[Locoliberty]

I am currently upgrading my system to separate pre-amp and power amps. One of my considerations is if the subwoofer outputs on the pre-amp are summed or maintain left and right output.

I know with subwoofers directionality isnt supposed to matter. But does it? Does having or losing the left or right information in the recording amount to some sort of loss?

Should I really put any weight in my pre-amp purchase if it has stereo subwoofer outputs or not?

My main considerations are Emotiva XSP-1, Parasound P5/P6, or NAD C 165BE. Only one of these has stereo subwoofer outputs.

Rest of system:
Bryston 4B-ST
Revel M126be
Svs sb2000

 

[sdurani]

The lower the frequency, the wider apart the transducers need to be to hear stereo. By the time you're down to the frequencies in the subwoofer range, the subs need to be directly to your sides, putting them 180 degrees apart. Placing them forward or rearward of your listening position shrinks that separation angle. Direct to side placement gives the best chance of pressurizing each ear differently. The effect is going range from subtle to negligible, happening very rarely.

The biggest obstacle is content. Aside from recordings by John Eargle for the Delos Records label, I don't know of many recordings that have truly decorrelated low frequencies (stereo bass). For the sake of mono compatibility, most recordings have the same low frequencies in both channels. So even if you place your subs to maximize the stereo bass effect, it will happen very rarely. Which is why I think it's a waste to use stereo subwoofer outputs as a deciding factor when shopping for pre-amps.

 

[m. zillch]

I know with subwoofers directionality isnt supposed to matter. But does it?

No. The auditory illusion which makes some people think they can sense a direction from the deep bass, and it is indeed their perception, is a manifestation of what's called the "proximity effect".

It is not too different from an illusion you are probably familiar with called "the ventriloquist illusion". Adults know full well that puppets can't talk and that the actual sound emanates from the puppeteer, but if you ask a small child they will swear it comes from the puppet's lips. That truly is their perception, but it is just an illusion.

 

[Scotth3886]

I am currently upgrading my system to separate pre-amp and power amps. One of my considerations is if the subwoofer outputs on the pre-amp are summed or maintain left and right output.

I know with subwoofers directionality isnt supposed to matter. But does it? Does having or losing the left or right information in the recording amount to some sort of loss?

Should I really put any weight in my pre-amp purchase if it has stereo subwoofer outputs or not?

My main considerations are Emotiva XSP-1, Parasound P5/P6, or NAD C 165BE. Only one of these has stereo subwoofer outputs.

Rest of system:
Bryston 4B-ST
Revel M126be
Svs sb2000

Yes, it can matter. I use stereo subs on one system and mono on the 2nd system. I feel it 'tightens' up location info such as the bass drum in some classical that isn't summed to mono. The bass drum is almost never in center in most classical that I'm aware of. I've tried stereo and running both subs in mono. And given that I don't have a sub out and I do extra pre-outs, it's just as easy one way or the other. If for some reason I didn't have pre-outs, but instead a sub out or two, I wouldn't buy the unit if they weren't stereo sub outs.

 

[Scotth3886]

The lower the frequency, the wider apart the transducers need to be to hear stereo. By the time you're down to the frequencies in the subwoofer range, the subs need to be directly to your sides, putting them 180 degrees apart. Placing them forward or rearward of your listening position shrinks that separation angle. Direct to side placement gives the best chance of pressurizing each ear differently. The effect is going range from subtle to negligible, happening very rarely.

The biggest obstacle is content. Aside from recordings by John Eargle for the Delos Records label, I don't know of many recordings that have truly decorrelated low frequencies (stereo bass). For the sake of mono compatibility, most recordings have the same low frequencies in both channels. So even if you place your subs to maximize the stereo bass effect, it will happen very rarely. Which is why I think it's a waste to use stereo subwoofer outputs as a deciding factor when shopping for pre-amps.

https://forums.stevehoffman.tv/threads/mono-bass-summed-channel-on-vinyl.104940/

"One of the first things I did when involved with a mastering project was to make sure the bass was not summed. As Barry mentioned this is strictly an optional process, but it was probably used more than not. It's a way to get a slightly higher overall level in the cut. Remember that cutting records deals with a lot of compromises. It's amazing that lp's sound as good as they do all things considered, but most agree that they can sound better than cd's where compromises are not as necessary. There are other optional mastering processes that are generally done, but that don't have to be, such as using the acceleration limiters.

