Subwoofer Questions

Usually it wouldn't matter if the speakers "respond" to 35Hz. The idea is to highpass the speakers a little higher, reducing excursion demand on the midbass woofer, and thus reducing distortion as well. That's the usual way to go about this. If, however, you have giant midbasses in your speakers, then it might make sense to transition to subwoofers as low as 30-40Hz. It's difficult to imagine that for any loud output level, the subwoofer wouldn't be cleaner than the midbass below about 35Hz, however I don't tend to model smallish (or normal / average) bass setups and speakers in small rooms. So perhaps things are a bit different when the subbass has just 1x 12" driver to rely upon. In those setups, I tend not to use a subwoofer at all and just rely on powered monitors (of course the sub would help, but space is always at a premium).
 
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I solved the space problem by building my dedicated music room to a separate building. No WAF or placement problems. I can cut holes to walls for infinite baffle without a blink of an eye :)
 
Let's add some objectivist-centric details for the newbies.

While there are more crossover topologies than I'm even aware of, classical crossovers typically require flat response at least an octave past the XO frequency. Alternatively, you can use the speaker's natural roll-off as part of the high-pass XO. For example, combine a sealed woofer's 2nd-order acoustic HP with a 2nd-order electrical HP to produce a 4th-order HP filter. Using either approach for a 30Hz XO would still require the main speaker to have controlled, well-defined response to 15Hz.

Simply adding a sub to a speaker that's still run full-range is not likely to produce an optimal crossover.

That said, spreading multiple bass sources around the room can help room modes, which could outweigh any issues with crossover phasing, etc.
 
Trying to crossover your mains to your subs at the absolute lowest frequency your mains will do is insane. Nenu is probably the only person on the planet doing this which is why it doesn't matter that subs won't crossover below 40 Hz.

If your sub won't do 40 Hz (really more like up to 80-100 Hz) better than your mains then you bought the wrong sub and all you're doing by crossing over at 25 Hz is wasting your subs ability and ensuring that you get the maximum amount of distortion out of your mains.
 
Nenu said:
You made an incorrect assumption and ignored the context of my post.
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Which assumption and context are those?

Crossing to subs 3 Hz above the -3 dB point of your speakers is dumb and objectively wrong. A speaker like B&Ws 802 with a -3 dB of 17 Hz has 0.3% distortion at 100 Hz and 1% at 80 Hz. Imagine what it is at 20 Hz.

Get a better sub and set your crossover at a point that makes sense. What you’re doing makes no sense whatsoever.
 
Lizard Testes said:
Which assumption and context are those?
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You assumed I am setting the crossover to the absolute lowest frequency of my speakers.
And you assume that I am the only person using the original method of hooking up a sub.
The context is to match the response of my speakers.

Crossing to subs 3 Hz above the -3 dB point of your speakers is dumb and objectively wrong.
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Not when that is the in room response as I described.

A speaker like B&Ws 802 with a -3 dB of 17 Hz has 0.3% distortion at 100 Hz and 1% at 80 Hz. Imagine what it is at 20 Hz.
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Perhaps you should tell B&W their speakers shouldnt be operated without a digitally controlled crossover and an external subwoofer.

Get a better sub and set your crossover at a point that makes sense. What you’re doing makes no sense whatsoever.
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Explain what is wrong with the sub I have?
And what it is that makes no sense and exactly why.
 
Nenu said:
Perhaps you should tell B&W their speakers shouldnt be operated without a digitally controlled crossover and an external subwoofer.
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Not a very smart thing to say. Even expensive full range speakers are always a compromise. B&W fully knows their distortion goes through the roof at low frequencies but they simply can't put a horn or larger 18-21" drivers to their product, which would be required to drop the distortion at low frequencies.
 
Nenu said:
You assumed I am setting the crossover to the absolute lowest frequency of my speakers.
And you assume that I am the only person using the original method of hooking up a sub.
The context is to match the response of my speakers.
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No, I didn't assume that you set the crossover to the absolute lowest frequency of your speakers. I assumed that you were telling the truth when you said your speakers roll off at 22 Hz and you set your crossover to 25 Hz. That's dumb as shit. There's a reason that every single response to your set up in this thread has been "uh, lol, wut?" and it's not because you're an audiophile genius that has figured out something that no one else has.


