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Old 28th September 2005, 05:15 PM   #51
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Quote:
Originally posted by Scottmoose
(works just the same, you just have to cut & paste into something like Word if you want to save)
<rant>Not Word please.... I'm fighting with one of those as we speak. Seems anytime something gets near Word it screws it up.

I wish there was a real WP available for PC users</rant>

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Old 28th September 2005, 05:27 PM   #52
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The Extremis & the SEAS is a good combo. The Extremis is certainly not bass shy (as i was preparing the chicken wings at the latest DIY-fest, they were playing some classical with some serious bass in it... my room is not small, and the amp was an EL34 PP, but i was being made quite nauseous as the waves of bass rolled into the kitchen.

You can consider the folding geometry of the Thor, but i would discard the actual dimensions. From the Scottmoose sim, that cab does embarrassingly poor at getting the bottom out of the Extremis that is possible -- it also has a large amount of ri[pple. I'll be very intersted in the more optimum sims -- i have 4 extremis sitting here and a TL in my queue of things to come up with. He comes up with dimensions i'll whip up a working drawing.

Do note that the mids of the Extremis -- thou reasonable for a 7" driver -- are no match to a WR or FR125, Fostex FE127 or FE108, or even an Aura.

Since you are bi-amping you might think about HF options that go lower (my 1st thought was any number of the 3" FRs) -- or at least do the design to make this kind of thing realizable leater.

As an example, I ended up with the left-overs from the North American Monsoon service depot and have some 40-50 subs with good drivers under my deck (check my AVB thread for details). I was going to do an experiment with 4 of the 8" units and a set of "non-existant" 3" TBs in a 3 box MTM XOed at ~300 Hz (ie just seal off the hole from the plate amp with a piece of ply that ties 2 woofer boxes together with the TB in its 1/4 litre cube sandwhiched in between...

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Old 28th September 2005, 06:27 PM   #53
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I appreciate the feedback.

I think I'll probably just stick with a tried and true design.
Leaving the hardcore experimentation for later, once I'm more confortable with the theory and the tools.

Back to the drawing board so to speak.

Cheers.
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Old 29th September 2005, 06:10 AM   #54
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Hey Scott

Quote:
Originally posted by Scottmoose
I think the important thing we need to keep in mind when considering all this, is, whether you go with the simulated or the measured data, Thor looks poor, especially considering its high price. If I wished to build a speaker in that price range, and I saw only the measured data for example, I would be very wary, especailly when I saw the crossover.
It looks fine in terms of measurement - very flat - and the measurement matches the claim that f3 = 45Hz

Quote:
Originally posted by Scottmoose
OK, why the differences, if we're assuming for the moment that my simulation is in the ball-park? Well, firstly, keep in mind that the measured data has clearly been heavily smoothed -speakers are not that flat in real life, and this disguises response aberrations. Looks like 1/3 or 1/2 octave smoothing to me. Note that the dip in woofer output circa 30Hz is still there on the measured data -it's simply been flattened out, which confirms this, at least to my satisfaction. Ditto the peak in vent output, though apparantly on the measured data it occurs a little lower, suggesting a slight error on my part on the vent dimensions -I hold my hand up on that one. It's not that significant though in the overall scheme of things.
[/B]
If as you say smoothing has been applied how do you explain the peaks & troughs in port output at higher frequencies? (Octave Frequency band widths increase as the frequency increases). Also look at the driver output, for evidence of this. The graph produced by the mathcad sims looks alot more "smoothed" in this region than the measured result. What accounts for this discrepancy?

If we assume the above to be true then we might say something in the model is not working correctly unless of course the model applies smoothing as well.

Quote:
Originally posted by Scottmoose
Below 100Hz in room, you won't get a huge performance boost. It'll be better than the anechoic response of course, but the vent output is too low, and being mounted high up, and firing horizontally rather than vertically it can't drive the room as well as a low mounted vent a la Lynn Olson's Ariel. Worse, you'll still have the 3-4db baffle-step losses Martin mentioned, which the crossover does not correct. And just to add a further fly in the ointment, the cabinet is full to the brim with a very heavy quantity of stuffing, which itself will cause the bass to sag further. Whichever way you look at the data, Thor will be significantly down at low frequencies. Only by listening to it in your own room however, will you be able to determine if it works well enough for your taste in your home."
[/B]
Doesn't room response usualy slope upwards @ 12db / octave? This is quite significant in terms of response. I have had experience of listening with my own ears to a speaker in an anechoic chamber. I can tell you that in that instance - low frequency output was dramaticaly less than inroom response. When I say dramaticaly - almost non audible.

