Lii F18 Open Baffle speaker

[Hondasnl]

Maybe in the futere I like to built some open baffles for my Lii F18 that I already have.

A sleek, simple, heavy and robust design for the very beautiful 18-inch full range driver of Lii.
Lii's biggest driver that they deliver at the moment I believe.

Consruction made of 4-layer 18mm solid MDF (glued togehter), total panel thickness is approx. 72mm in total.
Finished in desired veneer type and/or paint color combination.
The whole is glued together and placed on 3 robust and stable spikes.

Technical Data Lii F18 18 inch full range driver:
Impedance: 8 ohms
Power: 40-80W
Frequency response: Fu – 15k Hz
Fs: 38.7 Hz
SD: 119.46 cm²
Qms: 18,656
Qes: 0.985
Qts: 0.935
Sensitivity: 97.8dB（2.83V/1m）
Vas: 661.77 liters

MDF = 750 kg/m3

Driver 9 kg
Baffle = 0.036404210,018 m³ * 750 = 27,5 kg
Support 1 = 0.13086560,246 m³ * 750 = 9,8 kg
Support 2 = 0.003600000,000 m³ * 750 = 2,7 kg
Spikes = 2kg

Total weight: 51 kg.

Concept.

 

[jjasniew]

Perhaps you could sacrifice some of the baffle thickness and move that material into "wings" attached to the back of the baffle. This would increase the distance between the front of the cone and the back of it, while providing support structure to give the baffle stiffness.

 

[Hondasnl]

I get what you mean and have considered it 🙂 .
But I don't like the design with the "wings".

 

[gnat_leader]

You'd probably get better bass by removing the spikes and placing the baffle on the floor

 

[Hondasnl]

That is a good idea.
I can always install the spikes later if needed.

 

[rdf]

The short waveguide created by rear mounting will alter the frequency response. Maybe negative, maybe positive but worth testing the impact before committing to a final build.

 

[Hondasnl]

Hello friends. Hereby revised Concept without the spikes and position the driver at the frontside of the baffle.

 

[GM]

You'd probably get better bass by removing the spikes and placing the baffle on the floor

Indeed + if setting perpendicular it halves the needed baffle area, lowering gain BW ~0.707x.

 

[jjasniew]

if setting perpendicular

Is there any reason to tip back a FR speaker? I always thought stands that did that for planar mounted 2 and 3 ways pulled the tweeter backward in time - some - making the speaker a bit more phase-aligned and sounding a bit better.

 

[Hondasnl]

No I think not.

 

[GM]

It won't help with time alignment, you add an outboard tweeter somewhere just north of the horizontal to right for right speaker and vice versa and find the best overall baffle left/right offset; tilting back would be for changing polar response, room modes interaction and if wanting to 'fan' the sound, setting the driver on the baffle at floor level and tilt forward to create a 'V' slot mirror image.

Fun to experiment/learn with, but all are ~'head in vice' options when done with 'FR' drivers.

 

[rdf]

tilting back would be for changing polar response

A driver that size will be very directional from the midrange up. Without the tilt highs will be maximised toward seated calves. Since the planned baffle is so small anyway playing the raw drivers on ground at different angles to get a sense of the trade offs before committing is an option.

 

[GM]

As I said.😉

 

[rdf]

Yup, just amplifying. 📢

 

[Hondasnl]

My source of inspiration was the "Spatial Europe Pure 18".
Only my version is a little bit bigger and heavier.

Pure 18
Specifications
Frequency response: 40 Hz to 17 kHz
Operating efficiency: 98dB/W/m
Impedance: 8 ohms
Principle: 1 x 18" Open Baffle
Equipment: 1 x 18" LII Audio full-range loudspeaker
Dimensions HxWxD: 85 x 60 x 35 cm
Weight: 33kg

18-inch open-horn full-range loudspeaker with ultra-light diaphragm mass and single voice coil. The perfect point sound source with no routing components in the signal path.
Special features: LII Audio modified die-cast aluminum chassis 18-inch wideband (with bronze clamps) very high efficiency, acoustically adapted open horn enclosure with finished elements, heavy aluminum stand and strain relief for the cable of Spatial Europe Solidcore speaker recommended, spherical bronze tips with Spatial Europe absorber suitable for the weight of the PURE 18. (>info)
Option: for the equalization of the medium frequencies, we offer our Spatial Europe RCA cable. Here, an SMD circuit makes it possible to linearize the upper part of the medium frequencies.
Installation recommendation: distance front edge of loudspeaker - rear wall from 65 cm, listening distance from 2.5 m, listening room from 25 m².
Important: All Spatial Europe speaker models have a break-in time of up to 500 hours. We offer our customers and resellers a running-in service in our acoustic cabin.
Recommended amplifiers: Spatial Europe Amp Nº 3, Thivan Labs 300 B Anniversary, WITH Mid-EQ Spatial Europe SMD RCA cable, the PURE 18 can work with all good amps.

 

[Alffie]

Looks great.Have to make final baffles for my f15's also.Have made temporary ones to see if I like them.I like them a lot!.

 

[Hondasnl]

I also have had the F15's. Good drivers! Now I like to make something nice with the F18's 😍😍.

 

[Alffie]

How do the 18' s sound compared to the 15's?
I've been a Magnepan listener for 10 years and like the smaller baffles compared to my maggies.

 

[Hondasnl]

Looks great.Have to make final baffles for my f15's also.Have made temporary ones to see if I like them.I like them a lot!.

View attachment 1139162

Very nice and clean looking setup Alffie!!

 

[Alffie]

Thanks.