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Sub-woofer connection question

Hi all,

I have a Music-Hall a15.3 integrated amp and a JL Audio 8" "Dominion" powered sub-woofer.

The sub-woofer has speaker-level inputs (R & L, + & -) but also has line-level RCA inputs.

The amp has an RCA out as well as (of course) speaker-level out.

So I can connect the RCA out of the amp into the RCA in of the sub-woofer, but I can also piggy-back off the amp’s speaker connections to the sub-woofer’s speaker-level inputs.

I am not sure which method is better. I called Music-Hall and the guy (maybe it was Roy Hall but I am not sure) told me "I don’t like sub-woofers... just do what ever the sub-woofer manufacturer says".

But the JL Audio manual does not specify one method over the other.

I am new to sub-woofers, so I was hoping maybe somebody on the forum might be able to help.

Thanks in advance,

Eric Zwicky
Richmond VA


ezwicky
almarg's avatar
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almarg
9,670 posts
 
But the JL Audio manual does not specify one method over the other.
Actually, it does. On page 16 of the manual it states as follows:
Speaker Level Inputs: This feature is included for convenience when needing to connect the Dominion™ to a receiver or integrated amplifier that only offers speaker level outputs. The use of this feature is only recommended when no suitable line-level signal is available.
One reason for that recommendation might be that the "grounded/isolated switch" the sub provides, which can be useful if hum issues are present, affects just the RCA inputs and not the speaker-level inputs.

On the other hand, it is possible that the 10K impedance of the sub’s RCA inputs might be too low to be sonically optimal for the integrated amp’s pre-outs. (The output impedance of the pre-outs does not appear to be specified). Also, some people believe that in general it is best to provide the same signal to a sub as to the main speakers. So it would be preferable to evaluate it both ways.

Regards,
-- Al

ezwicky OP
26 posts
 
almarg wrote:

But the JL Audio manual does not specify one method over the other. 
Actually, it does. On page 16 of the manual it states as follows:
Speaker Level Inputs: This feature is included for convenience when needing to connect the Dominion™ to a receiver or integrated amplifier that only offers speaker level outputs. The use of this feature is only recommended when no suitable line-level signal is available.

Dang, I missed that, thanks.    So I will continue to use the RCA pre-out from my amp to the RCA in on the subs.    Thanks!
emailists
923 posts
 
Some sub manufacturers like REL suggest speaker level for better sound. On my Velodyne dd10+ Pair I think I like speaker level better, but I should try the test again. However the amps are extra special (hybrid BHK300’s - dealer for amps and subs) so that could be part of the magic.
I also run separate cables from the amp instead of piggybacking from the speaker.  
I run my mains full range and bring in the subs at 30-40 hZ.  
schubert
7,386 posts
 
Some people like atomic bomb base , some don't .
All a sub can do for me is let my speakers forget everything below 80hz .
ezwicky OP
26 posts
 
Well, I did a bunch of A-B listening, and decided the sub-woofer was not adding enough to the sound to make it worth the cost, and the prospective cost and effort of running a cable under the floor from my amp to the sub, so I returned it for store credit!     I am happy with just the sound of my speakers, but I thank you all for replying to my original post!

Eric
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