Running a sub with 2 channel . . .

**Bent** · 25 October 2004, 20:29 Monday

I'd say I agree that a sub is a necessity.
You can get better bass by having the sub in the "correct" place in your room - this "correct" place, likely a corner, is not likely the best place for onew of a pair of mains.

if you don't like "boom",move the sub around till you like it - I have lived without a sub for almost two weeks now, and I am really starting to miss having one. (But not for long....)

**Bam!** · 25 October 2004, 20:56 Monday

...have you tried using a simple speaker wire into the high pass of the sub.....hence keeping the speakers independant....hence using the sub below 40 hz......at very low volume.....

**NMG** · 25 October 2004, 21:55 Monday

Hey Bam!,

I'm a little slow tonight so please forgive me

I'm not exatcly sure I'm understanding your connection suggestion. Right now I'm running interconnects from the preouts on my preamp to the low level inputs to give the sub the signal. The only way I could see to activate the high pass output was to run interconnects from the sub back to the amp (there are no speaker wire inputs on the PW-2200).

I did try setting the crossover down to 50hz (that was the lowest setting on the back of the sub) but there was still a pretty noticeable gap between where my mains went down to and where the sub kicked in. I do have my main speakers out from the back and side walls a fair amount so that may be a factor in the type of bass response I am getting from them. The sub is close to a corner along the back wall of my room behind the main speakers.

Edit: Oops . . . I just checked my sub and there ARE speaker level inputs and outputs (which would activate the high pass filter).

**Chris D** · 25 October 2004, 22:26 Monday

If you're getting a crossover gap, I think you're going to want to turn your sub x-over setting UP, not down. Try it around 80Hz, and play with it. If you keep turning it down, you're just going to cut out more and more mid-range bass.

**NMG** · 26 October 2004, 02:37 Tuesday

Chris you are bang on. I actually have my crossover set at 70hz and everything blends together VERY well. I tried it at 50hz to start (minimum setting) because I figured that may have been okay since my speakers were getting the full signal. This wasn't the case and I did have to bump the crossover up until the sub balanced everything out.

I'd be interested to try my main speakers in a smaller room or with different positioning because I'm honestly a little surprised that I need the crossover setting that high. I suspect in a little different envirnoment, I wouldn't need it that high. I guess that the beauty of having a seperate sub. The flexibility of how it can be tailored to integrate with everything else is very nice.

**David Meek** · 26 October 2004, 09:37 Tuesday

Hi Neil, I too am running a sub with my full-range mains. My Aerial Acoustics 7Bs play down to the mid-30s, so I've got my Velodyne FSR-15 filling in the lowest octave or two. I've set my mains to FULL and set the sub's highpass filter to limit it to 45 Hz on down. That's given me the smoothest transition to date.

Absolutely experiment with your speakers' placement. You'll be very surprised at what a few inches of movement and a little change in the toe-in can do to alter the sound in your room. Hehe, it never ends. . . .

**ajpoe** · 26 October 2004, 10:29 Tuesday

NMG, I too have Paradigms (Studio 60s) and I run subs with my 2 channel DAC1 setup. My buddy has a full Athena SCT Series speaker system which incorporates powered subs with satellites into a single tower speaker that is full range. I liked it so much that I had to get the subs... I now have a P3 on each one of my 60s so they are basically running together as a full range speaker. I was surprised that even though the Paradigms do have pretty low extension, they need a sub to help. So surprised that I talked to my dealer about it. He told me that it could have something to do with the room but even in a pretty ideal situation, they really only play flat down to around 50-55 hz. I believe I have my subs dialed in around 70-80 hz and when I run a sine wave, I cannot tell when the sound crosses from the sub to the 60. I would say that you are just fine running your sub in 2 channel. It really all comes down to what makes you happy, and it sounds like the sub does this for you. I know they do for me. There are a lot of people that refuse to use a sub in 2 channel... I don't get it either, but I guess it's their preference.

AJ

**Bam!** · 26 October 2004, 17:14 Tuesday

...I'd just like to add that while the paradigms do go down pretty low.....55 - 60 hz...the sub IMO should be to fill in the really low bass....like 55 and below.....overlapping the frequencies makes sloppy and boomy bass IMO......also dynamically you can play the volume relatively lower and have great impact when listening to music with a sub....

