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Best way to hook up sub to a two channel system

post #1 of 32
Thread Starter 
I recently purchased a pair of B&W CM5 along with a Rotel RB1552 amplifier.
I'm using a Nuforce HDP as the preamp (2 channel RCA output). I'll be adding a subwoofer to the setup (either Hsu, SVS, or Rythmik).

The problem is there is no subwoofer output from the preamp so what's the best way to hook up the sub without degrading the audio signal?

I see a couple of options:
1. Run RCA Y splitters from the preamp. Two channels going to the amp and two channels to the sub's line level input

If I go with the SVS (SB13) I can run the output from my preamp to the line level input of the SB13; line level ouput of the SB13 to the input of the amp... but will that affect audio quality?

2. Line output from preamp to amp, then speaker level output from amp into the sub's speaker level input, then speaker level output from sub into speakers.

3. Line output from preamp to amp, then speaker level output A from amp to speakers, speaker level output B from amp to sub speaker level input.

4. Line output from preamp to amp, then amp's speaker output A's left channel to left speaker AND sub's left speaker input, amp's speaker output A's right channel to right speaker and sub's right speaker input.

From those options, which is the best?
post #2 of 32
I found best to run speaker wire from the power amp speaker terminals to the speaker terminals (high level input) on my SVS sub and to the speakers. The load of the sub will not stoff up the power amp. This way they matched in perfect.
post #3 of 32
Thread Starter 
Are you talking about doing something like this?
LL
post #4 of 32
That is it. Then you need to set the sub x-over freq and level. Don't forget phase and room size on the svs as well.
post #5 of 32
Buy a x-over like this Behringer CX2310.

The L/R outputs from the pre-amp go into it and the L/R high pass signals go from it to the amp, and the mono (or stereo if you buy 2 subs) low passed signal go to the sub.
post #6 of 32
I have a very nice Paradigm external crossover (might be interested in selling it--it's not in use). The preamp outputs connects to it, and there are several sets of outputs to connect to two subs. The Paradigm device contacts to the amp, but the frequencies below to crossover point go to the sub. The device has a volume control and a variable phase dial.
http://www.scowcroftandassociates.co...Literature.pdf
post #7 of 32
I have a sugestion for you. I would y split from preamp. In addition to that, i would consider a technique suggested from Dave of ascend, by plugin the port of your front. See this page for detail http://forum.ascendacoustics.com/showthread.php?t=3781 egarding Q plug A.
This may or may not work with your set up, but at least it wont cost you anything just to try it or maybe just abit finding the right plugs.
post #8 of 32
Thread Starter 
I decided to go with the svs sb13 (no speaker level i/o). Will either be splitting the signal at the preamp or use the SVS built in high pass filter out to amp.
post #9 of 32
Quote:
Originally Posted by tike71 View Post

I decided to go with the svs sb13 (no speaker level i/o). Will either be splitting the signal at the preamp or use the SVS built in high pass filter out to amp.

Good plan!
post #10 of 32
I also don't have sub out fom my preamp. I use a REL T-7 sub. It includes high level inputs and the cable that connect to the speaker outputs of my power amp. Works beautifully and seemlessly with my speakers. You can't tell the sub is there, but you can really tell it improves the overall quality.
post #11 of 32
Quote:
Originally Posted by RaceTripper View Post

You can't tell the sub is there, but you can really tell it improves the overall quality.

Assuming it is properly equalized with the rest of your system and you don't have a bad null or peak at your listening position, that's exactly how you want to integrate your sub. I like mine like that too.

IMO too many people seem to run their subs too hot, and too many of them like it that way. It's OK to like it that way, but that's not really how someone integrating a sub and looking for a flat FR ought to approach it. The sub should blend in unnoticed, like you said, and do its duty of handling the lower frequencies below about 80 Hz.
post #12 of 32
Thread Starter 
The frequency range for my bookshelfs are 52Hz-22kHz... should I set the crossover on the sub to 63Hz or 80Hz?
post #13 of 32
Quote:
Originally Posted by tike71 View Post

The frequency range for my bookshelfs are 52Hz-22kHz... should I set the crossover on the sub to 63Hz or 80Hz?

Try the lower setting first. Most people set their xover too high.
post #14 of 32
Quote:
Originally Posted by tike71 View Post

The frequency range for my bookshelfs are 52Hz-22kHz... should I set the crossover on the sub to 63Hz or 80Hz?

I would set it to 80Hz.

