Originally Posted by donottosmeok
Question regarding the OPPO BDP-103's settings, specifically, Crossover.
My OPPO utilizes the analog outs for two-channel audio. I listen with Polk Audio LSi15 speakers, which have an overall frequency response of 22Hz-27kHz, and -3dB limits of 32Hz-26kHz. The speaker's crossover frequencies are 150Hz, 800Hz, and 2.4kHz. Crossover slope for the woofer is 2nd Order LP, drivers are 1st Order HP and 2nd Order LP cascaded, and tweeter is 3rd Order HP. (All that means "not a darn thing" to me lol. All I know is, they all sound really good together.
So...my question is...is there an "optimal"
setting for the OPPO's Crossover, using these particular Polk Audio speakers? Should Crossover be left at the default--80Hz?
The options Setup gives me are: 40-160Hz (in steps of 10Hz), 200Hz, and 250Hz.
I don't know which one's "best"...or even if there is a "best" OPPO crossover frequency for the capabilities of my speakers. As I said, the default sounds great; I just don't know if it's "best." Could I be "missing out" on some of the music? (Yes, dumb question...but I just don't understand why there are so many choices for the Crossover setting!)
You didn't mention whether you have a Subwoofer in your system. If you DON'T, then of course the correct solution is to set Left Front / Right Front to LARGE in the OPPO -- which will disable Crossover processing for them and tell the OPPO to send the entire frequency range to Left Front / Right Front.
If you DO have a Subwoofer connected to the Sub Analog output jack of your 103, then I would suggest you set Left Front / Right Front to SMALL and experiment with Crossover settings of 70Hz, 80Hz, and 90Hz, to see if you can hear a reason to prefer one of those. If you can't hear a reason, 80Hz is a good "one size fits all" choice. (Technically the "reason" here would be how the different Crossover frequencies interact with the "bass response" of your room -- the increase or decrease of bass at different frequencies due to the geometry of your room, position of the speakers, reflection or absorption of bass at the walls, floors, ceiling, and etc.)
The Rule of Thumb is to find the -3dB lower frequency for your speakers and set the Crossover to no lower than TWICE that. In your case, that's 32Hz, and twice that is 64Hz, so 70Hz is the lowest Crossover you should try under the Rule of Thumb. The reason is that the Crossover rolls into effect over a span of about 1 octave (factor of 2 in frequency). So a 70Hz Crossover, for example, would still be sending important amounts of audio to your speakers down to about 35Hz. So you want to select a Crossover which allows the speakers to produce quality audio down through that octave below the Crossover. Meanwhile the Sub is getting all that bass steered via the Crossover, and it is the COMBO of the Sub output and the output of your speakers which determines the bass through that octave (70 Hz down to 35Hz in this example). Below 35Hz the bass getting to the main speakers is attenuated sufficiently that it doesn't really matter if the main speakers are not capable of reproducing it well. Down that low the SUB is doing all the work.
The recommended UPPER limit of 90Hz actually comes from three things. First of all, if the Crossover is sending steered bass up that high in frequency to the Sub, the Sub has to be able to reproduce it. Many Subs naturally roll off above 80Hz. By the way, the Subwoofer may have ITS OWN built-in Crossover, and if so, you want to DISABLE that Crossover (a setting on the Sub itself), or set it to the highest possible frequency choice to get it out of the way as much as possible -- so the high bass output of the Subwoofer is not artificially reduced. You can do this because the OPPO is handling the Crossover processing, so the Sub's Crossover is not also needed.
Second of all, male voices go down to around 100Hz, and if you set the Crossover higher that means some of that will go to the Sub, which is generally not as well suited to reproduce those.
Third of all, the higher the bass frequencies you send to the Sub, the more your ears can pick up that the sound is coming FROM the location of the Subwoofer. I.e., you can locate the sound "in the Subwoofer". Lower bass frequencies are not "localizable" (unless you have the Sub positioned too close to your seating). Lower bass works by "pressurizing" the entire volume of air in the room, setting up "standing waves", and so it appears to come "from all around you". The problem with sending localizable, higher bass frequencies to the Sub is that it screws up stereo imaging. I.e. the sound is coming from the wrong location.
(The internal Crossover frequency specs in the speakers themselves are not relevant to this. Those determine which of the several speaker drivers built into each speaker handle which range of frequencies out of the overall input to the speaker.)
There's another important step here if you are using a Sub, and that's to balance the volume output of the Sub to match the output of Left Front and Right Front. Technically, with any speakers set to SMALL, the Analog Sub output jack needs +15dB boost to match the levels of the main speaker Analog output jacks. Memorizing that exact number, and the reason for it are not important. You just have to check that things are correct to be sure your Sub blends well with the output of the main speakers. You adjust this by using the Volume knob ON THE SUB ITSELF, comparing test tones for Sub output against test tones to the LF/RF speakers.