Does an audio system need a subwoofer?

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Re: Does an audio system need a subwoofer?

Postby Jon Agner » Mon Aug 02, 2010 11:02 pm

rascal101 wrote:Sa aking pagkakaintindi kapag phase correct, time aligned po ang tunog.

Hindi ko po kabisado ang practices ng speaker makers. Ang sure lang ako, kapag nagsabay ang low freq at high freq sa speakers (lalo na iyung may passive crossover) hirap talaga ma distinguish ang low. Lalabas kasi na bumababa iyung impedance ng woofer capacitor dahil sa pagpasok high freq. Sa saglit na iyon o maikling sandaling iyon, halos wala tayong maririnig sa woofer.


Have you ever heard the sound of a full range single driver? If this is your belief, then I should not be hearing anything from my speakers :^) :^) :^)
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Re: Does an audio system need a subwoofer?

Postby Stagea » Tue Aug 03, 2010 5:05 am

Nakikigulo lang po, not meaning to contradict anyone. Just sharing my thoughts.

- Afaik, may parallel cap sa LF filter pag second order or higher yung cross, though that's after at least one inductor. Possible na may interaction siya (and some speakers can get quite capacitive), but a good amp and wiring with lots of damping and current capability should easily overcome this (or speakers with a consistently high impedance for amps with low current capacity). Biamping can also help fix this.

- How will you know how much phase correction ang kailangan ng system? Like sakin, supposedly capacitorless signal path (except sa speaker side), so dapat minimal ang phase shift. Hindi ba dapat iba iba ang needs ng different systems?

- Reverse polarity tweets will have an output wave opposite (180 degrees) of normal polarity, which can correct for phase issues around the cross point. In this case, a second order or a 12db/octave slope filter will have an output shifted by 180 degrees. Together, they render a waveform that is phase-correct, but is still offset/shifted in time domain, by the equivalent of half a waveform. The resulting phase shift introduced is also not constant throughout the frequency range due to component resonances (fortunately, absolute phase differences are supposedly quite inaudible). Even if the phase shift is constant, since different frequencies are also being shifted, the actual shift in unit time can vary significantly depending on the frequency (a 180 degree shift at 1kHz is delayed by a longer time versus a 180 degree shift at 10kHz).

- I don't agree that sa front-end ang most ng kailangan ayusin in a system, equally important ang ibang components. I think the transducers (being electromechanical) are the most prone to causing distortion/coloration, given that all other components are of good quality and are properly matched.

- And back to the topic, in my opinion a properly integrated sub can indeed help sa lows. However, not all systems (or material) need one, depende na din sa needs at preference nung mayari
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Re: Does an audio system need a subwoofer?

Postby rascal101 » Tue Aug 03, 2010 5:07 am

Have you ever heard the sound of a full range single driver? If this is your belief, then I should not be hearing anything from my speakers :^) :^) :^)

Yes. If you look closely to my statement, it is at the particular instant or moment in time when you have a high freq transient and a low freq signal this will lower the impedance of the crossover cap in parallel with the woofer. So at this very small period of time, there will be little or no sound at all from the woofer.
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Re: Does an audio system need a subwoofer?

Postby rascal101 » Tue Aug 03, 2010 5:13 am

arnoldc wrote:Oh my gulay, what is this?

1. Bumababa yung "impedance" ng woofer capacitor dahil sa pag pasok ng high frequency
2. Walang maririnig sa woofer

Do you even know what a capacitor does in this passive cross over you are describing? It limits the low frequency going to the tweeter. It will not impede the signal going to the woofer. It protects the tweeters from getting the low frequency that the tweeter will otherwise get without the capacitor.

A decent crossover will have a coil (inductor) to stop the high frequencies from going to the woofer.

Ipasok natin yung phase shift... A passive crossover will introduce a phase shift, for example a 6dB filter will have a 90 degree phase shift, so designers compensate for that by reverse phasing the tweeters.

So what were you saying again?

rascal101 wrote:Sa aking pagkakaintindi kapag phase correct, time aligned po ang tunog.

