SEAS FA22RCZ MLTL

[JimM]

I have built a SEAS FA22RCZ MLTL using Scott Moose dimensions as detailed in Seas FA22RCZ full range prosject. They are as follows internal dimensions 56in by 10.5in by 14in (HxWxD) Zd=21.125in Zvent 54in vent 4 in by 3.5 in. Design requirements: 1. Make the front panel removable so that if I don't like the results I can use the enclosure for another project. 2. Design enclosure to Scott Moose dimensions to obtain a Mass Loaded Transmission Line. 3. Use Baltic Birtch plywood for enclosure and use lining and stuffing per accepted full range designs. 4. Compare MLTL full range to my other speakers. Will post pictures of build and final results.

[JimM]

Pictures

[JimM]

More pictures

[planet10]

Is it just the picture



that makes it appear as if the front is angled wrt the rest of the box?

dave

[larryldspkr]

Very nice, any first impressions??

[JimM]

It's just the picture, the shelving filter is 1.5mh in parallel with 8 ohms. In the current configuration this is not a high sensitivity speaker it is around 88 db (estimate) efficient. Since the pictures were taken I have removed some of the stuffing which brought back a little more life to the over all sound without affecting the bass. the bass response is very good for a 8in single speaker, I can turn off my sub and not miss it at all. This speaker can play loud but does start to compress the sound at higher levels i.e. it is not as linear to power input from around 85db on up as it is to lower levels. I would assume this is to be expected from a single 8 in. speaker. The drivers must be close to published specs from Seas as the impedance plots were right on per simulated response using Jeff Bagley(sp) spead sheets, I do have wt3 impedance plots if any one is interested I can attempt to post them. These speakers require a fair amount of break in so give them a couple of weeks, I broke them in using a cardboard box playing them for 4 days stright in the garage at various levels before putting them into the MLTL. More on the overall sound later.

[larryldspkr]

Thanks for sharing, This is a project that caught my eye and looked very interesting. I'd be temped to remove the cavity stuffing and just line all the walls! If there are any nasty cavity air resonances they will show up on your WT3 impedance plot as spikes! In my experience it's easy to over stuff, and this can affect the mid bass and mid range sounding dull!
My two cents. :-)

[norman bates]

nice !!!!!!!!!!!!!!

I just came across these drivers.

I love that they (seas) supply the shelving filter component values.
Otherwise the freq response would be scary.
Quality parts should make a little improvement here.

Norman

[gaborbela]

Hello Jim
Can you share your enclosure information. Soon I want to build so similar enclosure about 65L for my Beyma 8"coaxial.
If you can share the website were I can find the enclosure parameters that would be great to.
Thank you
Greetings gabor

[JimM]

The mass loaded transmission line that the enclosure was built to was from Scoot Moose who I assume derived the dimensions from Martin King quater wave math cad worksheets. BTW thanks Scott for the layout as it seems to be dead on. If you want to build a vented enclosure then I suggest using Jeff Bagby woofer box and circuit designer which runs on Excell Google and then download it's free and a good program. As an example using Bagby for a vented enclosure of dimensions 40in by 10in by 14in (HxWxD outside dimensions) with a vent of 4in dia. by 6.98in long will give you the follwing:
Fd 38.68Hz 3db point 39.92 hz the same enclosure sealed will you a Fc 52.49hz with a Qtc of 0.612 and a 3db of 62.75hz.