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Subwoofer doubts: crossover setting for 60hz speakers

Hello there. I’m about to add a subwoofer through “high level” inputs to my stereo system, and I have some doubts. Nominally my speakers (Cabasse Riva) go down to 60hz. According to the stricter books, this means I should set the sub’s crossover to 120hz. Which would be a problem, since -from what I read- sound becomes “localizable” over 80hz, and my only spot to place the sub is a corner of the room. I guess that would severely affect soundstage, which is a deal-breaker for me. 

So my questions: 

1) Would it be ok if I set the sub’s crossover to 80hz? or would I be risking to create some kind of “gap” between sub and speakers? Do rememeber that I’ll hook the sub through “high level” inputs, so there'll be an increasing overlapping of frequencies above 60hz. 

2) Or would I be better off adding 2 subs instead of just one and setting them at, say, 100hz? Many audiophiles on the web advocate for double subs... 

Keep in mind here that my current options are: 1 excellent Velodyne spl1200r (that reaches 20hz), or 2 fairly good Focal sw700w (that reach only 40hz). If the answer to question 1 is "yes" -ie. if I may set the sub's crossover to 80hz without noticeable gap and preserving soundstage- I'll definitely go with the Velodyne.  

Thanks for ANY help -I need to move fast!


fedocable
fedocable OP
12 posts
 
Thanks for the reply. The problem here is that I cannot test the subs in my system before buying. And worse than that: I have absolutely no experience with subs. So, before taking the blind leap, I'm hoping to figure something out from the forum's audioholics. 
One other thing I should add is that I'm using a low power single ended tube amp -Unison Research's Simply Italy. Beautiful sound but, of course, not very strong on the bass.
timlub
2,039 posts
 

Hi fedocable,  I don't know anything about stricter books, but I've set a bunch of subs over the years. Bass does become directional between 80 and 100hz.  There is no absolute answer to your questions. Room nodes and woofer placement cause or correct most problems with bass. I've never heard of a normal procedure of placing a sub an octave above the rolloff of the main woofer. 

As for a single or double woofer?  Double woofers are harder to place and if a single woofer is done correctly, a double woofer won't help much, but if you are trying to achieve the ultimate, a second woofer takes you the rest of the way there. 

I would start with a single woofer, I'd cross it around 100hz, placing it away from the corners, between speakers would be good, get your gain as close as possible for a smooth transition. You will get very close to getting the woofer right or you will find a bass peak somewhere that won't go away. Either way, once your gains are good,  I'd then take the crossover down to 60hz and see how the blend is. Depending on the room, you could still be dealing with a bass peak and may need to cross even lower.  My guess is that it will be decent. Start dialing in frequency and phasing until you are a happy camper. If there are bass peaks that won't go away no matter what, see if you have a phase dial and start working on phase, if you still have peaks,  you'll need some sort of bass traps in the room to absorb unwanted nodes.  I hope this helps,  Tim

fedocable OP
12 posts
 
Thanks a lot, Tim. Extremely informative, just the kind of feedback I was hoping to get. I'll go with the Velodyne, no more doubts.
nrenter's avatar
nrenter
766 posts
 
IMHO, the main reason so many people have issues integrating subs into their system is that they try to cross them over WAY too high. If your -3dB point of your speakers is 60 Hz, I'd begin experimenting with a sub crossover point of 0.7 x 60 Hz = 42 Hz. Unless you are using a Vandersteen sub, you want the sub to just come up underneath your monitors...and usually not all the way up to the -3dB point of your speakers. 
fedocable OP
12 posts
 
All the more reassuring. Thanks!
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