I am attempting to integrate a sub (possibly) 2 using Lyngdorf's Roomperfect. I wanted to ask some questions about best practices in general with DSP. I currently have Kef R3 speakers and an SVS Micro 3000. I used Rew and moved my sub around potential locations until I got what I thought was the best REW chart for the sub alone. SVS recommended settings on their website state :
AV Receiver / Processor:
| Recommended Speaker/Subwoofer Crossover Frequency (Hz) | 80 Hz |
Stereo Pre-Amplifier or Receiver:
| Recommended Low Pass Filter Frequency Setting (Hz) | 60 Hz |
| Recommended Low Pass Filter Slope (dB/octave) | 24 dB/octave |
Questions for DSP are as follows:
- Are the SVS website settings for stereo pre-amp meant to be used in the SVS app so that the sub DSP is doing the low pass and slope? It reads to me like they are telling you to put those settings in your stereo pre-amp or receiver (assuming it has sub integration features).
- Would I use those settings and then use the sub's EQ feature to make as ideal test results as possible prior to running DSP? IE, use the 3 band EQ in SVS app to tame peaks and valleys associated with the sub first and then run the Lyngdorf DSP on top of that. I was worried that might result in the DSP trying to fight the EQ.
- I started with my sub at maximum volume and reduced volume until the REW chart showed valleys hitting house curve but nothing really below house curve. The result after DSP is that there is some boominess in men's voices when watching a show. My thinking was that I have heard it is always better to reduce peaks than try and fill valleys. I figured if I started with everything above the projected curve line the DSP could reduce peaks vs trying to fill valleys. Hopefully that makes sense. Here is the chart REW produced prior to my first attempt at DSP.
I am not sure why SVS would recommend 80Hz XO point for an AVR but a 60Hz XO point for a stereo preamp. My take on it is that you choose your XO point depending on how low your speakers go, and how high the subs go. You should look at main speaker distortion (usually very high at the lower limit of the woofers) and ask yourself if you want to remove those freqs and give it to the subwoofer.
If you have external DSP, I would disable the built-in DSP in the subwoofer. This is because all of them add additional latency, sometimes up to 30ms. This will mess up time alignment.
Point (3) is a bad idea because it will provoke filter ringing. If your sub is very high and your speakers are low, then the crossover will be asymmetrical and will not sum properly. Asymmetrical crossovers are more likely to ring. This may be the cause of your boomy sounding bass. If you have dips in your bass response, you should find a better position for your subwoofer, or consider deploying more subwoofers to even out the bass response.
- Kef port plugs or no plus to run the roomperfect? The kef manual states to use the the ring ports (not fully closed off) for my distance from the wall. It seems to me it would be smart to follow Kef's instructions but they are not written for people who use DSP. Perhaps this is a function where I start with Rew first to see which is a better result and then go that way.
If you are running subwoofers, you no longer need the ports on your main speakers for bass extension. Ports introduce problems of their own, e.g. an uncontrollable out-of-phase wave that is impossible to DSP. I would recommend plugging the port.
1. Right now my sub is hooked up using RCA with about a 12 foot distance using a sixteen feet cable. It passes 2 outlets. I do not notice any distortion or noise. Is there a limit to when you must use XLR? The SVS micro only has RCA.
2. Similar question - if I were to get two subs I would have the second sub with a cable run of between 20 and 28 feet depending upon location. It would pass 3 outlets and run parallel to the first subs cable. Would this require an XLR cable?
3. Does anyone know a smaller sub than can do XLR? Realistically I think the largest SVS I could do would be a 2000 and they don't start using XLR until the 4000 series. I went and looked at them this weekend and they are just too physically large for the place I would be able to put them and remain married. I looked at Rhythmic and it looks like you can get XLR connector on most of their subs but they are fairly substantially sized too. I also had kind of hard time following their website.
If is very unlikely that your RCA cable will pick up noise by going past two outlets. There is more potential for this to happen if RCA cables run parallel to power cables and not cross at right angles as in the case of a power outlet. Still, the potential for noise is not eliminated. If you worried about this, look at the Spectrogram or Waterfall and see if you have a "resonance" at 50Hz that does not drop in amplitude. If you see that, then you either have a ground loop or your cables are picking up noise.
I personally prefer XLR because I don't even want to worry about what the cables are doing. Like you, I am using long runs of cables (my subwoofer cables are 8m long ... that's about 26 feet). I know that if I owned RCA cables I would be taking measurements to see if my choice had any effect.