Hindi ko po kabisado ang practices ng speaker makers. Ang sure lang ako, kapag nagsabay ang low freq at high freq sa speakers (lalo na iyung may passive crossover) hirap talaga ma distinguish ang low. Lalabas kasi na bumababa iyung impedance ng woofer capacitor dahil sa pagpasok high freq. Sa saglit na iyon o maikling sandaling iyon, halos wala tayong maririnig sa woofer.


Sir Arnold, isn't that what I said that the crossover cap will have low impedance thus it will be the path of the signal to ground instead of the woofer. I never said anything about impeding anything to the tweeter.

At the instant or moment in time when you have a high freq transient and a low frequency signal .... Well the amp "sees" the speakers (also the crossover) and when it "sees" a C it will behave per its characteristics. I assumed that Xc = 1/(x*pi*f*C), so with a highish f (freq) I shall expect a low Xc (impedance). And the L in my 2nd order low pass filter will impede the high freq because of a rather high impedance Xl = 2*pi*f*L. So, you're saying my 2nd order L-C low pass filter is just like the first order L low pass filter, right? Sorry, I didn't know (my understanding is not right) that the freq response of the 2nd order low pass filter is just like the first order low pass filter. The resonant action of the L-C where it has a peak before it falls (on the freq response curve) should be ignored.
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Re: Does an audio system need a subwoofer?

Postby rascal101 » Tue Aug 03, 2010 5:42 am

If you can explain on the mechanical side of the speaker it would be of great help to people who focus more on the magnetic side.[/quote]

Of course there will always be an LF signal that will feed into the voice coil of the speaker, coming from the amp, unless you put a filter in between.

Now, on the mechanical side, basically, we are talking about transfer of energy, from electrical to mechanical right? Canthe LF/VLF signal produce enough voltage and current to enable the voice coil of a speaker to move back and forth? Can the movement of the voice coil produce enough power to agitate the air around it? In theory, yes it is possible. But then the next question is if there is a single driver speaker available in the market today that can do this? And I mean a single driver that can respond properly and efficiently w/in the entire audio bandwidth.

If there is one available today, then why do we still need to design and build speaker cabinets? Why do we need to build 2 way, 3-way, N-way and array speakers if one speaker can do it all? Right ;)

Nothing personal. This is just an exercise of our minds :)

Cheer up 'man, lahat naman tayo dito pinag-aralan na din 'yan ;) :)

-----------------
Sir JackD, thank you very much!
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Re: Does an audio system need a subwoofer?

Postby arnoldc » Tue Aug 03, 2010 7:32 am

That's text book rascal101, the formula is all over the internet and in books. You haven't proven anything. You think that by posting a textbook formula, you will sound credible?

Firstly, you start by saying the source must be phase correct, now nasa speaker na usapan, wala pa ding laman yung post mo.

BTW, bakit mo binura yung post mo na "kilala ko na kayo". Is that a threat?
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Re: Does an audio system need a subwoofer?

Postby kabubi » Tue Aug 03, 2010 10:01 am

arnoldc wrote:BTW, bakit mo binura yung post mo na "kilala ko na kayo". Is that a threat?


the "kilala ko na kayo" statement was meant for me after a little misunderstanding from the Braveheart picture. but we have explained things already, and everything is hunky-dory between us.

i think that Mel has tried to explain himself in the best possible way, amidst all the doubt and speculation to his views. the discussion has reached a crescendo and i feel that it is exhausted and has been exhausting already. to proceed further will only bring acrimony.
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Re: Does an audio system need a subwoofer?

Postby arnoldc » Tue Aug 03, 2010 10:26 am

Uhm, yun naman pala. So betterer na Kabubs...

To get this topic back on track, I do need a subwoofer. I have been posting in the past the problem with my room, which led to dozens of speakers being audition with the hope that one will come along the way which will not be influenced by the room characteristic.

Then came the long story how I did it...

Sadly, I'm back to a disadvantage again as I rotated my gears once more. There are reasons behind the move, but there is a compromise. I want to hear more, or perhaps my car audio is is influencing this move. No, no, I'm not into loud and proud thing, but I just want a little more depth.

