Where would you cross these over?

[Red Pill 101]

I recently got the Onkyo sks-ht750 speaker system.
http://www.onkyousa.com/model.cfm?m=...ss=Speaker&p=s

Currently, I have them crossed over at 120hz. I am wondering if this is too high, and would like anyone's advice. I'm thinking more around the 100hz range or so.

Frequency response is 60 Hz–50 kHz

Thanks in advance.

[ZedsDead]

I wouldn't consider myself an expert on this subject, but more often than not I have seen 80 hz recommended.

[crazyBLUE]

Originally Posted by ZedsDead

I wouldn't consider myself an expert on this subject, but more often than not I have seen 80 hz recommended.

+1

[Steve]

I used to have a set of those, and 80 Hz is where I set them.

[ozzman]

Originally Posted by fireman325

I used to have a set of those, and 80 Hz is where I set them.

Exactly

80hrz, all speakers set to small and if this unit has this feature set the bass just to "sub" not " both".

Both meaning the fronts and sub will take care of low HRZ you just want the sub to take care of it

[Yeha-Noha]

Originally Posted by Red Pill 101

I recently got the Onkyo sks-ht750 speaker system...Currently, I have them crossed over at 120hz. I am wondering if this is too high, and would like anyone's advice. I'm thinking more around the 100hz range or so.

Frequency response is 60 Hz–50 kHz

Thanks in advance.

Frequency response stated as 60 Hz - 50 KHz isn't very useful info without specifying the deviations in db within that range. Usually something like 60 Hz - 25 Hz, +/- 3 db is sufficient.

If those speakers are -3 db (f3) at 60 Hz, a crossover set at 80 Hz should do ok. Just keep in mind that speakers don't just cutoff below the crossover point nor do subwoofers simply cutoff above it. They overlap. A gap in that overlap results in an uneven response or even a 'hole' in the over response curve. It's a good practice to allow one octave overlap below and above the crossover point because crossover circuits have slopes that attenuate the frequencies above or below at some specified amount per octave, like -12 db / octave. That means with a 80 Hz crossover point with -12 db/octave slopes, a speaker should be capable of reproducing sound -12 db at 40 Hz, and a subwoofer -12 db at 160 Hz. Some ported speaker designs (or Theile alignments) may cutoff rather steeply below the bass f3 point meaning that it may not reproduce -12 db at 40 Hz so well. Closed box designs (without ports) tend to roll off low frequencies rather smoothly at around 12 db per octave below their f3 point. Thus a closed box speaker with f3 = 60 Hz and Qt = 0.7 should be capable of -12 db at 40 Hz with the crossover set to 80 Hz because in theory it should produce -12 db at 30 Hz.

Keep in mind that when I say it can reproduce -12 db at 30 Hz doesn't mean that speaker could be set to a 60 Hz crossover point. Because -12 db is relative to the volume level set while watching a movie. It just may happen that your speaker, although capable of -12 db at 30 Hz (f12 = 30) at low volume levels, may exceed it's cone excursion limits or voice coil temperature limits after setting the volume too loud. If that speaker's excursion or temperature curve limit crosses the 90 db mark at 30 Hz and the bass volume level during a movie reaches 102 db, you are at the critcal limit for that speaker. It's easy to reach such a level at 30 Hz during a movie that's heavy or loud in low bass content. So you see, just because I have this big tower speaker spec'd at -3 db or (f3) at 35 Hz, doesn't mean I can set it to large and run it full range. In fact, I might just barely get by with a 60 Hz crossover depending on its design including the voice coil temp and cone excursion limits. Subwoofers are designed to operate in this range. It's better to let them handle it.

That's why the common consensus is to use a 80 Hz crossover and set the speaker to small. It keeps most speakers designed for HT use out of trouble (except for those little tiny cubes and other small satellite type speakers found in HTIBs). It also prevents the subwoofer from producing voice content that allows the listener to isolate it from the center channel.

[Red Pill 101]

Thank you everyone for your replies. I lowered the cross over to 80hz on all speakers, and then decreased the subwoofer crossover from about 120hz to around 80hz. Everything sounds much better and more balanced.

Thanks again!

[Fors*]

Originally Posted by rwojtalewicz

Frequency response stated as 60 Hz - 50 KHz isn't very useful info without specifying the deviations in db within that range. Usually something like 60 Hz - 25 Hz, +/- 3 db is sufficient.

If those speakers are -3 db (f3) at 60 Hz, a crossover set at 80 Hz should do ok. Just keep in mind that speakers don't just cutoff below the crossover point nor do subwoofers simply cutoff above it. They overlap. A gap in that overlap results in an uneven response or even a 'hole' in the over response curve. It's a good practice to allow one octave overlap below and above the crossover point because crossover circuits have slopes that attenuate the frequencies above or below at some specified amount per octave, like -12 db / octave. That means with a 80 Hz crossover point with -12 db/octave slopes, a speaker should be capable of reproducing sound -12 db at 40 Hz, and a subwoofer -12 db at 160 Hz. Some ported speaker designs (or Theile alignments) may cutoff rather steeply below the bass f3 point meaning that it may not reproduce -12 db at 40 Hz so well. Closed box designs (without ports) tend to roll off low frequencies rather smoothly at around 12 db per octave below their f3 point. Thus a closed box speaker with f3 = 60 Hz and Qt = 0.7 should be capable of -12 db at 40 Hz with the crossover set to 80 Hz because in theory it should produce -12 db at 30 Hz.

Keep in mind that when I say it can reproduce -12 db at 30 Hz doesn't mean that speaker could be set to a 60 Hz crossover point. Because -12 db is relative to the volume level set while watching a movie. It just may happen that your speaker, although capable of -12 db at 30 Hz (f12 = 30) at low volume levels, may exceed it's cone excursion limits or voice coil temperature limits after setting the volume too loud. If that speaker's excursion or temperature curve limit crosses the 90 db mark at 30 Hz and the bass volume level during a movie reaches 102 db, you are at the critcal limit for that speaker. It's easy to reach such a level at 30 Hz during a movie that's heavy or loud in low bass content. So you see, just because I have this big tower speaker spec'd at -3 db or (f3) at 35 Hz, doesn't mean I can set it to large and run it full range. In fact, I might just barely get by with a 60 Hz crossover depending on its design including the voice coil temp and cone excursion limits. Subwoofers are designed to operate in this range. It's better to let them handle it.

That's why the common consensus is to use a 80 Hz crossover and set the speaker to small. It keeps most speakers designed for HT use out of trouble (except for those little tiny cubes and other small satellite type speakers found in HTIBs). It also prevents the subwoofer from producing voice content that allows the listener to isolate it from the center channel.

Awesome post rwojtalewicz! I am keeping this post for future reference for myself.