Woofer QTS explained 

To be honest, this is probably the most informative youtube that I've seen on audio

Thank you for your time. Even though there are others breaking down the spec's, not all make it easy to understand. This is the type of content that gives the consumer a better view on the products in question and how to properly use them. Keep up the good work.

Excellent explanation...havent seen any other video explaining Qts this simple

Pure clear nice soft simple English explanation keep it up i want more videos

thanks for the nice explanation !!

I like the way you describe the parameters in layman terms. I agree that a higher number for mechanical damping (less damping) is good when combined with higher electrical damping (lower number) for better attack and decay. Results in a more detailed bass.

Thanx! Now I know things better. Long ago I used to have french mid sized 2,5 way speakers with very little damping, bass reflex opening to the front. They were fairly expensive but the stands had no good wife acceptance factor. The stands were just physically useful, not for the eye. Their bass was so dry, that I assume, Qts, Qes were very low. The manufacturers even made the chassis in house. Same company also made smaller and larger enclosures using the same drivers. I think in a bigger enclosure the chassis sounded better, but I could not effort them. Sound slightly improved by using a PP layout with EL34.

Very helpful video- thanks!

Underdamped means Q larger than 0.5; overdamped is when Q is smaller than 0.5.

From what I've gathered there are three frequency areas a woofer can operate in. The +12db per octave lower area where position (force) is constant. If you were to apply a battery say 1.5 volt to the speaker then it pops forward say 2mm and that's it. That's what I mean by position = constant. It doesn't matter if we're at 2hz 5hz or 10hz.. Then there is the 6db per octave mid area around Fs where speed (voltage) is constant. And force (or current) tends to go to zero because the two forces cancel out. Then there is the flat 0db area where acceleration is constant. (and force is constant again). When the drivers qts is lowered that means it has a relatively lower electrical resistance that means that the area where the driver is 'in control', or the mid +6db/oct area, is widened. Here the voltage the driver generates more or less equals the voltage that's applied, that means 'speed is constant' so to speak. In the other two areas the lower 12db and the upper 0db one, the current is limited by the resistor so you're in a kind of force = constant regime. If there was no resistance some kind of superconducting speaker it would be in 6db per octave mode all the way. I hope that made any sense. At q 0.7 there is hardly any 6db slope area and it goes directly from 12db slope to 0db flatness.

Excellent job

Did you ever do a follow up video on calculating box dimensions based on woofer QTS? Or know of any good sources? I'm trying to design a bookshelf monitor :)

very helpful, thank you

Thanks! I was hoping you would talk about how those Q values impact ported vs sealed choises. I assume a high QTS would be best in a sealed box so it's less "boomy"? Likewise, a low QTS would be suited for a ported box to extend its boom? Really appreciate your content. This is good stuff!

In midrange maybe we need driver that have higher Qts like 1.5 or more.. if we see on tube amplifier, they have low damping factor and that's why they sound more musical on midrange.. the best way to use high qts driver by using open baffle design?? What do you think?

Thanks!

Those are horn hybrid woofers? been considering some lii audio full range. Prob try the 6.5" full range first.

Is there any way to look at the specs (in a speakers retail description) that I could look for when searching for a decent sub for infinite baffle? I'll see if I can find the specs on a Honda Accord trunk space...

A low qts on a PA driver can be fatiguing after a while. Above 0.3 it will start to start to sound a bit more natural and warmer

good morning ! Thank you sincerely for the really useful and well done explanation. I understand that a low qts is also a measure of the intrinsic quality of a driver, and i see that drivers with low qts have a very high cost. I've seen some JBL woofers with low Qts .... they have crazy sized magnets ! Scanspeak makes woofers with Qts of 0.2 ... and they have become a classic. Moreover I also believe truly in instrumental tests. A driver who has an impulse response like a tuning fork (i.e. with little damping) does not do anything good I think. I have a personal experience with a Dynaudio woofer with Qts = 1. it was slow to start and slow to stop ... even using powerful solid-state amps the bass was confused ... not convincing at all. Unable to transfer the sense of rythm for instance. I think it depended on the magnet being too small compared to the moving mass of the cone. It needed a much more powerful magnet. And actually the better version had a bigger magnet and much better bass response. I think the bass Qts is so important that lately I'm very interested in field coil drivers, a concept that can provide very low Qts ... but they must sound spectacular. Thanks again for the interesting and precious explanation. P.S. has i said that i believe strongly in measurements ? if only i could afford a well equipped lab ...

How does QTS relate to infinite baffle application. Some say higher QTS is good for infinite baffle. But when researching a perfect subwoofer, I see some free-air subwoofer with low QTS. It made me confused. Can you clarify this?

how to calculate Qes and Qms?

what about qts with open buffles ?

What are you on?

So "1.2 is a very high and 1.2 is a very low Qts" - I had to listen this 2 times. Instead of Qes, Qms and Qts declaring high or low, it probably would be less confusing declaring them hard vs soft or strong control vs weak control. or fast vs slow, just anything but high vs low. 0,707-alignment is the Qtc with f3=fc in a closed box and sure, to calculate it, the Qrs is involved, but it's definitely not the Qts of the stpeaker-driver. Looking at the other comments, I seem the only one unhappy with this mess. Well, i'm getting more and more used to it.

Thinking of using B&C 15DS115-4 in my vehicle in true infinite baffle application (vented to outside). I know they say that a high Q is best suited for IB application, but I like the very tight and hard kicking sound of pro audio drivers in general. Would this give me good results with some DSP?

The Q value especially the qms if you think about it is the same as the pedals on a piano maybe that is a better way of describing it like the sustained note and the damping note.

You did not mention infinite baffle with a high qts.

IN short, how do you get great Q values? No mass in moving parts? Lots of mass in moving parts? large cone? Tiny cone and stupid levels of excursion?

That a comma.

if you want to laugh check out the Savard Rap series specs

Check out HexiBase channel and Hempopotamusloudspeakers.com. two guys with some knowledge and products HEMP fiber cones!

very informative video, but horrible soundquality

Man... even with playback set to 2x this is too slow.

You are confusing me

Smh waste of my time