Axiom Home Page Forums General Discussion Advice from Axiom Owners Mixed Dual Sub system

I currently own an Energy 10in sub (ES10) and although it has served me well for over 10 years, it's time for a serious upgrade. Enter the EP500 in the equation, at least that's the plan.

My question is, do any of you see an issue in running both subs in my HT system ? The EP500 and the Energy ? I don't really have another place for my ES10 and I don't really want to sell it either.. I figured with both subs I can better bass integration, like Jakeman with his 2 EP600s AND 2 EP500s kind of idea..

I don't believe "sub matching" is that important in terms of brand / size but I though I would ask to see if anyone has had any issues doing what I am proposing.

Thank you

Cheers,

Steph

I think with proper placement, you might achieve good results. If possible, try opposite walls to help even out frequency response.

Thanks Randy, that's what I was thinking as well, I currently have my sub next to one of the side wall, middle of the wall and it sounds the best there. Up front with my mains is the place it sounds the worse, in my room anyways. So, one on each side of the listening position should really work well I think.

Sure, Stephane, give it a shot. Putting the subs at the midpoints of opposite sidewalls, as suggested in the Harman paper prepared by Dr. Toole and his colleagues, would cancel and/or avoid some of the room resonances, plus giving a 3db boost in loudness.

I was able to integrate my old M&K MX-200 into my M80, EP600 system but it took some doing. Placement was tricky as the room is not exactly acoustically friendly and flipping the phase switch was also needed. However once I found the right spot I wouldn't want to give it up. Unless of coarse it was for another EP600!

I have been wondering about dual subs as well. Practically all of the low bass in a movie soundtrack is recorded into one channel, the LFE. Even if it weren't, low frequencies are mainly non-directional such that only a few people can perceive separate sound sources below 70Hz. Since the EP-500 has a brick-wall cross-over implementation, there is no extension of output above the cross-over, thus making the EP-500 even more difficult to localize (easier to place) in a room. My pre/pro has the capability to run two subs and when all speakers are set to small, the left sub gets the bass from the center, left main ,and left surrounds, and the right sub gets the center, right main and right surrounds (in addition to LFE for both subs of course). While this bass distrubution is stereo, as compared with the LFE channel, inability of our ears to localize this low bass still applies. So, if one EP-500 is sufficient for a given size room, why would there be a benefit to using two subs? I would really like to hear others' thoughts (especially those of Jakeman and dllewel) on running two or more subs.
John

John

Here is one of the Harman white papers by Todd Welti that deals with why multiple subwoofers are necessary in a HT application. It solves several problems such as getting more output and accordingly lowering distortion, smoothing room nodes and obtaining flat frequency response in many seats not just the single sweet seat where you like to sit. The more subs you add the less problems with room nodes across more seats and the better low bass detail and articulation.


A couple of years ago I was watching an episode of 24 with my two sons and I was enjoying the LFE in my sweet spot. One of my teenagers sitting 3 feet to my left started to complain of very loud bass drowning out the voices. My other son 3ft to my right thought son#1 was just causing trouble and said he hardly heard any bass. Multiple subs to the rescue.

http://www.audiovideointeriors.com/images/archivesart/0106toolemultsubs.pdf

Your question about stereo subs are another matter and from the way you describe your processor I doubt you can get stereo subs with a dolby track since mono LFE and mono centre is being redirected to both subs. The only processor that I know that allows for stereo subs and a separated LFE only output is the Lexicon MC12.

Anytime I have experimented with stereo subs I have split the L main channel signal to one sub and the R to the other. I set the processor to no subwoofer to avoid sending the same mono redirected bass to each stereo sub. I then run a dedicated line directly from the dvd player to the sub. Overall its more trouble than its worth IMO since it creates tricky phase issues between the individual subs and speakers. In addition you need to also adjust the LFE loudness separately at the sub.

If you want stereo bass effects and your processor permits separate speaker bass management, a better way to go would be to cross full range speakers like the M80 at 40hz and run a pair of mono EP500s .

>>Since the EP-500 has a brick-wall cross-over implementation, there is no extension of output above the cross-over, thus making the EP-500 even more difficult to localize (easier to place) in a room.

I thought the brickwall filter was used to cut off extreme low frequencies (10Hz-type stuff), and that the crossover to mains was a conventional 24 db/8va filter. Not 100% sure though...

The EP subs use a brickwall digital high pass filter at 19hz for the 500 and 16hz for the 600 (23hz for the 400 ?) and 100hz digital low pass filters. I believe they are may be introducing a firmware update to increase the low pass to 120hz which will be helpful with blending monitors. When you set the crossover you are relying on the 24db (or in some cases a 12db sloping filter) in the processor which works "normally" as long as its in the band of the subs digital brickwalls.