I am of the thought that low bass directionality can be determined. I have always been able to tell where a mono subwoofer is located, though obviously many aren't able to do this, or aren't experienced enough to do it. Listen to records with stereo kick drums and see if you can tell that they are split left and right. Granted there are some higher frequencies with the kick drum that may help with localization.

Listen to 'Magic Man' from Heart's first lp where the bass is panned while it is decending in frequency. On a good full range system there can be pinpoint localization of it all the way down.

Doug Sclar, Feb 9, 2007"

From what I understand, Doug Sax never summed to mono either, unless a client requested it. Although I'd have to dig for a while to find the direct quote

 

[m. zillch]

Here Scott, this is part of a bigger project I'm working on, long term, but I did a rush job just now for you. Listen through your stereo sub rig and enjoy that bass.
[I had to keep it really short so the copyright police don't come and get me but this is everything where the bass [synthesizer I guess?] is moving laterally.
After this point it stays put in one position so I didn't record that part. ]

This is from CD but I plan to analyze it from LP and will compare the two in the future.

The strongest bass is around where I hover my cursor, around 49Hz. At certain points there's stuff even below that but not at the same level.

How does it sound compared to the LP? Notice anything off?

P.S. The spectrum Analyzer display, from Foobar, is showing a monophonic rendition of the two channels summed together. It is sometimes a little disconcerting that as the bass moves to the right across the sound stage the frequency gets deeper so the display bump moves to the left. Close your eyes however and you definitively hear the deep bass move from left to right and then back to the central area.

 

[Scotth3886]

Here Scott, this is part of a bigger project I'm working on, long term, but I did a rush job just now for you. Listen through your stereo sub rig and enjoy that bass.
[I had to keep it really short so the copyright police don't come and get me but this is everything where the bass [synthesizer I guess?] is moving laterally.
After this point it stays put in one position so I didn't record that part. ]

https://www.youtube.com/watch?v=v4yG4ohtx3g

This is from CD but I plan to analyze it from LP and will compare the two in the future.

The strongest bass is around where I hover my cursor, around 49Hz. At certain points there's stuff even below that but not at the same level.

How does it sound compared to the LP? Notice anything off?

P.S. The spectrum Analyzer display, from Foobar, is showing a monophonic rendition of the two channels summed together. It is sometimes a little disconcerting that as the bass moves to the right across the sound stage the frequency gets deeper so the display bump moves to the left. Close your eyes however and you definitively hear the deep bass move from left to right and then back to the central area.

Thanks. An album from Heart isn't really my thing anymore, so I haven't listened to it in ages, but best I can recall, I didn't think it went all that low. I do remember clearly being able to hear the back and forth one cycle each way and landing in center.

I have the LP I think, but not the CD and the LP I have somewhere would have been when it was first released.

 

[Scotth3886]

Edit: oops, I thought was a static screen shot. I listen several times on my little dipole ribbon on my desktop and I don't really hear it moving like I remember on the big system. I'll try some random ones from youtube and see if I hear any difference.

I don't hear it move much on this one either, but then again, this is a mono sub here at my desk

 

[Scotth3886]

I know I have the album because I once took a pic and posted it, but hell if I can find it. That's getting to be my story with everything anymore

 

[Scotth3886]

If I can find the LP, I'll be able to tell by simply putting my hand on a sub when it makes its move left and right or right and left … wherever it goes.

 

[Scotth3886]

Using the butt tester by sitting on the sub, it's not summed to mono on the LP. You can feel it in the ole keister. What a test instrument that is.

And the CD is summed to mono. Butt vibration stay the same on each side other than going lower in frequency. Very interesting.

And although the recording really sucks, you also hear more movement from side to side with the LP than the CD. The CD version still does it to an extent, but not nearly like the LP. If I had a lil energy tonight, I'd change the two subs back to mono and listen, but that will have to wait for another day since it's 1:47AM.

 

[WOKNROX]

I run stereo subs on my 2 channel rig. Although I don't use the sub output/s rather I use the L& R outputs on my preamp to my subs. I use the DSP's on the subwoofers to correct for room nods before I run the room correction on the pre-amp...as a speaker/sub unit each side.
This works very very well for me and sounds fantastic.

I vote run stereo subs.

 

[Scotth3886]

I run stereo subs on my 2 channel rig. Although I don't use the sub output/s rather I use the L& R outputs on my preamp to my subs. I use the DSP's on the subwoofers to correct for room nods before I run the room correction on the pre-amp...as a speaker/sub unit each side.
This works very very well for me and sounds fantastic.

I vote run stereo subs.

