Axiom Home Page Forums General Discussion Home Theater QS8 owners what is your crossover set at?

ok, thnx, i understand for the most part but im still wondering... when i get my 60's 150 and qs8's i plan to set the 150 and the qs8's to 90hertz (only level my receiver allows) and leave the 60's on "large" (my present yamaha allows for large mains as well as a sub) so that way theoretically my main will get the full range. however when i switch to an hk in the future (probably 435) im wondering if i can still do it this way, or do i have to cross one over at 100hz as bridgman said

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Can one of you please explain why there are two freq response ratings?

Freq Resp +/-3db (Hz ) 95 - 22kHz
Freq Resp +3dB- 9dB (Hz) 65 - 22kHz

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The only numbers that really count are the first ones(+/-3db 95Hz - 22kHz) because at those frequencies the speaker could be either up or down 3db @ 95dB. The second set is a companies way of say "look our speakers trail off but will produce sound at a certain frequency". The QS8 will be down -9db when you get to 65hz. Sure the QS8 will produce sound at 65hz, but if you look at all other numbers:

+/-3db 95Hz - 22kHz
+3dB/-9dB 65Hz - 22kHz
SPL in Room 1w/1m(dB): 95 dB

This should mean that the QS8 can produce a frequency response of 95Hz-22kHz @ 95dB and will produce sound in the 65Hz-22kHz, but the SPL will automatically lower by -9dB at 65Hz(86dB). The only numbers that count are the ones that show the highest SPL over a freq range. The other numbers are just marketing.

The QS8 do sound fantastic, but the freq respone is pretty poor. I haven't performed the comparison with the MA SFX yet, but I think even with the poor freq response of the QS8 the SFX has a lot of competition. With proper bass management the QS8 is a killer. If you use an HK, ICBM, sub setup like mine or can set your crossover 80hz or higher it's a real winner.

In my setup the QS8 is the absolute best sounding surround I've ever heard. Now I just need to setup the SFX and see how they sound.

Any of you folks have a couple of links to where these audio terms are defined as "standards?"

Also looking for a couple of "good" links to articles on how you are supposed to set your crossovers. I've got a hunch that it really doesn't matter that much because if you use the default receiver settings (flat response), the speakers take care of it for you, but I would like to prove myself wrong.

The beauty of the Outlaw ICBM between the processor and amps is that it will work even if you are playing DVD Audio or SACD which normally bypass all of your receiver's internal cross-over settings. With the ICBM you can set the x-over point for your Front (LR), Center, Surround (LR) and Back (mono) channels and you get stereo preouts for 2 subs.

If you have a really big room, then putting a sub under each speaker would approximate full range speakers in each position. But, since low frequencies are much less directional than higher frequencies, you really don't need a sub under each speaker. A properly placed sub will contribute to the 'wall of sound' effect and appear to be coming from the speakers, or if you really hit the sweet spot, it will sound like it's everywhere.

thanks again Legairre,

And I have to agree The QS-8's are great sounding speakers.

>>kk, i read that tutorial but i still dont understand what bridgman was talking about with the hk's as far as low pass filter and LFE

I don't blame you, I barely understand it myself

In a 5.1 system, the .1 channel is also called the LFE (Low Frequency Effects) channel. In a Dolby Digital soundtrack the "rules" for LFE are pretty specific (eg no content over 120 Hz) so you can just route the LFE channel (the .1) to your subwoofer without any worries.

In DTS and other standards, apparently, there is more variation from one recording to the next. I have read of a couple of cases where the .1 channel is actually full range (low and high frequencies) just like the other 5 channels. I guess that is why the LFE channel is usually run through a low pass filter (only letting the bass through) before going to the sub but I don't know for sure.

BTW, when we talk about "bass management" what we're referring to is the crossovers and mixers in the receiver which do things like :

- take signals from mains/surrounds/center and split them into low & high frequencies (if that speaker is set to "small")

- combine the low frequencies from "small" speakers (the 5) with the LFE channel (the .1) and send the result to the subwoofer

- sometimes allow low frequences frim "small" center and surrounds to be routed to "large" mains (eg. if you don't have a sub)

Bass management is built into all AV receivers and is also available in outboard units like the Outlaw box.

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As I recall, the only way to control the x-overs with the Outlaw ICBM for all sources is if you use separates.

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Sorry if I'm late on this one guys, but I just wanted to clarify this statement. You can also use the Outlaw ICBM for all sources if your receiver has pre-outs and main-ins. My NAD T762 has this and that's where I use my ICBM and it works great. Anyway, glad to hear you're enjoying the QS8's.

Hey guys, have any of you tried a third QS8 as a center back? I noticed Axiom sells them either as a pair or as a single speaker. I'm asking because I currently run 7.1 with two center back speakers 4ft apart and because of the 180 degree patern of the QS8 I don't think two would be necessary as center back speakers in a 13x24 room. I currently have direct radiators as my two center backs , but how would a single QS8 work as a center back?

Thanks
Legairre

I have a 5.2 system in my office, haven't set up the big HT system yet, but I ran a 7.2 system in my last place. When I set up the big system again, I think I'll leave it at 5.2. In any case, I don't think there is any 7.1 software, (movies or music) anyway, I don't think the back surrounds add much if your side surrounds are well placed. Bottom line, IMnsHO, if you want to go with a back surround, go with a single center, since the back channels are mono anyway.

Thanks 2x6spds,
Very few movies have descrete back center channel information. Most of the center back info is like you said "mono", but there are good bit of DTS-ES descrete 6.1 movies. Having two center back speakers is recommended for coverage not information, because 7.1 descrete movies don't exist in home theater yet.

I wasn't so much concerned about the mono vs. descrete issue, because I have dual direct radiating center backs now for coverage. What I was trying to find out is, if a QS8 would work well as a back channel speaker. The QS8 has a 180 degree dispersion and would cover a wide area so would one work instead of two. It's been recommended to only use direct radiators as center backs the same way it's recommended that direct radiators be used for side surrounds for DVD-A and SACD. Since the QS8 is a quadrapole design and not a dipole or bipole they seem to work well with DVD-A and SACD. I was wondering if they would also work as a center back and has anyone tried this.

Thanks
Legairre