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How Cheap is Your Sub?

Fitzcaraldo215

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I'm not sure how many audiophiles use subwoofers for 2 channel music listening in any context, wireless or not.

The review magazines rarely mention using them.

And many audiophile separates don't even have a subwoofer output jack.

I think for 2 channel traditional audio purists:

1. Subwoofers are associated with home theater, which they look down on
2. Subwoofers are associated with gaming and PCs, which they look down on
3. Subwoofers are associated with DSP room correction, which they look down on
I agree that many traditional audiophiles might not use subwoofers in stereo setups. But, a fair number of subwoofer reviews have appeared in TAS, for example and for what those reviews are worth. The recent Wilson WAMM Master Chronosonic system review by Jacob Heilbronn used Wilson subs to high praise. And, the infamous JonathanValin, among others, has reviewed subs a number of times. Kal has reviewed subs in Stereophile and there are some in their annual Recommended Components.

Yes, there are typically no sub outputs on stereo preamps/integrated amps. Many subs are fairly easy to hook up in stereo via low level inputs plus hi pass outputs for the mains, although some pricey subs have no internal xovers and need a separate xover box, JL Audio Fathom for example. Others have only a low pass filter = half of an xover on the sub side, with mains run full range. I personally do not like that configuration.
First you have to decide if you are actually going to run them as stereo subs or not...
  • As stereo subs, I used an active crossover before the amps, placed the subs near the L/R speakers, and to the AVR they were "large" speakers. A hybrid system.
  • I have also used the stereo sub setting in my processor (Emotiva XMC-1) and it treats the subs in stereo. Or so they say. It seemed to work OK.
  • Despite using stereo subs for decades, after going back and forth I am currently running them (four) as a mono swarm instead. The front pair and back pair are equidistant (as pairs) from the MLP so I am EQ'ing them as two individual subs to the processor for now.
    • Initially I used the continuous phase control on the subs to align the front and back pair, then connected them as a single sub to the processor.
    • I later tried the dual-mono setting to help time-align them and it worked, saving me the hassle of measuring and aligning phase manually, so that is how they are running now.
    • However you connect them the phase must be aligned at the crossover point so everything plays together at the MLP. I have used a combination of phase control on the subs and whatever the AVR/processor can do (have used Audyssey, MCACC, and currently Dirac Live, though delays are generally set by the component outside the actual room correction algorithm).
  • All my subs are hard-wired using RCA or XLR. Never tried wireless.
    • The front pair, which I have had for many years now, have RCA connections to the amp.
    • The rear pair, a recent addition, have XLR inputs and so I am using them. Part of the driver for XLR was because they are on a different power circuit (AC wall outlet, line, breaker) than the front pair and I didn't want to deal with ground loops. They are also at the back of the room so the cables are fairly long (50'; only really need about 30'~35', but I had 20' and 50' XLR cables around).
    • I have used splitters, separate sub outputs when available, and/or subs that have "pass through" connectors.
    • I have an aversion to using speaker-level inputs, both because they tend to exhibit higher noise, and because that by default means the mains are running full-range and to me that obviates one of the primary reasons for adding subs.
FWIWFM,
Don

Good stuff, Don.

If using a Mch processor, it is best to use the DSP bass management in the processor exclusively and not any xovers in the sub or prior to the amps. If that also uses DSP, it might add considerable latency, screwing up the speaker distance calibration by the processor.

I corresponded with a guy in England several years ago who was having that problem, as we eventually discovered with his Denon Mch prepro. He was using a Lyngdorf stereo DSP EQ and xover box for his subs plus main fronts, then calibrating the system with the Denon on top of that as though the fronts plus subs were two combined main plus sub, not four separate channels. Front, center and surround channels were badly out of synch timing wise. It was fixed by removing the Lyngdorf, using Denon bass management and straightforwardly calibrating subs and all other channels via the Denon. Voila!

I like the acoustic method via mike to accurately calibrate sub and other speaker distances, as provided by many even cheap HT processors. Many expensive ones do not have that, expecting the user to manually enter the tape measure distances. Mch Dirac also calibrates distances by mike as part of the calibration.