....for vinyl listening the detailing in the bass extension is even better with the sub on than on redbook......but that's just a :lol: add on I thought I'd throw in....

**Bruce** · 26 October 2004, 17:59 Tuesday

overlapping the frequencies makes sloppy and boomy bass IMO

This can be caused by an incorrectly implemented crossover and room modes.

As an example, many systems use ported mains which have an acoustic rolloff or slope (reduced SPL levels) anywhere from 18dB-36dB/octave at their f3 or low frequency extreme.

This makes it pretty tough to match with whatever crossover is provided on the sub , which many times has a 12dB, or 24dB/octave slope.

The final objective is to produce a seamless bridge between the two driver systems (mains and sub) below, at, and above the crossover frequency. This is very difficult to impossible with mismatched filter slopes as indicated above.

I've found the best way to implement this setup is to use a separate electronic crossover with symmetrical 24dB/octave slopes about one octave above the main speakers f3 (low frequency spec). This minimizes the effect of the main speakers low frequency rolloff on the crossover, making for a more seamless transition. Of course this is only my opinion, but this is a pretty common solution for integrating subs on the forums.

For instance in my case, my main towers have an f3=32Hz. I use an electronic crossover set to 60Hz and turn the crossover in the sub off. This provides the smoothest transition between mains and sub in my room. I did lots of measuring to arrive at this solution.

**Bam!** · 26 October 2004, 18:46 Tuesday

Originally posted by Bruce

This can be caused by an incorrectly implemented crossover and room modes.

As an example, many systems use ported mains which have an acoustic rolloff or slope (reduced SPL levels) anywhere from 18dB-36dB/octave at their f3 or low frequency extreme.

This makes it pretty tough to match with whatever crossover is provided on the sub , which many times has a 12dB, or 24dB/octave slope.

The final objective is to produce a seamless bridge between the two driver systems (mains and sub) below, at, and above the crossover frequency. This is very difficult to impossible with mismatched filter slopes as indicated above.

I've found the best way to implement this setup is to use a separate electronic crossover with symmetrical 24dB/octave slopes about one octave above the main speakers f3 (low frequency spec). This minimizes the effect of the main speakers low frequency rolloff on the crossover, making for a more seamless transition. Of course this is only my opinion, but this is a pretty common solution for integrating subs on the forums.

For instance in my case, my main towers have an f3=32Hz. I use an electronic crossover set to 60Hz and turn the crossover in the sub off. This provides the smoothest transition between mains and sub in my room. I did lots of measuring to arrive at this solution.

That's really good Bruce....and with that method and understanding......adding a sub in your 2 channel listening is super...

**Meat_PoPs** · 08 November 2004, 15:34 Monday

When incoporating a subwoofer into a system, phase coherency can be greatly affected by the sub's position aswell. Changing the direction the sub is facing, or position, even mildly can affect coherency aswell as room extension. At one point I spent no less than 7 hours just playing with small position changes of a system made up of a pair of adc soundshaper sattelites and a custom built 15" subwoofer. The sub and sat's had a pretty decent hole in responses (adc's down to 150hz flat, 100hz pushing it, sub up to 70hz flat, 90 pushing it). After all that play, I managed to make it coherent without any noticeable change when playing sine sweeps.
Of course, when wanting to impress friends enabling the sub band eq and making random objects dance across tables, and neigbours call police is fun, but not necessarily good sounding

**TTA89** · 08 November 2004, 17:37 Monday

I dont understand why you would set the Mains to Large and run them down full range only letting the sub do the very bottom. It doesn't make sense to me if you have a decent sub?

I cross mine at 80hz and figure it probably takes a load off the Reciever and the Speakers from having to reproduce the deep bass. The Sub has a 250 watt amp in it, why not let the sub do what its supposed to do? If you have it setup correctly you shouldnt hear the sub at all. I just don't understand why you would run all 3? I mean if you want more bass, turn up the sub and take some load off the receiver.

**NMG** · 08 November 2004, 18:47 Monday

Hey TTA89,

The only advantage I can think of when running the mains full range (and it might be insignificant) is that you get a "direct" signal from your source to your speakers without running it through the filters on the sub first. I suppose it is possible to have some degredation of the signal if you are going through the sub before coming back to the amp and then to the speakers. I suppose it might be easier to blend the two together as well, but like you said, if you have a decent sub, it shouldn't be a problem doing that with an 80hz crossover point. I know for a fact that my 2200 does a better job of bass output than my Studio 80's and it should seeing as how that is its sole purpose in life

I tried running the mains full range (what I'm doing right now) and high-passed and I thought there was a little more detail running the mains full range but it could be all in my head as well. It certainly wasn't night and day.

