Integrating Subwoofers to Main Rig Speakers

[XTRProf]

Mar 8, 2012 20:32:50 GMT Crispy said:

I have two M J Acoustics Reference 100 active subs in my system.
The picture below is showing the right hand side, the left hand side is the same minus the CD, XCanV2 + psu. Note the sub is in the corner.

Great, you will have a more immersive experience thru a more uniform spread of bass SPL.

Mar 8, 2012 20:32:50 GMT Crispy said:

The freq response of my Acoustic Energy AE1's are 35Hz - 30Khz
and the freq response of the subs are 13hz to 120Hz.

For a stand mounted speakers, it's pretty rare to see the light of 35 to 40 hz flat. More likley flat to about 80 hz. Some floorstander like mine can only see about 60 to 70 hz flat the most.

Btw, the MJ sub 10" or 12"? Ported or sealed? For 12" sealed, the most flat will reach about 27hz. Of course, corner gain will make the 27hz to about 20 to 23 hz for seal. Only measurment can check on that

Mar 8, 2012 20:32:50 GMT Crispy said:

They recommend that you should set the crossover to slightly above the lower freq response of your main speakers. EG: mine are set at 39Hz.

That's what I had roughly done. Well, until measurement then.

Mar 8, 2012 20:32:50 GMT Crispy said:

They say you should position your subs near to you main speakers, mine are near but in the corner of the rooms.

I concur. Same for the people from Emotiva where my subs come from. But the corner, Im don't agree as we need to consider the nodes and antinodes as well as resonances and many others that were talked on when I attended last year Hifi show on EQ technics. The best EQ is a mixture of physical layout that electronic EQ cannot dial out with electronic manipulation that electronics can dial out effectively. The best SQ is still proper physical layout which all studio and acoustic guys will agree on. I'm sure of that.

Mar 8, 2012 20:32:50 GMT Crispy said:

Then turn all controls to their lowest position.

Find a familiar piece of music with a good steady bass to listen to over and over while setting up the sub/s.

Increase the volume on the sub until the sub intrudes on the music then back it off.

The art is to mix in the sub so you can't tell where it's positioned - you just know it's there.

Initial set-ups may not be perfect at first, spend plenty of time auditioning and tweaking. The true art of blending in a sub is for it to go unnoticed.

Yup, that's confirmed for the fifth time. I'm there.

Mar 8, 2012 20:32:50 GMT Crispy said:

REL recommend you place the sub as far into a corner as possible, then slowly pull it out from the corner diagonally inch by inch until it exhibits the lowest bass extension.

Check out the link below - it's a manual to set up a REL sub but you may get some useful tips.


www.sumikoaudio.net/rel/manuals/Q-Series-Manual.pdf

Thanks for the Rel link. Let me read more of that.

TGIF again ........... Arrghhh, boss still around. No worry yet as it's 3.30pm local time. Still more than 2 hrs to go before sayonarah. That is provided he asks me to or he goes home.

[Deleted]

Chong,

That remark seems to be uncharacteristic but isn't really.

measuring speakers accurately in a room at a certain distance (or at the listening area) is impossible.
Graphs from speakers are measured in an an-echoic room and can appear to be 'flat' as hell.
However in a room at a certain distance the plot can be tens (not tenths) of dB's off in both directions due to radiation patterns and, reflections, standing waves, measuring axis/height as well as resonating (absorbing or amplifying) resonances of other items in the room.
When listening (experienced listener) most af these become irrelevant/compensated because the brain filters out some of the unnatural artifacts (sharp dips caused by cancellation for instance) that will show up in sinewave measurements but the brain 'ignores' also the brain 'calculates' room artifacts for a certain part.

Measuring wit a test tone therefore will only give slightly predictable/accurate readings when done right in front of the speaker (few cm's)

When measuring ported or more way systems one can only measure the unit (driver) somewhat accurate from a distance in a room.
Test tones are niot accurate and pink noise, wobble tones, terts noises or fast sweeps (that are averaged out) can give clues.
These all require software or special equipment.


Agreed about bass being felt differs from HP's
It's why one member uses a sub while listening to HP's to enhance the experience.


Phase determination by ear.

Set the freq range to overlap (sub to the X-over highest freq if possible)
listen for 'enhanced' lows or a dip around the overlap.

If dipped they are in the wrong phase.

One needs to remind that X-overs also exhibit phase shifts at their X'over freq that can be more than substantial for this test (depends on type and order of filtering) so in some cases isn't very clear to determine this way.

Hope this helps

[xerxes]

Rel really have a strange way to recommend the placement of the sub. Only the corner and the right speaker.

Rel recommend that you place the sub in a corner, not specifically in the corner behind the right speaker, that's was just the most convenient place for me.

