[Bumpy]

Now Lii Audio and specifically the W15 driver

This woofer is the outcome of a experimental development of open baffle with our full range drivers. With superb bass performance, this W-15 can bring good bass even on narrow open baffles. It has a transparent tone so can bring a good coherence with most of the full rangers or tweeters & midrangers.

It uses short coil and super thick washer design, leading to very weakened distortion, 15mm Xmax for a good bass.
With Lii Song paper cone of unique material, it has a wide frequency response and transparent sound so that it can coordinate with a great variety of full range drivers.
Double coil design let it competent to be adapted with amplifiers and connect in parallel or in series with other driver units, according to impedance.
The double coil makes it possible to be served as subwoofer, giving you more possibilities to play with these drivers.
As Lii Song driver developed by the same creator, this is a wonderful companion for other Lii Song full range drivers, especially on open baffle.

Related power – Maximum power: 100W – 150W
Nominal Inpendance Z: 8+8 Ohm
Fs: 27.6Hz
Qms: 14.6
Vas: 656 L
Cms: 0.6 mm/N
Mms: 95 g
Rms: 0.81 kg/S
Xmax: 15 mm(peak)
Xmech: 20 mm(peak)
Sd: 855 sqcm
Vd: 2.05L (p-p)
Qes: 0.97
Re: 3.12 ohm
Le: 0.04 mH
Z: 6.7 ohm
Bl: 6.1 T/m
Pe: 100W (cont.)
Qts: 0.79
Sensitiviry (2.83V / 1m): 91 .3dB （single coil）
Sensitiviry (2.83V / 1m): 95.6 dB （dual coil）
Weight (unit in package)  13.5KG

Not sure how having twin voice coils makes it better to serve as a sub.

[richidoo]

Le is voice coil inductance. It rolls off the high frequency extension, so you want it high enough to enable your speaker design, including the full crossover low pass bandwidth. You don't need the inductance of a tweeter.

Driver engineers never set out to design a OB driver, the market is too small. AE is an exception, but actually getting OB drivers from AE is not as easy as you think. All commercial drivers are designed for a box. Box raises system Q to allow low freq response @loud SPL while maintaining good transient response. Take away the box and the system Q drops, so you keep the good transient response but you lose the LF extension. How to get it back? Add bass boost EQ. There is no other way if you want to maintain transient response (detail,) and you do. They don't set out to design a driver for OB. You are going against the market. You are looking for a square peg that fits in a round hole. There is a spirit of pride and rebellion in the OB DIY community. It is fun, but in the long run you can't fool mother nature. If you like big scale music OB is a dead end. You'll be adding box subs, or going all box anyway. The myths about boxes are false. There is no box sound if the box is well designed and built. There are a lot more problems to overcome with OB than with box speaker to attain same level of SQ.

The Perceived wisdom is correct in advising high Q for those who choose to avoid better but more complex and more expensive solutions. Alpha (and AE) creates a flat bass frequency response without box, complex passive filters, or electronic EQ, separate amplifiers, cables, etc. Some people don't know how to do all that stuff. Alpha is cheap and plays blues and classic rock OK. Good enough for first DIY speaker. They will be back for more later. Then we explain about transient response and Q and never see them again. LOL They are correct in surmising that DIY is total waste of time and money for the music lover. It seems like staining the deck or changing spark plugs or unclogging the drain, but actually it's not. This is why high Q drivers exist, there is a demand in pro audio for more bass at low price and at expense of transient response. Of course some audiophiles will try it and some will like it, everybody's different, rainbow diversity, everybody loves Alphas. Let's move on.

The solution you are looking for you have already stated yourself.
"When we move onto more ambitious projects involving a limited range of frequencies (say less than 200Hz), EQ and dedicated amps, then high Qts and even high sensitivity become almost irrelevant."

yes, when you have another amplifier for bass you are set free of the "OB rules." With active amplification you can adjust the Q (FR) of any bass driver electronically. But even adjusting the FR does not correct the loose suspension and weak motor. Even with EQ the alpha will still sound the same. So any speaker with good suspension and strong motor will work, if you have active amplification and the means to contour the FR. If the speaker is good enough to obey the amp then you're all set. Additional advice, bigger is better for OB. If you're going to get new bass drivers go big. Dual 18" in parallel would provide huge acoustic impedance at low frequencies and allow playing 30Hz at very low SPL with very clear transient response. Make sure the amp can handle the load because you will be applying >20dB of EQ gain at 30Hz, then playing music very loud, so into 3 ohms paralleled load some amps will choke on the peaks of uncompressed music. And if you will peak at 500W your voice coils must be rated for that.

There are dozens of good speaker mfgs around the world. They all compete for the same business selling the same product. B&C is good, Beyma, Eminence, AE, it doesn't matter. Make sure the Q is lower than the system Q target, which is probably .7.  Most professional general purpose PA drivers are around .4-.5. If you're going to be doing DIY speakers then you'll have many years of choosing drivers ahead of you. You will learn which you like and which you don't so for now just pick any reputable brand and get started on this project. Don't intellectualize yourself into anxiety.

