crossover question.

[Cotizi]

i recently purchased a SVS PB10 to go along with my Panasonic XR25 reciever and some athena booksheves, centers etc....

My question is that my reciever only goes down to a 100hz crossover for the sub, and i think that something lower around 80 would sound way better. I think it would clean up the sound for HT especially. Anyways, how do i go about changing this? Do i need a whole new reciever or can i somehow get some kind of external crossover? Thanks as always.

 

[johsti]

I'm pretty sure 100Hz is the lowest crossover point on the xr25.

Which Athenas are you using?

 

[Cotizi]

AS-B2's for mains, AS-C1 for center, and some sony crap for surrounds. I know thats as low as the reciever goes, im asking what my options are. I really like the subwoofer, it just seems like it would maybe sound better at a lower X-over for HT purposes. I know u pro's out there wanta help a newbie!. Thanks!

 

[Buckle-meister]

...my reciever only goes down to a 100hz crossover for the sub, and i think that something lower around 80 would sound way better...

I wouldn't have thought so. The higher the crossover setting:

1. The less strain you are putting on the amp to drive the other speakers (good)

2. The less strain you are putting on the speakers to deliver frequencies that the sub is almost certainly better at reproducing (good)

The only downside I see to a crossover setting of 100Hz is that you may be able to perciece the location of the sub for frequencies from approximately 60Hz to 80Hz up (bad)

Regards

 

[WmAx]

I wouldn't have thought so. The higher the crossover setting:

1. The less strain you are putting on the amp to drive the other speakers (good)

2. The less strain you are putting on the speakers to deliver frequencies that the sub is almost certainly better at reproducing (good)

The only downside I see to a crossover setting of 100Hz is that you may be able to perciece the location of the sub for frequencies from approximately 60Hz to 80Hz up (bad)

Regards

While it might sound like a good idea to cross a sub at 100Hz(aside from the localization issue that you are already mentioned), in reality, it probably is not a good idea, unless the subwoofer cabinet was specifically designed to do so.

The residual higher frequencies that are output above the crossover frequency will be affected under the proper conditions. For example, take a 24" cube; this dimension will have an inherant strong cancellation/notch at 140 Hz, and an inherant substantial resonance at 281 Hz(this happens to reside in the most sensitive band for human hearing detection of resonances). If crossing this speaker over at 100Hz using a 2nd order crossover, a significant resonance will occur, centered at 281 Hz that is only a few dB under the reference signal amplitude(because the resonance will be amplified substantially in the cubed chamber). A cancellation/notch at 140Hz will also have an effect on response, in that amplitude will not decrease linearly as frequency rises. The subwoofer needs to have been specifically designed to handle such a crossover point/slope, by way of dividing chambers or by way of dense/thick acoustical damping materials. For a frequency as high as is proposed, to be effective, the internal dampening material should be 2" rigid fiberglass lined walls, or 4" acoustic foam lined walls, or a 100 percent heavily stuffed(with regular fiberglass) volume. Even with a 4th order slope, these precautions should probably be heeded if using this high of a crossover frequency if the physical conditions are as cited in my example.

This is, of course, a dynamic situation, and the specific circumstances(which are not yet known in sufficient detail) dictate what needs to be done for optimal behaviour.

-Chris

 

[j_garcia]

It should be fine with a 100Hz x-over. You won't localize 80Hz, but with a 100Hz x-over, sound will creep up into the 200-300 range, where you WILL potentially be able to localize it. This means you will need to adjust the volume carefully to get the best blend (preferably with an SPL meter), but it should work.

 

[Buckle-meister]

Thank you for that WmAx.

Seriously, thanks for the correction.

Regards

 

[skrivis]

linearly as frequency rises. The subwoofer needs to have been specifically designed to handle such a crossover point/slope, by way of dividing chambers or by way of dense/thick acoustical damping materials. For a frequency as high as is proposed, to be effective, the internal dampening material should be 2" rigid fiberglass lined walls, or 4" acoustic foam lined walls, or a 100 percent heavily stuffed(with regular fiberglass) volume. Even with a 4th order slope, these precautions should probably be heeded if using this high of a crossover frequency if the physical conditions are as cited in my example.
-Chris

Wouldn't putting the sheets of fiberglass or foam out in the enclosure work better than attaching it to the walls?

 

[WmAx]

Wouldn't putting the sheets of fiberglass or foam out in the enclosure work better than attaching it to the walls?

I presume you are referring to the point of maximum velocity. The problem with this idea is that it would be more complex to install sheets in this manner, because you have to have 1 layer(of sufficient co-efficient) positioned for each parrallel set of walls, so then it becomes an excercise in constructing a special insertable structure. It's easier to attach stuff to walls, and since the amount of materials needed are relatively cheap, there is no significant advantage to be had from using a center mounted structure(which would require less material to achieve the same overall effect).

-Chris

 

[jcPanny]

Crossover option

I think your sub has high level speaker inputs and outputs, in which case you could use the following option for adjusting the crossover.

1. In recever, set the mains to LARGE and sub to NONE. (I assume it has these options)
2. Connect the speaker wire from the receiver main connections to the inputs on the sub.
3. Connect speaker wire from the sub's speaker level outputs to the mains.
4. Use the crossover knob on the sub to set the crossover frequency to 80 Hz, etc.
5. Disconnect the RCA cable from sub to receiver.

 

[johsti]

Unfortunately, the PB10 doesn't have high level speaker inputs and outputs. It's one of the things SVS skimped on to keep the bargain price.

 

[j_garcia]

1. In recever, set the mains to LARGE and sub to NONE. (I assume it has these options)
2. Connect the speaker wire from the receiver main connections to the inputs on the sub.
3. Connect speaker wire from the sub's speaker level outputs to the mains.
4. Use the crossover knob on the sub to set the crossover frequency to 80 Hz, etc.
5. Disconnect the RCA cable from sub to receiver.

The x-over on nearly all subs does not affect the frequency being sent to the main speakers in this setup, so it is generally not going to be the best connection method. The x-over on the speaker level outputs is FIXED, and is often higher, possibly 100Hz or higher. There is no x-over adjustment nor speaker level inputs on the PB-10 as noted anyway.