Sundown X and Z v.4 Sound Difference : Visualized

[sundownz 197]

I know alot of folks have a hard time understanding my explanation of this all in text format; so lets visualize it based on some Klippel results.

I had the first Z v.4 15" prototype Klippel tested; as explained on the image the production model will test even better since I did a hyper-extended pole compared to the standard height pole extension on the sample but I haven't had a chance to actually re-do the test -- but I have verified in FEA and via doing similar comparisons with Klippel on other drivers with the same changes what the result would be.

The SA-12 is a production unit -- and most people know how an SA-12 sounds; and most people love it. It has what I would consider a good but "standard" suspension.

Notice how dramatic the FS shift is even at 2" p-p travel ? Many people that own an SA tend to push them all the way to 2.25-2.5" or so p-p travel (hard bottom is 2.65" p-p) so there would be even MORE parameter shifting.

Even more stand-out is the QTS shift over stroke since it is caused by both BL and CMS shifts.

Anyone with a box modeling program handy can tell you what THAT much shift in Fs and Qts will do to the response (VAS also shrinks along with CMS).

Now lets move onto the Z v.4

The FS shift at 2" p-p is almost non-existent by comparison. The Klippel tester ran out of steam before pushing the suspension to it's limits. Typically CMS limit is defined as a 50% shift which would be ~0.0875 mm/N on the graph; use your imagination and you can see that is around 4" p-p total travel.

Onto the Qts shift -- still MUCH better than the SA-12; and on production with the BL being more symmetrical thanks to the hyper-extended pole you would see more like a range of 28-35% or so here. The reason for this not being as low as the FS shift is that I am not using a "flat BL" topology. If I were to implement something like XBL^2 this shift could be as low as the FS shift over stroke... and I do plan to offer drivers with our new platform AND flat BL at some point.

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So, again, anyone with box modelling software can do the experiment themselves and model up what the driver does with a large amount of parameter shift compared to a lack thereof.

So hopefully that explains what you are hearing when you hear a new platform driver compared to a more traditional suspension driver. It is simply a LACK of distortion; there is nothing actually missing -- the drivers are not "missing the highs" -- they are just flat over stroke; they are only missing the *artificial* upper-bass spike created by traditional suspensions over stroke. In other words... they just aren't adding something that isn't really there.

So the question you have to ask yourself is do you WANT a flat and low distortion response or not ? Be honest. Some people don't like their distortion to be that low... and in general CMS related distortion is 2nd order and sounds relatively pleasing (like tube amps).

That being said... the new "SPL" cones will create a CMS curve that looks more like the SA-12 graphs; they will create the traditional sound with the upper-bass spike. When they are available order your driver accordingly to what you like :thumbsup: You can think of the new platform subs with "SPL" cones as a higher displacement version of the Z v.3 woofer -- so if you like those you would like a new platform driver with the "SPL" cone.

[jcarter1885 995]

Thanks for the dumbing it down for some of us Jacob