optimum wattage in subs

Looking at speaker mechanical and physical properties, can there be an optimum power in terms of levels of distortion say in subs, 600 watts per 18 driver seems to be preferred by some makers.

Yes...the cone is controlled by the A/C current within the field and excessive movement which is distortion , (that outside of the signal that the amp is producing) is damped by both the enclosure and the amplifier.

You really need to use your own judgement if you are not willing to destroy a woofer to find out the answer. There are numerous measuring tools that will enable you to estimate the distortion versus power of a particular loudspeaker.

From my experience, feeding an 18-inch woofer 600-800 watts has always been ideal for maximum output before mechanical and or thermal breakdown under long-term conditions. By 600 – 800 watts, I mean literally feeding the woofer 600-800 watts playing music material.

I also don’t mean adding a HPF which will reduce the workload to the woofer when asked to amplify very low frequencies. Such methods (HPF) will offer more power handling at the expense of low frequency extension.

Of course, once you add two, four, eight and/or sixteen 18-inch woofers to the equation, each loudspeaker will attain less wattage due to the coupling affect. All the woofers working together as a team and, generate more SPL than one operating singularly. So wattage needed to attain a certain amount of SPL is reduced, xmax is reduced while, attaining more SPL is greater.

As the variability comes into play, making your own judgement is the deciding factor based on what you have in terms of quantity in woofers in addition to amplifiers at your disposal to create an all things created equal scenario. Even manufactures offer an estimate on their power handling. This is why some manufactures offer dB loss figures based on power compression coming into play at the given wattage.

Best Regards,


Edited by Elliot Thompson - 27 March 2015 at 4:52pm

What you experienced is power compression coming into play. Moving from 800 watts to 2500 watts offers a near +5 dB gain. So you should hear a significant difference unless something is limiting the output. That limitation is the loudspeaker’s inability to offer more volume moving from 800 watts to 2500 watts.

There are plenty of users that are not paying attention to the power compression loss listed on some manufactures specifications sheet. They main concern is the wattage rating that’s that.

Some Loudspeaker Manufactures expect the customer to use High Pass Filtering and capitalise on that by, escalating the wattage rating. If you explore what type of frequency bandwidth manufactures use to estimate the wattage rating, you will understand why some manufactures endorse using a HPF.

The majority of pro audio loudspeaker manufactures will tell you the type of signal in addition to bandwidth used which, led to the wattage figure located on the loudspeaker’s specification sheet.

I recall when Beyma adopted the AES rating. Their entire loudspeaker range in terms of wattage increased all courtesy of the AES rating. So a Beyma 18 G550 that was once rated 750 watts pre-dating the AES rating is now 900 watts based on the AES rating. The differential in wattage is based on the HPF used in both ratings.    

If sound quality is the objective, you will need to use quantity to minimise distortion from not having enough loudspeakers being overdriven, while maintaining a High SPL from multiple speakers working together as a team.

Best Regards,


Edited by Elliot Thompson - 27 March 2015 at 7:49pm

Build PPSL box if you want to reduce distorsion.

It is common for speakers to achieve 2 to 3 decibels of compression at their program rating. That may not sound like a lot. However, if a loudspeaker falls within 3 decibels of power compression at it’s program rating, it basically means even if you fed the driver 3 decibels less than it’s program rating, it will be just as loud as if you fed the driver its program rating wattage.

Of course, if the manufacture escalated the program ratings, the power compression can be even higher at the program rating. If the manufacture chose not to offer power compression figures then, it may be difficult to get the answer from the manufacture. There are only a few companies that are willing to post power compression figures on their woofers.

Best Regards,   


Edited by Elliot Thompson - 27 March 2015 at 9:32pm