Quote:
Originally posted by Scottmoose
Depending on what you listen to and how large your room is, an alternative speaker you might like to look at is Bob Brines FTA-2000. It uses a single Fostex F200a full-range driver, and is pretty much flat in room from 30Hz - 20Khz. It'd cost a fair bit less than Thor too. You'll find it here: http://www.geocities.com/rbrines1/Pa...2000/Main.html
Perhaps not ideal for thrash metal or a very large room, but most anything else, it's a winner.
[/B]
Sorry - dont like full range. Also couldn't find any response plots here. Have they been measured? Could you point us to one? I am sure though that the upper frequency reponse of these will certainly not be as flat to 20k as the Thor even though it may be a good attempt.

Quote:
Originally posted by Scottmoose
The Ariel is also very good -no deep bass, but Lynn always stated it didn't, which is nice and honest of him, and it simulates and measures well. Both are cheaper, which means you could add a decent subwoofer from REL, or perhaps a pair of Linkwitz Thor (I kid you not!) monopolar subs, or the open baffle subs from his Phoenix project. That'd be what I'd do anyway!
[/B]
D'Appolito didn't claim Thor had deep bass which is also quite honest of him.

I think the thing we are forgetting about here is that generaly response below 40 Hz in real music is not all that common. I would prefer to have a speaker that does everything well over most of the range, instead of one that does so-so over all of it. I have heard the Seas excel drivers in a different configuration and love them in terms of higher frequency qualit and impact.

I will build the Tthor in its original config as well as possibly attempt the mathcad software sims and build a prototype of what I get there.

Thanks for you input this has been an interesting discussion.
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Old 29th September 2005, 05:37 PM   #55
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Quote:
Originally posted by Byrd


That still looks like a response plot without augmentation by the rear wave exiting the TL. Take a look at the delay. In fact it looks very similar to the response plot for the W18 driver measured anechoicly alone. These measurements I have been told are taken by placing the driver in a 6 litre sealed enclosure. Surely a T/L no matter how badly designed or mismatched should best this.

Take a look at this graph from the AE article. From what I understand - this shows the measured response simulated to anechoic response of the Thor, it combines both port and driver output. It does not include room gain.

If I have misread these please could you explain.
There is nothing simulated about the Seas measurement of the Thor. They put the speaker in the middle of the anechoic chamber with the mic about a meter away and then they run a simple frequency sweep and record the SPL. No MLS or quasi-anechoic windowing tricks are needed. Joe's measurements are more suspect because he's doing a lot of mathematical tricks to try to filter out the room and splice the port's response in.

You can look at the measured response of the Trym kit to see that Seas is capable of measuring a speaker with good bass.

http://www.seas.no/kit/Trym%20måling.pdf

That said, there should be more bass in a room than in an anechoic chamber so the anechoic measurements don't tell the whole story.
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Old 29th September 2005, 07:11 PM   #56
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Quote:
Originally posted by catapult


There is nothing simulated about the Seas measurement of the Thor. They put the speaker in the middle of the anechoic chamber with the mic about a meter away and then they run a simple frequency sweep and record the SPL. No MLS or quasi-anechoic windowing tricks are needed. Joe's measurements are more suspect because he's doing a lot of mathematical tricks to try to filter out the room and splice the port's response in.

You can look at the measured response of the Trym kit to see that Seas is capable of measuring a speaker with good bass.

http://www.seas.no/kit/Trym%20måling.pdf

That said, there should be more bass in a room than in an anechoic chamber so the anechoic measurements don't tell the whole story.
"The enclosure uses a newly developed transmission line configuration, derived both from sophisticated computer modeling, and extensive experimentation. The line is tapered, and filled with Dacron stuffing. The two W18E001 woofers excite the line at slightly different points, smoothing the response and increasing the range of bass output. The transmission line produces 4 dB of bass lift from 20Hz to 110HZ, with less than 1 dB of ripple. The -3dB point is 45Hz, with roll off of 12dB per octave below 45Hz. Usable in-room bass response extends well into the
low 30Hz range."