It also helps that my amp has no problem controlling my main speakers as far as bass output goes. If I were using a lesser amp, I'd high pass for sure. There are some pretty good arguments to be made for relieving the mains of lower bass output like you have suggested. I think allot of it comes down to personal taste and/or room and speaker interactions.

**ajpoe** · 09 November 2004, 00:40 Tuesday

I would cut the lower freqs off to my mains (and surrounds for that matter) if I had a good, inexpensive way of doing it. I believe it was Thomas who suggested I get the Paradigm X-30 to use as a high pass filter. In the HT section, I had asked about cutting the low freqs out of all my channels that have subs, one on each except my center. That would mean 2 X-30s and $600. I had originally asked about the FMOD high pass inline RCA filters to put on the inputs of my 1075 and cut the low freqs out of the Paradigms but Thomas said those are affected somehow by the amplifier and are really only meant for car audio.

I guess from what I've read in this thread is that the seemless transition from my sub to my main when using a sine wav isn't really seemless? I use SweepGen via my HTPC which feeds through my DAC1. I don't feel that I have boomy bass... I originally asked about cutting the lower freqs b/c I thought it might give me some more detail or clarity.

Right now I run a full range signal to my subs via subwoofer cables and to my amp via the interconnects by using Y adaptors. I use the built in crossover in the sub to blend into the mains (and surrounds), but I can't use the crossovers built in my 1068 for my mains because of the way I have it setup. Does anyone else have some creative ideas? Overall, I am very happy with my setup but I am wondering if there is something more I can squeek out of it.

AJ

**NMG** · 09 November 2004, 04:45 Tuesday

Well I played around with my sub settings tonight and got an even better blend between my sub and mains. I experimented with the phase setting and as a result, I'm now running the sub crossover at around 55-60hz and the volume is also down from where it was. I'm still feeding both my mains and sub a full range signal. I'm not exactly sure why adjusting the phase seemed to make such a difference, but it definitely bumped up the output on the sub to the point that I had to make some adjustments . . . it was overpowering my mains way too much. I figure I must have had some cancellation at the listening position before or something else. Oh well, I'm happy now

ajpoe, do your Athena subs have the ability to output a high pass signal back to your amp? That's how I did have my PW-2200 hooked up before (rolled off signal to the mains) and it worked well. I think the bottomline is that as long as you take the time to adjust everything, you can indeed get a pretty seamless blend with both your mains and subs getting a full range signal.

I'd be more concerned about rolling the bass off to your mains if you had bookshelf speakers or a much smaller amp driving them and hence you were concerned about it's ability to drive them cleanly at higher output levels. I wouldn't think you'd have any concerns with your Studio 60's or 1075 in those regards.

**TTA89** · 09 November 2004, 10:04 Tuesday

Originally posted by NMG

Hey TTA89,

The only advantage I can think of when running the mains full range (and it might be insignificant) is that you get a "direct" signal from your source to your speakers without running it through the filters on the sub first. I suppose it is possible to have some degredation of the signal if you are going through the sub before coming back to the amp and then to the speakers.

I'm not sure I understand what you mean? I don't run anything through the sub. I have 5 powered Speakers L,R,C,LR,RR and a Sub connected by a subwoofer cable on the Preout of the reciever. The Sub has its own 250 Watt Amp in it.

I tell the reciever to cross all channels at 80hz so the Sub gets the 80hz and below only. Nothing is going through the sub to something else. No filters.

**ajpoe** · 09 November 2004, 12:31 Tuesday

The Athena subs were designed to run with the Athena satellites attached to the top of them. They have 3 settings, 1 that sets the optimal crossover point in the sub for the S2 satellite, 1 that sets the optimal crossover point for the S3 satellite and then one that is for just using it as just a sub and a dialed crossover to blend. Unfortunately, the S2 and S3 are designed to run full range with the sub so there is no high pass filter to run through before going to the mains. My Polk sub in my bedroom has a high pass option that I use with my Paradigm Atoms. I run the speaker wire from the receiver to the Polk, then to the Atoms. It has a 80hz cut off so my Atoms don't have to try to play those low freqs. It does pretty well for a bedroom setup.

