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Sub hookup question

#1
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12/15/07 at 12:15pm
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I got the polk RM6750 5.1 speaker system and a Onkyo TX-SR304 receiver. WHat would be the best way to hook up the sub to this receiver? Heres the amazon page that shows the back of the receiver amazon.com/Onkyo-TX-SR304S-Channel-Theater-Receiver/dp/B000FJKJHU/ref=pd_bbs_sr_1?ie=UTF8&s=electronics&qid=1197714553&sr=8-1
Here is onkyo's website with the specs
onkyousa.com/model.cfm?m=TX-SR304&p=s&class=Receiver

Now on polkaudio.com they say do not hook it up to the subout cause most receivers have a filter and the sub also had a filter which hurts performance. They say use a preamp out or hook it up with speaker wire using the l/r front speaker hookups. Im not sure if my receiver has a preamp output looking at the specs on onkyo's page I see this.
Output Level and Impedance
TAPE REC ----- 200 mV, 470 ohm
PRE OUT ------ 1.0 V, 470 ohm

I also see the tape out on the amazon.com picture do you think that will work for my sub hookup cause im just a little confused. I also have no idea if my receiver has a filter on the subout or not???? Help please I want the best performance. Looking at it somemore I dont think it actually has another preout except the one for the sub.

Looking at it some more my receiver doesnt have the preamp outs but im still not sure if I should just use the sub out or hook it up with speaker wire.
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#2
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12/15/07 at 1:28pm
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Re: Sub hookup question

I sounds like the Polk system does not actually use a real sub. Just because it is in it's own cabinet does not mean it is actually a sub. It is more accurately referred to as a bass module. Most likely the other speakers MUST have their signal run through the bass module first, then on to them. So, you probably need to use speaker wires from the receiver to the speaker level inputs on the bass module, then out to the speakers.

If you ever decide to also get an actual sub, you would then hook it up to the sub pre-out and configure the other speakers to "Small" and send all low frequencies to the sub.

You can NOT use a tape out for the bass module, or a sub, for that matter.


They flutter behind you, your possible pasts.
Some bright-eyed and crazy, some frightened and lost.
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#3
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12/15/07 at 1:57pm
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Re: Sub hookup question

Yeh I think I will hook it up with speaker wire for now. Would other subs not have this filter they are talking about?
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#4
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12/15/07 at 2:13pm
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Re: Sub hookup question

Polk has a lot of other subs too though and this article was talking about all their systems in general.
This is the url
polkaudio.com/education/article.php?id=19
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#5
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12/15/07 at 8:21pm
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  • Location: Wilmington, NC
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Re: Sub hookup question

Some of the Polk article is based on early HT technology trends and is currently outdated info. Even the Pioneer 516 receiver I purchased last year for $100 on BF deal has adjustable crossover frequencies down to 80hz.

If you read further down in the article, they do get it right for the most part, IMO when describing what to do with their various speaker lines. I would disagree with them about their tower speakers and even powered towers when used with a competent sub. Even multiple 7" drivers are still less effective than a single good 10" or 12" driver in a proper cabinet...it's just physics. That's not even getting into the issue that the location for your mains to image best may not be so good for the room's bass response.

As others have said and the Polk recommendations confirm, the RM bass modules have both low and high pass crossovers onboard. Likely being passive, at least on the highpass, they're likely better tuned for the RM satellites than the text book ideal electronic crossover in the receiver. That's assuming the receiver even has a selectable frequency high enough for the satellites...some of those units need 200hz settings for proper integration and protection.

Back to traditional speakers, even towers. While it is certainly possible to get a good main/sub blend using the main speaker level outs only and working with the sub's onboard crossover, it'll usually take quite a bit of tinkering. With much less effort, the average user is going to get consistenly similar and probably better results using the receiver's bass management functions and the sub preout with the sub's onboard xover bypassed or turned to its highest setting to eliminate the potential problems with cascaded xovers.

-Brent
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#6
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12/15/07 at 8:58pm
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Re: Sub hookup question

So your saying with my RM6750 setup and my Onkyo TX-SR304 you think I should run the sub off the front speaker channels and then run the satellites off the sub?
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#7
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12/16/07 at 9:36am
  • Joined: October 2000
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Re: Sub hookup question

Quote:
Originally Posted by JJay03
So your saying with my RM6750 setup and my Onkyo TX-SR304 you think I should run the sub off the front speaker channels and then run the satellites off the sub?

Based on your original post and link to the Polk "white paper", I was going to say yes. I assumed you'd already read the manual for the RM-6750 set and it agreed with the white paper.

However, I just looked at the 6750's manual and Option #1 says set the bass module's crossover to its max setting and connect it via the receiver's preamp out. Set the receiver's BM to 120hz if possible with all main speakers to small. You may want to experiment with the actual frequency selected and placement of the bass module. 120hz is directional by most anybody's standards so it'll need to be between the l/r speakers for best results.

-Brent
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#8
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12/16/07 at 10:36am
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Re: Sub hookup question

John, you relaly need to stop thinking and referring to the bass module as a sub. A sub is an optional piece of equipment intended to extend the frequency range of your system. From what I can tell (and this is not unusual) the set of speakers you have are a cohesive system and all pieces MUST be used. The bass module is an absolutely required piece of the system, just as if it was in the same housing as the satellites, just larger. You MUST run the speaker output to the bass module, then on to the satellites.

As I said before, you can also add a sub, but you MUST still use the bass module in addition to the sub.


Of course, I haven't taken the time too look this all up for you. There are MANY different speaker configurations. I am just taking from your original post, which now seems to have been rather unreliable, based on Brant's post.


They flutter behind you, your possible pasts.
Some bright-eyed and crazy, some frightened and lost.
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#9
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12/16/07 at 8:01pm
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Re: Sub hookup question

Quote:
Originally Posted by JohnRice
John, you relaly need to stop thinking and referring to the bass module as a sub. A sub is an optional piece of equipment intended to extend the frequency range of your system. From what I can tell (and this is not unusual) the set of speakers you have are a cohesive system and all pieces MUST be used. The bass module is an absolutely required piece of the system, just as if it was in the same housing as the satellites, just larger. You MUST run the speaker output to the bass module, then on to the satellites.

As I said before, you can also add a sub, but you MUST still use the bass module in addition to the sub.


Of course, I haven't taken the time too look this all up for you. There are MANY different speaker configurations. I am just taking from your original post, which now seems to have been rather unreliable, based on Brant's post.

Thanks for the reply im sending you a PM.
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