Subwoofing without subs

[Mark Seaton]

They look smoothed to me. I guess it all looks really good then except the big dip which is likely a boundary. At what sample rate are you recording your logsweeps?

It is smoothed, but not numerically. In this case it is the 20dB/division and narrow vertical layout which make for graphic display smoothing. If the image was at least 800 pixels tall and zoomed to 5dB/division the results would look as you might expect. I would suggest ticking the 1/12th smoothing for the adjusted graph in the bass range. The most useful display would be a full range measurement with 1/6th octave smoothing partnered with a 1/12th octave graph zoomed horizontally for say 5-500Hz.

 

[Drew Neilson]

I have a pair of Dayton Audio Sub-1500, bought cheap cheap cheap a couple of years ago, for experimental purposes. They are vented and tuned to a claimed 23Hz.
However, it was after that time that I improved my measurement capabilities and added DSP.

Though I am necroposting, I was searching Bing for technical information about the Dayton Audio SUB- series of subwoofers--frequency range, SPL at various frequencies, total harmonic distortion at various frequencies at various SPL levels, and spectral decay--and this thread was in the results, probably due to the measurements that Ray performed on his equipment and room, even though those measurements didn't include his subwoofers. Though the SUB- series is a budget series, the SUB-1200 is currently recommended by The Wirecutter as the best budget subwoofer, and I am considering buying one of the models in this series. Ray, in this thread you referred to the SUB-1500 as "cheeze" woofers. Was that intended to be a put-down on the sound quality of the SUB-1500s? Do you still have and use the SUB-1500s, and would you mind posting some acoustic measurements of them?
I'm not an expert on audio specifications, and though I guess that I kind of understand frequency response range and spectral decay, I probably have a weaker understanding of harmonic distortion. I'm interested in subwoofers that cost no more than a few hundred dollars and that can play low- and ultra-low frequencies at the same SPL that my five speakers play mid-range and high frequencies, and do so with low harmonic distortion. I have a 5.0 speaker setup, not a 5.1 setup; I have a front-left speaker, a center speaker, a front-right speaker, a side-surround-left speaker, and a side-surround-right speaker, and no subwoofer. I'll probably provide details about my setup later. The Wirecutter gave a positive review of the SUB-1200 and I read a positive comment or two on AVSforum about one of the other models in this series (I can't remember which model or models at the moment), but I wanted to find measurements of the performance of any of the models in this series, and that is how I came across this thread (even though this thread doesn't measure the SUB-1500s, and instead only measures other things).

 

[Drew Neilson]

The specific query that I searched Bing with, without the brackets, is [Dayton Audio SUB (800 OR 1000 OR 1000L OR 1200 OR 1600) (THD OR TDH OR "total harmonic distortion" OR SNR OR S/N OR signal-to-noise-ratio) frequency SPL graph]. Google ignores parentheses in queries, while Bing does not, so that query would not work as written if I entered it into Google.

Whoops, I should've written '1500' instead of '1600' in the query, because there is a SUB-1500 but not a SUB-1600.

 

[RayDunzl]

Ray, in this thread you referred to the SUB-1500 as "cheeze" woofers. Was that intended to be a put-down on the sound quality of the SUB-1500s? Do you still have and use the SUB-1500s, and would you mind posting some acoustic measurements of them?

I call them Cheezewoofers, yes, and they are still here, haven't moved.

All four came in at less than the price of one desirable Rythmik, which is probably what I'd buy next. It's an experiment, since the mains woofers are quite adequate. I use the subs to add a little "body" to the lows, not to shake the house.

The power spec is minimal - 150W.

The controls are minimal - signal invert and low pass.


Using 4 of them and not high-passing the mains (12" sealed), allows all six woofers to operate at a -9dB level compared to just a pair of woofers.

-9dB reduces the voltage applied to those drivers by about 1/3, reducing the power applied, and probably reducing the distortions produced.

If 10V were applied to the single pair of woofers, that's 25W @ 4Ohms, and with the 6 woofers, -9db gives 3.33V and only 2.72W.

