Need help setting crossovers


Crossover need help please
Unregistered guest
Understanding that much of this depends on personal preference, I'd appreciate reading what others thnk and, perhaps more importantly, why. Not sure which exactly is important so I've include quite a bit of info below.

Receiver: HK 7200 - capable of setting crossovers for each speaker (20HZ-20KHZ)

Subwoofer: (JBL PB12)
Low pass frequency: continuously variable 50HZ-150HZ
High pass frequency: 150HZ when using speaker level outputs
Frequency response: 25HZ low pass crossover setting

Front/Surrounds: (JBL S36II)
Frequency response: 60HZ-20KHZ
Crossover frequency: 650HZ, 3000HZ

Center: (JBL S-Center)
Frequency response: 75HZ-20KHZ
Crossover frequency: 800HZ, 3200HZ

I currently have the crossovers set at 80HZ for all of the speakers.

Thanks guys!

J. Vigne
Unregistered guest
Where you set the X-over is a matter of personal preference and the way the sub couples to the room. There is, therefore, no single correct answer.
I have my sub set to 40 Hz because, to my ears, I get the best integration of my front speakers with the sub at that point. My front speakers are small bookshelfs that have a roll off below 50 Hz. (They are, technically, down 6 dB one octave lower which means they will respond to a signal as low as 25 Hz though this is mostly noise not a true frequency. Their real world response stops about 35 to 40 Hz.) This also gives me less directionality from the sub than setting the X-over higher.
80 Hz is a hold over from the THX specifications. It is a good starting point but does not have to be set in stone. It's your system and you can set levels where you think they work best. Mostly you need to make sure you have your sub in the best possible place in your room for good bass. Put "subwoofer placement" into a search engine and read a few articles on how to get the best sound out of a sub. After you have determined where the sub should go then you can adjust X-over points until you are happy with the results.
Remember that most subs have a roll off of 6 dB per octave when you use the reciever's X-over. The exact spec for your reciever or processor can be found in your owner's manual. If you place the X-over at 80 Hz you will still have sound coming from the sub up to 200 Hz or so. That gets into the range of male voices that will be reproduced by your front speakers and can muddy up the articulation of your system. Try several types of music and movies to determine where you think the system sounds best, you can always change it if you change your mind.
And most importantly, know that there is a big difference between more bass and good bass.

J. Vigne
Unregistered guest
Also try this material:

Thanks - Follow up
Unregistered guest
Thanks J. Vigne. To go lower, e.g., 60HZ, would be force my bookshelf speakers to produce lowers sounds and my subwoofer to produce higher sounds, correct? Based on my center's capability, I'd have to keep the X-over on that speaker higher.

Is it generally the case that X-overs on center speakers are kept higher because those speakers are intended to producet the higher sounds?

J. Vigne
Unregistered guest
Setting your x-over to 60 Hz at the reciever, not the subwoofer's settings, would let the front speakers produce lower frequencies but the sub would roll off the upper frequencies sooner. The sub would be doing less than if the X-over were set to 80 Hz. Your front three speakers can probably deal with this with no problem. Don't take manufacturer's specs as a true statement of anything, particularly when it comes to speakers. Set your speaker settings to small to keep extreme low frequencies from being directed toward your front speakers. Your front speakers will, with "small" and 60 Hz chosen, be allowed to roll off at their natural rate with only minor attentuation from the reciever's controls. Set your sub's X-over control to its highest setting or if you have a bypass switch set to to bypass the sub X-over completely.
By removing more of the upper frequencies from the sub you will still have plenty of deep bass that will be reproduced but the upper frequencies will be taken down sooner. If there is a 6dB roll off on your X-over to the sub the difference is: 80 Hz the sub will still be producing sounds at 160 Hz and will not be essentially silent until it reaches a -10dB level at somewhere around 270 Hz, which is well within the range of the male voice and will give a sense of directionality to the sub's output. At 60 Hz the sub will be -6dB at 120 Hz and will be down -10dB at somewhere around 180 Hz which is just at the limit of male voices and will limit the sense of directionality from the sub. A steeper roll off in the X-over (check the specs on your equipment in your owner's manual) will change those numbers but will not change the effect you are trying to achieve. You are not needing the reinforcement of the frequencies your main speakers can do well enough by themselves, you want to add in the frequencies that your main speakers simply can't achieve, below about 60 Hz.
I will stop here and tell you that, having sold audio for over 25 years, my tastes in music were not always the same as my clients and I adjusted what I did to please them in all cases. But what I have suggested to you should achieve more articulation of voices and a more open soundstage since the sub is not doing as much work. It should give you very little change in the amount of actual bass you hear with these settings, you have only changed how much upper frequency energy is being sent to the sub. If you feel you have cut the amount of bass response past where you would like to have it you can simply raise the level of your sub by 1 or 2dB, that's why you have those switches on your remote. Listen to a few movies and, if you listen to music over this system, try a few discs and see if you like it. Unless you just absolutely disagree with me on this I would suggest you let this remain your setting for at least a week of listening. If, at the end of that time, you want to go back you will hear what has changed more apparently as your ears will have become accustomed to the "new" sound. After living with more articulation for a week's time you can then judge whether the change has benefited your system. You might want to set these in presets if your reciever allows that function. That way you need only flip a switch to toggle between the two settings.
You may then, if you like what you have heard, try the X-over at 40 Hz.
You didn't ask, but I will add that I set my center speaker down several dB to give less sense of directionality to voices without eliminating the focus of voices in the screen area. I normally start with my center down about 5dB. This is purely an arbitrary number as I adjust my settings for center, sub and surrounds to siut what I want to hear out of any one movie or disc. The controls on my remote allow on the fly changes so I can adjust until I am satisfied with the sound. Since there aren't any real standards that discs are recorded at I don't think I should set and forget. I don't care for the surrounds to always be drawing attention to the fact that I have a surround system and my surrounds are normally set slightly lower than I would set for a client. But I give the client an explanantion of what I have done when I set up their system and I check back to see how they like the results. And it is their system so they are free to set things wherever they feel suits their tastes.

LFE option?
Unregistered guest
Would you suggest I use the LFE option on my sub and manage the x-overs from the receiver?

J. Vigne
Unregistered guest
I don't know how your sub is wired but if the owner's manual suggests this is essentially a bypass mode then the answer is yes. The HK has much better bass management than any reasonably priced subwoofer. Set the X-over on your sub to its highest setting when using this connection.
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