Compact subwoofer to complement JBL 305P Mkii?

[Blumlein 88]

Hi
To be on-Topic. IME the more subwoofers ( up to 4) the better the bass response. We don't only hear what comes from the speakers but also what comes from the room. Above the Schroder transition region we usually can tame the speakers with economical room treatments (cheap diffusers, absorbers, drapes, etc); below the Schroder , let say 400 Hz in most non-palatial homes, you are dealing with the room contribution in the bass. Under 150 Hz the rooms entirely takes over and due to the way we perceive bass, several subwoofers are better than one. At the price of the LSR310 one can get two cheese-subs that Ray Dunzl uses. At the price of two LSR310, 4 of these subwoofers. 4 integrated subs would translate in a very smooth low bass reproduction FR with the help of DSP and/or EQ. Best bass seems to be a room affair rather than a single Listening Position point affair ....
I will try to find a few articles sustaining my POV. They also explain why bass reproduction is paramount in the perception of rhythm. It is one area where many audio shrines , especially those based on expensive bass anemic audiophile mini-monitors characteristically fail. It doesn't help either that the placement of these speakers for imaging and midrange reproduction doesn't help in the bass either... but audiophiles are headstrong .. and often our hearing is not that great .. so ....

I agree with what you said. But stunta is wanting small. He is eschewing choices that are about 3 inches per side larger in efforts to keep his sub small. Suggesting 4 subs isn't going to work for him.

If you have the room, for reasons you describe, I think 4 cheeze subs better than one tremendously made and performing single sub. Of course if one is flush with space and money, 4 tremendously made subs is better still.

 

[stunta]

I have a REL Storm III sub waiting in the basement. I'll definitely consider adding more subs when the basement is ready.

I have the ASW608 with me now. Would there be any issue placing sub under a shelf but on the floor? It is front firing. I ask before trying because trying involves a bit of work with shelf reconfiguration, unplugging equipment etc.

Thanks

 

[March Audio]

Hi

While I have become a card-carrying "objectivist", I believe we need to take into account what we perceive, rightly or wrongly. Measurements came to be, to ascertain some of our perceptions , not the other way around. In my book there are differences between gear that under a given set of measurements sound the same. THD in particular as usually measured remains in my book as an insufficient metric, with most any units exhibiting vanishingly small level of such while sounding to my ear quite different. In the here and now, I would like members to continue posting their subjective impression even if it is to be challenged or even later reversed with proper observations, tests protocols , etc .. Such can only advance our knowmledge rather than declaring (hydrogen-audio-like) that we have reached perfection and that every gear sounds the same. Itt remains true that the differences may not be as great as the hyperbole would lead to believe, but we are again in the psychology of human emotions and perceptions: What is "small" and/or insignificant ( loudness wars among others) for most humans in term of audio differences may not be for the audiophiles.

On this, I have struggled also with the MiniDSP accessories in the signal chain. I am not yet persuaded that all DACs sound the same and am not pleased both emotionally and intellectually with the notion of cascading AD to DA conversions.. Something has to give and it usually does with a large degree of insatisfaction... subliminal often ... many find themselves not listening to their stereo as often.
The goal of these measurements should be IMO to further the enjoyment of reproduced music in one's home.

The minidsp processors I have used have one thing in common, they resample to 48 ir 96khz. This is the bit I am suspicious of. I agree that cascading conversions is intellectually displeasing, however I have recorded dacs enough times to know it can be extremely difficult to tell them apart.

When you start to control comparisons very tightly the differences often vanish or become very, very tiny. With respect, my reaction to your comment of "quite different" is that the comparisons were not tightly enough controlled. Audiophiles are no different to anyone else. Every time I have tested audiophiles they fail to show any sign of super auditory abilities. The alleged night and day differences that were there when sighted etc disapear.

Try listening to this comparison test from the Chord Mojo thread. If you want to do the test properly use something like foobar abx comparator.

http://alanmarch.hopto.org/sharing/3re1FgOSQ

There is very little to excited about in the difference of dacs these days. Amplifiers however do have a wider range of operational conditions. Different speakers may affect performance measured and audible. Speakers themselves do have a wide range of measured performance and sound.

 

[March Audio]

I have a REL Storm III sub waiting in the basement. I'll definitely consider adding more subs when the basement is ready.

I have the ASW608 with me now. Would there be any issue placing sub under a shelf but on the floor? It is front firing. I ask before trying because trying involves a bit of work with shelf reconfiguration, unplugging equipment etc.

Thanks

T hat was quick Shouldnt be a problem but remember the positioning of a single sub is going to affect performance significantly, with the room and interaction with the main speakers at crossover.

 

[March Audio]

What are the dimensions of your room?

 

[stunta]

What are the dimensions of your room?

21' x 12'. Speaker to sitting distance is about 8' - 10'. Speakers are to the left and right of the bay window (facing into the room - this I got right by myself! )

 

[March Audio]

Just to show the effect of sub positioning I used REW Room Sim to model your room. I guessed a bit on positioning but the major features/modes match up with your measurements in the OP.

Sub corner

Sub Mid

Sub 1/4

Sub + Main Corner

Mid

1/4

 

[stunta]

I am not familiar with the room simulator. How reliable is it? From the graphs, it looks like I don't need to do any room EQ after adding the sub? I am XO'd at 46 Hz.

