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Best way to connect a subwoofer for music listening

Jglr

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#1
I have a pair of bookshelf speakers and a subwoofer. Currently, I have the sub wired to an amp via high-in connections and out from the sub to my bookshelf speakers. Paul McGowan of PS Audio says that this is the best way of connecting everything for music, as it keeps the sub in phase with the speakers.

I just bought a new amplifier with a sub out. According to the manual that came with my sub, this is the best way to connect the sub. Unlike my current configuration, hooking it up this way allows for high level filtering. Because of how my sub is physically situated, using the sub out on the amp would be more convenient.

Which way of connecting the sub is better for music playback?
 

andreasmaaan

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#3
I have a pair of bookshelf speakers and a subwoofer. Currently, I have the sub wired to an amp via high-in connections and out from the sub to my bookshelf speakers. Paul McGowan of PS Audio says that this is the best way of connecting everything for music, as it keeps the sub in phase with the speakers.

I just bought a new amplifier with a sub out. According to the manual that came with my sub, this is the best way to connect the sub. Unlike my current configuration, hooking it up this way allows for high level filtering. Because of how my sub is physically situated, using the sub out on the amp would be more convenient.

Which way of connecting the sub is better for music playback?
I would have said line levels inputs 100% of the time unless high-level outputs are all that's available.

I'd be interested to hear what our old mate Paul has to say though, if you have a link? :)
 

Jglr

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#4
I would have said line levels inputs 100% of the time unless high-level outputs are all that's available.

I'd be interested to hear what our old mate Paul has to say though, if you have a link? :)
I think I may have seen it elsewhere, but he begins discussing it at about 5:35 of this video:
 

Jglr

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#5
I would have said line levels inputs 100% of the time unless high-level outputs are all that's available.

I'd be interested to hear what our old mate Paul has to say though, if you have a link? :)
Here's where I saw it originally. He goes into more detail:
 

GGroch

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#6
..... Paul McGowan of PS Audio says that this is the best way of connecting everything for music, as it keeps the sub in phase with the speakers.....Which way of connecting the sub is better for music playback?
Interesting question, I would love to see the pros and cons.

Initial thoughts:
- When you are hooking up a powered sub, you are never certain the polarity will be the same as your speakers, regardless of how you hook them up. I would assume if an amp has sub out that output would be in phase with its speaker outputs...but the sub could be wired out of phase with your speakers.

- Almost all subs have phase switches or knobs, that you can adjust by ear if you take the time to do it.

- Many amps with sub outs provide high pass/low pass options. This is almost always the case with AV Receivers. If yours has that you will probably want to use the sub out...particularly if you are using an amp with auto room compensation.
 

Ron Texas

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#10
My amp is an Onkyo A9110 stereo amp. It doesn't have room correction or an option to specify the size of my speakers.
Use the sub out anyway. Check and see if there are any options to set a crossover point or if there is any way to roll off the mains.
 

andreasmaaan

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#11
@Jglr, there would only be a problem if you're running a line-level output that has already been filtered into a sub-woofer input that is filtering the signal again. So long as you're line level input to the sub has not already been filtered, line-level is the best way to do it.

What's your setup? We can help you find the optimal way to do it.
 

PierreV

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#13
My amp is an Onkyo A9110 stereo amp. It doesn't have room correction or an option to specify the size of my speakers.
I've just had a look at the manual of your amplifier. I wouldn't worry too much about what McGowan says in this case.

Your amplifier has a LFE out and that is probably what you should use, but that depends somewhat on the sub-woofer you used (can you adjust the cutoff frequencies?). If your sub cutoff can be adjusted, just look up the response curve for speakers and adjust it around that.

In my home theater, I use to SVS PB2000, set them to LFE and adjusted the cutoff frequency in the AVR after looking at the frequency response curve of my main L&R speakers. If I had not been able to adjust that in the AVR, I would have adjusted at the subwoofer, but not all subwoofers support it.
If I hadn't been able to adjust the AVR or the subwoofers, I guess I would have measured and corrected with some equalization on the roon stream.

