Do have trim tools but stilll managed to scratch things up. That palce is so cramped and that paint is so fragile. Now my concern is more to fix what i damaged. S...

 

I have now done some testing using an RTA with calibrated mic.
My prior graphs were with an uncalibrated mic and without activating 'Linear' mode (the non-linear mode has an ever more pronounced bass boost).

I am attaching the drivers position frequency response. As you will see, the response is not too bad from about 400Hz up. However, from about 200Hz downward, there is a tremendous bass boost. The boost is 6db for the 200-100Hz octave and 12+db from 100Hz down to 50Hz. Also, due to the bandpass enclosure, the sub runs out of gas below 40Hz; not much in the bottom octave.

I assume the increasing bass response from 200Hz down is to overcome road noise. My understanding is that it is very common to increase a car systems response by about 3db per octave as frequency decreases to overcome road noise. The Bose boost is way beyond this, but still not directionally atypical. I have not found any way to overcome this. I wonder if there is a way to apply a custom EQ curve in my iPhone for music. I will need to research this to tame the Bass a little. Getting the bottom octave is likely hopeless given the bandpass sub design.

Switching out of Linear mode boosts the bass even more. Not desirable IMHO.
Lowering the BASS setting impacts too much midbass. Only way to address is to eq the source a bit.

I have not tested the rear mid/tweeter I ordered in detail (to save me cannibalizing my 997), but some quick tests suggest it is very efficient (99db@2.83V) and very low in impedance (1-2ohms; need to test more). I know there has been good result on this forum with 90db@2.83V efficient replacement speakers, keeping the Bose amp, but this is hard to imagine on paper. I think the Bose amp likely has fairly low voltage rails and will not be able to drive a less efficient speaker to significant volume; also there should be a large imbalance with the subs (sums should be too low relative to the replacement drivers). HOWEVER, it is possible that the large bass boost built into the system is compensated for by the lower efficiency replacement speakers. Who would have guessed! Just a theory.

db

 

Dbbarron, thanks very much for your contributions here. This would explain why I constantly eq'd my bass down several notches with the stock Bose system. Doesnt quite clarify why I ran the treble higher though. One of my surprises with the new system is that I'm running the stock tone controls flat now on digital audio.

I also noted that the Bose speakers were more efficient even than the 90db Focals. However, the surprise was the power of the Bose amp. Plenty to drive these speakers. These tests also confirm that the bass is still a bit over bloated with the stock sub. I stuffed my sub, which helped some, but didn't fully solve the problem. I still think that substituting the sub's drivers with higher quality units will have good results.

Im still convinced that anyone else that does the conversion will be very satisfied with the improved sound. Especially considering the expense.

 

Suggest printing this on a 40-80 dB scale. Look how many regions there are with 10+ dB swings (400 Hz, for example). Even neglecting the subwoofer resonant peak, the response is TERRIBLE. Overlay with a decent system would show just how bad it really is......

What amazes me is that Bose has been so successful at convincing people that their over-priced garbage is an "upgrade". PT Barnum was right.

 

What amazes me is that Bose has been so successful at convincing people that their over-priced garbage is an "upgrade". PT Barnum was right.[/QUOTE]

Not just here, with just about everything they make!

 

I goofed. Lower efficiency drivers would exacerbate the sub output relative to the rest of the system. Would love to see an RTA of RYEM3's system (even a quick and inexpensive measurement using the iphone's mic and using Audio Tools, a $20 RTA app (no affiliation)). Stuffing the sub should lower its output a little, but I really can't see the integration working with replacement lower efficiency drivers - at least on paper.

I did find some EQ apps for the iphone, but these will only work if they play the songs from the phones library, so forget about iTunes Match or PCM controls. I will mess with these anyway.

As to the response smoothness - yes I did notice this and it concerned me. However, this is a single measurement at a single listening position and car acoustics are difficult. Not sure what expectations should be.

db

 

As I noted, bass still seems a bit over bloated even after stuffing the sub. I knew this would be a possible consequence as all the new drivers are now less efficient than the sub. Hence the potential for a new set of drivers in the sub to calm down the bloat and probably add more impact.

 

Another possibility would be to add some form of adjustment to the input of the bose sub amp. Alternatively, start with some judicious EQ of the ipod output - I will play with the various apps out there for this.

db

 

Yeah, what an ugly curve...and that was WITH smoothing. (but thanks for posting it, dbbaron).

 

If you'd like a more accurate response curve, take several measurements a few inches apart in the space that your head would normally occupy, then average them together. You'll be surprised by how much the measurement differs each time. I typically take 6-8.

 

Anybody else completed the conversion? Chris maybe?

 

If anyone's interested, someone on the Boxster forum posted a budget install for $2,000 (ebay prices, including new HU, amps, speakers, wiring, etc.
https://www.6speedonline.com/forums/...ml#post3558980

 

As predicted, life got too busy. I am sitting here looking at all the speakers still in their boxes. Hope to do my first door work this weekend, but probably won't mount anything until during my holiday break (taking a week off after Xmas).

 

Same here. I decided I wasn't happy with PCM long term so I'll be removing that.. and once you remove that and realize that a new amp is cheaper than the MOST-HUR... it's a slippery slope.

 

No question about that. You only question whether or not you want to keep the steering wheel controls.

The sound with the bose amp is impressive, believe it or not. Even though the focal speakers are slightly less efficient.

Sorry, I wouldn't consider a $2000 install a budget project. After that much money, the guy still installed all kinds of different drivers with questionable compatibility. In such a system you might be able to eq out the differences, but the voicing is still likely to be different.

Still looking forward to hearing other results. Maybe Rick is done...