Therefore, I stole the subwoofer from my HT setup. It is a nice little Dali AW8 which is just 11" wide and that allowed it to fit nicely behind my personal-ref sized DIY speakers. However, even at 35Hz low-pass, I still think I'm getting too much. Yeah, yeah, there's a volume control but then I still have to buy another subwoofer for my HT.

The objective is now to get a really small subwoofer that will go low, yeah, yeah, wrong combination- small and low.

I've been looking at Energy, Fazon.. But if you know a smaller subwoofer that can do 35Hz LP (pwede na siguro 40Hz LP) that can keep up with the pace of my system, do post it here.

:)
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Re: Does an audio system need a subwoofer?

Postby JoeyGS » Tue Aug 03, 2010 10:41 am

Try Era sub from Noel of Audio Amplified. They have a 10 inch sealed sub good for audio. Bogsle, one of our members have used this and have paired with his VR1 bookshelves.

arnoldc wrote:
I've been looking at Energy, Fazon.. But if you know a smaller subwoofer that can do 35Hz LP (pwede na siguro 40Hz LP) that can keep up with the pace of my system, do post it here.

:)
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Re: Does an audio system need a subwoofer?

Postby muypogi » Tue Aug 03, 2010 10:44 am

arnoldc wrote:Uhm, yun naman pala. So betterer na Kabubs...

To get this topic back on track, I do need a subwoofer. I have been posting in the past the problem with my room, which led to dozens of speakers being audition with the hope that one will come along the way which will not be influenced by the room characteristic.

Then came the long story how I did it...

Sadly, I'm back to a disadvantage again as I rotated my gears once more. There are reasons behind the move, but there is a compromise. I want to hear more, or perhaps my car audio is is influencing this move. No, no, I'm not into loud and proud thing, but I just want a little more depth.

Therefore, I stole the subwoofer from my HT setup. It is a nice little Dali AW8 which is just 11" wide and that allowed it to fit nicely behind my personal-ref sized DIY speakers. However, even at 35Hz low-pass, I still think I'm getting too much. Yeah, yeah, there's a volume control but then I still have to buy another subwoofer for my HT.

The objective is now to get a really small subwoofer that will go low, yeah, yeah, wrong combination- small and low.

I've been looking at Energy, Fazon.. But if you know a smaller subwoofer that can do 35Hz LP (pwede na siguro 40Hz LP) that can keep up with the pace of my system, do post it here.

:)


Why don't you try some of the subs of Anthony (aka DIY_Master sa PDVD)? Had his 10 incher before and had very little trouble integrating it with my Dynaudio standmounts. Sold that sub to my father in law and konting tweak na lang (with his vintage KEFs) and hindi mo na malolocalize yung sub. . .

I'm saving up for a sealed 12 incher again from Anthony, so maybe you could drop him a line. . .
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Re: Does an audio system need a subwoofer?

Postby arnoldc » Tue Aug 03, 2010 11:33 am

JoeyGS, I checked the Era Sub 8, it is a bit bigger than my Dali AW8 but more powerful pa, i.e., 200W. Let's see.

@muypogi, thanks for the info.
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Re: Does an audio system need a subwoofer?

Postby JoeyGS » Tue Aug 03, 2010 11:47 am

You should check out if Noel still has an old stock of the Era sub 10. I think this model is not in their website anymore, but this is the one that's for audio application. The Era sub 8 is for HT application per my readings in their site.

Checkout the specs of the Era sub 10 at the bottom of the following web page:

http://www.thelisteningroom.ca/subwoofers.php

BTW, Bogsle is Nolan Lenon pala..I think you know him.


arnoldc wrote:JoeyGS, I checked the Era Sub 8, it is a bit bigger than my Dali AW8 but more powerful pa, i.e., 200W. Let's see.

@muypogi, thanks for the info.
Last edited by JoeyGS on Tue Aug 03, 2010 11:53 am, edited 2 times in total.
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Re: Does an audio system need a subwoofer?

