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Can Low Crossover Damage QS8s?
#120737 12/15/05 05:08 PM
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After two great years with my M60s, I finally got clearance for some QS8s, which I ordered today. (They are the consolation x-mas present my wife offered when she learned how much a 42" plasma costs. Good strategy if anyone's seeking one.) I'm also going to get a receiver to replace my Yamaha RV-1105, which was fine but lacks DPLII and can only crossover all settings at 100. I'll be choosing between an HK (435/635/640) and an Onkyo (703 or thereabouts).

So, what I'm wondering, as I ponder the receiver situation, is can you damage the QS8s if you leave them with a crossover below their range, say at 60? I don't think I'll go much lower than 60.

The answer might sway me between an Onkyo and an HK. The ability to set all speakers individually is very enticing on the HKs, but the Onkyos are definitely more affordable, and if I can get by with a 60 crossover on the QS8s, I could get the Onkyo. (I run my M60s on large with no crossover, b/c I don't like using the sub for music.) At some point in the next year I'll be upgrading my center, either with an Ascend 340c or, if Axiom listens to the buzz, a ported Axiom center that goes down past 90. So I know when I reach that point, I'll want to set the center crossover at 60.

Any thoughts or ideas on how the QS8s will do at 60? Theoretically, can you damage them even if they were set to large? Not that I'd do that, but my understanding is that very little bass gets sent to the surround channels anyway.

Austinbirdman


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Re: Can Low Crossover Damage QS8s?
#120738 12/15/05 05:58 PM
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I don't think you would damage them, but you will probably have a huge sonic hole between the speakers lower limit and the sub's upper cutoff frequency. I'd say if you get a receiver with a global crossover, use 80hz. If you have quadruple crossovers, you can set the 8's to 80-90hz and the 60's to 60hz.

Re: Can Low Crossover Damage QS8s?
#120739 12/15/05 06:15 PM
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No, you won't damage them. If you send a signal lower than the QS8's can reproduce, it simply won't reproduce those lower frequencies. No damage will be done.

I also highly doubt you'll hear any sort of "hole" in the sound. How much below 80Hz data do you really think is being mixed specificly for the surround channels?



Re: Can Low Crossover Damage QS8s?
#120740 12/15/05 06:20 PM
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I agree with Spiff as far as mixes for the surrounds. Although I wonder about SACD/DVD-A.


"That's some catch, that Catch-22." "It's the best there is." M22ti VP150 EP350 QS8 M3Ti
Re: Can Low Crossover Damage QS8s?
#120741 12/15/05 06:39 PM
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I dunno what the numbers really are in practice; but when we all went from Pro Logic to D-D(and DTS) we also went from limited frequency inputs for the surrounds, to full range.

I do know that my M3s out back put out some pretty low stuff when asked to do so.

Check out some other forums; some folks are even using subs in back to augment their surrounds!

......now if Axiom would consider some QS10s with 6.5"s.....

Re: Can Low Crossover Damage QS8s?
#120742 12/15/05 07:05 PM
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Changing the crossover won't make the QS8's go any lower though.

It's very likely that whatever below 80Hz frequencies that are being sent to the surround channels are also being sent to the mains and center channel as well.

So the cure to any preceived "hole" in the sound isn't a individual cross over, it's a surround speaker capable of reproducing lower frequencies.



Re: Can Low Crossover Damage QS8s?
#120743 12/15/05 07:36 PM
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Yup,....that's where a nice set of QS10s with 6.5" drivers in a really Big(or ported!)Box could certainly do the trick!!

Re: Can Low Crossover Damage QS8s?
#120744 12/15/05 07:42 PM
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Thanks for the input. Spiff as always makes sense - but I'm a bit confused as to the crossover on the qs8s. I'll tool around when they come, but shouldn't it be set at 100, since 95 is their low-end cut-off +/-3db?

If that's the case (100), I may have to go with the HK, knowing my goal for a center is 80 or 60 as a crossover.

On the other hand, if I can compromise with 80 all around, the Onkyo will give me more watts per dollar. I'll set the current center, an Energy eXL-C (rated to 60 Hz, which I don't believe), at 80 along with the new QS8s and leave my m60s on large.

Austinbirdman


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Re: Can Low Crossover Damage QS8s?
#120745 12/15/05 07:49 PM
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Thankfully; crossover points don't cause an instantanious mega db per octave fall off.

They fall off gradually enough that you probably won't hear a hole at all if crossing at 80hz.


Besides.....


....that's what most everybody here on the forum crosses their QS8s at anyway!!!

Works for them!!

Re: Can Low Crossover Damage QS8s?
#120746 12/15/05 08:02 PM
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Austinbirdman,

I have an older Onkyo 601 and it powers my M60's, VP 150 and 3 QS8's just fine. I have all speakers set to small and my dual SVS subs crossed at 80.

I have used Onkyo over the years and have been very pleased with their performance. Although one shouldn't buy on warranty coverage alone, as with most units if they last 30 days without problems they are usually "in it for the long haul" but the Onkyo's have a 2 year warranty whereas the H/K's only have 1 year.

