2 Subwoofers

[Nervous]

<font color='#000000'>Hey guys! Nice forum you have here and it looks like its still growing.
I have a question about having 2 subs for HT.
What are the advantages/disadvantages of having 2 subs in a home theatre setup? &nbsp;Will improper placement hurt rather than help the sound?
I guess that's 2 questions.

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[Yamahaluver]

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Nervous : <font color='#000000'>Hey guys! Nice forum you have here and it looks like its still growing.
I have a question about having 2 subs for HT.
What are the advantages/disadvantages of having 2 subs in a home theatre setup? &nbsp;Will improper placement hurt rather than help the sound?
I guess that's 2 questions.

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<font color='#000000'>Two subs are good if they are of the same charecteristic and power output. They have to be placed next to your main speakers at any cost or else you will suffer phase cancellation and booming bass with exceptionaly poor imaging.

My advice, save the money, get one good high power sub and big tower speakers for main speakers. Couple the main speakers to a powerful amp and select both for sub out and designate main speakers as 'Large' if you have a DSP Pro Logic amp like Yamaha AZ-1 etc. The big tower speakers combined with your amp and sub will give you all the bass you need with the right imaging and slam.</font>

 

[Nervous]

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Yamahaluver : <font color='#000000'>They have to be placed next to your main speakers at any cost or else you will suffer phase cancellation and booming bass with exceptionaly poor imaging.</font>

<font color='#000000'>Is this true even if the subs are in-phase ie. set to 0 degrees? &nbsp;

Pls advise which situation on this site would apply.
http://www.sfu.ca/sca/Manuals/ZAAPf/p/phase.html</font>

 

[Yamahaluver]

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Nervous : <font color='#000000'><table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>Quote (Yamahaluver @ Mar. 08 2003,03:05)</td></tr><tr><td id="QUOTE">They have to be placed next to your main speakers at any cost or else you will suffer phase cancellation and booming bass with exceptionaly poor imaging.

Is this true even if the subs are in-phase ie. set to 0 degrees? &nbsp;

Pls advise which situation on this site would apply.
http://www.sfu.ca/sca/Manuals/ZAAPf/p/phase.html</font></td></tr></table>
<font color='#000000'>Even if they were to be in phase imaging would be seriously affected. I have tried the experiment with two Yamaha YST 800 subs. The temptation of two 800 watts subs firing was too great for me to resist. I had to make sure they were kept right next to teh main speakers. Even the Yamaha manual states that they have to be in close proximity to the main speakers.</font>

 

[Nervous]

<font color='#000000'>Sorry but I'm having a hard time understanding why it would affect the imaging since the subs arent in stereo. &nbsp;Can you explain further? Thanks.</font>

 

[Yamahaluver]

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Nervous : <font color='#000000'>Sorry but I'm having a hard time understanding why it would affect the imaging since the subs arent in stereo. &nbsp;Can you explain further? Thanks.</font>

<font color='#000000'>Here is my understanding of what happens with two improperly placed subs, the standing waves cancel each other out, also some materials are recorded with low frequency stereo signals, notably classical music recordings and then more problem arises.

Didn't work out for me unless the subs were placed close to the main speakers.</font>

 

[Audioholics]

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Yamahaluver : <font color='#000000'>Here is my understanding of what happens with two improperly placed subs, the standing waves cancel each other out, also some materials are recorded with low frequency stereo signals, notably classical music recordings and then more problem arises.

Didn't work out for me unless the subs were placed close to the main speakers.</font>

<font color='#000000'>Yamahaluver is correct about standing waves and phase cancellation. However, you will find that the room characteristics (perhaps even more than your speakers) will drive the placement of the sub, even one sub can provide a challenge with regards to placement.

If you haven't read this article, it has some great suggestions for placing your first sub, then you'll need to do even more work on positioning a second one.

If your main speakers do not support frequencies much below 70Hz, then your battle will be with the room, and each other (the subs), not your imaging. I have 2 subs, but the second one isin my office, not my HT room!

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[Nervous]

<font color='#000000'>Thanks alot guys, it is very clear to me now.
You guys are good.

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[Yamahaluver]

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Nervous : <font color='#000000'>Thanks alot guys, it is very clear to me now.
You guys are good.

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<font color='#000000'>You can try a simple experiment if you already have a sub, try placing it in center position right between your main speakers and see the bass dissappear. The reason for that is that the wall facing the sub is generating enough reflected standing waves to cancel out the sub's own waves.</font>