Cross-over Question

I have a Denon 3805, Axiom M60's (Front), Axiom QS8's (Surround) and an Axiom VP-150 (Center). I also have an SV Subwoofer.

Currently, all speakers are set to SMALL and Sub is LFE Only. Cross-over is set at 60 Hz. I set it there because my M60's can play below 40 Hz, but the QS8's only go to 65 Hz. So I compromised...

So my question is, basically, should one set the cross-over to match the front speakers (i.e, as low as the fronts will play, even if the surrounds won't play that low) -- or to match the rear speakers (i.e, only as low as the rear speakers will play, even if I'm giving up some front bass)?

What do you think?

I think your best bet is to set your fronts to large and your center and surrounds to small.

GeneticDrift said:

I think your best bet is to set your fronts to large and your center and surrounds to small.

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I'm with GD on this. And I have the same set up (albeit with an Onkyo receiver)... that's how I'm set up. Large fronts, the rest smalls. Crossover is at 60, except for DVD-A and SACD.

I have all my speakers set to small. Crossover @ 60. Largest drivers are 6.5

Does it matter where the internal crossover on the front speakers is set to? My Polk RTI12's are factory set at 120.

Zarg said:

I have a Denon 3805, Axiom M60's (Front), Axiom QS8's (Surround) and an Axiom VP-150 (Center). I also have an SV Subwoofer.

Currently, all speakers are set to SMALL and Sub is LFE Only. Cross-over is set at 60 Hz. I set it there because my M60's can play below 40 Hz, but the QS8's only go to 65 Hz. So I compromised...

So my question is, basically, should one set the cross-over to match the front speakers (i.e, as low as the fronts will play, even if the surrounds won't play that low) -- or to match the rear speakers (i.e, only as low as the rear speakers will play, even if I'm giving up some front bass)?

What do you think?

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Your sub setting seems incorrect to me. I don't have a 3805, but there should be setting so the sub is accepting a signal all the time, not just for LFEs. It would seem to me that with your current settings you would not be getting a signal at all to any of your speakers for music below 60 Hz or anything else that is not an LFE. If I were in were in your shoes I would keep all my speakers set to small and have the sub setting on the 3805 for sub being active all the time. Your cross over setting at 60 Hz seems to be in the ball park IMO.

Need Advice - Re: Crossover

I have a Pioneer VSX-514 av receiver and a Yamaha NS-P100 HT. What is the best crossover frequency setup will do? The current configuration is:
F(S) C(*) S(*) SW(Yes) Frequency 200Hz.

because I disabled the center and surround ch and I just want to test the stereo sound.

Hope you guy's dont mind me jumping in and asking if i'm setup correctly.I have a rotel rsx1056 with B&W 603s3's(44hz-22KHZ).Right now they are set to small with 60 crossover.Is this correct or would i be better off setting the speakers to large.thanks

A crossover is not a brick wall, there will still be sound both above and below the x-over point going to the respective speakers, though slowly reducting in level to each as you move away from the x-over point. Depending on how steep the slope is, you should expect some sound around 1 octave above for the sub and at least 1 octave below for the other speakers.

For the M60s/QS8s, that's a tough call. Basically, I'd try it on 80Hz and 60Hz and see which sounds better, depending on your taste. If it sounds good to you now, I'd suspect leaving it on 60Hz will be your best bet.

I disagree with setting the mains to large. If your speakers don't get down to the low 20s, which few speakers do, set them to small with the lowest x-over you can select, the way Zarg has done.

Does it matter where the internal crossover on the front speakers is set to? My Polk RTI12's are factory set at 120.

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You can't adjust this.

enrique said:

Hope you guy's dont mind me jumping in and asking if i'm setup correctly.I have a rotel rsx1056 with B&W 603s3's(44hz-22KHZ).Right now they are set to small with 60 crossover.Is this correct or would i be better off setting the speakers to large.thanks

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This would be fine. A speaker should not be set to large unless it is capable of 20hz-20khz +/-3db. Unless of course it is not one's preference.

