• From: Orlando, Florida, USA
  • Registered: 2007-12-16
  • Posts: 68

Topic: Fireface, etc. Room EQ -- low/high pass for XO urgently needed

I have a client who is currently using one of those cheap DSP units dedicated to room EQ and crossover for subwoofers. As I mentioned in another post, the sound and performance of these boxes is so inferior to that of the RME gear!

So I started to recommend to him the Fireface UCX II to replace his cheap box. But when I looked into the Fireface at a fellow engineer's place, we discovered that the Room EQ is missing an essential component: low pass and high pass filters suitable for use in crossovers to subwoofers: that is, 12, 18 and 24 dB/octave filters in Butterworth, Bessel and Linkwitz-Riley shapes. At least some of these filters. I did not check if a polarity switch is available, but that would also be useful since depending on the filter order, the polarity of one half of the crossover needs to be reversed.

Please, RME, make it so. So far I don't see any other good sounding candidates for Room EQ combined with interface on the market.

bobkatz's Website

2 Reply by MC

  • MC
  • MC
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  • From: Germany/Thailand
  • Registered: 2007-04-06
  • Posts: 25,599

Re: Fireface, etc. Room EQ -- low/high pass for XO urgently needed

The existing high and low pass filters easily allow to build 12, 24 (and even higher) 2-way crossovers manually. Polarity also exist per channel. You might have overlooked that there are two of these per channel in the normal 3-band PEQ, setting these to the same values gives 24 dB/oct. In the Room EQ you even have three high/low pass filters, that you can use together with the 3-band PEQ, and finally you could also use loopback to combine this with the 3-band input PEQ (two more high or low pass)

But we do not have plans to turn the RoomEQ into a crossover solution. This is outside of the scope of these units and the way TotalMix FX is designed. Doing this manually is possible if you know what you do (selecting the correct phase and Q values), and IMHO requires to be able to measure the result to make sure the setup works as intended. And it gets completely awkward in a three way setup, so it's limited to sub+satellite anyway.

I had planned to showcase this application (I did all the setups and measurements to verify) but had to conclude that this is an unmanagable minefield for most users and will just cause frustration or wrong results - so skipped that idea.

Regards
Matthias Carstens
RME

MC's Website

  • From: Orlando, Florida, USA
  • Registered: 2007-12-16
  • Posts: 68

Re: Fireface, etc. Room EQ -- low/high pass for XO urgently needed

Thanks, MC. I did not think there was adjustable Q in the filters, but if by combining filters we can get up to 24 dB/octave it might do fine. I might need some hand holding to build a sat/sub arrangement if I can convince my client to buy the UCX but of course I trust you that it's doable!

Best,

Bob



MC wrote:

The existing high and low pass filters easily allow to build 12, 24 (and even higher) 2-way crossovers manually. Polarity also exist per channel. You might have overlooked that there are two of these per channel in the normal 3-band PEQ, setting these to the same values gives 24 dB/oct. In the Room EQ you even have three high/low pass filters, that you can use together with the 3-band PEQ, and finally you could also use loopback to combine this with the 3-band input PEQ (two more high or low pass)

But we do not have plans to turn the RoomEQ into a crossover solution. This is outside of the scope of these units and the way TotalMix FX is designed. Doing this manually is possible if you know what you do (selecting the correct phase and Q values), and IMHO requires to be able to measure the result to make sure the setup works as intended. And it gets completely awkward in a three way setup, so it's limited to sub+satellite anyway.

I had planned to showcase this application (I did all the setups and measurements to verify) but had to conclude that this is an unmanagable minefield for most users and will just cause frustration or wrong results - so skipped that idea.

bobkatz's Website