Seas WWTMWW center

[norcad]

My Seas 3-way wide baffle front speakers need some company!

https://www.htguide.com/forum/showthread.php?t=30421

And its gonna be a pretty big one!
Well I think its big, but maybe you guys are used to see them even bigger........

The front speakers are 3-way with Seas 27TFFC tweet, Seas MCA15RCY mid and Seas CA26RFX bass.

The goals:
- Match the sound of the front speakers, both in quality and pressure, even in the bass region.
- Be an easy load for my receiver (Denon AVR-3806)
- Use about the same crossover points.
- Fit my TV furniture
- And of course, only Seas drivers!

The solution:
Tweeter: 27TFFC
Mid: MCA15RCY
Bass: 4 x CA18RNX!
XO: 3-400hz 2. order and 3000hz 3.order (as in the front speakers)
Enclosure: 29(H) x 98(W) x 50(D) cm

The mid and tweet will have the same location and enclosure as in the front speakers.
Four CA18RNX will be connected two in series and the two pairs in parallel.
One pair of CA18 will share the same enclosure and a 3" port.

Here is a drawing:

[TacoD]

Wow great project. This will be a full range center. By the way if it fits your AV furniture, what are you using as furniture?

[norcad]

Well it doesnt fit IN my furniture, but on top of it!

[Paul W]

Ah! A real center channel! Too often viewed as "not so important". This should be a good one.

I've used the MCA15RCY in a tapered open line with very light stuffing behind the driver, increasing to heavy stuffing at the end of the line and was very pleased with the result.

[norcad]

Lets look at some simulation of the bass output from this center vs front speakers:

This is from Unibox, and speak for itself!




And from the Bassbox, blue=center:









This looks promising!

[tf1216]

What's the benefit of the added pair of 7" drivers?

[norcad]

What's the benefit of the added pair of 7" drivers?

First of all, it makes the load easier for the receiver. With two bass drivers coupled in parallel, the receiver would "see" an impedance of 4ohm. And most likely drop to 2-3ohm in the midbass area.
Second is that with double cone area, the drivers cone displacement (stroke) will be half, meaning lower distortion and they can handle more power.
Both the receiver and the speaker itself will get higher headroom.
Third is that it looks impressing! :T :lol:

An another solution would be 3,5-way, and use the added bass drivers as BSC, but that would make an heavier load.

So the question is rather the other way around; why use only one pair of 7" drivers!
The only answer to that is, smaller enclosure.

[norcad]

Its time to start building the cabinet.

Baffle:




Bracing:



Bracings and bottom:

[norcad]

Some more building pictures:

Midrange enclosure:




The frontbaffle from behind:




And finally the baffle, drivers and ports in place:



Backplate, stuffing, cables, measurements and xo is next on the todo list.

[norcad]

No interest of a big centerspeaker?
Some replys would be great folks!

Interior pictures, that shows how the bracing holds the bass magnets, and that the tubes are very close to the top plate. Maybe angled pipes would be better?






The size of it, compared to my Epos ELS3C center speaker:



And finally with my 40" Sony on top:



Well its rather huge, the question is what it will sound like.
Now its time for some measurements!

[Jed]

Looks awesome Norcad. I like how you are using all SEAS drivers as well. So many Dayton drivers are used around here, it is nice to see something different.

Even though we might be quiet, we're all just watching the build with admiration. Keep the pics coming.

[Bent]

I'm watching

[norcad]

There is one thing I forgot to show you, the simulated baffle diffraction!
Event though the drivers and mid enclosure is the same as in the front speakers, the different baffle shape and size will affect the sound.
The question is where, how much and if I can do anything about it.
The baffle step will also be different, and of course the placement of the speaker it self, will be different than the front speakers.
While the front speakers are standing in "free air", this center speaker is closer to the floor, and my TV makes an extension to the baffle.

Here is the simulated baffle of the speaker itself:



A peak around 800hz for the mid, that I probably has to deal with, and a peak at 2khz on the tweeter.
Baffle step is where I wanted it to be, and it should be OK to set the crossover point in the 3-400hz area.

When I put my TV on top, it will be something like this:



The tweeter looks better, and the peak at 800hz is a little lower and wider.
Baffle step is pushed even further down, not bad!