SEAS Thor transmission line speaker project
Three years ago I got fed up listening to my 20 year old pair of Tannoy Eclipse speakers. They had given good service for a long time in many countries but were nothing special, sound-wise. I'd always liked the sound of TL speakers so started looking around for a good design and drivers.
I found the SEAS Thor through Madisound's web site and downloaded the plans from SEAS. I ordered the drivers and most of the crossover components from Madisound; the slightly expensive shipping was worth it for a large order like this.
I found the SEAS Thor through Madisound's web site and downloaded the plans from SEAS. I ordered the drivers and most of the crossover components from Madisound; the slightly expensive shipping was worth it for a large order like this.
About Thors
If you Google the SEAS Thor you'll find a lot of discussions on the "expert" DIY HiFi forums, most of which you should just ignore as, like most HiFi talk, its largely highly opinionated B-S. On the other hand, many people have reported favourable results and I sensibly thought I'd listen to these instead of the opinionated know-it-alls. I was aiming for a controlled, tight low end response and an accurate mid and treble, which in the end was what I ended up with. If you want sub-40Hz at house-rattling levels, a TL isn't going to deliver it in any case. Thats what sub woofers are for. Large speakers also have to satisfy some aesthetic parameters (WAF) and the Thors do this very nicely.
Building the Thors
I was lucky enough to find a cabinet maker with a large panel saw who cut the 25mm MDF for me to high accuracy; without this the project would have been orders of magnitude more difficult and less successful. Everything clamped and screwed together easily enough.
One Thor before the second side was glued and screwed into place.
The veneer....
It's not very easy to get veneer sheets here in Melbourne; I finally found a commercial supplier and ordered some sheets of cherry in crown and cross sawn. If I'd known more then, I'd not have bought the (very nice looking) crown cut, or even cherry of any kind....
All seemed well while I glued on the sheets, grain matched L-R etc., using the latest water based contact adhesive (BIG, BIG mistake)....
They looked truly superb until I started lacquering with water based polyurethane (mistake 3, fortunately the last), when the ****** water based contact cement went "soft" and the crown cut cherry started growing again.
Encouraged by my wife to NOT burn them, we ironed the damn veneer back, using CA glue, prayers, curses etc etc., and re-laquered with real polyurethane. The veneer still lifts off in places- fortunately, not always very obviously- and I learned a lot of speaker building lessons (choose the veneer carefully, test it, the glues and lacquers very thoroughly!).
All seemed well while I glued on the sheets, grain matched L-R etc., using the latest water based contact adhesive (BIG, BIG mistake)....
They looked truly superb until I started lacquering with water based polyurethane (mistake 3, fortunately the last), when the ****** water based contact cement went "soft" and the crown cut cherry started growing again.
Encouraged by my wife to NOT burn them, we ironed the damn veneer back, using CA glue, prayers, curses etc etc., and re-laquered with real polyurethane. The veneer still lifts off in places- fortunately, not always very obviously- and I learned a lot of speaker building lessons (choose the veneer carefully, test it, the glues and lacquers very thoroughly!).
Crossovers
My wife sourced and hand-carried back from China, two huge chunks of solid walnut for the plinths. I drilled and chiselled out cavities for the crossover circuits as well as four terminal posts for bi-wiring (which I've not yet bothered with).
Final assembly...
Here's the speaker wired to the crossover and ready to be sealed up. You can see the pure silk fluff used for the damping (instead of BAF).
The end result
The end result, so long as you don't notice the bubbles in the veneer, are worth the considerable time and effort, and certainly sound much nicer than $2000 commercial boxes (ugh).
Without access to at least a large and accurate panel saw, I'd not attempt to make these speakers (or any other boxes, for that matter), as I don't think a DIY hand circular saw is sufficiently accurate and a DIY table saw cannot handle the 8 x 4 sheets of heavy MDF.
Without access to at least a large and accurate panel saw, I'd not attempt to make these speakers (or any other boxes, for that matter), as I don't think a DIY hand circular saw is sufficiently accurate and a DIY table saw cannot handle the 8 x 4 sheets of heavy MDF.