In my main systems, where I don't have LFE out and where I use SVS SB16 ultra, I just hooked the subs to the pre-amp/line out RCA in one case and balanced preamp out in the other case. I then used the SVS recommended setting for my speakers and I am reasonably happy with the result.

Going back to McGowan's video, while I wouldn't say he is your typical con-artist, I feel that some of the things he says are questionable. Many people here will question the affirmation that well-measuring amps and preamps sound different (in theory, they should not, but amp-speaker matching is the real world issue imho) but even if we accept that they do, it won't matter much compared to positioning and room effects.

I would love to see a DBT where two amps are compared driving subwoofers only :):)

The phase issue can be complex and generate endless debates, but again I feel it is a bit secondary for bass (vs room positioning) unless some kind of processing introduces unfortunate delays and that it will again matter less than room positioning. SVS subs can adjust phase, and yes, one can find positions where you can almost cancel it but most minor shifts are inaudible imho.
 

Jglr

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#15
Thanks everyone for the helpful advice. It seems practical to use the subwoofer out.

I am a little confused about where the signal crossover should be controlled in my setup. I do have a crossover control on the subwoofer, but it is unclear to me whether my amp will only send low frequencies to the sub or the whole signal. I plan on using the amp in direct mode with the sub out activated.
 

PierreV

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#16
Thanks everyone for the helpful advice. It seems practical to use the subwoofer out.

I am a little confused about where the signal crossover should be controlled in my setup. I do have a crossover control on the subwoofer, but it is unclear to me whether my amp will only send low frequencies to the sub or the whole signal. I plan on using the amp in direct mode with the sub out activated.
On the subwoofer. I can't find any info on what you LFE outputs and it seems the crossover frequency isn't user configurable anyway. So what are your main speakers?
 

Ron Texas

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#17
Thanks everyone for the helpful advice. It seems practical to use the subwoofer out.

I am a little confused about where the signal crossover should be controlled in my setup. I do have a crossover control on the subwoofer, but it is unclear to me whether my amp will only send low frequencies to the sub or the whole signal. I plan on using the amp in direct mode with the sub out activated.
Normally, sub out only sends low frequencies.
 

GGroch

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#18
......it is unclear to me whether my amp will only send low frequencies to the sub or the whole signal. I plan on using the amp in direct mode with the sub out activated.
Jglr, I just read through the full manual and I am probably more confused than you on this. No where does it say whether the sub out is filtered. Outputs labeled LFE are almost always filtered..but sub outs you never know. If you have a powered full range speaker of any kind you could connect it to the sub output and listen to see if you get full range or just bass.

The manual is confusing on the Subwoofer "Auto/On/Off" as well. It says:
Auto : The subwoofer signal is not output when the DIRECT function (p11) is on.
On : The subwoofer signal is always output.
Off : The subwoofer signal output is stopped, and the effect on sound quality can be moderated within the unit. It is recommended to set this off if you are not using a subwoofer.

So, if you choose Auto the sub out will not be active in Direct mode.
I have no idea what Off "the effect on sound quality can be moderated within the unit" means.

If that isn't enough to scare you, read their explaination of the "Phase Matched Bass" function. I think it is a 3dB bass boost for listening at low volumes...but I had to figure that out through google, not the manual.
 

andreasmaaan

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#19
@Jglr, just use the line outputs from the amplifier IMHO. The subwoofer will mix the two channels to mono. That will avoid doubt regarding whether the amp is pre-filtering the output.
 

Jglr

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#20
@Jglr, just use the line outputs from the amplifier IMHO. The subwoofer will mix the two channels to mono. That will avoid doubt regarding whether the amp is pre-filtering the output.
I was thinking the same thing. Is it better to use the crossover on the sub? Also, could I test to see if the subwoofer out is bass only by raising it's crossover to 40hz and playing a higher frequency tone through the system? Presumably, if it plays to the amp is sending the whole signal.
 

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