system, tuning by ear is OK.
Looking at specs and trying to determine a x over point can be problematic.
If it sounds good...well...then it sounds good  ;D
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Jeff Bankston

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Re: Finding trhe perfect x-over point
« Reply #2 on: August 01, 2015, 07:47:12 pm »

when ever i have built a new speaker system i look at the factory recomended frequency upper and lower range limits. i use an active crossover and have a seperate amp for the number of different drivers i'm using. i have test music i use. i adjust the crossover point between 2 drivers at a time and i have a couple of sound guy friends come over so they can tell me what there ears like. i have found that the old audiophile crossover point of 130hz to be the best sounding between the woofer and the mid. the mid and the horn always has a sweet spot and it varies with the drivers. i have Radian 2" 850PB drivers with DDS horns i use on everything including my home system. the sweet spot for the horn to a 10" mid is 1960hz , and 1500hz when using the horn with a 12" mid. the crossover points are well within the manufacturers frequency range. if i cross my horns lower the sound becomes harder and not as smooth. if i cross higher lots of music detail becomes vailed. In the 80's John Solicito of JSE Infinate slope loudspeaker fame told me that once you got the drivers in there frequency range the rest was listening and you have several people evaluate the sound. use good undistorted recordings. i tried playing with the crossovers once before we did sound check with the other guys on stage jamming and came up with the same crossover points i had. i have used a lot of different brands of drivers over the years. i have used 12db/oct , 18db/oct and for many years i only use the Ashly 24db/oct crossovers. if you want to use passive crossovers use the same type and slope that you would use for an active to get the same results. also try different polarity on all the drivers while you adjusting the crossovers to see whats best. and its best to do this outside with the speaker on a small platform up off the ground or pavement and in the middle of a yard with no wind. it can be a hassle but you only have to do it once unless you change drivers types and brands.
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Tim Weaver

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AllenDeneau

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Re: Finding trhe perfect x-over point
« Reply #4 on: August 03, 2015, 11:47:53 am »

http://www.prosoundweb.com/article/tuning_without_tools_working_through_a_system_to_get_it_up_to_speed1/

Thanks guys...

Seems general consensus is to use my ears unless I have something like SMAART...

Like I said, I'm pretty happy with my results but I was just wondering if there was a quicker, easier or better way to accomplish this task.

Tim, great article. I've read it a few times in the past and it's always good to revisit. Correct me if I missed it but your article dealt more with matching up pass bands and equalization and how it effects the x-over point, yes? Are you using a measurement tool to set your x-over point?

Keith, I agree that specs are many times problematic, I usually just look at them to give me a general idea of what I want and/or need to do with regard to a starting point. Agreed, if it sounds good, it is good

Jeff, thanks for the detailed description..
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Tim Weaver

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Re: Finding trhe perfect x-over point
« Reply #5 on: August 03, 2015, 02:37:49 pm »


Thanks guys...

Seems general consensus is to use my ears unless I have something like SMAART...

Like I said, I'm pretty happy with my results but I was just wondering if there was a quicker, easier or better way to accomplish this task.

Tim, great article. I've read it a few times in the past and it's always good to revisit. Correct me if I missed it but your article dealt more with matching up pass bands and equalization and how it effects the x-over point, yes? Are you using a measurement tool to set your x-over point?

Keith, I agree that specs are many times problematic, I usually just look at them to give me a general idea of what I want and/or need to do with regard to a starting point. Agreed, if it sounds good, it is good

Jeff, thanks for the detailed description..

Crossover points are usually based on the manufacturers suggestions. Especially the high pass frequencies.

So, pick whatever frequency the manufacturer suggests, then match up the low pass of the sub so that it plays nice. In other words, high pass is fixed and you adjust the low pass to match it.
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AllenDeneau

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Re: Finding trhe perfect x-over point
« Reply #6 on: August 03, 2015, 05:05:32 pm »

Crossover points are usually based on the manufacturers suggestions. Especially the high pass frequencies.

So, pick whatever frequency the manufacturer suggests, then match up the low pass of the sub so that it plays nice. In other words, high pass is fixed and you adjust the low pass to match it.

Understood and agreed. The SP2G has a -3dB down point at 65Hz which is much lower than I need it to go with the SP118 subs. The Sp118 manual states that a "minimum recommended active crossover frequency and slope" is 90Hz at 18dB which I tried and it sounds ok, but 80-85Hz, I think is where I landed, sounds better. I use the -6dB point for the upper corner for the sub and the lower corner for the main. This gives me minimal overlap, per my ears only, and also helps reduce some of the 100Hz mud in the system organically.

It sounds pretty good to me but that's not to say it can't sound better, that's why I was asking if there were other ways I hadn't considered.

I was just wondering if there were other ways to accomplish what I've been doing.
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Tim Weaver

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Re: Finding trhe perfect x-over point
« Reply #7 on: August 03, 2015, 08:54:25 pm »

Not really. Unless you have much bigger and better toys.

I think you are on the right track.
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Jeff Bankston

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Re: Finding trhe perfect x-over point
« Reply #8 on: August 04, 2015, 12:31:22 am »

Understood and agreed. The SP2G has a -3dB down point at 65Hz which is much lower than I need it to go with the SP118 subs. The Sp118 manual states that a "minimum recommended active crossover frequency and slope" is 90Hz at 18dB which I tried and it sounds ok, but 80-85Hz, I think is where I landed, sounds better. I use the -6dB point for the upper corner for the sub and the lower corner for the main. This gives me minimal overlap, per my ears only, and also helps reduce some of the 100Hz mud in the system organically.

It sounds pretty good to me but that's not to say it can't sound better, that's why I was asking if there were other ways I hadn't considered.

I was just wondering if there were other ways to accomplish what I've been doing.
try 130hz. i have tried many different woofer to mids crossover points and 120-140 always sounds best. i dont agree with crossing below 120 on the woofer to mids.
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Tim Weaver

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Re: Finding trhe perfect x-over point
« Reply #9 on: August 04, 2015, 10:24:16 am »


try 130hz. i have tried many different woofer to mids crossover points and 120-140 always sounds best. i dont agree with crossing below 120 on the woofer to mids.

This doesn't make any sense at all.

What if his subs won't play up that high? There really is no right answer for a crossover point. It depends on everything in the system. Not just the low mid driver.
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ProSoundWeb Community

Re: Finding trhe perfect x-over point
« Reply #9 on: August 04, 2015, 10:24:16 am »


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