Subwoofer crossovers

I'll take the other side of Brad's argument.

Unless you're using full-range room EQ (ala Audyssey), the most audible of the passive-treatment resistive, room induced, problems occur between +/- 60hz and +/- 110hz in most rooms (IME, anyway). Bassbusters are great, but their effectiveness starts to diminish below 100hz, and is generally, entirely gone by +/- 70hz, IME.

If you're using subs, you can address these thorny problems with careful placement of the subs and/or deciated subwoofer EQ (SVS or Velodyne). Either way, the subs need to be the source of the output in this mid/upper bass range if they're going to the tool used to fix the problem. This means the subs need to roll off fairly high: somewhere north of 75hz in every room I've set up.

This usually makes a good "hand-off" to unfiltered mains impossible, unless the mains have no bass at all. Something like the Sunfire Ribbon Monitor might work, but most high-end mains have sufficient bass to relegate the sub-woofer to deepest bass only. You can't run the subs high enough to fix the nasty problem that subs are best suited to fix - unless you low cut the main speakers.

That's a mistake IMO. I know many, many folks prefer to eliminate an active x-over, but at 80hz, I find that even a modest cost unit like the NHT x-2 is very, very hard to detect. Of course, this "undetectability" depends both on the system in question and the listener in question, but I've A/B'd the X-2 in some very high end chains and, with suitable program material (i.e. no bass at all), I can't hear the difference. Also, of course, YMMV, on that one.

It's entirely possible that a truly crappy low cut for the mains like that in the Velodyne SMS-1 may be a different story. I'd agree that decent active x-over is important. But, shy of that, I believe that any deterioration introduced by a decent active x-over is (IMHO) likely to be swamped by the benefits of crossing the subs out higher in frequency than is usually possible when the mains are run full-range.

A lot of people note that there are also benefits to relieving certain mains of the heavy lifting in the mid/upper bass, as well, but - IMO- that's just a little icing on the cake.

Just the other side of the coin.

Marty

Marty, not an unreasonable argument, but keep in mind that by crossing over to your subs at say 100Hz in order to get typical room modes in range of the EQ you apply on the subs, you are not only running the mains through an active filter. You are also turning your full range system into a satellite sub system.

I had a dialogue with a guy who was doing just that (basically using Avalon Eidolons as satellites!), and advised against it. He has since gone another direction I believe. It all depends on your room. If you have some horrific boomy modes the satellite + EQ'ed sub approach may sound better, but in a half decent room it probably won't.

There are a few alternatives though. Use the Rives Parc 3 band analog EQ unit (<300Hz) in the mains signal part. I had one of those for a while but never used it. The second option is to get a speaker with separate woofer cabinet and monitor, get an external cross-over, bi-amp them and apply EQ only to the woofer cabinet. In fact, the Vandersteens do just that out of the box. Their woofer cabinet is active and has build in EQ. The Salk Soundscapes would allow you to do that to, as do verity audios (you need to get the external cross-over). I toyed with this idea, but after measuring my room in REW and finding out my mode aroun 100 hz was less than 10db I decided not to bother.

I cross at 75 hz in my current room, because that's as low as I can go and make it work. I have gotten below 70hz in a previous room, but never down to 60hz.

My point is that full range speakers in free space start to exhibit really difficult behavior somewhere not too, too far below 100hz in most rooms. Wherever that point is, that's where I feel that you're best off crossing to subs (if you're using subs), because the subs will almost certainly allow better behavior.

Whether that makes your system a sat/sub or not isn't really that important to me. Not to me, anyway, tho others might be more concerned.

Marty

BTW, Have you ever crossed your Verity Parsifal mains straight to the JL subs without the Verity bass cabs? I also have P/Es and tried it once with my Rythmik subs. I know that it's odd (and might not be appropriate for a long term configuration), but it was both interesting and educational, (and reasonably easy with the SMS), if nothing else. I'd be curious to see how it flew with your JLs.

Edorr,
Sorry for the loooong delay in replying to you.
I saw no reply's after 2 week and thought this was a dead thread.

I am using my Sarastro II's full range. They have an 11 inch bass driver but I like how the JL's load the room and with Floyd music they add that very low fast bass. I crossover the JL's at 35Hz since they are being used with 2 channel. I would not want them at a much higher crossover since the Sarastro's sound great in full range.
I have tried a few subs and for 2 channel I prefer the JL's they are the fastest sub I have found I just wish it had an LFE input.

Yes I want the Meridian to handle the subs crossover & EQ's when in theater mode.

Martykl,
The NHT x-2 sound very interesting and the cost is minimal but is there a better unit available.
I like the fact it has an LFE input. Do you know if it overrides the stereo input?

This thread is getting interesting.
Thanks for the reply's

Would have been interesting but I never thought of it and never tried. Now I never will because I sold my my Verities and I am using Eidolon Visions.