subs and distortion

The Judge

I know everyone has their Favorite sub.
I am in the market for one but when I see the numbers, that is all I see.
I know that Polk will tell us a FR within -3db or whatever but I never see a distortion percentage. Very few speaker companies exposed those figures.
When buying a sub for 500 to a grand and since it covers a usually 2 to 3 octaves of the music, I do want to know what the THD is at its playing range. If my sub I am going to buy will play down to 20 cycles I don't want the distortion to be 20% at that Frequency.

Someone please enlighten me.

J_Kennedy

HSU or SVS will be good places to start.

Music Joe

I'm looking at subs too. I'm forming the idea of getting one that's overkill and operating it well within its comfort zone.

speakergeek

Music Joe wrote: »

I'm looking at subs too. I'm forming the idea of getting one that's overkill and operating it well within its comfort zone.

Very good idea. That's exactly why I chose the sub I chose.
I've come no where near maxing it out either. More headroom is good. Subs that are operating well within their design margins have less distortion than those being pushed. But you will need one that can handle 20 hz effortlessy.

ShinAce

Frequency response can be measured with as little as a fraction of a watt.

The only time you will see a distortion spec is for the amp output. Genre 300WRMS @ 4 ohm (2% THD). At this power level, the woofer likely has higher distortion specs, but this is hardly ever stated. You can expect 10% distortion from a sub at full power.

Face

On a big sub you can always turn down the gain. On a small sub, running near full gain is never a good thing. Go big or go home.

ShinAce

I say go home big.

The Judge

ShinAce wrote: »

Frequency response can be measured with as little as a fraction of a watt.

The only time you will see a distortion spec is for the amp output. Genre 300WRMS @ 4 ohm (2% THD). At this power level, the woofer likely has higher distortion specs, but this is hardly ever stated. You can expect 10% distortion from a sub at full power.

How many people run a sub at full power?
Do the specs mean anything without distortion figures?
I'm sure there are great quality subs like the one mentioned.
Where did you get the 10% figure?

[Deleted User]

Hello,
The good thing about relatively high amounts of distortion, in sub-woofers, is that it comes in the form of "doubling". This is a palatable form of distortion that most, inexperienced, owners prefer. If the sound is supposed to be 40Hz, for example, a sub-woofer will not only give 40Hz but 80Hz and 160Hz, adding even order harmonics to the fundamental 40Hz signal.
Regards, Ken

ShinAce

Typical distortion for a driver from non-linearities and break-up(resonance) modes is in the order of 3% at higher volumes. It does not decrease much with lower power. Electrostatics can improve on this figure by a full order of magnitude.

When these measurements are made, clipping of the amplifier is not allowed. In the real world, this is allowed and can result in much higher distortion due to gain compression(voice coil heating), power compression, and clipped signals. 10% is a ball park figure just to exemplify how much distortion can be produced by a speaker.

Jed Leland

Hello,
While electrostatic speakers have their own share of problems, the push-pull nature of the drive mechanism does reduce distortion. When properly placed and driven by the correct associated electronics and source material they are very low in distortion.
Subwoofers that use a band-pass design are also inherently low in distortion, providing all the parameters of good design are met.
Jed

ShinAce

Just for kicks, does anyone know how horns stack up?

Jed Leland

Sorry, my friend, not my cup o' tea. I know Mr. Klipsch always preached the reduction in doplar distortion by high efficiency components. For me, I'm too bothered by the mid range coloration the horn elements add. I know there are many extremely pleased and dedicated horn speaker owners and I always work to keep an open mind and appreciate their point of view.
Voices just never seem to sound "right" to me, more "hifi" I've spent too much time listening to real acoustic music, I suppose.

speakergeek

Never liked horn element speakers myself. Always sounded too bright (forward) to me.

ShinAce

Using a horn for the midrange hasn't even crossed my mind when I posted that.

I was contraining myself to the sub 120 Hz zone. As means to better load the woofer and reduce cone excursion, I imagine a horn would do very well distortion wise.