Also, the excursion of the individual drivers would be similarly reduced (no calculation).

I'm not an expert on audio specifications, and though I guess that I kind of understand frequency response range and spectral decay, I probably have a weaker understanding of harmonic distortion.

Harmonic distortion - what should be a sine wave (single frequency) is reproduced with additional tones (generally at lower levels) at integer multiples of the desired pure frequency.

This happens with the speaker cone flexing, or the suspension subtly limiting the movement, or from the electronics. It changes the sound by adding uncommanded frequencies.

Example construct. Relative levels, and number of harmonics present, and phase relative to fundamental will be different in a real device, but here's an example construct:






Subs Measure:

At the listening position in my asymmetrical room.

Orange, left bottom sub no correction applied
Blue, Green - paired left and right, as used at the time of the measurement, with miniDSP OpenDRC adjusting the fullrange signal, and 2x4HD in front of the subs (old measurement)

Other measures aren't too meaningful isolated from the contribution of the mains.

Distortion maybe, though single tones tend to register a little lower distortion than with a quick sweep.

Looking at the single raw sub distortion, the THD number is dominated by the 2nd harmonic, which tends to be rather innocuous, and the higher number harmonics are below the noise floor of the room at these frequencies, so, ???.

 

[Drew Neilson]

Subs Measure:

At the listening position in my asymmetrical room.

Orange, left bottom sub no correction applied

"Left bottom" means what? The left sub, behind your primary listening position?

Blue, Green - paired left and right, as used at the time of the measurement, with miniDSP OpenDRC adjusting the fullrange signal, and 2x4HD in front of the subs (old measurement)

If this part is only about your mains, then that's not relevant to me, but I don't know what '2x4HD' means.

Other measures aren't too meaningful isolated from the contribution of the mains.

Actually, I think that they are, because I don't need to know the measurement of your mains, I only need to know the measurements of the SUB-1500 (and now that I think about it, if you're using four of them, that's going to provide a different graph than if only one of them is tested, and if only one of them is tested, then its location in the room matters, since you're not in an anaeoic (I know that I didn't spell that correctly) chamber.

Looking at the single raw sub distortion, the THD number is dominated by the 2nd harmonic, which tends to be rather innocuous, and the higher number harmonics are below the noise floor of the room at these frequencies, so, ???.

View attachment 38941

Maybe what I'm trying to ask is, does the SUB-1500 (or, in your case, multiple SUB-1500s) have audible distortion? Something that tells you that it's a cheap sub, and not an expensive one. Or maybe what I'm trying to ask is, would I be able to hear a difference in sound quality between a SUB-1500 and a higher-end subwoofer?

 

[RayDunzl]

"Left bottom" means what? The left sub, behind your primary listening position?

Two subs stacked adjacent to and outboard each of the mains. Left bottom is the one on the floor next to the left speaker.

If this part is only about your mains, then that's not relevant to me, but I don't know what '2x4HD' means.

It's subs only.

2x4HD is a miniDSP device - two channels in, four out, EQ, level matching, cutoff filters, etc.

Actually, I think that they are, because I don't need to know the measurement of your mains

Mains aren't included above.

The problem with additional measures - even more room dependent - lots of wavy lines, not sharp measures as you get with the analysis of a full range signal.

I only need to know the measurements of the SUB-1500 (and now that I think about it, if you're using four of them, that's going to provide a different graph than if only one of them is tested, and if only one of them is tested, then its location in the room matters, since you're not in an anaeoic (I know that I didn't spell that correctly) chamber

Measurements above shows the frequency response of one by itself with no DSP and two paired with DSP, left, and right, at the listening position, in this asymmetrical room.

Maybe what I'm trying to ask is, does the SUB-1500 (or, in your case, multiple SUB-1500s) have audible distortion?

"Bass" in music is (probably) never without higher harmonics (audible timbre), so, difficult to say.

With test sines, depending on the level, you hear things resonating in the house, and may hear some harmonics.

Make it too loud, yes, hear distortion tones. Make it useful levels, maybe not. I'm not a bass-head.