On my larger Hegel integrated I don't have a sub out to use so it's one of the extra pair of preouts so stereo subs are just as easy or maybe easier than mono subs. Even on material that's summed to mono, which is most of it, I don't see any downside to using the subs in stereo so I do.

 

[m. zillch]

It probably doesn't always matter but there's a difference: in some setups there is a theoretical advantage to using summed to mono subs because this ensures they are perfectly in phase with each other, at least if they are at the same distance to the listener. With stereophonic subs you can have a scenario where in some songs the L and R happens to be out of phase with each other at say 50Hz. What ends up happening is there is severe cancellation as they suck the energy out of each other at that frequency. All content at 50Hz will seem absent or at least subdued. In this scenario the bass content will actually increase by turning one of the two stereophonic subs off!

This is basically why music through full range speakers, put out of relative phase to each other, sounds bass shy as well.
---

EQ takes less processing power in mono too. Instead of the processor needing to devote half it's computing power to the L sub and the other half to the R sub, All computer processing power is dedicated to a single task: the one channel of deep bass.

 

[WOKNROX]

On my larger Hegel integrated I don't have a sub out to use so it's one of the extra pair of preouts so stereo subs are just as easy or maybe easier than mono subs. Even on material that's summed to mono, which is most of it, I don't see any downside to using the subs in stereo so I do.

Sometimes thing get lost in all this technology...and I'm certainly not that technical... I just know what sounds good.

Take the legendary and arguably the best speakers ever made the Infinity IRS 5's... they use stereo sub stacks, 6 servo controlled subs on each side. They sound absolutely beautiful..!

I own the Mirage OM5's with powered subs built in and the Vandersteen 5's with built in subs....
Both are wonderful sounding subs in stereo.

I just picked up a set of VMPS RM40 speakers paired with a set of Rythmik FV18's in stereo and although I'm still dialing these in...this setup is on it's way to being the best I've ever heard....

For me... stereo subs all the way!!
For 2 channel rigs...
Multi channel rigs is a completely different story.

 

[Scotth3886]

Sometimes thing get lost in all this technology...and I'm certainly not that technical... I just know what sounds good.

Take the legendary and arguably the best speakers ever made the Infinity IRS 5's... they use stereo sub stacks, 6 servo controlled subs on each side. They sound absolutely beautiful..!

I own the Mirage OM5's with powered subs built in and the Vandersteen 5's with built in subs....
Both are wonderful sounding subs in stereo.

I just picked up a set of VMPS RM40 speakers paired with a set of Rythmik FV18's in stereo and although I'm still dialing these in...this setup is on it's way to being the best I've ever heard....

For me... stereo subs all the way!!
For 2 channel rigs...
Multi channel rigs is a completely different story.

My Martin Logan Statements used a woofer stack on each side in stereo

https://www.martinlogan.com/uploads/documents/brochures/brochure_statement.pdf

True, a little on the hefty side at 1,900 pounds

 

[WOKNROX]

My Martin Logan Statements used a woofer stack on each side in stereo

https://www.martinlogan.com/uploads/documents/brochures/brochure_statement.pdf

True, a little on the hefty side at 1,900 pounds

VERY NICE speakers you have there sir!!!
I bet they sound very open and transparent..along with very impactful bass as well.

 

[WOKNROX]

It probably doesn't always matter but there's a difference: in some setups there is a theoretical advantage to using summed to mono subs because this ensures they are perfectly in phase with each other, at least if they are at the same distance to the listener. With stereophonic subs you can have a scenario where in some songs the L and R happens to be out of phase with each other at say 50Hz. What ends up happening is there is severe cancellation as they suck the energy out of each other at that frequency. All content at 50Hz will seem absent or at least subdued. In this scenario the bass content will actually increase by turning one of the two stereophonic subs off!

This is basically why music through full range speakers, put out of relative phase to each other, sounds bass shy as well.
---

EQ takes less processing power in mono too. Instead of the processor needing to devote half it's computing power to the L sub and the other half to the R sub, All computer processing power is dedicated to a single task: the one channel of deep bass.

I personally dont experience any of the issues you describe....lucky I guess.

 

[Scotth3886]

VERY NICE speakers you have there sir!!!
I bet they sound very open and transparent..along with very impactful bass as well.

Had. This was in the 90s. I had these and SoundLab A1s, and yes, at the same time.

 

[WOKNROX]

Had. This was in the 90s. I had these and SoundLab A1s, and yes, at the same time.

That's why I'm such a hoarder... I always kick myself later when I let thi go go..lol

Sometimes I wonder what kind of gear the technically savvy guys are listening to...?