Optimum Subwoofer Crossover

[Hobbit]

As a corollary to the Subwoofer dB Level Poll is there an ideal crossover point to use for 1) music and 2) home theater assuming the sub is used in conjunction with decent set of full range front L/R speakers?

Audysses on my new pre/pro sets the crossover 40hz. My old pre/pro the choices were small/large and it was recomended to set the x-over to small, 80hz, for speakers with a woofer <8", which I did. In both setups I had the same sub/front speakers.

 

[Steve81]

There's no single ideal that applies to all setups, though 80Hz tends to be a good starting point. Out of curiosity, what are you running currently in the way of speakers and a sub?

 

[j_garcia]

Yep. Same answer as it would be to the other one. If you want a generic answer, there isn't one because it depends ENTIRELY on your setup.

 

[Hobbit]

There's no single ideal that applies to all setups, though 80Hz tends to be a good starting point. Out of curiosity, what are you running currently in the way of speakers and a sub?

On the thread I linked to quite a few people like to set their subs a hot. That being the case, it's logical that how the sub's level is set verses crossover is pertinent. Setting a sub at +5db with a 40hz x-over is surely different than setting it at +5db with an 120hz x-over.

That's why with music I strive to set my sub so I don't notice the transition from the speaker to the sub. Also, from my experience, how movies are probably mixed, I can get away with boosting the sub up w/o this effect becoming noticeable.

Which brings me back to the original post. Is there a (near) optimal crossover for a full range speaker? THX likes the 80hz x-over. Which may be true for LFE effects and a hooter sub the way movies are mixed...

 

[j_garcia]

As was already mentioned, without knowing the capability of your speakers, there is NO WAY to answer your question. THX does not simply "like" 80Hz, 80Hz is the THX SPECIFICATION and you build the system around that, not the other way around. "Full range speaker" to me means 20Hz capable at which point you technically would not need a sub. That is not likely nor usually feasible in most setups, thus why we are asking for information about your exact speakers or at least a -3dB spec on the bottom end.

 

[Steve81]

Is there a (near) optimal crossover for a full range speaker?

Like I said, 80Hz is usually a good starting point, but a lot depends on the individual setup and the how the room impacts the response of your speakers. With respect to the 80Hz standard, you don't really want to go much over that mark, as sub localization can become an issue. Below that point, you'll need fairly robust speakers if you plan on high playback levels. See rule #3 for more on that:
The Decibel (dB) Scale & Audio Rules 101

 

[j_garcia]

I will also add that Audessey may be good, but it is not always right.

 

[Hobbit]

As was already mentioned, without knowing the capability of your speakers, there is NO WAY to answer your question. THX does not simply "like" 80Hz, 80Hz is the THX SPECIFICATION and you build the system around that, not the other way around. "Full range speaker" to me means 20Hz capable at which point you technically would not need a sub. That is not likely nor usually feasible in most setups, thus why we are asking for information about your exact speakers or at least a -3dB spec on the bottom end.

I'm plenty happy with my setup (BP10s and Paradigm 15" sub) . Barring your's an Steve's well thought out responses, it appeared the majority of people in that thread set their subs hot. No one questioned their speakers, sub, crossover, or quality of their SPL. Some validated this by saying they like a lot of bass. Maybe my post should have been why would you set your sub hot? To me it can be annoying effect with music, but seems OK with most action movies. I've listened to many people's setups where at some low to moderate volume level the bass drum can throw you across the room.

Sorry for my poor THX wording, I'm fully aware of what they do. The point being they chose this probably after some research into the matter (including sound and cost effectiveness). I would think this has some to do with movies having a lot of dialog which doesn't overlap with the explosions and crashes that are using the LFEs.

 

[Steve81]

I'm plenty happy with my setup (BP10s and Paradigm 15" sub) .

FWIW, in spite of Def Tech's specs, BP10s are not what most would consider full range speakers.

Maybe my post should have been why would you set your sub hot?

That's purely a matter of preference.

 

[j_garcia]

FWIW, in spite of Def Tech's specs, BP10s are not what most would consider full range speakers.


That's purely a matter of preference.

Yep and yep. Some like more bass, that does not make it "right" just what the individual likes, so there sort of isn't a "right", there is calibrated and your personal preference and they often aren't the same. I usually calibrate and leave it like that for a while to see how I like it. If I don't, I tweak it to where I like which was about +1dB hot in my old room but not in the current room. If someone is running their sub +5db or more hot it potentially means the sub isn't cutting the mustard; aka not a good sub, not properly sized for the room and/or poorly placed but not always.

Deftech is well known to "fluff" their specs, so I wouldn't use their specs for system configuration. The THX spec used 80Hz because it keeps the sub below the point of easy localization and gives the mains good enough midrange presence while offloading the heavy work to the sub's amp instead.