SLOB project

[Ray P]

I've been playing with Micro-cap to try and learn a bit more; I now know how to adjust the 'depth' of the broad equalisation 'notch' centred at aroun 3KHz (ref the plot a couple of posts back).

[Ray P]

I'm working on the CAD drawings for the build this afternoon, focussing on the base section that'll house the bass driver, onto which the baffle will bolt - got me thinking about the baffle...

I would like to use acrylic for the baffle but I'm not sure how thick it needs to be and I know some here have experience with it. 12mm seems to be commonly available but not sure if that is thick enough? The suppliers of acrylic sheet that I've looked at have 20mm as the next thickness. Thoughts from the panel?

BTW, In the first instance I plan to use a cheap ply baffle.

[IslandPink]

I think 12mm is too thin.
James used 15mm throughout on the Quasars. I have used 20mm in the front of mine ( 2 pieces with a 12.5° angle between them ). That's nice and weighty.

[Ray P]

I think 12mm is too thin.

Yes, that's my thinking too.

[Ray P]

Mark, with the drive units arriving soon we'll have to make an arrangment for me to come up to your place so you can measure them and have a quick listen. It would be convenient if I could tie it in with collecting the CNC'ed birch ply - current thinking is to get the work done by KFJ Audio (vendors of the Frugal Horn flat pack) who are based in Warwickshire.

Anyway, plenty of time, just putting it out there for now.

Ray

[IslandPink]

You are welcome more or less any weekend, Ray. My January and February weekends are rarely spoken for. I can adjust any of my regular visits to my mum based on your schedule , given a couple of weeks notice. I have a spare Perspex baffle with some holes that can probably be adapted to hold the Lii unit , if you want.

[Ray P]

Sounds good Mark. let me get a schedule for the CNC work and we'll get a date into our diaries.

[Ray P]

Lii Audio speakers are out for delivery! Hopefully the driver will read the note and leave them with my neighbour should I be out on my bike.

[rowuk]

Surface area x excursion=sound output. You are talking about huge baffles. That creates a large need to either dampen (ugly with transparent materials) or create many isolated “panes” that do not get excited by the single driver. Stiffening the structure just moves the resonance higher up in frequency - makes it more audible. I would think that anything less than 25mm would have audible artifacts unless you can find a good looking decouple scheme.

If you had 2 thinner layers of plexiglass and filled between them with colored sand, it could be attractive and acoustically dead at the same time. The patterns from the colored sand could change over time.

[Ray P]

I've just collected the Lii Audio Fast-10S units from the neighbour. They were well packaged, double-boxed with lots of foam and there are no obvious signs of damage.

I've had a quick peek and first impressions are positive, they look nicely put together.

Oh, and there were no additional costs for VAT or import duty.

Food beckons now so I'll have a proper look and post some pictures later, probably tomorrow, along with any observations about their construction.

[Toppsy]

Oh, and there were no additional costs for VAT or import duty.

Hope this proves true for you Ray. However, in my own experience when I bought some ESL speaker kits from Australia I also thought I have paid all the duties and relevant taxes etc. at source and was not charged any addition Import Duties and VAT charges when the courier delivered the speakers to my door. So I thought, like you, I had got away with having to pay any additional UK taxes etc, That was until about 10 days after delivery I got an invoice in the post from the courier company for import tax, VAT and the courier charges for clearing by goods through customs. The import duty was based on the total cost of the goods plus the shipping charges and then the VAT was added on to this new total cost at the then current going rate. To say I was gutted was an understatement.

[IslandPink]

Ace ! As soon as you get chance, Ray, just prop it up on the floor and clip-lead it to your speaker cables and have a listen. The upper mids and treble will be more or less OK to judge. See if it sounds good on female vocals and any trebly stuff like guitars , percussion, bells etc. I'm all ears ! ( not literally ).

[IslandPink]

Surface area x excursion=sound output. You are talking about huge baffles. That creates a large need to either dampen (ugly with transparent materials) or create many isolated “panes” that do not get excited by the single driver. Stiffening the structure just moves the resonance higher up in frequency - makes it more audible. I would think that anything less than 25mm would have audible artifacts unless you can find a good looking decouple scheme.

If you had 2 thinner layers of plexiglass and filled between them with colored sand, it could be attractive and acoustically dead at the same time. The patterns from the colored sand could change over time.

You make it sound like nobody could get OB to work, Rowuk, but in fact we've had some great sounds over the years from a number of OB projects shown at our meetings.
I'm not a fan of big flat baffles - having (slanted) side-wings to stiffen things up and extend the effective baffle size is the way to go, in my books. I also don't buy this theory that stiffening = higher Freq = just as bad . I've only ever had positive results from stiffening speaker sides or baffles. The amplitude decreases dramatically when you add stiffening ribs or side panels.
Two thinner pieces of Perspex with sand in the middle sounds fine unless you also want the Perspex to make the thing transparent and hence more room friendly - as I do.

[JohnG]

I have just seen a offer on another forum, where Lii Audio Items are being given a 20% Discount.
If this is of interest, and there is no beef about my putting the link on here, let me know, and I will put on the classifieds section.

[Ray P]

I have just seen a offer on another forum, where Lii Audio Items are being given a 20% Discount.
If this is of interest, and there is no beef about my putting the link on here, let me know, and I will put on the classifieds section.

The Fast-10S units I've just taken delivery of were discounted by 25%.