With regard to having two subs, I don't think that's necessary, unless you have a large room as the amount of air they can move is cumulative, so two smaller subs is like having one with a larger speaker cone.

Because the wavelength of low bass frequencies is greater than the width between the ears it is said that humans can't detect where low bass is coming from, so the placement of the sub is not critical and you should locate the sub where it has the best effect, where it "energises" the room most.

Here's some more reading: www.soundonsound.com/sos/apr07/articles/subwoofers.htm

[XTRProf]

Mar 9, 2012 14:39:45 GMT xerxes said:

With regard to having two subs, I don't think that's necessary, unless you have a large room as the amount of air they can move is cumulative, so two smaller subs is like having one with a larger speaker cone.

Because the wavelength of low bass frequencies is greater than the width between the ears it is said that humans can't detect where low bass is coming from, so the placement of the sub is not critical and you should locate the sub where it has the best effect, where it "energises" the room most.

Actually, I'm referring to the uniformity of bass SPL thru out the room. Although low bass is none directional but the spl uniformity will not be if we have only one sub at one corner as the bass is radiating from that place only and the SPL will not be as wholesome as when bass spl fills the whole place better. SPL goes down with distance for whatever frequency, btw. That's why hifi nuts are talking of sub not having enough spl when the active amp is not of sufficient power. Initially, I also don't understand what that is all about but now I understand as previously, I was just thinking like you about bass being non directional as a direct relationship to spl and those hifi nuts are talking of spl uniformity and not about bass coming from where.

I agreed, when the listening place is small, one sub of enough power is already enough. This uniformity will be more obvious in a larger listening area. If someone OCD like me, I will still go for 2 subs in a small place.

Frans has 2 15" subs and he is not so subjective OCD like me.

[XTRProf]

Mar 9, 2012 9:53:26 GMT @solderdude said:

Phase determination by ear.

Set the freq range to overlap (sub to the X-over highest freq if possible)
listen for 'enhanced' lows or a dip around the overlap.

If dipped they are in the wrong phase.

One needs to remind that X-overs also exhibit phase shifts at their X'over freq that can be more than substantial for this test (depends on type and order of filtering) so in some cases isn't very clear to determine this way.

Hope this helps

Yup, it does obviously help by double confirming. Yesternight, I just turned the phase knob from 0 to 45 degrees (that's what in the sub digital menu) to try. Heard a slight increase in bass. Turn to 90 degress, wah, very obvious, man! Turn to 135 degrees and bass goes down. I must be imagining things, I hear the imaging turn "out of phase" as well. Not so shiok like before. Heh, heh, I can manage to turn down the gain to +3db after this and I'm in more hifi heaven until the confirmation and further fine tuning thru measurement.

Hearing from the sub area, as I need to turn the knob and my sub is not with a remote, really can't hear much difference. But at the listening position, much more obvious and subs are supposed to be directionless. Oh yeah, I tend to be in my old self again. Damn it! We are talking of SPL and not whether directional or not.

[XTRProf]

Yesternight, try the loudness war CD ..............





Wow, not bad at all with all the bass that was obviously not so evident taking a front seat. Yeah, the gyrating bass and not the boom, boom, boom bass. Arrrghhh........., still can hear the distortion to the voice and the drums for some tracks.

Really, I didn't know there is so much bass on this CD as well.

[rowuk]

Mar 7, 2012 5:29:45 GMT XTRProf said:

Btw, have you place the subs on any isolation platform to further improve the sub sound quality? Something like Subdude. With that, I think will use the metal spikes again as that will already anchor the subs well to prevent it from rattling. That's the problem with current subs. They produce so much power (600 Wrms, btw) to rattle about on their own when thye are not heavy enough.

I don't believe in bandaids and don't have wooden floors so isolation platforms hurt more than they help.

If the subs need more mass, any gravestone cutter can cut custom stone to make your subwoofer more massive - and look better at the same time. A thick slab on the top is normally enough, a slab on the left and right can really increase the WAF!

There is another side to this however proven by B&W with their matrix series. More mass means more potential stored energy. For LF reproduction, I can't verify that, but mid bass for sure.

The size of the subwoofer has to be matched to the room otherwise compression chamber effects like in an automobile change the way that we perceive low frequencies.

[XTRProf]

Mar 11, 2012 22:13:37 GMT rowuk said:

If the subs need more mass, any gravestone cutter can cut custom stone to make your subwoofer more massive - and look better at the same time. A thick slab on the top is normally enough, a slab on the left and right can really increase the WAF!

There is another side to this however proven by B&W with their matrix series. More mass means more potential stored energy. For LF reproduction, I can't verify that, but mid bass for sure.