Postby kabubi » Tue Aug 03, 2010 11:48 am

does a subwoofer have to have a cone of at least 10-12 inches diameter?
what is the smallest acceptable driver size for a subwoofer, one that will be acceptable to many WS hobbyists? 6 in? 8 in?

ang full range driver ba, puedeng gawin sub? puedeng dalawang 6 in driver sa isang channel ng sub?

salamat!
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Re: Does an audio system need a subwoofer?

Postby qguy » Tue Aug 03, 2010 12:01 pm

I think the most common acceptable size is 12 inch, then again there a lot of factors, woofer size is just one of them.

Full range driver ??? Well if it can reach 20HZ why not ?, but if there was such a driver then there would be no use for a subwoofer




kabubi wrote:does a subwoofer have to have a cone of at least 10-12 inches diameter?
what is the smallest acceptable driver size for a subwoofer, one that will be acceptable to many WS hobbyists? 6 in? 8 in?

ang full range driver ba, puedeng gawin sub? puedeng dalawang 6 in driver sa isang channel ng sub?

salamat!
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Re: Does an audio system need a subwoofer?

Postby arnoldc » Tue Aug 03, 2010 12:02 pm

Yes, ako ang BI ni Nolan :)

Kabubs,

re: size, nakita mo na sa YouTube yung world's smallest subwoofer? Not that I would use one, pero it is freaking small. So while size does matter, being a subwoofer isn't about size anymore.

There are "dedicated" subwoofer drivers as small as 5", specially for car applications. I actually thought of making a subwoofer using amp and driver for car audio.

My car does not have a subwoofer, I'm using the stock coaxial drivers in the rear using active low-pass @ 80Hz. Sakay ka and listen and you will understand my home audio predicament.
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Re: Does an audio system need a subwoofer?

Postby arnoldc » Tue Aug 03, 2010 12:05 pm

@qguy, based on what survey yan na 12" ang most common? o yan lang nasa isip mo?

Why 20Hz? magic number ba yan? Is that the only thing that matters in subwoofer design?
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Re: Does an audio system need a subwoofer?

Postby Squirrelnutzipper » Tue Aug 03, 2010 12:16 pm

arnoldc wrote:@qguy, based on what survey yan na 12" ang most common? o yan lang nasa isip mo?

Why 20Hz? magic number ba yan? Is that the only thing that matters in subwoofer design?

I think that the answer here is a little more complex. Not only the dirver size is a relevant consideration, but also the enclosure volume is something that needs to be considered. If equalization is employed, the enclosure size can be reduced and even sealed, not ported. In such cases, the driver size would seem to be not as critical. What about line arrays for sub bass, utilizing more than one driver and single channel versus multi channel?
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Re: Does an audio system need a subwoofer?

Postby qguy » Tue Aug 03, 2010 12:16 pm

Arnold,

Read my answer it says there "I think" Do I need to explain this ?

Like I said earlier maraming factors ang subwoofer design.

Why 20hz, Yes, you are correct, its my Magic number. Whats yours ? seriously I uses a 20hz as reference, it can be lower like 19hz, or 18 hz. :devil: My point is that if the full range driver can go deep then it can be used as a subwoofer

arnoldc wrote:@qguy, based on what survey yan na 12" ang most common? o yan lang nasa isip mo?

Why 20Hz? magic number ba yan? Is that the only thing that matters in subwoofer design?
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Re: Does an audio system need a subwoofer?

Postby heidel » Tue Aug 03, 2010 12:28 pm

Wow!! dami ko natutunan sa thread na to...naalala ko tuloy yung wireless communication subject ko nung college about Filter. Base sa natutunan ko pareho din ng paliwanag ni sir arnoldc. High Pass Filter, the capacitor will allow the high frequency to pass the low frequency will be filtered just like the cross-over circuit of tweeter. Low Pass Filter, the coil will allow the low frequency to pass and the high frequency will be filtered, same with cross-over circuit of woofer. Pakitama na lang po ninyo ako kung mali ang pagkakaintindi ko....
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Re: Does an audio system need a subwoofer?

Postby arnoldc » Tue Aug 03, 2010 12:29 pm

The most common sizes are 8", 10", 12", 15" and 18". The less common sizes are 5.5", 7", and 20".

There. Generic yan, galing sa web :lol:
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