As for EQ, you can do passive filters so you only need one amp per speaker, but this is complex and expensive by the time it is all done. With active bass amp you can filter the signal before the amp with some advantages. Beware the professional audio speaker management / xo  boxes like dbx, behringer. They make adjusting the crossover points and volume settings easy but they aren't audiophile sound quality. You can learn to make your own active analog line level filter for very low cost and with the highest sound quality. See Elliott Sound.

[Bumpy]

Thanks Richidoo excellent advice.

I have been running OBs for about 4 years, based originally on the Lampizator p17 design with Saba Greencone and vintage Altec 416Bs.

I have upgraded the mid/tweeter through vintage Supravox RTF 64s, SEAS Exotic W8s to CubeAudio FC8s. My journey there is probably finished.

The Altecs were built more for midrange not as sub 200Hz drivers so were replaced with Alphas, but its time to move up again.

Zero filters on the Cube Audios and EQ with separate amp on the bass drivers.

[Tyson]

Richidoo is right, a good OB system that's able to do bass with power is going to be large, because it requires a lot of displacement in the bass to hit the lows with power. 

If I was going to DIY an OB speaker from scratch, for myself, I'd probably do a Beyma AMT run down to 800 hz, then a pair of AE Diploe 18's in a 2.5 way config, with the top 18 going to 800hz and the bottom 18 just filling in where the low end roll off starts for the top 18. 

Not cheap, but you'll get incredible bass and a relatively simple setup after the crossover work is all done.

[Bumpy]

A tiny problem I have is that I am based in the UK and most recommendation are US centric, but we get by.

[bladesmith]

High Qts for open baffle speakers. (Woofers)
Eminence are ok, i use the alpha 15a's..
But there are always better, spending twice the amount
will always help.. I think the alpha 15a's goes for about 150.00 each..

[FullRangeMan]

Its was $69/each.

[bladesmith]

Could be, there are some deals out there..
One thing I found with eminence alpha 15's is that they need a very heavy, rigid foundation/construction around them, whether OB or enclosed...

Its was $69/each.

[WGH]

Back in April, 1990 Audio magazine published a detailed article by Ralph E. Gonzalez about the Bassis parametric bass equalizer including circuit board design, parts lists, construction, adjustment and use.
Here is a .pdf of the article:
http://wghwoodworking.com/audio/bassis.pdf




 >> Marchand BASSIS wm8 Manual <<

Marchand has assembled BASSIS equalizers from $690 - $1150.
https://www.marchandelec.com/wm8-bass-equalizer.html




Room and Sub EQ 101: How to use parametric EQ to flatten your bass
http://www.acousticfrontiers.com/2013111room-and-sub-eq-101-how-to-use-parametric-eq-to-flatten-your-html/

[Monsoon]

Only listening to 200Hz and down will sound terrible.  I've done it many times in order to work with designs.  No Matter how you work it, those frequencies are not fun by themselves.

This right here.
The simple fact is that it's the midrange that gives us most of the good stuff.

[FullRangeMan]

Not sure how having twin voice coils makes it better to serve as a sub.

Its like to have 2 woofers to the amp push and just have 1 cone to emit sound, I rather could prefer 2 regular woofers in this case, I will skip woofers with 2 VC, I cant find any benefit but Iam not an engineer fortunately.

[FullRangeMan]

This right here.
The simple fact is that it's the midrange that gives us most of the good stuff.

+1. This range usually are called mid-bass, also referred as pleasure range in music.

[ketchup]

+1. This range usually are called mid-bass, also referred as pleasure range in music.

Totally agree.  I biamp my Magnepans, and if my bass amp comes on before the mid/high amps, it sounds like mud.  As soon as the mid/high amps come on, it sounds like sweet music.

[Bumpy]

Lets do a comparison:)  For my requirements I am gravitating towards Faital Pro 15PR400. I am drawn to high Bl, low Fs, good sensitivity, 3 inch voice coil,  and reasonable Xmax.  So what is the worthwhile competition

Here are the specs:

Technical Parameters

Nominal Impedance - 8 Ohm
Minimum Impedance - 5.9 Ohm
AES Power Handling (1) - 400 W
Maximum Power Handling (2) - 800 W
Sensitivity (1W/1m) - 99 dB
Frequency Range - 35-4000 Hz
Voice Coil Diameter - 77 mm (3 in)
Winding Material - Al
Former Material - Glass Fiber
Winding Depth - 15 mm (0.59 in)
Magnetic Gap Depth - 10.5 mm (0.41 in)
Flux Density - 1.15 T
Magnet - Neodymium Slug
Basket Material - Aluminum
Demodulation - No
Cone Surround (3) - Accordion (4 waves)
NET Air Volume filled by Loudspeaker - 3.7 l (0.131 ft^3)
Spider Profile - 1x constant height waves