Yup, simpler the better. So I changed the metal spikes to rubber "spikes" and the issue is gone. No more rattling although I still prefer metal spikes for a more controlled bass subjectively. But, what the heck, now there is more subjective bass due to the more mechanical "coupling" to the floor.

Mar 11, 2012 22:13:37 GMT rowuk said:

The size of the subwoofer has to be matched to the room otherwise compression chamber effects like in an automobile change the way that we perceive low frequencies.

Can you elaborate on that of how to choose the correct size subwoofers for the room? Something interesting coming up.

Also, since you have 3 subs where did you place the subs for a more even SPL? 2 in front and one at the back? Yeah, I assumed your 3 subs are for a stereo setup and not a HT.

[XTRProf]

Next to test with organ music. Where are my discs, damn it!

[XTRProf]

You think current subs are good enough? Wait till you see this prototype .......................






The full details: www.ludoislabs.com/Giant_Speaker.html

[rowuk]

Part of the DC to light frequency response addicts? Here is the subwoofer for YOU!



news.cnet.com/8301-17938_105-9781302-1.html

hackaday.com/2006/09/27/rotary-subwoofer/

It is real and it works!

[XTRProf]

Mar 15, 2012 22:02:10 GMT rowuk said:

Part of the DC to light frequency response addicts? Here is the subwoofer for YOU!



news.cnet.com/8301-17938_105-9781302-1.html

hackaday.com/2006/09/27/rotary-subwoofer/

It is real and it works!

At USD 13k better to wait for the uni students to perfect theirs.

Prof Frans will be delighted!

[Deleted]

Mine goes down to 16Hz (0dB)
2x 40cm actively compensated alu-cone woofers in closed housing. (200 Watt RMS)
There isn't any relevant audio info below those frequencies so why bother.
If you ever heard (sorry felt) a pure 16Hz sinewave you'll understand.

mine is nothing like this one though:
www.ohgizmo.com/2006/03/06/the-biggest-subwoofer-ever-made/

or this one:
www.youtube.com/watch?v=o36Kp6veJ6c

there are some really sick DIY'ers around:
curiousphotos.blogspot.com/2009/12/biggest-subwoofer-in-world.html

[XTRProf]

Still trying to get my act togather. So with almost unlimited free time now, start digging again and found this:


True Audio TrueRTA Audio Spectrum Analyzer Software
True Audio’s Level Two (1/3 per octave) TrueRTA™ is a real-time software-based audio instrument for testing and evaluating audio systems using a PC with basic sound capability. TrueRTA™ also includes a digital voltmeter that reads true rms voltage and dBu levels, and an audio spectrum analyzer. To set up your own audio test lab you will need a digital voltmeter to calibrate TrueRTA™ for your sound card and a collection of cables and adapters for connecting electronic gear to your sound card for testing. Most sound card jacks are 1/8 inch. If you want to do acoustic testing of loudspeakers in addition to the above you will need a calibrated microphone (True Audio recommends the Dayton Audio EMM-6), a microphone preamplifier or mixer, an audio power amplifier to drive the speaker under test, and cables to connect the line-out of the sound card to the input of the audio power amp. Software can be upgraded to Level Three (1/6th octave) or Level Four (1/24th octave). Minimum System Requirements: 500MHz Pentium III processor and 64MB of RAM


Link here: www.parts-express.com/pe/pshowdetl.cfm?&Partnumber=500-944


How far or it's about the same as the free here:


www.hometheatershack.com/roomeq/

[Deleted]

Hi Chong
Is that the program that comes in 4 levels, with the last one selling for $99 ? I thought about getting that one, but couldn't justify spending $99 at the time.
Regards
Alex

P.S.
You may be the wrong side of 50, but you are far from unemployable. Put those qualifications to use and grab a better job than before !

[XTRProf]

Apr 11, 2012 1:32:49 GMT @sandyk said:

Is that the program that comes in 4 levels, with the last one selling for $99 ? I thought about getting that one, but couldn't justify spending $99 at the time.

Yup, 4 levels. You don't need to start at level 4. Can start at level 2 and can be upgraded along the way. So just need to start at a level that you need and not forced into us. Anyway, everything are the same (if I'm not wrong) except for the resolution for the different level.

Btw, what calibrated mic + mic amp with phantom PS you will be using with if bought?

Apr 11, 2012 1:32:49 GMT @sandyk said:

P.S.
You may be the wrong side of 50, but you are far from unemployable. Put those qualifications to use and grab a better job than before

Thanks. May go into "own" transport biz if still nothing up and going for about a month. But for that, I just can't get pass the point that I have to work everyday like Chris's restaurant biz. But definitely, the renumeration will be much better than what I was getting before and also it's my time and not my "bonded" boss's time. There are just too many youngsters and foreigners to compete jobs with in Singapore.