Speaker Processing Advice

D

Daniel McAllister

Freshman
Oct 4, 2012
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Perhaps it's just too late in the evening to think straight, but I'm struggling to work out the best way to set this up...

3-way system with subs + 15" mid/high bi-amp speakers (with no passive network)

Ignoring the subs for the moment, I'm needing to set this up with a Peavey VSX 48 processor. A little dated and quirky, but should have plenty of processing for the job. The suggested data from the speaker manufacturer is:

80Hz lowpass - (54Hz, Q0.6), (96Hz, Q1.3)
80Hz highpass - (118.5Hz, Q0.6), (66.7Hz, Q1.3)

1.2KHz lowpass - (810Hz, Q0.6), (1.44KHz, Q1.3)
1.2KHz highpass - (1.78KHz, Q0.6), (1.0Khz, Q1.3)

They suggest LR24 filters. Then there's a list of 5 suggested EQ points as well, which is straightforward.

I can't think of a way to do it in quite so much detail. Obviously LR24 filters at 80Hz and 1.2KHz is fine, but the rest of it...? Or is this overly complicating things for the potential gain?!

All thoughts welcomed. In the meantime I may wake up tomorrow and realise it's a stupid question!
 
Re: Speaker Processing Advice

Daniel McAllister said:
Perhaps it's just too late in the evening to think straight, but I'm struggling to work out the best way to set this up...

3-way system with subs + 15" mid/high bi-amp speakers (with no passive network)

Ignoring the subs for the moment, I'm needing to set this up with a Peavey VSX 48 processor. A little dated and quirky, but should have plenty of processing for the job. The suggested data from the speaker manufacturer is:

80Hz lowpass - (54Hz, Q0.6), (96Hz, Q1.3)
80Hz highpass - (118.5Hz, Q0.6), (66.7Hz, Q1.3)

1.2KHz lowpass - (810Hz, Q0.6), (1.44KHz, Q1.3)
1.2KHz highpass - (1.78KHz, Q0.6), (1.0Khz, Q1.3)

They suggest LR24 filters. Then there's a list of 5 suggested EQ points as well, which is straightforward.

I can't think of a way to do it in quite so much detail. Obviously LR24 filters at 80Hz and 1.2KHz is fine, but the rest of it...? Or is this overly complicating things for the potential gain?!

All thoughts welcomed. In the meantime I may wake up tomorrow and realise it's a stupid question!
Click to expand...

If it is the Q and different freq that are confusing you (I'm just taking a guess there), then I would not worry about it.

Put in the LR24 filters at the specified freq to start.

There are different ways to "construct" filters, depending on what is available and how the "math" is done.

BUT REMEMBER-simply entering the values in a DSP may or MAY NOT give you same results as if you sued the actual DSP those numbers came from.

There is A LOT (and a little) varience between different DSPs. Sometimes even DSPs from the same manufacturer with a very similar "series" name.

But the "simple numbers" are a start anyway and better than nothing.
 
Re: Speaker Processing Advice

Your subs will likely be much happier if you include a 30 hz hi pass as well. Are you asking why the EQ points are needed? My experience is to always start with the factory DSP settings, measure with an FFT analyzer in the near field, adjust the DSP as needed. Finally listen to something your familiar with and see if it actually sounds good. It helps to have a reference speaker handy that you already like the sound of for comparison.
 
Re: Speaker Processing Advice

Ivan, I thought you may well be the first to respond! Yes, it's the specification of both sides of the crossover slopes that's confusing me - I'm not really aware of how to accomplish that with any of the common DSP units. Am I missing something?! I take your point about not all DSPs calculating things in the same way anyway, but I figured using the provided settings as close as possible would probably be a decent starting point.


Riley, the subs are powered anyway, and they'll be crossed around 80-100Hz with the tops (and with a HPF). It's more the settings between the low/mid and high drivers on the tops that I'm trying to clarify. There's 5 suggested EQ points separate to the crossover data that I've listed above - I've added those as PEQs on the crossover inputs already.


Even if the simple answer is to just put an LR24 at 80Hz and 1.2KHz and play around by ear from there, I'm still curious as to how you'd accomplish emulating the exact suggested settings on a typical DSP unit.
 
Re: Speaker Processing Advice

Daniel McAllister said:
! Yes, it's the specification of both sides of the crossover slopes that's confusing me - I'm not really aware of how to accomplish that with any of the common DSP units. Am I missing something?!
Click to expand...

It does seem an unusual combination of data points to give if it's only referring to the crossover, could you post a screenprint of that page of the manual or a link to where it might be online please?
 
