Low Frequency Extension

[boy.kroy 1]

I see you still have the PG Ti12d Elite. That thing is a low end monster if box parameters are designed properly. Personally I have 4 in a common chamber tuned at 28Hz. Check out phoenixphorum.com and search for the 12d Elite. Here are a couple links of a guy that put one in a lexus tuned to 25Hz:

http://phoenixphorum.com/my-car-at-the-las...html?highlight=

http://phoenixphorum.com/updates-on-my-box...html?highlight=

How did yours measure because mine were way off of the manufacturers specs maybe double, something thats really not good if i were using there recommended ported enclosure( id either have one really damged sub or it would sound horrible). And when i did my research on the forums i was told by a number of people that the optimum sealed box is a whole cubic foot larger than the recommmended kind of like the new xxx. I Dont want to be told that a sub is meant for small enclosures just so they can sell a sub, and then when i measure it for myself it comes back huge! Either they are lying or they were talking about a half of sub. But im willing to bet it is the QC.

[KU40 173]

A sub's specs will not be different by twofold because of quality control. If they're off by that much, it's a completely different sub. Specs are normally off by 10% at the most, and normally not even close to that, even after break-in time. Either your instrument wasn't calibrated correctly, or something.

[boy.kroy 1]

I think i am going to keep the pg ti12d and put it in a 2.5-2.6 cu.ft sealed and buy something else and compare them installed on the same amp in there required boxes.

[boy.kroy 1]

A sub's specs will not be different by twofold because of quality control. If they're off by that much, it's a completely different sub. Specs are normally off by 10% at the most, and normally not even close to that, even after break-in time. Either your instrument wasn't calibrated correctly, or something.

anyone have access to klippel id let them test it!

[boy.kroy 1]

A sub's specs will not be different by twofold because of quality control. If they're off by that much, it's a completely different sub. Specs are normally off by 10% at the most, and normally not even close to that, even after break-in time. Either your instrument wasn't calibrated correctly, or something.

Specs enclosed with the sub:

Fs-25.2

Qts-0.55

Qes-0.616

Vas-47.70L

Re-1.47(Parallel)

Car Audio and Electronics Specs(December 2002):

Fs-25.50

Qts-0.47

Qes-0.54

Vas-36.20

Re-1.52(Parallel)

My specs via WT2:

Fs-36-37

Qts-0.68-0.76*

Qes-0.78-0.87*

Vas-33.43L-40L

Re-1.6(parallel)

*Qts-Qes variations are probably because of testing in series and parallel that i performed and recorded but didnt make a note for my self of which was which but it is the range of a number of passes on the wt2, Fs is in parallel

[KU40 173]

is your sub the 2002 model? If not, the specs could easily be different between model years between yours and the one in CAE. Manufacturers almost always tinker with things for new model years, just like vehicle manufacturers. But there is no way that Fs should be that off between yours and published specs. That hints at a completely different soft part assembly if that's happening. So your machine must be wrong, IMO. Or else they sent the wrong specs with the sub in the box.

[boy.kroy 1]

is your sub the 2002 model? If not, the specs could easily be different between model years between yours and the one in CAE. Manufacturers almost always tinker with things for new model years, just like vehicle manufacturers. But there is no way that Fs should be that off between yours and published specs. That hints at a completely different soft part assembly if that's happening. So your machine must be wrong, IMO. Or else they sent the wrong specs with the sub in the box.

I thought that was a little wierd also that the Fs was the only Spec that Was way off, but the wt2 also gives a fo measurement that is more consistent with the factory Fs spec but i thought the Fs and Fo was the same thing.

[culzero 0]

boykroy what part of the country do you live in?

[boy.kroy 1]

boykroy what part of the country do you live in?

Under a rock in Delaware

[boy.kroy 1]

Some caution is required when using and interpreting T/S parameters. Perhaps first is that manufacturer values may not match individual units. Their values are almost never individually taken, but are at best averages across a production run. In addition, there are inevitable manufacturing variations across a driver's production. As well, driver characteristics change somewhat after they enter use. And so the T/S parameters which apply to a particular driver will be, to some extent unique and can only be found with certainty after a period of use.

It is also important to understand that most T/S parameters are linearized small signal values. An analysis based on them is an idealized view of driver behavior, since the actual values of these parameters vary in all drivers: with drive level, with voice coil temperature, over the life of the driver, etc. Cms increases the farther the coil moves from rest. Bl is generally maximum at rest, and drops as the voice coil approaches Xmax. Re increases as the coil heats and the value will typically double by 270

[boy.kroy 1]

The mechanical components in typical speaker drivers may change over time. Paper, a popular material in cone fabrication, absorbs moisture easily and unless treated may lose some structural rigidity over time. This may be reduced by coating with water-impregnable material such as resins. Cracks compromise structural rigidity and are generally non-repairable. Temperature has a strong, generally reversible effect; suspension materials become stiffer at lower temperatures. The suspension also unergoes changes from chemical and environmental effects associated with aging such as exposure to ultraviolet light, and oxidation which affect foam and natural rubber badly, though butyl, nitrile, or SBR rubber, or rubber-plastic alloys such as Santoprene are more stable). Foam is highly prone to disintegration after 10 to 15 years. The changes in behavior from aging are rarely positive, and since the environment that they are used in is a major factor, the effects are not easily predicted. Gilbert Briggs, founder of Wharfedale Loudspeakers in the UK, undertook several studies of aging effects in speaker drivers in the 1950s and 1960s, publishing some of the data in his book, Loudspeakers.

There are also mechanical changes which occur in the moving components during use. In this case, however, most of the changes seem to occur early in the life of the driver, and are almost certainly due to relaxation in flexing mechanical parts of the driver (e.g., surround, spider, etc). Several studies have been published documenting substantial changes in the T/S parameters over the first few hours of use, some parameters changing as much as 15%+ over these initial periods. Other studies suggest little change, or reversible changes after only the first few minutes. This variability is largely related to the particular characteristics of specific materials, and reputable manufacturers take them into account. While there are a great many anecdotal reports of the audible effects of such changes in published speaker reviews, the relationship of such early changes to subjective sound quality reports is not completely clear. Some changes early in driver life are complementary (such as a reduction in Fs accompanied by a rise in Vas) and result in minimal net changes (small fractions of a dB) in frequency response. If the performance of speaker system is critical, as in high value or heavily equalized systems, it is sensible to measure T/S parameters after a period of run-in, and to model the effects of normal parameter changes.