Aura Driver & Sub Pairing

[mfishmike]

I am finishing the re-designing & construction of my mains and intend to build a sub.
My choice at this time is the very pricey Aura 15" driver in a ported cabinet. Has anyone here used this driver and can tell me anything about it's performance? I'm running a Legacy Point One now, and am wondering if I'll have any problems running two different model subs together. The Rotel 1065 has separate sub pre-outs for 2 subs.
Any thoughts in here??????

My current project can be seen at:

http://groups.yahoo.com/group/mfishmike

All comments encouraged, pro & con.....Thanks in advance
Mike Cason

[ThomasW]

It would be nice to be able to see the pics, without having to join still another Yahoo group.......

Jon's had several contacts with one the the Aura engineers, so I'm sure he'll have some input. Currently he's traveling on the east coast. He'll be home this w/e.

My thoughts on using nonidentical subs are don't. Use one or the other




theAudioWorx
Klone-Audio

[Al Garay]

Mike,

You might find some messages regarding Aura drivers in the Madisound forum. I recall Jeff Dillon speaking very highly of them.

http://www.madisound.com/cgi-bin/discuss.cgi?

Otherwise, I would consider the JBL SUB1500's which are used in the $4k Revel subs and are on sale at PE.

http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=299-750

Hope that helps,

Al

[mfishmike]

I just stuck a couple in the photo section.

You suggested use one or the other. At this time, I'm very happy with the Legacy, but I have heard use two subs if you can. I intend to either build two identical subs, and sell the Legacy, so the ones I build need to really be good. My other thought was to build a really good one, and operate the two "different subs" at different levels as not to cancel each other.

This is why I thought the Aura would fit the bill.....I'll check the Madisound forum's Jeff Dillon too.....Thanks for the inputs....

[brucek]

operate the two "different subs" at different levels as not to cancel each other

What does 'at different levels' mean? :?: :?:

[mfishmike]

That would mean to keep one of the gains turned down less, probably the near-field unit

[brucek]

am wondering if I'll have any problems running two different model subs together.

Mike,

Using two dissimilar subs is a common mistake made when someone has a sub and wants to add a second. They step up several notches in the food chain and don't want to get rid of their first sub, thinking it will add to the mix.

Using two subs creates advantages that are few and disadvantages that are many. You can indeed gain headroom by adding a second sub. Two subs doesn't make your subs any louder, it simply gives you headroom when you need it. For example, consider a sub that has a response from 20Hz - 100Hz and it produces a certain SP level in a room. If you add a second identical co-located sub with the same response and have the level controls set the same, the two will reinforce each other and be 'louder'. To compensate for this, you will be able to turn both subs down to reach the same level you had with one. But now you have increased the headroom for the same SPL output. You can handle bigger explosions etc. without compression of the signal because neither sub is overloading and can handle the transient.

So two subs are a good thing - but here's the rub. To give it a chance to work you need to use identical response subs that are co-located so they effectively act as one. Anything else and you're asking for trouble. Corner positioning is considered the best location for a sub. Some people get away with separating two subs, but most don't (or don't realize the problem).

If I electrically combine two sine wave signals that are 180 degrees out of phase, the resultant signal will be zero. The same situation occurs with acoustic energy (sound). Since two subs will be producing exactly the same signal you can hope the acoustical energy will be in phase and won't produce any cancellation. But in reality when two subs are located at different spots in a room and have the ability to excite all the room modes, (since in a home theater where the room dimensions conveniently create axial resonance's that are centered in the all important 20Hz to 100Hz spectrum) - each subs acoustical output will have many common frequencies that are out of phase and will cancel each other. You can try and compensate for this nightmare with a parametric equalizer (BFD), but it's quite difficult with two subs.

Now, add to the mix the fact that the second sub doesn't have the same response.
Consider for instance if the second sub has an identical response to the first except that it has a poorer bottom end and is down 3db at 29Hz compared to the first sub. The two subs will reinforce each other across their spectrum (if you're lucky enough to get them in phase at all those frequencies) and produce a response that drops off where the poorer subs output lowers at <30Hz. Since you will be required to turn both subs down to an overall calibrated listening level, you now have a low end response that drops off created by the mixing reinforcement of the poorer sub. You will be holding the better sub back by mixing it with a lesser sub.

My advice. Get one good sub and use a parametric equalizer to tone down the first order effects at the primary axial modes.

brucek

[mfishmike]

Bruce,

Wow & thanks.......so much to know!!! I have since moved the Legacy to the corner (about 1.5') from each wall, and it sounds great.

The dollars needed to be spent to exceed the Legacy's performance could be better spent on an amp to assist the two mains, like the Rotel 1090 to drive the combined 4- 12" Lambda woofers in them.

Thanks for your lengthy reply and knowledge..... That's what these forums are for.....and btw, this one is really great.....I play with 3 of them.....Mike Cason