Two subs for stereo music - in parallel or separate?

[JerryLove]

That effect is going to happen anyway with phase difference stereo. Much better it happen in the signal bath than in the room where there are problems already, in the below 80 Hz range.

I have great respect for your knowledge here, but that's just a silly statement.

It's more-or-less impossible to get 100% cancellation from a sub in a real room (and besides: that's a worry with dual mono as well). It is completely possible in the electrial domain with real-world examples. Tell me how far apart the stereo recording mics were and we can compute what frequencies will be completely cancelled out.

There are no ill effects of using the bass management of a receiver pre/pro to drive a sub from sources without a LFE channel that I know of.

No stereo for directional sound and intereferance for out-of-phase sound.

 

[JerryLove]

Well, yeah, that's what this thread is really asking about. Is there such a thing as stereo bass and is it worth having? It looks like there's a divergence of opinion on that matter.

It's not opinion that a stereo recording 180 degrees out of phase will cancel to 0db when converted to mono.

It's not an issue in movies (which simply put don't use stereo that low) but can be for music.

I have the option of using he crossover in the SVS sub, an extenal (Behringer) crossover, and of running speaker lines straight and the sub through the SVS LPF. if I use the SVS crossover, I think I loose the ability to use REW and the Behringer FD to equalize the room.

Running through a crossover than a filter afterwards sounds like a bad idea to me.

TLS Guy, if the B&W 800d (for instance) would sound better with the mid/high ranges physically separated from the two mono low range subs, why wouldn't they set up the speakers that way? They certainly don't mention bi-amping and driving the low freq. drivers with the same mono signal.

The accoustic seperation between the three cabinets on the 800d is signifigant. Physically moving them would be a problem as the LF drivers include frequencies that are directional.

 

[TLS Guy]

It's not opinion that a stereo recording 180 degrees out of phase will cancel to 0db when converted to mono.

What you say is true at face value. However such a situation will never occur in practice.

Just one reason is that only a portion of the sound would be direct sound anyway, so there will be all sorts of reflections of the fundamental. There will be multiple waves of the fundamental with all major of phase angles and intensities.

I'm going to tell for the record except for truly integrated systems the feed to multiple subs should be mono and that is accepted engineering practice. Results are better that way. Above 90 to 100 Hz it is a different matter. Subs are best fed a mono summed signal.

 

[jp_over]

What you say is true at face value. However such a situation will never occur in practice.

Just one reason is that only a portion of the sound would be direct sound anyway, so there will be all sorts of reflections of the fundamental. There will be multiple waves of the fundamental with all major of phase angles and intensities.

I'm going to tell for the record except for truly integrated systems the feed to multiple subs should be mono and that is accepted engineering practice. Results are better that way. Above 90 to 100 Hz it is a different matter. Subs are best fed a mono summed signal.

With all these things considered, at this point in the HT + music system are the benefits of dual subs worth it for a medium room using full range speakers such as the B&W 801 or 802? Or, do the new .2 systems make it easier to integrate multiple subs appropriately?

Thanks!

 

[TLS Guy]

With all these things considered, at this point in the HT + music system are the benefits of dual subs worth it for a medium room using full range speakers such as the B&W 801 or 802? Or, do the new .2 systems make it easier to integrate multiple subs appropriately?

Thanks!

You can integrate subs with such speakers, but always set the crossover to large, and use the subs very gently gradually filling in below 40 to 60 Hz.

When I integrated a sub with 800 Ds, I started rolling them in about 50 Hz.

If you don't have a sub, then you have no LFE channel, unless you build an active system that can capture the LFE signal like I have. To make a truly full range speaker that includes the LFE channel takes some creative engineering.

The 0.2 system helps little with integration. Both outputs are the same, they are just buffered, so two subs do not halve the input impedance like using one output would.