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[John Roberts {JR}]

In audio chains the weakest links (for linearity and accuracy) are the start and end point (microphones and loudspeakers). The middle ware is generally far more linear and accurate.

Specifically about DSP, modern path performance is quite good, but look for available manufacturer presets for your particular boxes. That can make a far larger difference than path performance.

JR

[Ivan Beaver]

Hi Gordon-

I think you need to search for some of JR's threads about the reckoning of filter "Q" amongst the various DSP manufacturers.  It also may help to find out who makes the loudspeaker manufacturer's DSP as the filters are likely to be computed the same way.

Otherwise if you just enter the numbers you're not guaranteed to get the same acoustic results.

Here is some of what I have measured in various DSPs and differences

I have seen Qs that are twice or half of other manufacturers (and inbetween that).

I have seen xover freq be close to 1 octave off.

I have seen the gain change based on the Q.  So as you change the Q the gain goes up and down.

I have seen attack times on limiters be very different than what the simply number represents.

I will not mention manufacturers, but some of these are from some of the most highly respected manufacturers.

You MUST measure to get the proper results.

DO NOT assume that the numbers are all the same.

[John Roberts {JR}]

Here is some of what I have measured in various DSPs and differences

I have seen Qs that are twice or half of other manufacturers (and inbetween that).

I have seen xover freq be close to 1 octave off.

I have seen the gain change based on the Q.  So as you change the Q the gain goes up and down.

I have seen attack times on limiters be very different than what the simply number represents.

I will not mention manufacturers, but some of these are from some of the most highly respected manufacturers.

You MUST measure to get the proper results.

DO NOT assume that the numbers are all the same.

Come on Ivan you are scaring the children....

How about telling him what works...?

Use a DSP recommended by your speaker MFR hopefully with presets for your given speakers (that work).

JR

[David Sturzenbecher]

Use a DSP recommended by your speaker MFR hopefully with presets for your given speakers (that work).

The days of having a personal choice what DSP you use for loudspeaker management, are gone (unless of course your boxes have a Fulcrum Acoustics badge on them).  If you want your boxes to sound like the manufacture intended, buy the DSP they tell you to buy.

[John Roberts {JR}]

The days of having a personal choice what DSP you use for loudspeaker management, are gone (unless of course your boxes have a Fulcrum Acoustics badge on them).  If you want your boxes to sound like the manufacture intended, buy the DSP they tell you to buy.

I tried to get AES to standardize definitions but I'm old and tired and they XXXX...

JR

[Frank Koenig]

I tried to get AES to standardize definitions but I'm old and tired and they XXXX...

Hey, that's one good thing about FIR. Coefficients are coefficients -- there's no screwing around. Of course you could specify IIR filters the same way and avoid all the confusion but that's not what happened. I think the underlying problem is that speaker manufacturers have little incentive to make it easy to port settings from one DSP to another and, in fact, have a disincentive if they sell processing boxes. Good evening. --Frank

[Gordon Brinton]

Thanks, everyone.

The speakers I am about to purchase are RCF NX 45-A. They are powered and have DSP built in, but no High-Pass filter. (Go figure.) Furthermore, my subs (another brand,) don't have hpf output, forcing me to use an outboard crossover. I do have an older analog crossover, but I really feel the need to upgrade/replace it soon.

The only speaker management function I need is the basic crossover since the speakers already have fairly good DSP protection.

Anyway, the RCF DX 4008 and DX 2006 do not have presets or factory configs built-in for any of their speaker models...(the best I can tell). It looks as if they are simple "dial it in yourself" units like the ones I had listed in my original post.

Thanks for all of the insight.

[Bradford "BJ" James]

Ah, that changes things then. In that case, I’d just go with a basic Ashly analogue unit. You don’t need all the bells and do dads, just a reliable, simple xover.

[Frank Koenig]

I’d just go with a basic Ashly analogue unit.

I beg to differ. For a practical sub crossover you need variable delay, and that can only be achieved digitally. (Unless you get real lucky or have inordinate flexibility in speaker placement )

Having said that, you might get the delay functionality from your mixer in which case you'll need separate sub and main inputs to the crossover with the split occurring upstream in the mixer, as with "aux fed" subs. -F

[David Winners]

I suggest the Behringer DCX2496. 3 inputs, enclosing AES, 6 outputs and plenty of DSP. It's flexible, easy to program from the front of the unit, sounds good. I've had 2 in racks with 4 channel amplifiers for 3 years now and haven't had a bit of trouble.

[ProSoundWeb Community]