Focal 10K 515 vs. Peerless 830847 xxls 12

[paulspencer]

A low pass (LP) filter is one that passes low freq but filters out the rest. A plate amp will have a variable low pass to cross over to the mains. The corner frequency is where it begins to filter. So a 2nd order 12db/octave LP will be -3db at its corner frequency, then roll off 12db/octave below that. Say you set such a filter to 40 Hz, the filter will be -3db at 40 Hz, then -15db @ 80 Hz, -27db @ 160 Hz

You could keep the focals in their existing box, with F3 around 40 Hz or so, then use the XLS to fill in the bottom, so set the LP filter at the F3 point of the focals.

Get the pro version of WinISD - pro alpha. It allows you to do filters as well. You should include them in the design. When you try it you will see what I mean. What looks good without filters, will be all wrong when you include them.

 

[Nichol1997]

A low pass (LP) filter is one that passes low freq but filters out the rest. A plate amp will have a variable low pass to cross over to the mains. The corner frequency is where it begins to filter. So a 2nd order 12db/octave LP will be -3db at its corner frequency, then roll off 12db/octave below that. Say you set such a filter to 40 Hz, the filter will be -3db at 40 Hz, then -15db @ 80 Hz, -27db @ 160 Hz

You could keep the focals in their existing box, with F3 around 40 Hz or so, then use the XLS to fill in the bottom, so set the LP filter at the F3 point of the focals.

Get the pro version of WinISD - pro alpha. It allows you to do filters as well. You should include them in the design. When you try it you will see what I mean. What looks good without filters, will be all wrong when you include them.

I understand what you are saying but I need a little clarification. The Peerless has a lowpass filter of -3 dB @ 100 Hz, -27 dB @ 200 Hz, -51 dB @400 Hz, -75 dB @800 Hz, and -99dB @1600 Hz. The frequency response of the Peerless supplied by the manufacturer has a small dip around 550 Hz and does'nt start rolling off until 2000 Hz.

So, why should I be worried about the summation of the electrical filter and the natural frequency rolloff of the driver? At 1600 Hz the level that the speaker is playing at is down 99 decibels, I won't be able to hear it at this level.

Here is a link to see the frequency response of the Peerless:
http://www.madisound.com/pdf/peerless/830847.pdf

 

[paulspencer]

I understand what you are saying but I need a little clarification. The Peerless has a lowpass filter of -3 dB @ 100 Hz, -27 dB @ 200 Hz, -51 dB @400 Hz, -75 dB @800 Hz, and -99dB @1600 Hz. The frequency response of the Peerless supplied by the manufacturer has a small dip around 550 Hz and does'nt start rolling off until 2000 Hz.

So you have a 4th order with an fc @ 100 Hz

Originally posted by Nichol1997


So, why should I be worried about the summation of the electrical filter and the natural frequency rolloff of the driver? At 1600 Hz the level that the speaker is playing at is down 99 decibels, I won't be able to hear it at this level.

You should always consider this as the important thing which determines performance and integration is the sum of both electrical and acoustic slopes. In this case you have a flat response for 4 octaves above the fc, hence the response of the filter will not be altered by the driver response, which is good. In integrating your sub with mains, you need to also consider the electrical and acoustic rolloff, as they should have the same summed fc and slope.

For your mains, what you want is for them to be sealed with an acoustic F3 @ 100 Hz and 2nd order rolloff. You then put a 2nd order highpass (HP) at 100 Hz. With a 4th both mains and sub should then be -6db @ 100 Hz and they will sum perfectly.

If you wanted to put a 4LR (4th order Linkwitz Riley) on the mains, they would need 2 octaves on either side of the fc in which they are flat to get all the advantages possible of the 4LR filter. This is not really practical, as this would mean the mains would need to be flat down to 25 Hz just to be able to cross at 100 Hz!

The easiest integration would be to cross the XLS low at the F6 of the focals and leave it at that.

 

[Nichol1997]

Nichol,

Unless the 2 drivers have the exact same high frequency rolloff, you won't do well using the same same 24dB/octave electrical filter for both.

When you compare crossover topologies, you need to take into account the driver's natural rolloff. That is, you need to compare the acoustic response, which is a combination of the electrical filter's transfer function + driver's natural rolloff.

You are comparing an apple to an orange.
At least get out your textas and paint the orange green.

Looking at the frequency response of the Peerless:
http://www.madisound.com/pdf/peerless/830847.pdf
I should be able to cross it over at 100 Hz, 24 dB/oct without having a problem.

I think that I am giving a fair comparison of the two drivers for the frequencies that I am asking it to play. Can you please explain why I am comparing an apple to an orange given the fact that I am only asking it to play a limited frequency range?

 

[paulspencer]

Can you please explain why I am comparing an apple to an orange given the fact that I am only asking it to play a limited frequency range?

We have already done that one to death. Have a look back over the posts on this thread. In a nutshell: look at that big peak in the response with the XLS in that box. If it were merely that the XLS went deeper, then that's not so bad.

We have talked about a few different issues that aren't directly related to doing a quick comparison, so don't confuse that.

 

[Nichol1997]

We have already done that one to death. Have a look back over the posts on this thread. In a nutshell: look at that big peak in the response with the XLS in that box. If it were merely that the XLS went deeper, then that's not so bad.

We have talked about a few different issues that aren't directly related to doing a quick comparison, so don't confuse that.

Okay, I think I see where I am confused by Tktran303's comment.
He made this comment without first looking at the natural frequency response of either driver. If he had done this then he would have known that the lowpass crossover point of 100 Hz is fine for both drivers.

I assumed that he knew this and was stating that I need to make adjustments to my crossover points before I can compare them.

 

[owdi]

It sounds like you prefer a leaner sound. The peerless has a thicker bottom end which takes your attention away from the mids.

As has been suggested, try stuffing the ports of the peerless subwoofer. Something as quick as rolling up a towel and sticking it in the port will make a huge difference.

Dan