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  1. #1

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    Question The mystery of crossovers and khz

    Hello everyone--

    It's me again...I want to start by saying I think you guys are great and all the posts I have read in recent weeks have helped me to understand and learn a tremendous amount about stereo and theater sound--thank you to everyone who takes the time to share their knowledge, enthusiasm, and advice.

    I just finished setting up my humble system, and have read through the manuals too many times to confess, but of course, I still have questions, especially when it comes to fine-tuning my system so I can get the most out of it...

    I'm running an H/K avr525 with RT55Is as fronts, CSI40 as center, RTI38s as rears and a PSW404 as my sub...all speakers are connected with 12G cable and the sub with a Monster cable that has RCA connectors--my fronts and center are bi-wired--I hope this gives you a good picture of what I'm dealing with. I use this system for watching DVDs and playing CDs. I hope my question is not so silly that I will feel stupid :)

    In the set-up menu for the amp, it is asking me about speaker set-up and crossover--I understand the speaker part (large or small, etc) but I don't really understand the crossover part--they state in the manual that "100" is "normal" or "average" but based on what I spent so far on this system, I can't consider this "average" so I need some help in fine-tuning so I can justify 3 months of salary *LOL* I've played with the numbers a bit but I'm not sure if I'm "tweaking" this properly--I understand that if it sounds good to me then its fine, but I want it to sound its best, and then I can make personal adjustments as I gain experience.

    Thanks again for your time and advice...

  2. #2

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    That 525 is an excellent receiver...

    It lets you set the crossover point for different inputs, including the multichannel inputs, really cool...

    Anyway, the crossover point is the point at which signals will stop being sent to the speakers, from that point down. So, if you set the XO to 100, everything above 100 hz will be sent to the speaker in question, everything below 100 will NOT be sent to the speaker. Obviously, the lower the hz the lower the frequency, the low frequency stuff is of course all the bass...

    What are the options for the XO point?

    So if you have small speaker speakers, you'd set the XO high so that the low stuff is being directed elsewhere, as small speakers are typically not great at producing bass. But if you have large speakers, you'd set it lower. For example, I have the RTi150s and I do all my bass through those, so I set those at the lowest level possible, so that all the signal is being sent to those.

    Hope this helps...
    Main HT
    Magnepan 1.6QR fronts, POlk R15 surrounds, Pioneer SC-25, Parasound Halo A23, Oppo BDP-105, Panasonic TC-P60ZT60, Sony PS3, Apple TV

    Bedroom System
    Polk Blackstone TL3, Polk PSWi225 Wireless Sub, HK 3490 Integrated, Oppo BDP-103, Sharp Aquos 32" TV, Apple TV

    Office Rig
    27" iMac w/Amarra, AudioQuest Dragonfly 1.2, Focal XS Book, Schiit Valhalla, Cypher Labs Theorem 720, Philips Fidelio X1, Sennheiser HD600, HiFiMan HE-500, B&W P7, LG 47LM7600, Sony PS3, Apple TV

  3. #3

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    In general the x/o is the point at which frequencies below this level will have the dB level rolled off going to the "small" speakers or in other words the small speakers won't be as loud below this frequency level.

    This should be set more or less at the same point at which the sub takes over producing frequencies on its high end.

    In looking at the specs for the 404 its x/o can apparently be set in the range of 60 - 160Hz.

    The lower you make the crossovers of both the small speakers and the sub the less directional the sound will be. At 100 hz you will probably still be able to tell where the low bass is coming from i.e. the corner where the sub is, at 80 hz or somewhat below that point you will start losing the perception of where it's coming from.

    For initial testing purposes I would set the sub and the receivers settings at 80 hz assuming they both have that capability and then I would see how it sounds i.e. can you tell were the low bass is coming from or does it seem to come from everywhere.

    Beyond that you can use a series of test tones which there are links to in posts here to test the flatness of the volume that is produced at 100 hz and below. It will show you whether there is a dip between where the speakers leave off and the sub picks up or if there is too much overlap ( a peak ) etc. Additionally it will also show you whether the gain should be turned up or down on the sub to produce a flatter more realistic response across frequenies at 100 hz and below.

  4. #4

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    Welcome to Club Polk and the world of Audio. Yes it can be a bit expensive but you have a great system to begin with. Your speakers are very good choices and will work well with each other.

    Since you describe a 5.1 system I assume you will be doing HT. I will try to describe crossover within this context. The THX Home Theater DVD standard is a crossover point of 80hz, as the others said when watching a disc the audio frequencies above this setting will be sent by the H&K to the correct speaker just set your H&K to Dolby Digital or DTS or THX if the DVD you are playing offers this software. Set subwoofer to On. The frequencies below 80hz will then be sent to your 404 sub instead of the speaker they would otherwise go to. Note that all frequencies on the LFE track ( the .1 in 5.1) will automatically go to the sub. As suggested set sub crossover to 80hz at this point.

    Your speakers spec out to being able to handle frequencies below 80 hz, so you could set your crossover lower and see how you like it. All this falls under the catergory of Bass Management you can do a search here on this topic you can also go to [THX.COM] to get much more info.

    Beyond all this you really need a radio shack SPL meter to calibrate your system and I would recommend a set up disc. There are several available. If you already did this so much the better, if not you will likely notice a big improvement in your DVD viewing experience. If you are going to be doing 5.1 channel music its a bit of different animal as far as bass management. I am not familiar enough with your receiver to really take on your options.

    Again welcome, as you have noticed a wealth of info here. I may have missed a detail but thats the jist of it. Hope I did not confuse you to much.
    Last edited by reeltrouble1; 04-30-2004 at 07:25 PM.
    REEL TIME THEATRE
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    HTS5000


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    Everthing Matters...Tubes Rule...and It's Over until it's Not Over

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