The risk of damage to the bass drivers is increased as well (when set to large), if the speaker is not capable of very low frequencies. When a speaker is asked to play below it's tuning frequency (most home enclosures are ported (bass reflex) designs), the air in the enclosure and port stop acting like a spring. The air in the enclosure unloads. The woofer will basically flop around with very little control. Power compression also sets in very easily at this point. Thermal and/or mechanical damage could happen fairly easy.

If the speaker is not full range (20hz-20khz +/-3db) set the crossover. If all of the speakers in the system do not have similar response characteristics, set the crossover based on the speaker with the highest frequency of low end response. (I hope tah makes sense).

Example:

Center: 45hz-20khz +/-3db

Mains: 38hz-21khz +/-3db

Surrounds: 58hz-20khz +/-3db

Rear surrounds: 58Hz-20khz +/-3db

In this case the Crossover should be set to 60hz, as the rear surrounds are only good down to 58hz. This is why speaker matching/selection is very important. Sometimes it is one speaker (center?) in a system that requires a crossover point to be higher than desired. Choose your speakers wisely.

In this case the Crossover should be set to 60hz, as the rear surrounds are only good down to 58hz.

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I agree with everything in your post annunaki, except this last satement. You do NOT want to set the x-over at the point at which the speakers naturally start to roll off. What this will most likely do is create a dip or even a gap below the x-over point when the speaker starts to naturally roll off before the x-over does. You have to set the x-over point higher than where the speaker roll off (-3dB) in order to allow it to completely cover the range it is being sent, depending on the x-over.

Most receivers with adjustable x-over only allow 20Hz increments, so assuming 60, 80, 100 and 120Hz with your example, with the speakers that have the highest roll off of -3dB at 58Hz, I would first try the 80Hz x-over and then 100hz. With 100Hz, this may make the sub begin to be easily locallized and one may be able to hear the transition between the mains and the sub with lower midrange and vocals.

My personal speakers are -3dB at 55Hz (all 5 are identical) and I use an 80hz x-over. It works great.

So basically to be a full range speaker they have to go down to 20hz. Would a f/r of 29hz-27khz be consider a full range speaker? If not, it should then be set as small. On the other hand if a center channel has the higher low f/r of 78hz, the x over will be 80hz. Am l in the right track?

Thanks for your input. Now, if I set the x over to either 60hz or 80hz, where should I set the sub x over?

Would'nt it be better to send say 80Hz or 60Hz to the Sub from the receiver then set the sub to 150Hz ? that way your not double filtering ?

sorry.. still trying to understand this stuff

I think we getting the idea but still some doubts. Now, what do you mean by "double rolloff/cut of frequencies and double filtering"?

Hello
For this set up I would try small 80Hz if you have a global x-over
If not you may want to try 60Hz for fronts (but I think that is too low for the 60's.) 80- 90Hz for the VP-150 and 80-90 Hz for the QS-8 I have a review coming up for the M-80, VP-150 and QS-8 complete with LMS frequency response

Mulester7, I'd really apreciate your info. Lets see how it sounds now with the new settings. I finally have all the speaker set to small, receiver x over down to 80hz and the sub x over set to 80hz. Now, I do have the receiver set to deliver lfe to sub and front speakers. How that sound? And again thanks.

Mulester7,

My final setting is: front r/l large (can't use the sm 155 small) the center and sub are set to small. Sub and receiver x over both to 60hz. Perfect match.

puertorro said:

Mulester7,

My final setting is: front r/l large (can't use the sm 155 small) the center and sub are set to small. Sub and receiver x over both to 60hz. Perfect match.

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.....good to hear that, Puertorro.....

J Garcia,

If the speaker is capable to +/-3db at 58hz and is a ported design, it will roll off at -24db/oct. naturally. I do not see how starting the crossover (Most receivers are 12db/oct.) at 60hz will have any real negative effect. If anything, it would be of benefit, as there would be a theoretical 36db/oct. roll off from that point. 12db/oct. from the crossover, and 24db/oct. natural rolloff from ported enclosure. The last time I checked sharper slopes were not bad. Especially if it is only one set of speakers. The subwoofer will make up for any dip in response anyway. And should remain very omni-directional at 60hz.