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Old 27th September 2005, 08:56 AM   #31
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Originally posted by JDeV
So, do you guys actually want to tell me now, that I have just spend a s..t house full of money on an "acclaimed/designed/highly reviewed" speaker , that are actually pretty useless?
Only you can decide -- I certainly can't tell you that... i've not heard them. I have just suspected something fishy since i 1st read the article. It will be interesting to hear your comments after you've listened for a while.

dave
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Old 27th September 2005, 09:22 AM   #32
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Driver & terminus response curves? Your wish is my command Dave. Coming up in the next post. For now, while I wait for my other PC, which has the MathCad curves on, a few other observations. As for the audioXpress graph looking flat, indeed it does look flat. There's a reason for that. First, note how there is nothing even resembling a jagged peak or dip in the plot, indicating smoothing, most likely 1/2 octave. Now observe the 'woofer pair' curve, which is the most relevant one, and how it sags at 100Hz. Finally, note the slight trunkating of the graph, which disguises aberations.

Joe is certainly not stupid, he is one of the great designers of modern times, but however many excuses are made for it, on the lines of 'it doesn't look too bad', Thor is not one of his better efforts. Agreed with the idea that he probably just doesn't have a whole lot of experience with TL design, though, going by the audioXpress article, he went about it in what I would consider a highly amaturish way unworthy of him. Thor's an externally handsome speaker, using some very pretty drivers, which are also very good (OK Martin: I won't give up on them just yet!), but looking at the plot, you can equal or better them in this respect for half the price. Yes, I know, plots aren't everything, but they do tell you a lot. For example that you'll need a massive boost from room gain to get down the the 25Hz frequently mentioned by subjective listeners. Fair enough, I won't argue, but that's the room they're listening to, not the speakers, which is not, in my view, ideal. Thor is a rocky design in my view. But on a positive note, compared to most commercial designs of equivelent price, they're streets ahead. Which just goes to show what a rip off commercial speakers are. It's by no means the worst speaker out there. But it's far from being the best. If you've built them, enjoy them. You've got some terrific drivers in a rather dodgy cabinet (and I hear dark mutterings about the crossover too, but that's for another day). We'll try to come up with something better for them to go in shortly. At least, being MDF, the cabinet isn't overly expensive to make, and represents only a minimal part of the material (if not the time) costs.

You know the old type (pre Martin's MathCad sheets) TL I really admire? Lynn Olson's Ariel. Half the price of the Thor, and a complete pig to build, but it works well for what it is. They don't have low bass, but Lynn never claimed they did. It all seems less pretentious to me somehow. There's art in there, but there's also some good enginnering sense too. Well selected drivers with no break-up modes in the band they're used in, so they require no notch-filters, independent lines for the two Vifa mid-bass drivers in MTM configuration: a little over the top perhaps, but the idea's not without merit. I've built the Ariel, and admire it. The bloke I sold them to was over the moon with them.

By the way Martin, I've just fired a lengthy missive off to Hifi World magazine regarding your work (and a few other things), as I'm frankly apalled at the lack of recognition you've recieved for all your work. OK, so you don't have a famous name like the blokes you've mentioned, but you're the one who came up with a way to model a TL properly, not them. Whether anything'll come of it, I don't know, but they've been running some DIY TL articles of late, most based on the old methods, so with any luck they might decide to read and / or publish it. I wasn't aware that people were deciding to patent 'new' work almost identical to what you'd done years ago. One doesn't know whether to laugh or cry really.

Cheers for now -extra graphs on their way
Best
Scott
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Old 27th September 2005, 09:59 AM   #33
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As requested:
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File Type: jpg thor predicted woofer & terminus far field spl response.jpg (66.8 KB, 2256 views)
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Old 27th September 2005, 10:00 AM   #34
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And the rest: might as well! 'ere be the predicted woofer displacement:
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Old 27th September 2005, 10:02 AM   #35
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Another... This time Thor's predicted TL system and IB impedence to mull over:
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Old 27th September 2005, 10:03 AM   #36
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And, just for fun (it's the last!) , the predicted system time response.
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Old 27th September 2005, 11:43 AM   #37
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Thanks for those breakdown Scott

Now the question that I have is why is the predicted port output different to the actual measured?
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Old 27th September 2005, 05:35 PM   #38
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Hi Scott,

Quote:
I wasn't aware that people were deciding to patent 'new' work almost identical to what you'd done years ago. One doesn't know whether to laugh or cry really.
In this case, I can only smile and walk away. But it does start me thinking about how much info I should make avalable when posting any future speaker designs on my site.
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Old 27th September 2005, 07:26 PM   #39
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I wasn't aware that people were deciding to patent 'new' work almost identical to what you'd done years ago. One doesn't know whether to laugh or cry really.
I think a letter writing campaign to aXp is called for. Rick has been doing good work with his "TLs for Dummies" series but claiming uniquiness & patent protection is WAY over the top.

Maybe we should start a new thread (when i reviewed his article i complained to him about these comments and said i'd squawk if he kept them in the published article)

dave
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Old 27th September 2005, 10:20 PM   #40
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Good plan Dave. Consider me behind it 100%.

Martin -I don't blame you. I have benefited in many ways from your work, but never financially. I think you've already guessed my views on that matter. I've seen this sort of thing happen before, in other, non audio areas, and it gets my goat every time.

Why are the simulated and measured outputs different? Well, the curves are basically very similar. Did you remember to apply to the MathCad charts the +6db boost gained in system efficiency for having paralleled drivers when comparing to the measured data?

Regards
Scott
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