- the sub is better in that range

- a crossover is not a brick wall, some above 80 will go to sub and some below 80 will go to mains

- removing the 80Hz and lower lets both the amp and mains operate with less stress
post #15 of 32
Thread Starter 
I'll test the low pass filter at 63hz and 80hz and use whichever sounds better and play around with the high pass filter a little.
post #16 of 32
Quote:
Originally Posted by tike71 View Post

The frequency range for my bookshelfs are 52Hz-22kHz... should I set the crossover on the sub to 63Hz or 80Hz?

Set wherever it sounds best. Try all the different increments to find out what's going to work best for you with your gear in your room. Ideally lower is better when you want to run subs hot as far as crossovers go.
post #17 of 32
Quote:
Originally Posted by tike71 View Post

I decided to go with the svs sb13 (no speaker level i/o). Will either be splitting the signal at the preamp or use the SVS built in high pass filter out to amp.

Quote:
Originally Posted by tike71 View Post

The frequency range for my bookshelfs are 52Hz-22kHz... should I set the crossover on the sub to 63Hz or 80Hz?

So, how you connect the sub is important. I assume you are saying that the sub has pre-amp level outputs that you know are high-passed. At what frequency are they high-passed? This would be very important, not necessarily in determining at exactly what value to set the sub's low-pass filter (it's not a crossover, btw), but in dictating what low-pass filter setting is best for your particular setup in your particular room. If you are going to use the sub's high-pass filter, then you would probably want to adjust the sub's low-pass more appropriately for whatever frequency your speakers are being high-passed. If you are not going to high-pass off of the sub, then you would want to adjust the sub's low-pass frequency to something that is probably closer to your speaker low-end capability.

In either case, though, you will want to adjust the sub's low-pass filter setting empirically to whatever provides the best measured response or to whatever provides the sound that is most pleasing to you (these may or may not be the same thing). Because of the effects of the room, no matter how you connect the speakers (high-passed or not), what setting for the sub's low-pass is best may not be so intuitively apparent. There is no correct answer to where, exactly, to set the sub's low-pass filter in either configuration.


EDIT: Yes, I see now that the sub has adjustable high-pass filter settings. Nice. But you'll have a lot of stuff, there, to fiddle with. Yikes. The frequencies of both the high and low-pass filters as well as their respective slopes. Bear in mind that the best setting for the frequency of each filter and their slopes may or may not necessarily be identical. Your room and listening preference will dictate this.
post #18 of 32
Thread Starter 
Decided not to use the high pass filter from the sub and just split the signal at the preamp. Bass transition from speaker to sub sounded best with the low-pass filter set at 80hz with -12db slope.
post #19 of 32
post #20 of 32
You'd think that to bump an 18mo thread you'd put in something useful.
post #21 of 32
Quote:
Originally Posted by A9X-308 View Post

You'd think that to bump an 18mo thread you'd put in something useful.

The unsubscribe option can be useful. tongue.gif
post #22 of 32
Quote:
Originally Posted by A9X-308 View Post

You'd think that to bump an 18mo thread you'd put in something useful.
I think there must be something broken with search results on the forums or something, because this has been happening a lot for the last month or so.
post #23 of 32
Quote:
Originally Posted by tike71 View Post

Decided not to use the high pass filter from the sub and just split the signal at the preamp. Bass transition from speaker to sub sounded best with the low-pass filter set at 80hz with -12db slope.

Been there, did something like that for a while.

Eventually I moved to using an AVR with true bass management, and it was a big step up.

Using a HP filter saves the LF & RF speakers from struggling with bass and makes them sound much cleaner.

You should set the crossover to as high of a frequency as you can without messing up the soundstage by having the subwoofer give cues to its location. This turned out to be 80 Hz for me.
post #24 of 32
Quote:
Originally Posted by arnyk View Post

Been there, did something like that for a while.

Eventually I moved to using an AVR with true bass management, and it was a big step up.

Using a HP filter saves the LF & RF speakers from struggling with bass and makes them sound much cleaner.

You should set the crossover to as high of a frequency as you can without messing up the soundstage by having the subwoofer give cues to its location. This turned out to be 80 Hz for me.

That may be fine if you have an AVR for digital playback. Don't they use a DSP for bass management?