Or maybe what I'm trying to ask is, would I be able to hear a difference in sound quality between a SUB-1500 and a higher-end subwoofer?

I would hope so, while testing.

Audio Buddy has a pair of Rythmiks. They "test" better. He doesn't complain when he comes here and listens to music on Beer Saturday.

I don't get wowed when I go to his place, though I might take note of some things I don't necessarily hear here. But, different rooms confound things, and theres an $1800 difference comparing two of each.

 

[mikewxyz]

Ray: Your question seems almost rhetorical. You already have a set-up where you can compare with and without subs in your own listening room. Who could provide any additional data to that? The measured performance of your current situation is impressive.

I’ve wondered the same thing WRT my own system but I don’t have subs. In fact, I’ve never heard subs in a legit 2 way audio set up - only in a crazy HT setting. For me, it’s a lot of work to order, set-up and trial then return everything if I don’t like it well enough.

I would be surprised if the differences you hear in your friends system translates to your listening environment with the Rythmik subs.

Mike

 

[MediumRare]

If you have flat response at the MLP to 7 Hz then you certainly don't need them to smooth the response. You may or may not obtain lower distortion by purchasing dedicated subs but the trade includes cost, space, and integration with your current system. I am a great believer in letting subs do the job they are designed for but in your case my answer, with no other info, would be "no".

My only intuitive suggestion is: since you already have multiple subs (your two mains) the issue is an conveniently located room anti-node. I think you have said as much. More subs are IMO not going to change that and will add other complexities. Therefore, you could attempt to locate an offending resonant location in the room (a corner?) and treat that.

 

[DonH56]

My only intuitive suggestion is: since you already have multiple subs (your two mains) the issue is An in conveniently located room anti-node. I think you have said as much. More subs are IMO not going to change that and will add other complexities. Therefore, you could attempt to locate an offending resonant location in the room (a corner?) and treat that.

Think you meant to quote @RayDunzl there... About the only thing our systems have in common is that they both reach to about 7 Hz in-room.

 

[MediumRare]

Think you meant to quote @RayDunzl there... About the only thing our systems have in common is that they both reach to about 7 Hz in-room.

Don, I quoted you because I found your comment to be exactly apt. For me that was "the last word". But I still had throw in my ha-penneth.

@RayDunzl I didn’t realize this thread was so old. Did you ever resolve your question to your own satisfaction?

 

[MediumRare]

My room is 18'6" long, and the left 1/3 is open and the wall there is 27'10". Something like this:

View attachment 2814

I imagine you’ve tried all sorts or room wavelength calculators. Did you find any helpful insights?

 

[RayDunzl]

I imagine you’ve tried all sorts or room wavelength calculators. Did you find any helpful insights?

All the free tools expect a rectangular room.

So, while interesting, not so predictive for here.

 

[DonH56]

Predicting response in a non-rectangular room is tricky and usually takes something like COMSOL or a dedicated audio analysis program (big bucks). I can usually come close if the room is not too crazy since you can estimate path lengths. Curved rooms much harder, open rooms forget it.

 

[audimus]

Not to mention acoustic distance for reflections can be different from physical distances. Stone castles are different than wooden shacks.

For the old topic, it is easier to say when you need subs than when you don’t.

1. Mains not so good at low frequencies which is quite common.
2. Amp driving speakers struggles or gets hot while driving full range and can benefit from powered subs even if such subs are in the same enclosure as the mains not necessarily separate
3. Fidelity of woofers in mains even if they can reach high SPLs isn’t great - may be cheaper to supplement with subs than upgrading the whole speaker
4. The cross over in the mains is too high for woofers or too low for mids and cannot be changed which has impact on fidelity and/or longevity at loud volumes.
5. Placement difficult for mains in the room to get full range AND good imaging.
6. If you don’t already have the speakers, it might be more economical to get a 2.x than a full range 2.0 for same quality of sound. Many more choices of speakers when you don’t need to go low.
7. You move in circles where having many subs is a prestige thing.