Woofer QTS explained
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- Опубліковано 15 лип 2024
- In this video I am explaining the importance of getting good bass from your woofer, by knowing your QTS from Thiele-Small parameters.
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A dedicated website with more detailed information is currently in the works - keep an eye on audiovega.com/. I specialize in refoaming a diverse range of brands, having a wealth of experience with JBL, Cerwin Vega, Snell, Dali, Bang and Olufsen, and Scan-speak drivers. My proficiency particularly lies in refurbishing and upgrading crossovers, as well as carrying out driver replacements and upgrades that often necessitate precise measurements and calculations. Trust that your audio equipment is in capable hands.
Kind regards
Kent Larsen - Навчання та стиль
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.
I had to pause the video to affirm what he is saying. There are SOO many videos talking about thiele small parameters and they are all technical and they all say the same thing. I want (NEED) to hear the practical implications of these parameters. So THANK YOU for doing just that!
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@Ares Santino yup, have been using instaflixxer for years myself :D
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 !!
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.
Very helpful video- thanks!
Thank you Gavin
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.
very helpful, thank you
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.
Underdamped means Q larger than 0.5; overdamped is when Q is smaller than 0.5.
Excellent job
Thanks!
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 :)
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
You have a lot of experience my friend!..🎉❤👏👏👏🥇🤫keep the good stuff secret
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!
John Fisher thank you for your comment, you are exactly right about the higher qts is great for a sealed box. The presentation of the sound is highly depended on q values so this won't be the last word on the subject.
Yes, qes higher, to lower the EBP number. An EBP of 50 and below would be a sealed chamber. Ebp 50 to 100 bass reflex and bandpass, above 100 horn loaded
@@tomthumb6269 It depends what you're going for. While a QTS of > 0.7 would almost certainly make a terrible tuned port driver, it also wouldn't make a very great sealed enclosure, unless it had a massively huge box. The lower the Qts, the smaller the box requirements, the better the damping, and you have the option to adjust the QTC of a sealed enclosure to your liking. Qtc of 0.707 is the generic go-to for most flat frequency response and then have a 12dB/Oct roll-off. QTS of 0.5 has the best impulse response with no overshoot, being critically damped. A QTS of 0.577 is a Bessel response, and would have the fastest impulse return rate with the least overshoot.
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?
Those are horn hybrid woofers? been considering some lii audio full range. Prob try the 6.5" full range first.
what about qts with open buffles ?
pretty sure subs with a qts of 7 or above shoud generally be put in an free air or open baffle enclosure.
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...
The qts should be above 0,7 to have substance enough to play infinite baffle. Good Xmax is more needed because a box is not assisting the throw.
@@AudioTalk above 0.7? I saw where somebody said that the bigger (actual diameter 18" sub for example) the sub, the better performance if I'm going to let the trunk space be the enclosure. Back in the 90's I took the backseat out of a Ford Festiva and built a wall for 2 12" Kickers Comps; And I put a Punch-75 on each one using a crossover. This was all new equipment (in the 90s). I didn't think it would sound good because the subs called for a 2ft x 2ft enclosure for each speaker. But they performed amazing! The lows were extreme (for the time). And that's one reason I've looked for the older Stillwater design Kicker lately; with no luck.
@@barnes29510 yes, 0,7 but max 1,0, typically woofers with higher qts would be low quality, but that is anecdotal because its possible to create a driver with higher qts and maintain a good driver, I just haven't seen it.
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 ...
Scan-speak is lying! The real Scan-Speak parameters very far from the datasheet. And real Qts all Scan-Speak high. Scan-speaks also have cheapest baskets in the world, the diffusers cheap and magnetic system very weak, therefore Qts high.
@@user-hu4ez6ew2q hi I am shocked Their drivers are used in very expensive speakers
May I ask you speaking of woofers which brands in your opinion offer the best value for money? Thanks a lot and kind regards gino
@@gino3286 Are you from Italy? Gino? For the most accurate answer to your question, very desirable to know the answer to this question.
I wrote you a comment, but Kent deletes it. Apparently He does not want and is afraid to face the truth. How can I write to you? You have email? I will tell you the honest truth. I know about all companies in the world in the sound industry. Honestly.
@@user-hu4ez6ew2q hi yes of course i have an email but i prefer not to show it
However i think it would be surprising that a brand like Scanspeak published wrong data in the specifications sheets. Did you measure them ?
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.
I agree with you my Diy dual opposed 12 inch Scan-Speak subwoofer has a Qtc of 0.90 in a 55 liter box, to lower the Qtc to 0.707 the box must be 134 liter.
A box with Qtc 0.50 must be 200 liter and sound like a blurry base mess.
Qtc 0.8 to 0.9 is the sweet spot for SQ and fast base in smaller boxes.
With the DSP on the Hypex amp i tuned the sub on 22hz+-3db.
@@palmspar Qtc of 0.8 already cuts the volume nearly in half, lifting the peak dB only 0.21dB.
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?
A low Q driver in infinite baffle will be anemic without DSP, so its possible to increase Q with DSP and then use a low Q driver. But without it the bass response will be anemic if you are under 0,7 in qts. Under 0,7 is what you called overdamped and it will cause the driver to roll of to early and with no substance, but it will be very nuanced.
how to calculate Qes and Qms?
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.
John sweda thank you so much for your comment. And yes certainly if one has played an instrument that is a helpful angle.
if you want to laugh check out the Savard Rap series specs
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?
Good question, a qts of 0,17 is very low and will without doing something about it will be basically no bass. Tight bass is around 0,6 to 0,7 in qts for IB, most Hifi speakers are aimed at 0,707 called butterworth alignment and it pretty tight. But if you can raise the Q in your DSP to 0,7 or whatever you prefer, you are good, but without that will the bass will be beyond anemic.
Audio Talk thanks for the reply. How would I raise the q with dsp? The sub has something like 16mm Xmax and plenty of power handling, so I was planning to just eq the low bass up to flat, or slightly boosted, with the dsp
@@grandpixel its only if your DSP modul has that ability, in the DSP software it will say Q along side choosing the frequency and how many dBs you wanna boost. If it doesnt say that in there, raising the level wont help. But you will use more power from the amp to this, where the box will hand you this for free, so I dont recommend this driver for IB
Audio Talk but I believe that “q” is referring to the damping or falling off of the frequency being adjusted. It changes the scope or width of the adjustment, but has no effect on the electrical or total q of the driver or speaker system itself.
I am still not convinced that this wouldn’t work well. I kind of want to try it but these drivers are PRICEY! If it doesn’t work very well it will be sort of a waste. I suppose I could always sell at a discount.
Audio Talk also you say that a vented box can hand you reduced damping for “free” but it’s not really free. It comes at a cost of having that trail at the end of every sound, which reduces transparency and accuracy, am I right?
That a comma.
What are you on?
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?
very informative video, but horrible soundquality
Check out HexiBase channel and Hempopotamusloudspeakers.com. two guys with some knowledge and products HEMP fiber cones!
You are confusing me
Man... even with playback set to 2x this is too slow.
Smh waste of my time