I am not sure if you noticed but on Thors main page that leads to the graph you linked to the fact that the above is stated which does not lock up with the graph that they have displayed for the Thor. Is this statement on their site incorrect?

I wouldn't say "Joe" is doing alot of mathematical tricks, but rather the CLIO system he uses. Is CLIO really as bad as all that to show a 45 Hz f3 where an anechoic response shows an f3 of 100Hz? mIf so there is no hope for any DIYers unless they have access to an anechoic chamber. My closest is about 500 Meters away
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Old 29th September 2005, 07:22 PM   #57
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I'd rather you gentlemen than me -we clearly have rather different ideas about what constitutes a well engineered and measuring speaker. I suspect we're going to agree to disagree -fine with me, I like a debate, and, likewise, I've thoroughly enjoyed this one. I also sincerely hope you enjoy your Thors when they are built -perhaps you could give us some feedback when they're completed? The more user reports and measurements the better I say. Out of interest, what sort of power-amps will you be using with them?

You're not alone in having experience in anechoic listening -so have I. Anechoic bass should be much less than in room -that's the point. Under those conditions, you're only listening to the speaker. Personally though, I don't like using too much room gain, for that very reason: you're listening to the room, not the drive units. Not always a good plan. How much is applied, and where in the frequency range rather depends upon the room size and its furnishings, which is unpredictable to say the least. One of the reasons I also like open baffles, a la Linkwitz. No mentions that Thor has deep bass? Well, from the number of comments in that article regarding strong output at 25Hz... Draw your own conclusions there I reckon! (Though I don't hold Dr J. D. responsible for that.)

I can understand why many people dislike full-range units -that said; heard a good one of late? Most of the old ones were poor, but the new Fostex and Lowther units are frankly astounding. Not quite as flat as a multi-way speaker, but they have slightly different priorities -the usual trade offs in speaker design: gain one thing, sacrifice another. For your interest, I've got a response graph of Bob's FTA-2000s somewhere -I'll dig it out when I have a moment as you asked. Bob's site has become smaller of late -too many people were pinching his designs I suspect, though I haven't yet asked him.

It's interesting that we actually agree on many points though you might not believe it -I too favour high quality mids and highs over broader, but lower quality output over a wider range, and I like these Seas drivers a lot. My primary concern lies in the fact that you can match and beat this performance though for around half the price with Ariel for example, but we've already discussed that.

Oh, one last graph for your interest. Meet the Thor cabinet -with a single Seas Excel driver. Everything else is exactly as per the standard cabinet Joe designed. I smiled a wry smile. Actually, the ripple you see will actually be less than shown here, as the driver placement needs a fractional modification, which I didn't put in. Blame the doubled Vas of the paralleled drivers. I confess to being impressed (though I still don't like high mounted vents!). This looks much better.

Best regards & enjoy the music
Scott
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Old 29th September 2005, 07:31 PM   #58
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Quote:
Originally posted by planet10


<rant>Not Word please.... I'm fighting with one of those as we speak. Seems anytime something gets near Word it screws it up.

I wish there was a real WP available for PC users</rant>

dave
I know the feeling Dave -Bring back WordPerfect, that's what I say. I never had any problem with that. I still have v5, on an 8086 with 40mb HD, 2 5.25" FDD drives and Hercules green-screen monitor! And it still works...

Best
Scott
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Old 29th September 2005, 07:32 PM   #59
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That is interesting. As I say I will build the Thors as they are first - then do some fiddling. Will be over the next 2 / 3 months. (If the drive units ever arrive that is)

I have also mailed Seas on the apperent discrepancy - because that sort of thing drives me nuts as you can tell. The reason probably being in South Africa we are so far away from everything that when other people **** specs up - we pay for shipping and its not cheap or easy.
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Old 29th September 2005, 07:32 PM   #60
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Quote:
Originally posted by Scottmoose
Oh, one last graph for your interest. Meet the Thor cabinet -with a single Seas Excel driver. Everything else is exactly as per the standard cabinet Joe designed. I smiled a wry smile. Actually, the ripple you see will actually be less than shown here, as the driver placement needs a fractional modification, which I didn't put in. Blame the doubled Vas of the paralleled drivers. I confess to being impressed (though I still don't like high mounted vents!). This looks much better.
Almost makes you think he forgot to multiply by 2. So an easy fix for the Thor might be to double the cross-section all the way round :^)

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