But, many subs have a DSP front end internally, introducing delay which is typically not specified by the sub's maker. That can introduce a significant difference between true acoustic distance and tape measure distance, hence timing. The result calculated acoustically from the mike calibration may still not be perfect in terms of phase. But, Mark Seton has suggested that the sub distance parameter in the HT processor can be varied somewhat while measuring with REW, etc. to dial in better phase alignment.
 
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watchnerd

watchnerd

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But, many subs have a DSP front end internally, introducing delay which is typically not specified by the sub's maker. That can introduce a significant difference between true acoustic distance and tape measure distance, hence timing. The result calculated acoustically from the mike calibration may still not be perfect in terms of phase. But, Mark Seton has suggested that the sub distance parameter in the HT processor can be varied somewhat while measuring with REW, etc. to dial in better phase alignment.

Now you're making me wonder about latency issues for wireless subs....

(I've never used one)
 

Soniclife

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Now you're making me wonder about latency issues for wireless subs....

(I've never used one)
The devialet configurator let's you delay the mains, so it might not matter.
 

Frank Dernie

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I have a single ancient REL Studio sub, bought from Richard Lord before he retired and sold up.
I use it for films and often switch it on if I am using my horn speakers which tail off below 40Hz but don't usually on music with the Goldmunds which are pretty well full range themselves.
I haven't hot room in my man-cave/junk store for more subs
 

March Audio

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Well that worked :) !

Pushed the button on the 4 B&W ASW608 subs. Sat them in the corners and ran the usual Acourate process. There is very little variation in bass around the room, its tight and extended.

Measurement results:



4 subs no avg.png
4 subs psy.png
4 subs impulse.png
4 subs waterfall.png
 
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oivavoi

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Interesting thread. The only thing which makes me skeptical about the idea of distributed subs througout the room is how it may affect transients and things in the time domain - how "fast" the bass is.

Anecdotal personal evidence: It is only rarely that I perceive reproduced bass to sound like real bass from acoustic instruments. If I play the deepest notes on a grand piano, it's down to 27 hz. If I jam with a guy who plays upright bass, his deepest notes will reach almost as deep. The deepest notes from an upright bass or a grand piano never sound boomy to me. Hifi bass, on the other hand, almost always have a "boomy" or "wooly" caracter, to a certain extent.

I have no idea why this is, though. But it is clear to me that even though the frequency response may be there, it doesn't mean that it sounds real - not to my ears at least. Furthermore, I don't have enough experience to weigh in on the multiple subs/few quality subs debate. I've heard both "multiple sub rooms" and "quality sub rooms" that ranged from acceptable to bad.

Btw, I've stumbled across some research lately that seems to confirm that frequency response may not be the only thing that matters when it comes to bass: http://www.aes.org/e-lib/browse.cfm?elib=18211
 
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watchnerd

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Interesting thread. The only thing which makes me skeptical about the idea of distributed subs througout the room is how it may affect transients and things in the time domain - how "fast" the bass is.

Anecdotal personal evidence: It is only rarely that I perceive reproduced bass to sound like real bass from acoustic instruments. If I play the deepest notes on a grand piano, it's down to 27 hz. If I jam with a guy who plays upright bass, his deepest notes will reach almost as deep. The deepest notes from an upright bass or a grand piano never sound boomy to me. Hifi bass, on the other hand, almost always have a "boomy" or "wooly" caracter, to a certain extent.

I have no idea why this is, though. But it is clear to me that even though the frequency response may be there, it doesn't mean that it sounds real - not to my ears at least. Furthermore, I don't have enough experience to weigh in on the multiple subs/few quality subs debate. I've heard both "multiple sub rooms" and "quality sub rooms" that ranged from acceptable to bad.

Btw, I've stumbled across some research lately that seems to confirm that frequency response may not be the only thing that matters when it comes to bass: http://www.aes.org/e-lib/browse.cfm?elib=18211

I don't have access to the whole paper, but reading the abstract makes me think "well, duh, of course transient / impulse response matters".

I would more surprised if it didn't matter.
 

oivavoi

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I don't have access to the whole paper, but reading the abstract makes me think "well, duh, of course transient / impulse response matters".

