Does an audio system need a subwoofer?

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Re: Does an audio system need a subwoofer?

Postby qguy » Tue Aug 03, 2010 12:44 pm

When it comes to sub, my thinking is that you have to consider the size of your woofer (The main loudspeakers woofer, not the subwoofer), while having a 15 or 18 inch sub is great, it may not blend well with a tiny bookshelf speaker with a 4.5 or 5.5 inch woofer, The sub is as an extension of your main speakers, it has to blend well with the mains loudspeakers. I have a M&K 12 inch sub before and it mated very well to a KEF 105.2 (which had 12 inch woofers too). I now use an Usher X-719 with a 7 inch woofer, what I notice is that that parang may butas sa mid bass. the system goes low but lack some punch in the midbass.
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Re: Does an audio system need a subwoofer?

Postby Nelson de Leon » Tue Aug 03, 2010 2:59 pm

qguy wrote:When it comes to sub, my thinking is that you have to consider the size of your woofer (The main loudspeakers woofer, not the subwoofer), while having a 15 or 18 inch sub is great, it may not blend well with a tiny bookshelf speaker with a 4.5 or 5.5 inch woofer, The sub is as an extension of your main speakers, it has to blend well with the mains loudspeakers. I have a M&K 12 inch sub before and it mated very well to a KEF 105.2 (which had 12 inch woofers too). I now use an Usher X-719 with a 7 inch woofer, what I notice is that that parang may butas sa mid bass. the system goes low but lack some punch in the midbass.


Kung itataas ang xover point ng sub, ma-over-power na kaya ang midbass?
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Re: Does an audio system need a subwoofer?

Postby ojof00l » Tue Aug 03, 2010 10:34 pm

nelson, im using a sub (150hz cutoff) in my audio system :)

in my case, hindi naman na-overpower ang midbass
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Re: Does an audio system need a subwoofer?

Postby qguy » Wed Aug 04, 2010 6:03 am

I did try raising the crossover point, the mid bass was improved on new wave tracks, but on good recorded cds I sense something was still wrong, i can explain it but parang may mali pa rin. I need a bigger fronts :-)
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Re: Does an audio system need a subwoofer?

Postby JoeyGS » Wed Aug 04, 2010 9:21 am

qguy wrote:I did try raising the crossover point, the mid bass was improved on new wave tracks, - Could it be that this setting corrected to what was missing in the recording?


but on good recorded cds I sense something was still wrong, - Could it be that since the source material is already ok, then there is no need to overlap the frequencies?


i can explain it but parang may mali pa rin. I need a bigger fronts :- ) There could be no problem in your gears, just needed proper set-up or settings
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Re: Does an audio system need a subwoofer?

Postby Jon Agner » Wed Aug 04, 2010 9:27 am

qguy wrote:I did try raising the crossover point, the mid bass was improved on new wave tracks, but on good recorded cds I sense something was still wrong, i can explain it but parang may mali pa rin. I need a bigger fronts :-)


Perhaps not bigger fronts but probably there may be midbass frequency cancellations at your listening spot.
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Re: Does an audio system need a subwoofer?

Postby JoeyGS » Wed Aug 04, 2010 9:34 am

I totally agree with you, Jon. I had the same experience when I transferred into a different listening room. Likewise, speaker set-up and room acoustics play a big part in really extracting those frequencies. With improper speaker placement and room acoustics, frequencies can either be canceled or muddled.


Jon Agner wrote:
qguy wrote:I did try raising the crossover point, the mid bass was improved on new wave tracks, but on good recorded cds I sense something was still wrong, i can explain it but parang may mali pa rin. I need a bigger fronts :-)


Perhaps not bigger fronts but probably there may be midbass frequency cancellations at your listening spot.
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Re: Does an audio system need a subwoofer?

Postby Jon Agner » Wed Aug 04, 2010 6:00 pm

JoeyGS wrote:I totally agree with you, Jon. I had the same experience when I transferred into a different listening room. Likewise, speaker set-up and room acoustics play a big part in really extracting those frequencies. With improper speaker placement and room acoustics, frequencies can either be canceled or muddled.


Jon Agner wrote:
qguy wrote:I did try raising the crossover point, the mid bass was improved on new wave tracks, but on good recorded cds I sense something was still wrong, i can explain it but parang may mali pa rin. I need a bigger fronts :-)


Perhaps not bigger fronts but probably there may be midbass frequency cancellations at your listening spot.


True, sometimes even just a change in your listening spot can alter what you hear
:)
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Re: Does an audio system need a subwoofer?

