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Mikett 27th September 2004 11:27 PM

Changed Pioneer Coaxials to Sony Components
I just changed out some Pioneer Coaxials (6.5") to some 5 1/4 Sony Components I had removed from a previous car. (1999)

The Pioneers sounded poor. It did not have any low end to speak of and no top end. Vintage 1992.

Before the changeout, I tested the Sony speakers and it did have a fairly reasonable Fs, I simply tapped it.

After installing it, there is practically no midbass or lower sounds. I expected to get some cabin gain to help out. So I modelled the speaker. I suspect the driver to have a fairly low Vas and judging by the big magnet, low Qts. Effciency seems low as well, not as loud as the Pioneer Coaxials. ( High Qes)

Judging by the modelling, I suspect the -3dB point to be around 150 Hz. If this is true, then many of those component systems are going to sound very thin like mine. Or are the Sony Components I have just horrible. ( I used these with a sub before and never really noticed the thin sound)

Anyone ever experience something similar?

BillFitzmaurice 28th September 2004 04:21 AM

Tapping is not exactly the accepted method if deriving Fs, and even if Fs is low a low Qts cancels that out anyway. If you're going to do any modeling that's worthwhile you need to either obtain or measure- with measuring equipment- the specs.

The average vehicle gets cabin gain below 100 Hz at best, and more like below 60 Hz on average. Cabin gain at 100-150 Hz is pretty much non-existent.

Both Pioneer and Sony make medium quality drivers at best, and their mounting determines potential performance; any driver will only work to its best potential when mounted in a properly designed and built cabinet according to its measured, and not estimated, T/S specs.

Mikett 28th September 2004 12:19 PM

That pretty much sort of goes along the lines I suspected.
If cabin gain starts around 60Hz, and you have a 5 1/4 driver with at best typically 50-60Hz, Fs and you have Qts anywhere below .5, then the F3 is way up there in an infinite baffle setting.
Not good. My sub has an F3 in the 45-50Hz range, that leaves me with a "hole between 70-120Hz.

I'll have to dig out my SPL meter somewhere and burn some test tones.

Mikett 30th September 2004 06:26 PM

I did some checking and read someone's review of the infinity 6000Cs. Here he mentioned that the 2nd order crossover is best modified on component systems by reversing the phase of the tweeter if it is mounted far from the woofer, which it is.
Second, he also inidcated that the tweeter level needs to be reduced if it is mounted on the top of the doors. Again, mine are.

So I reduced the tweeter level by 4 dB with an Lpad consisting of a couple resistors and reversed the phase of the tweeter!

I chose 4dB because, I suspected that the system was probably voiced with cloth interiors and I have leather which is less absorptive.

Total transformation!!!! I'm very pleased with the sound now

BillFitzmaurice 1st October 2004 02:47 PM

2nd order crossovers result in a 90 degree phase shift of the signal to each driver and in most cases requires that the drivers be wired out of phase with each other to compensate for this.

As a doubling in distance from the source results in a 6dB reduction of SPL it's normal practice to pad the tweeter output when they are mounted high, which is where they should be for proper dispersion and imaging.

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