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#280800 - 11/28/09 03:28 PM Do I need 2 channels to run 2 subs?
aspicer1 Offline
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Registered: 06/02/07
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Loc: Virginia
I am going to go to a dual sub setup in my new theater. I was just told that adding a "Y" adapter is all I need to do as the subs are self powered. Is there any benefit to upgrading the receiver to a multi channel sub output or is this "Y" adapter just as good?
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#280801 - 11/28/09 03:31 PM Re: Do I need 2 channels to run 2 subs? [Re: aspicer1]
EFalardeau Offline
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The advantage of multi-output (on some receivers) is the ability to set level and distance independently. If you have two subs placed at very different distance from your mains, it might be worth it, at lest in the long run. How much is it necessary right now (or even ever), I don't know, but I guess it depends a lot on positionning and if the subs are from different models or brands.
Subs experts are bound to join in soon on this topic!
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#280802 - 11/28/09 03:48 PM Re: Do I need 2 channels to run 2 subs? [Re: EFalardeau]
jakewash Offline
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A Y adapter will suffice, you have to set up the subs so that they are both calibrated to the same level or slightly lower than the speakers, as the dual subs have more over all output, about 3db for subs in different places within the room and if co-located about 6db more. Once you have them calibated, you can run Audyysey and it should help smooth things out even more.

Having a receiver that has dual sub outputs AND is capable of adjusting each subs output independently is obviously more advantagous as the receiver will make the required adjustments for you on each sub, but not all receivers have this ability yet.
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#280811 - 11/28/09 07:56 PM Re: Do I need 2 channels to run 2 subs? [Re: jakewash]
SirQuack Offline
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The others pretty much summed things up. If you can find a receiver that has multiple Sub Preouts, that have independent settings good luck and pull out the $$$$$. The last time I looked, only the top of the line Denon's and a few other had independant multiple sub out jacks and would allow you to set each sub seperately.

I have found that if you calibrate each sub, one by one, then turn them both on you will get good results. Distance (delay) is always fun, especially when one sub has a DSP chip.
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#280812 - 11/28/09 08:08 PM Re: Do I need 2 channels to run 2 subs? [Re: SirQuack]
CV Online   confused
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 Originally Posted By: sirquack
Distance (delay) is always fun, especially when one sub has a DSP chip.


Total tangent, but speaking of DSP chips, do you think Axiom will ever offer speakers with their own amps and DSP chips? It just seems that if they're using a DSP to flatten the frequency response of their subs as much as possible, they'd be tempted to do the same with their other speakers. I know other manufacturers offer powered speakers, but who out there is actually using DSPs for something other than their subwoofers? Just curious.

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#280815 - 11/28/09 08:59 PM Re: Do I need 2 channels to run 2 subs? [Re: CV]
ClubNeon Offline
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Registered: 02/06/09
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Loc: Western Maryland, USA
The DSP depends upon knowing how the speaker is going to behave, shaping the output of the amp to take that predicted behavior and make the actual response flat. The problem is that much above 100 Hz, and there becomes too many variables, happening too fast, that it's impossible to flatten the response of the speaker with the same level of accuracy which is possible with a much slower moving target.

If you think about it, the room correction software in modern receivers is attempting to accomplish the same thing--with the added variable of room response thrown in. You see what a mixed bag that is.

Additional: Although I would love to see Axiom make affordable mono-block amps targeted at their own speakers. Maybe with a mounting system to which directly attach them in a safe and secure manor. So you run a power cord and an RCA or XLR connection over to each one.


Edited by ClubNeon (11/28/09 09:02 PM)
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#280817 - 11/28/09 09:18 PM Re: Do I need 2 channels to run 2 subs? [Re: ClubNeon]
Micah Offline
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Registered: 11/16/08
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I didn't think the DSP chip was meant to 'flatten' bass response, I thought the whole idea was to keep the amp from distorting... or is that the same thing?

I always thought it was more of a safety feature from damaging the speaker than it was a tool to help its actual musical performance.
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#280818 - 11/28/09 09:23 PM Re: Do I need 2 channels to run 2 subs? [Re: ClubNeon]
CV Online   confused
Founder, Axiom Upgrade Club
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Registered: 07/20/06
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 Originally Posted By: ClubNeon
The DSP depends upon knowing how the speaker is going to behave, shaping the output of the amp to take that predicted behavior and make the actual response flat. The problem is that much above 100 Hz, and there becomes too many variables, happening too fast, that it's impossible to flatten the response of the speaker with the same level of accuracy which is possible with a much slower moving target.


Impossible for how many more years? How fast does the processing power of DSPs increase, and how much processing power is needed to take care of the audible range? Those would be interesting figures to know. And as far as room correction software goes, you'd think that SOMEONE out there offering multi-thousand dollar equipment would be able to include enough processing power. I keep dreaming, anyway.

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#280819 - 11/28/09 09:28 PM Re: Do I need 2 channels to run 2 subs? [Re: ClubNeon]
CV Online   confused
Founder, Axiom Upgrade Club
shareholder in the making

Registered: 07/20/06
Posts: 11734
Loc: Richland, WA, USA
 Originally Posted By: ClubNeon
Additional: Although I would love to see Axiom make affordable mono-block amps targeted at their own speakers. Maybe with a mounting system to which directly attach them in a safe and secure manor. So you run a power cord and an RCA or XLR connection over to each one.


That sounds like a nice idea, and affordable would be appreciated. I managed to spring for the A1400-8 at the preorder price, but if I want to try out the newer sound modes at some point with the extra channels, it would be nice to mate it with another Axiom amp that uses the same technology. I'd love to have an A1400-2 for my mains, but it's hard to justify the price.

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#280820 - 11/28/09 09:30 PM Re: Do I need 2 channels to run 2 subs? [Re: Micah]
CV Online   confused
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 Originally Posted By: Micah
I didn't think the DSP chip was meant to 'flatten' bass response, I thought the whole idea was to keep the amp from distorting... or is that the same thing?

I always thought it was more of a safety feature from damaging the speaker than it was a tool to help its actual musical performance.


I think it accomplishes both. From the EP800 product page:

 Quote:
The Intelligent DSP wants things to go smoothly all the time - no bumps in the road. Using a digital roadmap, the special algorithm controls every frequency from 13 Hz to 150 Hz, never deviating more than 1 dB through this entire range.


It sounds like it definitely works at keeping the output even at every frequency.

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