Re: Speaker Processing Advice

What are the speakers? It will be much easier for someone to make an informed response if they know what you are talking about.

Mac
 
Re: Speaker Processing Advice

David Morison said:
It does seem an unusual combination of data points to give if it's only referring to the crossover, could you post a screenprint of that page of the manual or a link to where it might be online please?
Click to expand...

http://pas-toc.com/pdf/S2response.PDF

PAS FT2.2 speakers


I'm sure people will have comments to make on the choice of speakers, but they'd never been used before and were cheap, very cheap!
 
Re: Speaker Processing Advice

Daniel McAllister said:
http://pas-toc.com/pdf/S2response.PDF

PAS FT2.2 speakers
Click to expand...

Right, so the blurb there says:
The Dividing Filters used in this processor are 24dB/Octave (4 pole) “Linear Phase”. They are a proprietary filter type which is not available in digital processors. The best thing to substitute is 24 dB/Octave (4 pole) “Linkwitz-Riley”.
Click to expand...

So it looks like they're using two different 2nd order filters stacked to create their custom 4th order alignment, presumably because it better matched the requirements of the particular combinations of drivers.
So you wouldn't try to replicate the
80Hz lowpass - (54Hz, Q0.6), (96Hz, Q1.3)
80Hz highpass - (118.5Hz, Q0.6), (66.7Hz, Q1.3)

1.2KHz lowpass - (810Hz, Q0.6), (1.44KHz, Q1.3)
1.2KHz highpass - (1.78KHz, Q0.6), (1.0Khz, Q1.3)
Click to expand...
as well as using a conventional 4th order LR, you'd just use the conventional filter (and tweak as needed if you have access to something like SMAART to get a clearer idea what's going on between the drivers at crossover).
Here's the differentce, PAS in green and LR in red.
PAS proprietary vs LR.png

Hope this helps,
David.
 
Re: Speaker Processing Advice

Daniel McAllister said:
Perhaps it's just too late in the evening to think straight, but I'm struggling to work out the best way to set this up...

3-way system with subs + 15" mid/high bi-amp speakers (with no passive network)

Ignoring the subs for the moment, I'm needing to set this up with a Peavey VSX 48 processor. A little dated and quirky, but should have plenty of processing for the job. The suggested data from the speaker manufacturer is:

80Hz lowpass - (54Hz, Q0.6), (96Hz, Q1.3)
80Hz highpass - (118.5Hz, Q0.6), (66.7Hz, Q1.3)

1.2KHz lowpass - (810Hz, Q0.6), (1.44KHz, Q1.3)
1.2KHz highpass - (1.78KHz, Q0.6), (1.0Khz, Q1.3)

They suggest LR24 filters. Then there's a list of 5 suggested EQ points as well, which is straightforward.

I can't think of a way to do it in quite so much detail. Obviously LR24 filters at 80Hz and 1.2KHz is fine, but the rest of it...? Or is this overly complicating things for the potential gain?!

All thoughts welcomed. In the meantime I may wake up tomorrow and realise it's a stupid question!
Click to expand...

Nah...not stupid.

I can't help much with talking to DSP du jour but I remember filters from 30 years ago when I was designing (analog) crossovers.

Those filter alignments are not LR, which use identical stacked 2 pole Butterworth alignments. Staggering the poles above and below the XO point is typical of a Chebyshev alignment. The Chebyshev alignment plays games by trading increased ripple in the passband before roll-off in exchange for steeper slopes in the cut-off region. I don't think I've ever seen Chebyshev used in crossovers (but what do I know :-) ).

The LR is popular for how the two bandpasses meld together in the crossover region. The phase lead and lag add up to one full rotation to be back in phase again,,, (at least on paper or for listening to steady state tones).

Standard LR alignments are not a bad place to start.

JR
 
Re: Speaker Processing Advice

Thanks everyone - especially David and John for the explanations! DSP all set now (including limiters), so once the amps arrive I'll be ready to take a listen and do some tweaking.

Last question...

From the graph on the manufacturer's link, I'm presuming it's suggesting that the output from the HF section of the crossover should be set about 10db less than the low/mid section..? (the two amplifier voltage gains are matched)
 
Re: Speaker Processing Advice

Daniel McAllister said:
Last question...

From the graph on the manufacturer's link, I'm presuming it's suggesting that the output from the HF section of the crossover should be set about 10db less than the low/mid section..? (the two amplifier voltage gains are matched)
Click to expand...
That could very well be correct. The HF drivers are usually the ones with the highest sensitivity in a cabinet-so they require less drive level to have the same SPL
 
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