As I had said before, I am very happy with my system but was interested in trying to make some tweeks just to see how much more I could get out of it. The 1075 is plenty of juice, I just thought that if I could take some of the lower freqs out of the Paradigms, it might give me some more clarity and take some stress off the 1075 (even though it doesn't seem to be stressing at all). I have already played around with the phase and dial settings on the subs to get the best blend I could. I used the sine wav program to see if my ear could detect any gaps, booms, or cancellations. While it isn't perfect, neither my buddy or I could tell when the sound moved from the subs to the mains. Also, I am not able to move the subs around too much because this setup is in my main living room and I am concerned with how it all looks too. They are currently just sitting right beside my studio 60s (about a fist size space between them) facing foward. The actual sub is down firing.

AJ

**NMG** · 09 November 2004, 13:53 Tuesday

Originally posted by TTA89

I'm not sure I understand what you mean? I don't run anything through the sub. I have 5 powered Speakers L,R,C,LR,RR and a Sub connected by a subwoofer cable on the Preout of the reciever. The Sub has its own 250 Watt Amp in it.

I tell the reciever to cross all channels at 80hz so the Sub gets the 80hz and below only. Nothing is going through the sub to something else. No filters.

Hey TTA89,

I was talking more about a 2 channel system (where you don't have bass management features built into the amp or processor) where you would run the preouts to the sub and then use the subs high pass filter (to cut the low frequencies to the main speakers) to run your cables from it back to the amp. My old Integrated amp only had one set of preouts so if I wanted to use the high pass feature, the signal was "interrupted" in the sense that it went to the sub before getting back to the speakers. I'm not sure how much (if any) signal degredation there wouldv'e been. Like I said, I thought I could detect a little but I certainly wouldn't bet my gear on it

My new preamp has 2 sets of preouts so I don't really have to worry about it, the signal goes right from the preamp to the amp (with the second preout used to the sub). I'm not cutting the low bass to my mains in this setup. I would think that a dedicated processor or a seperate crossover unit would be more capable of performing the filtering task than the sub controls.

ajpoe, I can't think of much more that you could do. I know that generally speaking, you get the most bass output from a corner placement and that you tend to get more accuracy if you get them out from the corners. Much depends on room dynamics though. You could spend days trying to get that "perfect" positioning.

**ajpoe** · 09 November 2004, 14:15 Tuesday

Originally posted by NMG

ajpoe, I can't think of much more that you could do. I know that generally speaking, you get the most bass output from a corner placement and that you tend to get more accuracy if you get them out from the corners. Much depends on room dynamics though. You could spend days trying to get that "perfect" positioning.

Yeah, that's why I'm thinking I should just put up the white flag and be happy with it. When I had a .1 sub, I put it in the corner... but since I'm running 4 now I don't need to worry about that. May be I'll eventually get a dedicated room set up so I can move things around a bit more freely. I have space in the basement to do a small HT room but I'm torn as to whether I want to do that or not.

The bottom line is that having the subs running with my mains while listening to 2 channel is a big improvement IMO over just running the Studio 60s and no sub. But, there is always more to learn in the hobby/addiction and I'm always open to reading more ideas and suggestions.

AJ

**NMG** · 09 November 2004, 14:23 Tuesday

Originally posted by ajpoe

The bottom line is that having the subs running with my mains while listening to 2 channel is a big improvement IMO over just running the Studio 60s and no sub. AJ

I would agree with you 150% on that one :T

I'd love to get a dedicated listening room so I could "play" with everything all over again . . . LOL.

**Bruce** · 09 November 2004, 20:40 Tuesday

One way to get a 5.1 (or 7.1) and 2-channel system to work well with sub(s) is to set the Surrounds and Center to Small (xover=80Hz?), the Mains to Large, the Sub=NO, and put a single stereo electronic crossover from the main L&R preouts between the Mains and sub(s). This sends all LFE bass and re-directed bass from ALL small speakers to the L&R Main preouts.

If you have Large Mains (f3=30Hz or less), then this allows you to use a symmetrical electrical crossover (preferably a 24dB/octave L-R) between Mains and sub(s) and tune/select the crossover frequency to match your speakers and room. For Mains with an f3=30Hz, a xover @60Hz (1 octave higher) works well.