EDIT: REW doesn't seem to have the option to generate filters from the room simulation response. So what is the purpose of this?

 

[RayDunzl]

How reliable is it?

If you have rectangular room and know the reflection coeeficients it might be good.

It you don't (who does?) then it's just something to consider.

 

[March Audio]

I am not familiar with the room simulator. How reliable is it? From the graphs, it looks like I don't need to do any room EQ after adding the sub? I am XO'd at 46 Hz.

EDIT: REW doesn't seem to have the option to generate filters from the room simulation response. So what is the purpose of this?

The purpose was simply to show you the effect of moving your sub through some basic room positions, plus it gives you a reasonable idea where problems may be encountered such as the 60Hz dip at 1/4 position.

REW is actually pretty good in terms of frequency accuracy but not in terms of amplitude due to the unknown absorption coefficients of your room. You should always measure. The simulation shows your major mode to be around 47Hz, which ties up with the measurement you posted. Produce a waterfall of your measurement and you will see it has a long tail/decay time. I set the simulation to bring in the sub below 50Hz as your main speakers go down this far. I would have expected to see a bit of a hump at the 28Hz mode, but it is the width mode and may not be excited as much.

 

[stunta]

Measured the sub today. Main speakers were turned off. Besides the 47 Hz hump I was already seeing, the rest looks kinda flat. Is this unusual? Am I doing something wrong? Subjectively, the bass seems fine at my sitting position (boomy in other rooms but that's a different topic I guess). Should I measure with speakers ON as well?

Thanks

 

[March Audio]

I can see you have a hump at about 26Hz which lines up with the width mode shown in REW above. What you need to do now is click on the waterfall graph and show the decay times. I predict you will see longer decay times at 26Hz and 47Hz. The dip at 55Hz is a bit lower than REW predicted.

The subs are EQd (dont know if you have played with the different settings), so its not that unusual.

You could tune the roll off frequency to be a bit lower to minimise the impact of the 47Hz mode.

Also definitely take some measurements with the mains playing to see how it behaves. You are likely to get cancellations in the crossover region which might require the sub position/phase to be adjusted.

 

[stunta]

REW did not generate any filter other than the one at 47Hz. The waterfall graph is below. I am not sure if i am interpreting this right - the longest decay below 30Hz seems to be around 29Hz. What am I supposed to do with this? Is this something that can be mitigated with EQ or do I need physical things like bass traps?

 

[March Audio]

Can you save and post the REW measurement file? If you manipulate the scales you will get a clearer picture of whats going on. The longest decay is around 25/26Hz. Dont worry about what filters REW has set for the moment.

EQ can mitigate it (for the one listening position). Bass traps simply wont be effective at that low a frequency, well at least not at any practical size. Also the subjective impact at that low a frequency may not be that much to worry about

 

[stunta]

The longest decay is around 25/26Hz

How did you reach this conclusion? I am trying to understand how to interpret this waterfall graph. I see 0 - 300 ms on one axis - is the decay time?

REW file is here: https://1drv.ms/u/s!ApfaNoH___1jgoFL8XiPSqWtD7xuzg

 

[Blumlein 88]

How did you reach this conclusion? I am trying to understand how to interpret this waterfall graph. I see 0 - 300 ms on one axis - is the decay time?

REW file is here: https://1drv.ms/u/s!ApfaNoH___1jgoFL8XiPSqWtD7xuzg

Yes the millisceond axis is the decay time from the initial signal. I think he assumed since the 26 hz or so area had decayed the least by the time it reached 300 msec it would end up being the longest. In the waterfall each step forward shows the response at that time after the initial signal.

If you click on the gear in the upper right corner while looking at the waterfall plot, you can increase the time range to something longer like say 1000 msec.

 

[RayDunzl]

When looking at waterfalls and low frequencies, you might want to take pervasive ambient lows into consideration.

Here's mine. Just the current ambient noise floor, no sweep tone.

Could be misinterpreted as decay/holdover/resonance of a low frequency sweep.

Measured an hour later, it's a bit different:

Airplane (turboprop) flew over, not real close:

Quiet again, but different:

Changed again:

I quit.

 

[March Audio]

How did you reach this conclusion? I am trying to understand how to interpret this waterfall graph. I see 0 - 300 ms on one axis - is the decay time?

REW file is here: https://1drv.ms/u/s!ApfaNoH___1jgoFL8XiPSqWtD7xuzg

To be honest, I really wouldnt worry too much about the 25 Hz mode. Its too low to get excited very much. A touch of EQ on the 45 will tame it nicely, but its really not that bad, I have seen a lot worse. Ignore the stuff below 20Hz. Without some kind of bass management, ie also being able to filter the mains properly, the results will be sub optimal. Do the measurements again with the main speakers running and up to 200Hz.

 

[March Audio]

A room I endured once upon a time

 

[stunta]

Ah, I was not using the Waterfall tab you were using. It makes more sense now. How do you get the nice color gradients on your waterfall?

I am still not clear on what one would do if the long decay times were indeed a real issue? Can you please explain what the exact mitigation would be?

I will measure again with speakers + sub. I suppose this will bring out any issues at my crossover points with reinforced bass.

Thanks for the feedback and help. This is good learning for me.