But it's different with a two channel system, which is what this thread is about, especially if it's used for analog playback. I use a REL in a mostly analog two channel system. REL recommends using as low as a crossover point as possible, which is what I do, just to provide bass extension to my speakers, and not to take over any bass it is already capable of. If I turn the crossover even a little bit high (am at about 33 Hz) then the midrange loses definition and detail. I have an old Harmonia Mundi recording (analog LP) of the Bach Toccata and Fugue in D Minor that demonstrates this very well.
post #25 of 32
Quote:
Originally Posted by RaceTripper View Post

That may be fine if you have an AVR for digital playback. Don't they use a DSP for bass management?
But it's different with a two channel system, which is what this thread is about, especially if it's used for analog playback.
You don't need an AVR; an external xover does what is needed and it doesn't need to be digital..
Quote:
Originally Posted by RaceTripper View Post

I use a REL in a mostly analog two channel system. REL recommends using as low as a crossover point as possible, which is what I do, just to provide bass extension to my speakers, and not to take over any bass it is already capable of.
Irrespective of what REL say, that's the wrong approach, but one that suits them because of what they sell. Get the LF out of the L/R speakers and you'll reduce distortion considerably. Where is best to cross to mains depends upon the mains and where they start to run out of volume displacement at LF.
post #26 of 32
Quote:
Originally Posted by A9X-308 View Post

You don't need an AVR; an external xover does what is needed and it doesn't need to be digital..
Irrespective of what REL say, that's the wrong approach, but one that suits them because of what they sell. Get the LF out of the L/R speakers and you'll reduce distortion considerably. Where is best to cross to mains depends upon the mains and where they start to run out of volume displacement at LF.

A higher crossover sounds worse with my speakers and sub. I tried it. I agree with REL and my dealer on setup of their subs.
post #27 of 32
Quote:
Originally Posted by RaceTripper View Post

Quote:
Originally Posted by arnyk View Post

Been there, did something like that for a while.

Eventually I moved to using an AVR with true bass management, and it was a big step up.

Using a HP filter saves the LF & RF speakers from struggling with bass and makes them sound much cleaner.

You should set the crossover to as high of a frequency as you can without messing up the soundstage by having the subwoofer give cues to its location. This turned out to be 80 Hz for me.

That may be fine if you have an AVR for digital playback. Don't they use a DSP for bass management?

Sure they do. You can come up with a pretty good duplication of what an AVR does with the right 2-channel 2-way electronic crossover.

Quote:
But it's different with a two channel system, which is what this thread is about, especially if it's used for analog playback.

I don't know why analog playback would make a difference, unless by analog you mean LP in which case you are dealing with lower basic sound quality due to the well-known audible limitations of the LP.

As questionable as LP playback is, I think it would still benefit from clean bass response, which is what you avoid when you feed low bass into your main speakers.
Quote:
I use a REL in a mostly analog two channel system. REL recommends using as low as a crossover point as possible, which is what I do, just to provide bass extension to my speakers, and not to take over any bass it is already capable of.

The questionable thinking there being that just because speakers have some kind of response at low frequencies doesn't mean that it is clean response.
Quote:
If I turn the crossover even a little bit high (am at about 33 Hz) then the midrange loses definition and detail.

Pushing a source with inherent LF noise such as the LP through a 6 1/2" woofer is like asking, no demanding audible IM distortion.

I suspect that you are confusing modulation of the midrange with LF noise and low notes with "Definition and detail".
Quote:
I have an old Harmonia Mundi recording (analog LP) of the Bach Toccata and Fugue in D Minor that demonstrates this very well.

More likely you are seeking a familiar rendition of IM distortion from your previous system as opposed to clean sound. 33 Hz is way, way too low for CM5s.
post #28 of 32
I wasn't talking about CM5s. I have never had nor heard them.

My observations on my system are not just with analog playback, but digital as well. It doesn't matter. I have my system dialed in to what sounds best to me. I don't believe you can really tell me what I am hearing when you have not heard my system. Even my dealer understands he has to come and listen to make any kind of useful assessment.
post #29 of 32
Quote:
Originally Posted by RaceTripper View Post

I wasn't talking about CM5s. I have never had nor heard them.

My observations on my system are not just with analog playback, but digital as well. It doesn't matter. I have my system dialed in to what sounds best to me.

What sounds best to you can change as your listening becomes more fully informed.
Quote:
I don't believe you can really tell me what I am hearing when you have not heard my system.

If your system contains some from-outer-space, violates-all-of-the-rules-of-physics secret sauce, then that would be true. The sound of small woofers getting too much LF has a particular signature.
Quote:
Even my dealer understands he has to come and listen to make any kind of useful assessment.

If he is unbiased then that would be:

(1) A good thing
(2) A rare occasion.
post #30 of 32
Quote:
Originally Posted by arnyk View Post

What sounds best to you can change as your listening becomes more fully informed...

I've been listening to music live and recorded for 40+ years (including seven years in undergrad/grad music programs). My listening isn't going to get much more fully informed than it is now.
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