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Discussion Starter #1
Hello,

What is the best method for selecting the "correct" crossover frequency for stereo music listening. My mains are capable to 35 hz. Dual subs capable to 18hz.

Thanks,
 

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What is the best method for selecting the "correct" crossover frequency for stereo music listening
An octave above the speakers cutoff. So, if your speakers extend to 35Hz, then 80Hz would be correct.

brucek
 

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Thanks brucek,

I've read some say that you should use a crossover that is smoothest around your selected cross-over point. I've been using 60hz but I'll try 80hz, per your suggestion, and see how that sounds. Would speaker measurements at various cross-over points allow me to verify your suggestion? If so, please explain what I should be looking for.

Thanks again.
 

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Would speaker measurements at various cross-over points allow me to verify your suggestion?
Sure. Take a measure of your mains using a 60Hz crossover. Then take a measure of your sub using the same crossover. Then overlay them in REW and see if it looks like it's going to be possible.
Then take a measure of the sub + mains and see if it looks good at the crossover (once you've played with the subs phase control to get the smoothest transition).

See the response below in a perfect world. It shows the sub and then the mains response for a 60Hz crossover in blue. At the crossover they're both 6dB down. If combined the overall response will be as shown in gray. If it could only be as lovely as this.

Repeat above for 80Hz and make a decision..

Crossover 60 sub plus mains.jpg

brucek
 

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Oops, my mistake, I checked my speakers manual and it said -10db 28hz entension (sorry, I was going from memory when I said 35hz). Brucek, would you still recommend trying 60hz and 80hz? 60hz would be an octave above the maximum extension of my speaker, correct?

Also, couldn't one pretty much use any cross-over frequency (e.g. 40hz, 50hz, 60hz, 70hz, 80hz) and simply adjust the gain on the sub to smooth out the frequency response below the cross-over point? For example, if one had things relatively flat at say 80hz (both above and below the cross-over point) and then changed the cross-over point to lets say 50hz, there would likely be an output drop in the frequencies below 50hz vs. those above. Then, by increasing the sub gain, you should be able to get a smooth frequency response similar to what one got at 80hz. Isn't this correct?
 

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Oops, my mistake, I checked my speakers manual and it said -10db 28hz entension (sorry, I was going from memory when I said 35hz). Brucek, would you still recommend trying 60hz and 80hz? 60hz would be an octave above the maximum extension of my speaker, correct?

Also, couldn't one pretty much use any cross-over frequency (e.g. 40hz, 50hz, 60hz, 70hz, 80hz) and simply adjust the gain on the sub to smooth out the frequency response below the cross-over point? For example, if one had things relatively flat at say 80hz (both above and below the cross-over point) and then changed the cross-over point to lets say 50hz, there would likely be an output drop in the frequencies below 50hz vs. those above. Then, by increasing the sub gain, you should be able to get a smooth frequency response similar to what one got at 80hz. Isn't this correct?
There are many things to consider when choosing a crossover, room acoustics play a big part. The main reason most recommend 80Hz is that is where most subs work the best and where the mains usually start to roll off even if they state they go lower it wont be at as high an SPL during low volume listening levels you wont hear/feel the lower frequencies. By using 80Hz the sub can reproduce the lower frequencies with much less effort and thus that is why it is recommended.
I personally have tried 60Hz on my system and always go back to 80Hz as it just sounds smoother, My mains go down to 32Hz as well.
 

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I checked my speakers manual and it said -10db 28hz extension (sorry, I was going from memory when I said 35hz). Brucek, would you still recommend trying 60hz and 80hz? 60hz would be an octave above the maximum extension of my speaker, correct?
No, 60Hz wouldn't be an octave above your extension. The spec of -10dB @28Hz isn't a standard. The extension is usually assumed spec'd at -3dB. Pure marketing when a speaker is spec'd with a -10dB extension. Your original guess of 35Hz would be more realistic of your extension, if the spec at 28Hz is -10dB.
Stick to an 80Hz crossover.

couldn't one pretty much use any cross-over frequency (e.g. 40hz, 50hz, 60hz, 70hz, 80hz) and simply adjust the gain on the sub to smooth out the frequency response below the cross-over point?
No... the mains need to extend down to the crossover with usable signal. If they can't, there will be a loss of signal between the sub and the mains transition.

brucek
 
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