I've recently finished a pair of SEAS Thor TL's (using the current SEAS Thor infos), and have a newbie about the crossovers. The crossover frequency is (I believe) supposed to be about 2500Hz and the tweeter third order circuit components indeed correspond -approximately- to this (and I've even measured it with a sig gen and scope), but the 2 paralleled W18E001 (so nominally 4ohms) are driven through a 1mH choke. A 4600Hz notch filter is also there to remove a driver resonance at that frequency. But no matter which way I look at it, 1mH looks like a first order crossover for 4 ohms at 640Hz, not 2500! I can't imagine that the enclosure design compensates for such a low crossover and although the basic Thor design has its critics at the lower end, I wasn't aware of the mid-range being reported defective. By 2500Hz the output will 12db down. Also, there's the issue of crossover phase shift (90 deg for 1st order, -90 for 3rd). The speakers also sound pretty fine (to me), image well etc. So, what am I missing here? 
(Apologies if this Q already has an answer in the Thor discussions but I couldn't find it!).
(Apologies if this Q already has an answer in the Thor discussions but I couldn't find it!).
Dave, thanks. Looking at the SEAS data graph (and ignoring the various resonances), I can indeed see a roll off from about 2kHz onwards. Still, why did they (D'Apollito?) start the xover 3db slope from ~650Hz rather than 2500? Is this something to do with baffle step correction (?!) (or am I just showing even more ignorance!)?
Tim.
Tim.
Ah. Very interesting. Even if its a flawed TL design and only my first build effort, I'm learning a lot from these and then discovering diyaudio.com....! So much to learn. I'm very glad I didn't just shell out $2000 for a pair of commercial boxes but went this DIY route instead. Much more satisfying all round! Many thanks Dave.
Tim.
Tim.
DIY can easily become an addiction (MuHaHaa). Enjoy them. and know that they can be made even better,
http://www.diyaudio.com/forums/multi-way/64799-clarity-seas-thor-kit.html
dave
http://www.diyaudio.com/forums/multi-way/64799-clarity-seas-thor-kit.html
dave
acebritbiker, do make sure you read the above thread before putting saw to wood.
Hi Shaun, is that "putting saw to wood" of my present Thors or of a new pair ?!
I see that there are 103 pages (so far) in the Clarity on Seas Thor Kit.... thread. Not sure that if I'd read this lot before making my Thor's, I'd have continued, given up, or just gone mad! On balance, I'm probably glad I made them as they are, as they were finished without too much pain or delay. And now I see there are many, many ways to make something more refined, or different, or better.... Probably the best thing is I will never walk into a shop and buy a pair of ready made speakers, as I nearly did late last year! Cheers,
Tim.
I see that there are 103 pages (so far) in the Clarity on Seas Thor Kit.... thread. Not sure that if I'd read this lot before making my Thor's, I'd have continued, given up, or just gone mad! On balance, I'm probably glad I made them as they are, as they were finished without too much pain or delay. And now I see there are many, many ways to make something more refined, or different, or better.... Probably the best thing is I will never walk into a shop and buy a pair of ready made speakers, as I nearly did late last year! Cheers,
Tim.
Oops! I somehow missed that you had built them already. planet10's comment about improvements to be had over the original enclosure design relates its bass-shyness. I have built the original Thor box for a friend some years back. Another friend built one of the later Fat Thor enclosures. The friend who built the original Thors was bitterly disappointed and the DIY world has not heard from him since, whereas the other friend is just chuffed with this speakers.
Shaun, I hope your friend #1 didn't hurt himself. To be candid, unless I'd read the various and far ranging posts on the Thors, I'd not have thought about mine being bass shy, and -in fact- still don't (!) as they satisfy my needs for listening to mainly chamber music (incl. pipe organ) and vocals etc. I did audition one or two more "bassy" sounding commercial boxes but overall they disappointed (& I went DIY). The Thors have a clean and controlled bass that I find to my liking. I'm sure that my listening room defects far outweigh Thor design related problems. The room resonances extend up to high audio frequencies and are quite amazing to hear: does everyone have these problems? I'm amazed that the speakers can form an image at all!! Cheers,
Tim.
Tim.
Yes - Whatever happened to him?
The ones i built were actually the Small Thors, and they are brilliant - thanks Dave & Scottmoose. They do need a reasonable environment though. They far out do (quality and quantity) a pair of Jamo D590's which are supposed to be quite bassy.
Soon there is going to be a "Clarity on the 18W8531's" thread
I have Martin's sheets now though and a fair idea on how to use them.I had a question about the Thor xo.
Does the first-order electrical filter on the midbass, plus the notch, cut the resonant peak region sufficiently? I like cutting those regions at least about 60dB compared to the base SPL. I believe metal-cone drivers ring a lot in their resonant regions and this is a time-smearing thing, not just a pure SPL unevenness, therefore there's no way to eliminate the colouring that they add if you allow that portion of their response graph to be audible.
I've seen Jon Marsh' designs with similar Dayton RS180 drivers over at htguide.com, and his CE filters do an excellent job of eliminating the cone-breakup region from the final output. I thought that that approach made sense; it's the diametric opposite of an electrical first-order in some respects.
Has anyone modeled the Thor crossover (or those midbass drivers) on a 9" wide baffle with the Thor xo? I skimmed through the "Clarity on Seas Thor" thread but that discussion seems to focus more on the bass reproduction and enclosure construction.
Edit: sorry, but as I write this post, I also chanced upon this one on htguide which is asking almost exactly the same question. Sorry for the duplication.
Does the first-order electrical filter on the midbass, plus the notch, cut the resonant peak region sufficiently? I like cutting those regions at least about 60dB compared to the base SPL. I believe metal-cone drivers ring a lot in their resonant regions and this is a time-smearing thing, not just a pure SPL unevenness, therefore there's no way to eliminate the colouring that they add if you allow that portion of their response graph to be audible.
I've seen Jon Marsh' designs with similar Dayton RS180 drivers over at htguide.com, and his CE filters do an excellent job of eliminating the cone-breakup region from the final output. I thought that that approach made sense; it's the diametric opposite of an electrical first-order in some respects.
Has anyone modeled the Thor crossover (or those midbass drivers) on a 9" wide baffle with the Thor xo? I skimmed through the "Clarity on Seas Thor" thread but that discussion seems to focus more on the bass reproduction and enclosure construction.
Edit: sorry, but as I write this post, I also chanced upon this one on htguide which is asking almost exactly the same question. Sorry for the duplication.
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