Postby the porcupine » Wed Aug 04, 2010 11:33 pm

JoeyGS wrote:
qguy wrote:I did try raising the crossover point, the mid bass was improved on new wave tracks, - Could it be that this setting corrected to what was missing in the recording?


but on good recorded cds I sense something was still wrong, - Could it be that since the source material is already ok, then there is no need to overlap the frequencies?



+ 1

This is why I advocate neutral calibration of subs that extend the lower frequency range while maintaining the flat overall frequency response of the entire system.
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Re: Does an audio system need a subwoofer?

Postby Nelson de Leon » Thu Aug 05, 2010 12:02 am

the porcupine wrote:
JoeyGS wrote:
qguy wrote:I did try raising the crossover point, the mid bass was improved on new wave tracks, - Could it be that this setting corrected to what was missing in the recording?


but on good recorded cds I sense something was still wrong, - Could it be that since the source material is already ok, then there is no need to overlap the frequencies?



+ 1

This is why I advocate neutral calibration of subs that extend the lower frequency range while maintaining the flat overall frequency response of the entire system.



Sir, can you kindly share the procedure?
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Re: Does an audio system need a subwoofer?

Postby the porcupine » Thu Aug 05, 2010 1:25 am

Some methods have been mentioned in this thread already.

My method is a bit complicated and takes a lot of patience but the results are very much worth it (YMMV). I'm sure there are better/easier methods out there so feel free to search for them.

Basically, measure the frequency response of your main speakers using Real Time Analyzer software with a calibrated measurement microphone. You can also use an SPL Meter, test tone sweeps and a spreadsheet. From the resulting frequency response graph, take note of where the lower frequencies attenuate and use that as a reference for setting the crossover point of the sub. Measure the audio system again but this time with the sub. If you notice a peak or dip in the crossover freq of the graph, adjust the crossover setting of the sub accordingly to get the flattest possible response in the crossover point. Take the opportunity to match the volume level of the sub's lower frequencies with the main speaker's frequencies while doing this. Since there will be a lot of re-measuring and adjusting to achieve the best integration of the subs and main speakers, using a real-time analyzer makes all the difference since its much easier and faster to use than the spreadsheet method.

Prior to doing all this, I would recommend getting a subwoofer that can go down flat to 20Hz with very little distortion. It is also best to determine the best sounding placement of the sub in the listening room as well as the right phase setting. Low frequencies are arguably the most difficult to tame in a room thus requiring acoustic room treatment like bass traps to help achieve flat response. Using multiple subwoofers helps significantly in flattening low freq response in any room. If you like, you can use a (Parametric) equalizer along with the RTA and a measurement mic to equalize the frequencies in your listening spot after doing all of the above. Use this sparingly, though, as extreme boosts and cuts tend to introduce distortion and artifacts.
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Re: Does an audio system need a subwoofer?

Postby joe3rp » Thu Aug 05, 2010 6:10 am

the porcupine wrote:Prior to doing all this, I would recommend getting a subwoofer that can go down flat to 20Hz with very little distortion


Sir,
What Subwoofer do you recommend, is this available in the Philippines?
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Re: Does an audio system need a subwoofer?

Postby the porcupine » Thu Aug 05, 2010 8:26 am

You can try SVS subwoofers which is locally distributed by http://www.mkcinternational.com/.
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Re: Does an audio system need a subwoofer?

Postby arnoldc » Thu Aug 05, 2010 8:33 am

re: RTA software, it needs to have enough resolution to make this excercise worthwhile. Free versions only give us a few. But for those who have not tried it, search for jDFT (runs on old OS, suggest running on Virtual Windows XP), trueRTA, or even Smaart if you want to buy.

You can use Radio Shack SPL meter with mic as the calibration file for that is freely available, or get a Beringher ECM800 and if you're really into it, put in a Beringher UB802 mixer.
Last edited by arnoldc on Thu Aug 05, 2010 9:04 am, edited 1 time in total.
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Re: Does an audio system need a subwoofer?

Postby brady » Thu Aug 05, 2010 8:42 am

without equipment (until Keith gave his old SPL to a poor provinciano), i just adjusted cut off by "ear" Downside is it took me --- I think --- an entire month. hehehe. just lay out your network on breadboard for convenient soldering and desoldering.

am just using a cheap and used 15 incher, in a sealed box, powered by a 50 watt SS push-pull amp (from a surplus store).
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Re: Does an audio system need a subwoofer?

Postby Nelson de Leon » Thu Aug 05, 2010 11:34 am

the porcupine wrote:Some methods have been mentioned in this thread already.

My method is a bit complicated and takes a lot of patience but the results are very much worth it (YMMV). I'm sure there are better/easier methods out there so feel free to search for them.