Thiele and small parameters

Fs - 35 Hz
Re - 5.1 Ohm
Qes - 0.34
Qms - 6.0
Qts - 0.32
Vas - 223 l (7.88 ft^3)
Sd - 805 cm^2 (124.78 in^2)
Xmax (4) - 5.75 mm
Xdamage (5) - 15.5 mm
Mms - 85.2 g
Bl - 16.7 N/A
Le - 0.75 mH
Mmd - 72.5 g
Cms - 0.24 mm/N
Rms - 3.11 Kg/s
Eta Zero - 2.71 %
EBP - 103 Hz

[richidoo]

You may find these threads useful:

https://www.diyaudio.com/community/threads/low-distortion-wide-bandwidth-pro-15-and-18-drivers.367679/

https://www.talkbass.com/threads/eminence-kappa-lite-3015-vs-faital-pro-15pr400.877152/

http://www.loudspeakerdatabase.com/Faital/15PR400

[FullRangeMan]

IMO with Qts 0.32 and EBP 103 this Faital are suited to a big BR box not an OB.
Sensitivity=99dB  but  Electric Efficiency=2.71% are a mid range value, not hi, but could be interesting to know how it perform in an OB panel.

Xdamage =15.5 mm is small (max excursion)
Rms = 3.11 Kg/s show it use a hard suspension.

[richidoo]

IMO with Qts 0.32 and EBP 103 this Faital are suited to a big BR box not an OB.

The Q of the system is changed by the electronic EQ, aka bass boost. Any typical box driver with lower Q can be EQd in dipole to the desired target .6-.7 system Q.  But you can't EQ a driver with higher Q like Eminence Alpha down to lower target Q, because the driver cannot obey the amp. That's the problem stated in OP. 

I like the lowish Q of the FaitalPro. That means well damped and easily controlled by the amplifier and easily sculpted to the desired FR.
With 15" you only need a couple mm excursion, even in boosted LF. Xmax not a problem.

[FullRangeMan]

Lets do a comparison:)  For my requirements I am gravitating towards Faital Pro 15PR400. I am drawn to high Bl, low Fs, good sensitivity, 3 inch voice coil,  and reasonable Xmax.  So what is the worthwhile competition

high Bl, low Fs, good sensitivity, 3 inch voice coil,  and reasonable Xmax.
Theses are hi performance motor specs, very common requirements on the woofer market currently, plenty of options.

To avoid use EQ I could use the new Lii Audio W-18 OB woofer Qts=0.607, 18'' may be suffice to your room.
Li W-18

[Woodsage]

The Q of the system is changed by the electronic EQ, aka bass boost. Any typical box driver with lower Q can be EQd in dipole to the desired target .6-.7 system Q.  But you can't EQ a driver with higher Q like Eminence Alpha down to lower target Q, because the driver cannot obey the amp. That's the problem stated in OP. 

I like the lowish Q of the FaitalPro. That means well damped and easily controlled by the amplifier and easily sculpted to the desired FR.
With 15" you only need a couple mm excursion, even in boosted LF. Xmax not a problem.

Go for it and let us know how it turns out!

high Bl, low Fs, good sensitivity, 3 inch voice coil,  and reasonable Xmax.
Theses are hi performance motor specs, very common requirements on the woofer market currently, plenty of options.

To avoid use EQ I could use the new Lii Audio W-18 OB woofer Qts=0.607, 18'' may be suffice to your room.
Li W-18

FullRangeMan,

You seem to heartily endorse the Lii F15, F18 and the W15. Have you ever heard any of these drivers?

I ask because I have heard the F15’s and was less than impressed. I am still interested in the W15, it looks like it holds some promise. But I would be interested to hear the opinion of someone with direct experience with the driver.

[Bumpy]

FullRangeMan,

You seem to heartily endorse the Lii F15, F18 and the W15. Have you ever heard any of these drivers?

I ask because I have heard the F15’s and was less than impressed. I am still interested in the W15, it looks like it holds some promise. But I would be interested to hear the opinion of someone with direct experience with the driver.

I too am somewhat sceptical about the Lii drivers although I have heard none of them. There are none as far as I am aware in the UK.

Their reputation has been built on clever marketing and giving away free drivers to profiled individuals who not surprisingly eulogise about how good they are. Others have said Lii play fast and loose with TS specs. Nobody I have challenged on the forums has been able or willing to compare them to other recognised quality drivers. If all you have driven is Fords then a BMW is fast and fabulous, but its still not a Ferrari.

My own experience is that just last week I set about ordering a pair of W-15s from the Spanish distributor. I got a price which seemed cheap, so I double checked in writing. Unfortunately W15s were not in stock, so as a sweetener (after placing the order) they would send me a free pair of 6" drivers. Having checked out custom duties VAT etc I went back to order, but the price had more than doubled. They apologised for lying to me but would not compromise. I told them to stick it.