And talking about subs, decades ago, and before all programs from the net that one could use nowadays....

the guideline used to be "you need size to move air"; thus, the bigger the better. Of course, that takes into account comparable excursion, magnets, etc. And let us not forget box design, size, ported, sealed, porting, diaphragm, etc.

I guess women were right: size does matter! LOL!

Nowadays, with different and exotic materials, super magnets, etc., I am totally lost.

 

Not sure about the sound quality of a subwoofer. Certainly bass frequency is a factor of surface area and excursion.

Sounds like riding a bike. You can go 25 mph in your biggest gear, pedaling a slow cadence. Or you can go 25 mph pedaling a medium gear at a higher cadence. Which is better?

You can reproduce 30 hz with an 18" woofer with very limited excursion. Or you can produce 30 hz with a 10" woofer with higher excursion. Mass will play a part as you need to move something much farther very quickly. More excursion will also generate more heat. Which is better? Not a simple factor of producing the frequency. Certainly there are design limitations - not sure you could engineer an 8" woofer with enough excursion to reproduce 20 hz, but perhaps 4 of them together could. Would that be better than one 18" woofer?

I will concede that running the 6.5's and the subwoofer was a decent combination, but running the 8's in the system is much better integration. With the 6.5's, way too much of the lower end of the music was coming from the sub.

 

The sound quality of a subwoofer can be predicted mostly by its frequency response down to 20Hz, the linearity of the response, and its ability to do so with low distortion. The ability to provide a flat response down to 20Hz (even with the cabin response added in) is limited in smaller woofers. As excursion increases with small woofers (to get the same output), so does the distortion. And the distortion (or mechanical/thermal) limited ability to provide a decent volume level at lower frequencies is also a problem = you can't play "low and loud." This is why surface area and linear excursion are important. It's also very basic stuff for subwoofer design. You also can't cheat physics. It's the law!

Yep. At some point, there is a compromise between the ability to provide low-frequency output and losing efficiency from moving a massive cone. Hint: It's not 6.5-8" for a subwoofer. It's bigger.

That depends. If the 8" drivers are in optimally designed enclosures, and they are operating at a volume well within their linear excursion, and they are tuned/equalized to produce a flat response down to 20Hz, maybe you could offset the lower total surface area. Not easy to do. It also depends on the performance of the 18" woofer in comparison. Consider the Velodyne DD-18 or the TC 18" woofer for home theater. Both provide world class bass and they get away with the large cone mass.

Important point: woofer distortion sounds terrible. And the further your voice coil drives itself away from its resting position, the less control there is over the cone. The result is increasing distortion until the sound is unbearable or you've reached the thermal or mechanical limits of the driver. This is why small drivers cannot produce clean, undistorted outputs at lower frequencies - because their cones are operating outside their linear excursion limits.

If you're happy with your system, that's all that matters.

 

No disagreements here. That Velodyne is an incredible sub. There are other Class A's that also deliver super performance with smaller drivers, but it is all about design, efficiency and cabinet design. I'm still amazed at the bass that can be generated these days with smaller drivers.

Anyway, I think 8's in the doors certainly improved the low end bass response of my system. What do you think would be a good budget solution to the Bose sub?

 

From all this discussion, all i can conclude is, after the speaker upgrade of our brothers here, the weak link will be the bose sub woofer at the back which are driven by 2 smallish 5. Somehting drivers! Seriously i had a system in my s class that i was trying to improve i changed the head unit and added a powered sub. I was still unsatisfied with sound...i simply disconnected the two so called subs at the rear deck and i had what i was looking for. Clear sound with bass! I think they were 2 6" drivers and it too was bose.

 

So, are you installed yet?

 

Hey brother, operation installation shall commence this weekend, i hope. Door clips arrived thursday so im good to go. Just need the time to do it. Time to get that jig saw out of the box.
One thing though that i am thinking. Too late but, this speaker upgrade will improve soind but i am now thinking i will not get what i want. Speakers are speakers and if the signal from the headunit is crappy, sound will still be carappy.
I think the basic whould be speakers and head unit.
The hur is too expensive and will get out of the reason for this post. Now if we can find a headunit that is simply a plug and play with the porsche wiring using the bose amps...then we have discovered the secret...
My initial results after the tweeter install was good but after a week its ho hummm. Generally sounding the same to my ears and still "cheap". The 8"s shoild really go in to balance the system now. Will surely report here after install.

 

Will need some encouragin words from our brothers here who have done the install again.

 

RyeM3,


Could you please post your current parts list with the new 8" door components? Thanks for all the work on this thread!


Chris

 

I realize at 22 pages the thread has taken on a life of its own!

Components are listed in detail on the first page. Since then, I've substituted IS200 8" woofers for the 6.5" woofers from the IS165s. I now have tweeters from those sets in the dash tweeter locations and the center channel in the dash. Using the Focal 100CVXs in the door and another pair in the rear panels. That's it. I've also stuffed the sub, but not sure that had much benefit.

The system is balanced and kicks butt!

 

Bro, just relax and do it! The tweeters are a modest benefit. Did you disconnect the center? If you didn't it drowns out the tweeters with crappy sound. Are you doing the midranges in the door too? If not, those midranges will also drown out the good sound. If you don't change them, you should at least disconnect them. Also, if you're not changing the rears, then you need to disconnect them too. They are more efficient and will fill your car with lousy sound after you add the others. It is important in any system to use matched components throughout.

You aren't finding a plug and play head unit. Porsche is way too limited a market. The interface to the Bose amp is fiber optic, no one uses that (that I know of). The MOST HUR adaptor is $600. Might as well throw out the amp too and save money.

What kind of signal do you plan to use? FM radio? That's not happening. A Dension or NAV TV for an iPod? Are your digital files uncompressed? If you run uncompressed music through one of these interfaces into your stock head unit, you will be amazed at the results. But, garbage in, garbage out.

 

There you brother. My encouraging words... Will be trying out this weekend, and yes i have the mid ranges too. The only speakers left behind will be the rear ones and the center one. I will try to disconnect the center one but i think its more difficult to remove the cover than the ones on the side. The center grille also has the sunlight senson for the ac so should be more critical. But free time will surely see me doing the install.

 

Has anyone who has performed this upgrade measured the performance of the original Bose drivers? I am really curious about sensitivity but would also like to know the basic T/S parameters.

Knowing sensitivity would help match a component system replacement driver.

 

Why would you want the T/S params of drivers that aren't performing well? The point is to NOT sound that bad, right?

It would be more helpful to know the amps' data - crossover freq and slope, output power and impedance/channel, etc. That would give you what you need to know to match sensitivities.

Knowing the effective volume of the "enclosures" might also be nice, but I really don't see a use for the data on the Bose drivers, other than as something to avoid....

 

Out of curiosity, has anyone done a RTA sweep or equivalent on the Bose system?

From what I hear when I listen, it sounds as if there are some HUGE presence peaks and a really big gap in the lower midrange/upper bass. Can anybody confirm?

Second thought - is it fixable with pre-EQ, or are the drivers incapable of a full-range response? Is it possible to use one of the "pre-EQ" systems that re-records your source material with EQ to inverse match your system response?

I've had the Bose now for only a week, and it's making me want to puke. Why on earth does Porsche put such an incredibly bad sound system into a car that's otherwise fantastic? My wife's Mini has a Harman-Kardon that sounds FAR better.....