I would more surprised if it didn't matter.

True. The question is whether the same approach that is optimal for frequency response also is optimal for transients and impulse response. I have no idea.
 

oivavoi

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Here's the article in question btw: http://docdro.id/rn0ksLr

Re-reading it now, I see that they emphasize that frequency response also is important. But there's other things as well. My take-away from that is that bass quality probably has a lot to do with size and cubic, since larger rooms often have less problems with room modes etc. And also that absorbtion in the bass will almost always be a good idea, probably.
 
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watchnerd

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Here's the article in question btw: http://docdro.id/rn0ksLr

Re-reading it now, I see that they emphasize that frequency response also is important. But there's other things as well. My take-away from that is that bass quality probably has a lot to do with size and cubic, since larger rooms often have less problems with room modes etc. And also that absorbtion in the bass will almost always be a good idea, probably.

Some interesting findings in their regarding convolution and perceived degradation.

Also the statement that it is wrong to use octave or third octave bands when describing room decay.
 

March Audio

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Interesting thread. The only thing which makes me skeptical about the idea of distributed subs througout the room is how it may affect transients and things in the time domain - how "fast" the bass is.

Anecdotal personal evidence: It is only rarely that I perceive reproduced bass to sound like real bass from acoustic instruments. If I play the deepest notes on a grand piano, it's down to 27 hz. If I jam with a guy who plays upright bass, his deepest notes will reach almost as deep. The deepest notes from an upright bass or a grand piano never sound boomy to me. Hifi bass, on the other hand, almost always have a "boomy" or "wooly" caracter, to a certain extent.

I have no idea why this is, though. But it is clear to me that even though the frequency response may be there, it doesn't mean that it sounds real - not to my ears at least. Furthermore, I don't have enough experience to weigh in on the multiple subs/few quality subs debate. I've heard both "multiple sub rooms" and "quality sub rooms" that ranged from acceptable to bad.

Btw, I've stumbled across some research lately that seems to confirm that frequency response may not be the only thing that matters when it comes to bass: http://www.aes.org/e-lib/browse.cfm?elib=18211

I understand the reasoning for your concerns, however my experience is that this is not a problem. Firstly I choose closed box speakers and subs as they have better transient response, secondly in my system I have the capability to time align the drivers. Interestingly I haven't finished that process and yet still achieve the impulse response shown above with the basic Acourate process.

Subjectively the bass has improved over the one sub solution. You can see in the waterfall plot above the lack of modes and overhang in the sub range. It is very tight. Another subjective observation I would make is that with a single sub non centrally located (ie not between the main speakers) I have always been able to detect a subtle "phasiness" to the LF sound. That's completely gone.

I hear what you are saying about "hifi" bass, but if you are experiencing this it is probably more attributable to room acoustic issues - too high an RT in the low frequencies and prominent room modes.
 

March Audio

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True. The question is whether the same approach that is optimal for frequency response also is optimal for transients and impulse response. I have no idea.

This is why I use Acourate software for the speaker crossover filters and time alignment. It uses FIR filters which, in simplistic terms, can adjust phase and frequency.
 

Dialectic

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This is why I use Acourate software for the speaker crossover filters and time alignment. It uses FIR filters which, in simplistic terms, can adjust phase and frequency.

A very promising experiment. How are the subs connected? Are they all connected to one mono subwoofer channel?

I'm thinking about experimenting similarly myself.
 

March Audio

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A very promising experiment. How are the subs connected? Are they all connected to one mono subwoofer channel?

I'm thinking about experimenting similarly myself.

For music the left and right channels are summed into mono and fed to all subs. However they will be properly time aligned when I get time. For theatre use the AVR does have 2 sub outputs so front and rear are fed respectively from those.

Use REW if you want to do some room simulation and see the effect of multiple subs and positioning.

upload_2017-10-30_12-35-2.png
 

DonH56

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Yes but do not have a miniDSP so have not actually implemented the results. When I get time and a miniDSP to play with...

Andy is also a member here and is a very nice, and sharp, person (at least online... ;) ). He is very supportive and very upfront about what the program can and cannot do.
 
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