1 or 2 Titanic MKIII 15 kits or PC Ultra?

[dragonfyr]

Yep, you have simplified all things audio significantly! So, at the risk of being a smart aleck (he said with a big grin....)

Now, if we can just get the Thiele/Small parameters for the the La Scala and the Khorn woofers, we can determine which is better.

Opps, so they are the same? Oh, no problem - then we can reliably say that the response characteristics of the speakers are identical!

It is so nice to be able to remove cabinet topologies (why do those idiots worry about 1st or 4th order alignments, isobaric versus tuned bandpass vesus bass reflex? Or what is that horn nonsense? I wish speaker design was as simple as looking at a few Thiele/Small parameters.

And how does Don Keele manage to evaluate speakers without ripping them apart and doing destructive analysis!? ;-)

And we won't even get into more complex interdriver interactions in suchconfigurations as line arrays, bessels, etc. as they just confuse the issue.

So I guess the answer is simply to find a driver with the lowest Qts and all my worries are over.

A driver's parameters are indeed useful, but to attempt to derive the total system response from them is not a reliable measure.

But if you are seriously into examining the Thiele/Small parameters, you owe it to yourself to get a copy of Benson's "Theory and Design of Loudspeaker Enclosures" ISBN 0963892908. It is more comprehensive and detailed then what Thiele/Small published and goes beyond their work.

Come to the next Loudspeaker Design Seminar. I'm not sure who will do the learning, but I am sure one group will be enlightened. And you can Ask Don Keele how he does it!

[michael hurd]

At the risk of being too simple, I dare say you cannot make a silk purse from a sow's ear. Keeping that in mind, let us compare apples to apples, as you had alluded to before.

I agree also that a mediocre woofer in a superb cabinet, should perform well. A better woofer in a mediocre cabinet will also perform good, but it truly is not the best it could be.

I do not recall where saying that two different cabinets, using the same woofer ( motor ), will have the same response characteristics.

Thiele/Small Parameters are fine for modeling for small signal analysis, but at higher output levels, the transducer can become increasingly non-linear. Magnetic force is down, at high excursions, due to less amount of wire in the gap. Suspensions can also become non-linear, as well as causing extraneous noises.

This is why Dumax is different than small signal analysis, it allows you to look at the driver behavior at larger excursions.

Moving on, it seems that there are several ways to minimize distortion caused by driver characteristics.

1> Increase driver diameter, reduces the amount of excursion required for the amount of output, in like enclosures. IE: 12" woofer in ported cabinet tuned to X hz, versus a 15" woofer in a ported cabinet, tuned to the same frequency

2> Increase motor strength at the ends of the VC. Several companies have come up with different ways of varying the winding technique, so that there is more wire in the gap at the ends of the voice coil. This means the tranducer will have more uniform motor strenth.

3> Increase the size of the voice coil. This increases the amount of turns of wire in the gap, increasing the motor strenth. Same goes for using an edgewound rectangular wire, increased BL product.

4> By using an edgewound coil, the gap can be made smaller, resulting in higher sensitivity, also aids in cooling. Downside is that the suspension must be more accurate, or the coil can rub and short in the gap.

5> Optimize the suspension characteristics for the amount of cone travel. What good is having a suspension that stretches tight at 14 mm travel, when the motor is good for 18 mm? Larger diameter spiders are required for long travel.

6> Larger magnet, or a switch to a different magnetic material, say neodymium has a profound effect on the Bl product, after all, you are increasing the B.

[TVodhanel]

Hi all,

A couple of quick comments/corrections.

1)the "chart" referenced for the Ultra excursion is simply a generic chart provided to customers to give them an idea of how excursion demands change as the extension setting on the subwoofer is lowered. The casual HT enthusiast doesn't often realize the trade offs involved. The current motor and suspension on the Ultra driver is good for (slightly)over an inch each way in linear travel.

2)instead of one manufacturer telling you a competitor's product measured XYZ...wouldn't it be best to look for INDEPENDENT data on the product? For example, we have somebody questioning the THD of our PCi models, yet when Tom Nousaine measured or 20-39cs/PCi...it hit 109.5dB from 25-63hz(average clean output capabilities from 25-63hz))...very,very few subwoofers at any price have exceeded that(and Nousaine has measured hundreds of subwoofers now). The Ultra series has had its THD measured by John Johnson and it was very, very low (hometheaterhifi.com)...although he doesn't use a test method that lends itself to easy comparisons between models. The $429 PB10 has been *extensively* tested/measured by Ed Mullen (hometheaterhifi.com) Again, very,very low distortion. In fact, in every (independent)distortion test SVS has been involved with...our products have measured exceptionally well.

Is it possible one of our direct competitors got a used/second sample of a SVS product and it didn't measure as well? Sure...who knows what happens to any product after it has been shipped numerous times. Also, it is VERY EASY to design a test to make any product look less than stellar. For example, if you have one of our 25-31PC+ subwoofers...leave it in 25hz mode and measure the distortion at 20hz...or better yet...16hz..

Ed Mullen is reviewing subwoofer for the hometheaterhifi site now...and he includes a TON of objective test data. It would be *very* cool to see some of our competitors agree to send in their $400ish models to see how they compare to the SVS PB10 he just review? Talk is talk...let's see the data(from an independent source!).

Tom V.

SVS

[sivadselim]

hi TV

do you have a reliable link to the nousaine list? preferably the one that includes the rsw15.

all the old links that i had to it are dead now.