Best of luck with your choice..
Rick

Re: Can Low Crossover Damage QS8s?
#120747 12/15/05 08:29 PM
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Set the cross over point in accordance to your mains (as they can go lower than any other speakers you have) I have my cross over set at 60Hz, and all speakers set to small.

You don't need to, nor would you want to set it based on the highest frequency rated speaker (the surround), as you'll be robbing your mains of their duties in those ranges.

Nearly everybody sets their crossover between 60-80Hz. There is a reason for this. 1) At that range you get into the non-directional bass frequencies, so letting your sub handle those areas won't draw attention to itself. and 2) above that number is the upper-bass range, which is both directional, and usually better reproduced by your other speakers. (remember, subwoofers serve a very specific purpose, LFE!)

Don't over think it. Slap some QS8's up on the walls, and play around with the crossover settings. I'd try 40, 60 and 80 and stick with the one you like the sound of best. No harm will come to your speakers, regardless of what you choose.




Re: Can Low Crossover Damage QS8s?
#120748 12/16/05 02:25 AM
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AB,regardless of the crossover flexibility that a particular receiver may offer, there may be little reason to set a crossover lower than 80Hz on any speaker. THX and others found that to be a good compromise, being low enough so that the sub generally can't be easily localized and being high enough to take a significant part of the lowest bass burden off the mains(and the amps driving them)and putting it onto the sub, where it belongs.

Be that as it may, you really don't have to make the choice that you discuss; the Onkyo 703 has individual crossover settings for the different groups of speakers, similar to the provision in the HK models.


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Re: Can Low Crossover Damage QS8s?
#120749 12/16/05 06:58 AM
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In reply to:

the Onkyo 703 has individual crossover settings for the different groups of speakers, similar to the provision in the HK models.



I can confirm that as well, for I almost purchased an Onkyo before deciding on my Pioneer Elite.


Sutter

Re: Can Low Crossover Damage QS8s?
#120750 12/16/05 09:52 PM
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Can I just get a stamp that says "What JohnK said"?

Bren R.

Re: Can Low Crossover Damage QS8s?
#120751 12/18/05 02:20 PM
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Bren!! Holy Crap man, where have you been?!? prison?!? welcome back brother. i was just listening to your cd the other day and thinking that we hadn't seen you in a while.


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Re: Can Low Crossover Damage QS8s?
#120752 12/19/05 12:49 AM
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<<Brett McLaughlin writes in ecoustics.com :

quote:
--------------------------------------------------------------------------------
A final thing to note is you have to be wary of processors that allow you to set different crossover points for different speakers. With the exception of some very high-end processors, you should not use this feature. The vast majority of processors with this "feature" high-pass each speaker's signal at the frequency you specify, and send it to the speaker. This is good. However, to feed the sub, the processor will sum the full-range signals from all the full-range channels and the LFE channel, and then low-pass this signal at the lowest crossover point you set. So, if you have your surround crossover set to 100 Hz and your main crossover set to 40 Hz, there will be a 60-Hz hole in your surround channels' responses. This is not good. THX chose 80 Hz as its bass management crossover point for a reason; trust their research and experimentation.
-------------------------------------------------------------------------------->>

I picked this up on the Outlaw forum. Is this correct?

Re: Can Low Crossover Damage QS8s?
#120753 12/19/05 03:21 AM
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I don't think so, but I'm not certain. My H/K lets you set the sub crossover separately from the others, so as long as that's set high enough (I think) it takes care of the rest. Could be wrong; but there's no way to turn off the feature other than setting everything the same.


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Re: Can Low Crossover Damage QS8s?
#120754 12/19/05 09:01 AM
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>>I picked this up on the Outlaw forum. Is this correct?

I sure hope not, and I really hope it's not true for HK receivers

Maybe we can contact the author for clarification ?


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Re: Can Low Crossover Damage QS8s?
#120755 12/19/05 06:17 PM
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Link to ecoustics article

Sorry I didn't get this earlier.

Re: Can Low Crossover Damage QS8s?
#120756 12/19/05 11:05 PM
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For Outlaw's 990 Pre/pre:

In reply to:

The Model 990 does not take the lowest crossover point and apply it to the summed sub signal as suggested of lower end products in this article. The information is summed and sent in its entirety to the LFE channel.




Maybe it works this way for H/K as well.

Re: Can Low Crossover Damage QS8s?
#120757 12/20/05 02:27 AM
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Apparently even the older HKs(e.g. the 525)didn't have this problem if set up correctly, but a supplement to the manual was issued to explain this. The newer models apparently don't require this precaution; a setting exists for a low-pass on the LFE alone, which doesn't affect low bass redirected from "small" speakers.


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Enjoy the music, not the equipment.


Re: Can Low Crossover Damage QS8s?
#120758 12/20/05 03:03 AM
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You know, that supplement always seemed blindingly obvious to me. Of course you'd want to set the sub high enough to cover everything. Maybe the author missed that bit...

Always remember, even if you read it on the internet, on a "real" site, it could be wrong...


I am the Doctor, and THIS... is my SPOON!
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