Harmonic distortion at 96db

[goat76]

It's hard to make a reliable distortion measurement in a living room without getting interference/resonances from the room itself. I wanted to contribute to this thread and make a distortion measurement of my ATC SCM11, preferably at a distance of 1 meter and at a level of 96dB. But damn, I just realized I don't want to play them that loud for the sake of my neighbors, and resonances from the room itself are starting to contaminate the measurement. If I only had a free field...

However, I could measure at a distance of 60 centimeters, with a level of 90 dB, without any obvious room interference contaminating the measurement. It looks like this, and I think it's pretty good for a fairly small 11-litre 2-way bookshelf speaker.

 

[Heinrich]

It's like wtf not many speakers play 96db with low harmonic distortion ?

It's like wtf not many speakers play 96db with low harmonic distortion! (Exclamation mark.)

Most recently, Santa gifted me some time, I came to supplement my subs with a pair of subs. Now HD is down from 3% to way below 1% down to 30Hz at highest level ever needed. It works subjectively, means there is huge benefit.

On the other hand, and what all first commentary missed is the very fact, that lower distortion is often achieved by limiting the real bass output. Low tuning with a stiff suspension in a small enclosure would do the cheap trick. E/g the JBL A130 as recommended skyrockets distortion below 60Hz. Not exacly what you want.

So better watch the scientific bass output when comparing distortion figures. Think it this way: what if the measurements were done all speakers equalized to the same output at all frequencies, bass included.

 

[aarons915]

Not to take this discussion in another direction but the better question to ask is if you really need this much capability? I just plugged in 96db/1W/1m into an SPL calculator and at 10 feet listening distance with just 2 speakers that is an average SPL of 92 db at your listening position. You should probably measure the SPL you like to listen at because this is an extremely loud volume which will cause permanent hearing damage in just a few hours, each time you listen that long.

 

[OldHvyMec]

this is an extremely loud volume

It sure is. VERY loud, especially over any period of time. If you add that to the seated position, I would definitely be squirming in a very short period of time, like under 3-5 minutes. That is very close to earplugs or ear muff territory for me.

Regards

 

[gasolin75]

It's like wtf not many speakers play 96db with low harmonic distortion! (Exclamation mark.)

Most recently, Santa gifted me some time, I came to supplement my subs with a pair of subs. Now HD is down from 3% to way below 1% down to 30Hz at highest level ever needed. It works subjectively, means there is huge benefit.

On the other hand, and what all first commentary missed is the very fact, that lower distortion is often achieved by limiting the real bass output. Low tuning with a stiff suspension in a small enclosure would do the cheap trick. E/g the JBL A130 as recommended skyrockets distortion below 60Hz. Not exacly what you want.

So better watch the scientific bass output when comparing distortion figures. Think it this way: what if the measurements were done all speakers equalized to the same output at all frequencies, bass included.

Sealed speaker ?

Many use a subwoofer, not so much for much lower bass extention but for better sound from the main speakers + lower distortion in the bass because a big sub (relative to the main speakers) helps play bass

 

[Sokel]

It's hard to make a reliable distortion measurement in a living room without getting interference/resonances from the room itself. I wanted to contribute to this thread and make a distortion measurement of my ATC SCM11, preferably at a distance of 1 meter and at a level of 96dB. But damn, I just realized I don't want to play them that loud for the sake of my neighbors, and resonances from the room itself are starting to contaminate the measurement. If I only had a free field...

However, I could measure at a distance of 60 centimeters, with a level of 90 dB, without any obvious room interference contaminating the measurement. It looks like this, and I think it's pretty good for a fairly small 11-litre 2-way bookshelf speaker.

View attachment 501313

View attachment 501314

I've done a couple myself too at another thread, here (no close neighbors, my house is detached all around :

"System" SINAD

Would the concept of "system" SINAD (from source to speakers) be useful in component selection for a good stereo system? Let's assume a listening SPL of 85dB @ 1m, and a room noise floor of around 40dB SPL. Assuming +20dB headroom for signal peaks, and another -20dB noise headroom. A system...

www.audiosciencereview.com

One of them is at the SPL we're talking here, or a little higher, all at the listening position, 2.8 meters away.
I agree, not reliable, lots of things at play, only indicative.

It's a big-ish 3-way though, so physics are in place.

At the same thread I have a very nearfield measurement of the woofer alone (F3 at 31Hz and anything above 250Hz is not valid as it crosses to mids, more to the thread)

 

[goat76]

@Sokel

Yes, a free field measurement is needed for a more reliable result, as room resonances could be seen in my measurements with a louder signal. I figured that out by moving both the loudspeaker and the microphone a little bit in the room, but keeping the distance and the loudness. The amplitude of the resonances changed depending on the position, which to me indicates that the resonances are room-related and not speaker-related.

Even if I had the equipment to make measurements somewhere outside, I don't think I'm dedicated enough to do all that work.

 

[ssashton]

Realistically, most bookshelf / standmount speakers aim to balance 'reasonable' SPL with as much low bass extension as possible. Why? Because deep bass from a small speaker sells well. So the port is usually tuned around 40hz.

If you know that the speaker will be high-pass filtered at 80hz, the port could be tuned around 100hz and the SPL ability will increase by nearly 6dB in the bass and distortion will drop. You could also use a larger woofer in the same cabinet size, because you don't ask it to play very low (the system Q can be higher).

The second paragraph describes the type of speaker the original poster would need - large woofer compared to the box size and a high tuned port. It is not common in hi-fi or studio monitors, but it is similar to the design philosophy of PA / live sound speakers. Perhaps something like a stage wedge would do the job.