This also allows the sub to be used for 2-channel as well as multichannel HT without changing any settings.

I have found this method provides the best integration of a sub(s) with the main speakers, IMO.

I have no connection with Marchand, but have been a happy satisfied user for the last 5 years of an XM9-L crossover.

Here is some info on Marchand xover modules, you need one module for the L-channel and one for R-channel plus some kind of power supply:

XM1-K Electronic Crossover Kit + manual and all parts $ 25.00
XM1-A Electronic Crossover Assembled and tested $ 30.00

link to Marchand info http://www.marchandelec.com/xm1.html

**Meat_PoPs** · 11 November 2004, 17:22 Thursday

Originally posted by Bruce

One way to get a 5.1 (or 7.1) and 2-channel system to work well with sub(s) is to set the Surrounds and Center to Small (xover=80Hz?), the Mains to Large, the Sub=NO, and put a single stereo electronic crossover from the main L&R preouts between the Mains and sub(s). This sends all LFE bass and re-directed bass from ALL small speakers to the L&R Main preouts.

The only possible problem I can see out of this is an extra crossover pass and a decent amount of extra processing. You are now mixing an lfe signal (and lf component of 3 other channels) in with the mains, which is then being passed through another crossover. Interaction between the two crossover networks due to differing crossover points and slopes is going to be unavoidable, and you will be introducting quite a bit of phase shift from the networks. It IS a good solution, but not the best. I've used that settup in the past myself, and was happy with it.

**Bruce** · 11 November 2004, 18:54 Thursday

You are now mixing an lfe signal (and lf component of 3 other channels) in with the mains, which is then being passed through another crossover. Interaction between the two crossover networks due to differing crossover points and slopes is going to be unavoidable, and you will be introducting quite a bit of phase shift from the networks.

The DD/DTS algorithms running on the DSP chips are designed to handle re-directing bass. In the case I described, I'm not sure where you see an interaction between two crossovers and two crossover slopes. The algorithm in the DSP chip handles the bass manipulation and sends the resulting combined homogenous signal out through the L&R preouts.

I simply take that homogenous output signal from the L&R preouts and run it through a Linkwitz-Riley zero degree angle offset (actually 360 degree = very slight group delay) 24dB/octave crossover between mains and sub(s). I don't find any "quite a bit of phase shift" issues, even after measuring phase with the ETF5 acoustic measurement program.

By the way, the powered sub's internal crossover is disengaged, because the electronic crossover (Marchand XM9-L) is handling it.

Are we talking about the same setup?

It IS a good solution, but not the best. I've used that settup in the past myself, and was happy with it.

What would you describe as the best?

**Meat_PoPs** · 26 November 2004, 16:44 Friday

That is very true when running dd/dts content, but when listening to a two channel source, then two series crossover networks come into play. The crossover you're using (as you described 360deg shift) is of much better quality in this respect and would show much less consequences in this settup, from a logical standpoint anyhow. Everything sounds different than it looks on paper

**Bruce** · 27 November 2004, 11:50 Saturday

Meat,

When I'm listening to 2-channel, the only crossover engaged is the Marchand electronic (symmetrical 4th order L-R), the prepro isn't even in the signal path (remember, the sub is not plugged into the prepro's sub-out, and the prepro's speaker setup menu is set to sub=NO). The acoustic rolloff effect of the mains on the crossover result is minimized because the xover frequency is a full octave above the speakers f3.

Could you help me understand where you get the two series crossovers coming into play?

By the way, I don't use the prepro for 2-channel, I use the analog outs of the CD player as inputs to the Marchand (through a stereo preamp). Many newer prepros provide an analog bypass or PCM playback mode with no DSP or speaker management (i.e. Mains=Large, no sub) that would work the same way with an electronic xover.

2-channel signal path:
L&R analog Source signal (CD, TT-preamp, FM) --> stereo preamp L&R input (CD, AUX-1, FM)
stereo preamp L&R output --> Marchand xover L&R input
Marchand L&R high-pass output (>60Hz) --> L&R amp inputs for Main speakers
Marchand L&R low-pass output (<60Hz, SUM L&R) --> Mono sub input (internal xover disabled)

My DD/DTS 5.1 processor gets connected as follows:
HT prepro L&R preout (Large) --> stereo preamp L&R input (AUX-2)

Running a sub with 2 channel . . .

Running a sub with 2 channel . . .

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