Basically, measure the frequency response of your main speakers using Real Time Analyzer software with a calibrated measurement microphone. You can also use an SPL Meter, test tone sweeps and a spreadsheet. From the resulting frequency response graph, take note of where the lower frequencies attenuate and use that as a reference for setting the crossover point of the sub. Measure the audio system again but this time with the sub. If you notice a peak or dip in the crossover freq of the graph, adjust the crossover setting of the sub accordingly to get the flattest possible response in the crossover point. Take the opportunity to match the volume level of the sub's lower frequencies with the main speaker's frequencies while doing this. Since there will be a lot of re-measuring and adjusting to achieve the best integration of the subs and main speakers, using a real-time analyzer makes all the difference since its much easier and faster to use than the spreadsheet method.

Prior to doing all this, I would recommend getting a subwoofer that can go down flat to 20Hz with very little distortion. It is also best to determine the best sounding placement of the sub in the listening room as well as the right phase setting. Low frequencies are arguably the most difficult to tame in a room thus requiring acoustic room treatment like bass traps to help achieve flat response. Using multiple subwoofers helps significantly in flattening low freq response in any room. If you like, you can use a (Parametric) equalizer along with the RTA and a measurement mic to equalize the frequencies in your listening spot after doing all of the above. Use this sparingly, though, as extreme boosts and cuts tend to introduce distortion and artifacts.


Got it.

SVC is good. It can be tuned manually by blocking the ports. I was contemplating on purchasing one until Stagea suggested that i use my old car audio sub.It's an L ported tower design ( for minimal footprint ) tuned to 28hz. trod93 aka Tony made the enclosure and marcopilyo supplied the amp using the built-in sub xover function of the av/r. It did go low and i was very satisfied with the results at a fraction of the cost of branded subs in the same power range. I used it mainly for HT. For audio purposes, probably tuning the enclosure to 40-60 hz region would do.
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Re: Does an audio system need a subwoofer?

Postby Stagea » Thu Aug 05, 2010 1:27 pm

@Nelson

Your box is tuned to 23Hz. :D Anechoic F3 based on WinISD is 20Hz, and an F6 of about 18Hz. With your amp power at hand, I computed it so that the driver remains within its linear limits for the entire audible range.

In your elongated room, I was assuming that cabin gain would start setting in at around 34Hz (I made estimates based on a 10m x 4m x 3m room). Given the leaky nature of the room (open back door and staircase), I just assumed half of typical transfer function at about 6db/octave. With this at hand, in-room F3 will shift to about 18Hz, and F6 may be as low as 16Hz. However, the room gain will give you a 2/3 octave peak centered at around tuning frequency (it's only a 2db bump at the most though). I was assuming that this bump will be welcome for the added rumble anyway (for HT purposes). It should perform maximally flat (musical) in a bigger room (or when your front doors and windows are open as well).

The T/S parameters of your driver lend well to decent home integration. Aside from the mentioned peak, it plots near flat (especially with the help of a weak axial mode at around 34Hz, correcting the driver's actual response).

My HT system is less fortunate (square room that is probably sealed a bit better). Though my sub should extend better (in-room F3 of about 16Hz, and F6 of about 13Hz), it has a very broad 2 octave peak centering at 34Hz. This gives it a lot of authority with certain movies (ground shaking is easily achieved), but the upper LFE frequencies (70-100Hz) can sound weak at lower volumes, giving it a bit less initial impact during explosions. It doesn't have much problem with music though, because I cross them at 40Hz (upper frequencies are handled by the main speakers).
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Re: Does an audio system need a subwoofer?

Postby Nelson de Leon » Thu Aug 12, 2010 2:09 am

Guess who has twin subwoofers for his hi fi? :)

/\
I
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Re: Does an audio system need a subwoofer?

Postby Nelson de Leon » Fri Aug 13, 2010 6:35 am

@ Stagea:

Reviews naman on your new dual sub system. ;)
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Re: Does an audio system need a subwoofer?

Postby Stagea » Fri Aug 13, 2010 7:07 am

Nelson de Leon wrote:@ Stagea:

Reviews naman on your new dual sub system. ;)


Lokoloko ka Master Nelson. I just wanted discrete left and right LF output kaya dalawa, just in case there are tracks out there with this capability. Saka may localization ng konti pag isa dahil downfiring yung ports ng subs ko, magvavibrate kasi yung hardwood flooring.

I spent about an hour yesterday tweaking the gain control and LPF. It ALMOST sounds right now, but the LPF doesn't seem to go low enough (I wish I can run a HPF on my mains LOL). I got things integrated relatively well though. I think I need to lower the gain a notch more, as the room modes are getting excited.
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