Ratio of sub vs speaker watts

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swede

Copper - Posts: 125

Joined: July 31, 2004

Location: United States

Posted: June 16, 2005 at 10:38 PM / IP Logged

Is there a set ratio for sub vs speaker wattage? I can't imagine (although I could swear I've heard some) having a 20w x 4 + 1000 x 1 set up.

As of now I'm at 110w x4 + either a 300w or 600w x 1 and don't want to lopside it. I realize I could just turn the gains down if thats too much, but I still want to do this methodically correct.

Thanks.

Subtlety is EVERYTHING.

stevdart

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Posted: June 16, 2005 at 10:57 PM / IP Logged

There are a lot of considerations to your question. One, high freqencies take very little power, and our ears can tolerate only very little response. Mid freqs take more power than the tweeters, and our ears hear freqs in that range much easier than the higher and lower freqs. Not to mention that everybody's hearing is different.

Sub freqs take about 10 times the power for the same db level (that's off the top of my head as I can't think of where to go for reference...) as the higher freqs. And if you're trying for a great SQ setup, the power required to produce a tone at 20 Hz is 8 times greater than the power required to produce 50 Hz, IIRC.

A sealed sub enclosure will need more power than a vented one. One sub might have a sensitivity of 90 db while another has 87 db....a difference of one having twice the output as the other with 1 watt of input. And of course there's the mixing of the music source, where the sub, low and high freqs are accentuated and the mids are attenuated...so that playback is normal and natural to listen to using one single power supply.

So...to set a standard for a sub-to-highs power ratio would be a lesson in futility. If someone posts that there is indeed such a thing, I'll learn about it right along with you. But I'm willing to bet there are some tried-and-true Rules of Thumb.

I'm using 4 X 50 and 1 X 200, but I'm betting that the 50 watts to each speaker is more like 35 watts at the most at highest volume levels. At the same time, I bet the sub is using a little more than 70% of the power available to it.

Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

Poormanq45

Silver - Posts: 597

Joined: October 27, 2004

Location: United States

Posted: June 16, 2005 at 11:27 PM / IP Logged

stevedart wrote:

And if you're trying for a great SQ setup, the power required to produce a tone at 20 Hz is 8 times greater than the power required to produce 50 Hz, IIRC.

Nope, it's all the same. A doubling of output(3dB) still requires a doubling of power.

A high efficieny driver can put out close to 100dB at 20Hz with 1w@1m

THe problem that is quickly run into is the excursion limits. Of course Xmax only limits maximum SPL. You can start out at 110dB @30hz with only ~3~5mm PTP excursion. But then to increase 3db you need 4times that 12~15mm, then 24~30mm then 48~60mm, etc.. You can see that you quickly run out of suspension. THe same applies for lowering frequency. Half the frequency quadruple the excursion

swede

Copper - Posts: 125

Joined: July 31, 2004

Location: United States

Posted: June 17, 2005 at 9:18 AM / IP Logged

I ask this because as of now I haven't made the decision on the sub amp yet. About 16 years ago I had my first "real" system installed by an area shop. It was all Yamaha (before Sanyo ruined them). They had a single 35x4 amp to all 4 speakers, and (2) 500w x 1 amps going to each of 2 12" subs. It sounded great (to me - at the time) but it was ALL BASS. I had to have the sub controller sitting on rock bottom 75% of the time just to keep my head from doing the "Scanners" explosion.

Personally with 110w (RMS @ 4ohm) x 4 I don't think they will be drowned out with either the 300w or 600w going to the sub. Even JL's 500/5 "only" has 250w to the sub as compared to the 115(?!)x2 + 25w x 2.

Just wanted to know if indeed there was a method to the madness.

Subtlety is EVERYTHING.

Poormanq45

Silver - Posts: 597

Joined: October 27, 2004

Location: United States

Posted: June 17, 2005 at 9:51 AM / IP Logged

Not really. You should use WinISD to model your sub/enclousure to find out the max RMS output. Then find a set of mains and amp(s) that can play to that level.

I ALWAYS recommend that you get a nice set of mains AND and amp to power them BEFORE you get a sub. THEN if you still want more bass you can get a sub.

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Ratio of sub vs speaker watts

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