Not when that is the in room response as I described.
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In room response has nothing to do with distortion at the extreme levels of your speaker's sound reproduction. The fact that you don't understand this is a big red flag.

Perhaps you should tell B&W their speakers shouldnt be operated without a digitally controlled crossover and an external subwoofer.
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Lol this is just flat out ignorant. Having a "digitally controlled crossover and an external subwoofer" does not change the FACT that you're running your mains so deep that they're objectively distorting like hell.

Explain what is wrong with the sub I have?
And what it is that makes no sense and exactly why.
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If your sub can't do better at 40 Hz than your mains then it's a POS or is at best an extremely poor match to your mains. The reason subs don't have a settable crossover point below 40 Hz IS NOT because no one on the planet (except for you) has mains that can go below 40 Hz. It's because anyone that wants to cross to their subs below 40 Hz is an idiot. And really it's more like anyone that wants to cross below 80 Hz is an idiot.

If your golden ear thinks this is the best way to set up your speakers then bully for you, keep it that way, but trying to tell people that they should consider doing it for their systems is moronic and doing anyone that might actually listen to you a disservice.
 
If your room/home setup would allow it, I'd go for an Infinite Baffle sub setup. If done right, it should obliterate any box sub and depending on what your going for, do so cheaper as well. Especially since you are talking potential HT down the road.

Check this out: http://www.facstaff.bucknell.edu/esantane/movies/ibsub.html Some great info here and an amazing system. - "I can measure over 130dB (response mode set to slow/average, not fast) at the opening of each manifold and over 120dB at the primary listening position that is 17 feet away! Talk about bang-for-the-buck! For just about a grand..."

My system is half of his, a dual 15" IB setup, which for my room size is probably a bit overkill. I'll never go back to a box...

Look into it, might be an option and fun as well, not to mention damned impressive to show off.
 
Sabrewulf... said:
If your room/home setup would allow it, I'd go for an Infinite Baffle sub setup. If done right, it should obliterate any box sub and depending on what your going for, do so cheaper as well. Especially since you are talking potential HT down the road.

Check this out: http://www.facstaff.bucknell.edu/esantane/movies/ibsub.html Some great info here and an amazing system. - "I can measure over 130dB (response mode set to slow/average, not fast) at the opening of each manifold and over 120dB at the primary listening position that is 17 feet away! Talk about bang-for-the-buck! For just about a grand..."

My system is half of his, a dual 15" IB setup, which for my room size is probably a bit overkill. I'll never go back to a box...

Look into it, might be an option and fun as well, not to mention damned impressive to show off.
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The entire right side of my HT (~24') is drywall in between it and an unfinished ~4000' cubic foot storage area. I really know dick about DIY subs but I know enough that I think this is prime for some kind of crazy IB type setup.

What size is your room?
 
Lizard Testes said:
The entire right side of my HT (~24') is drywall in between it and an unfinished ~4000' cubic foot storage area. I really know dick about DIY subs but I know enough that I think this is prime for some kind of crazy IB type setup.

What size is your room?
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12' x 24' - My gaming PC is on one side of the enclosed room and also uses the subs, Home Theater in the middle. I also use Tactile Transducers in my gaming chair and couch. Really amazing experience on top of the killer sub.

Not hard to put something together, lots of info out there. You don't need massive amps to drive them because their not restricted like a box sub, very efficient. I have one of these, more than I need by far, but was a good price at $250. Would easily drive 4 15's or even 18's. They are PRO amps, so there is the fan noise unless you do a fan mod. I just have it on the other side of the wall and use a remote control RF switch to turn it on/off.

Check out this guys bad ass IB setup who "used to run 2x Velodyne ULD-18’s" box subs until "Having gotten IB ‘religion’" - http://www.jonathanfoulkes.com/Home_Theater/Speakers/IBInstallStory.htm
 
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Looking into it further I really would love to do something like a 4x18" (or 2x2x18") IB but at the same time I think I already have enough sub to rattle the dishes in my neighbors houses, so may not be worth it.

I'm gonna try and talk myself into it though.
 
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