thesteve

So I was sparked by Malibu955's recent posts on the subject and remembered I had a pair of highly acclaimed MB Quart QM19 tweeters from the early 90's laying around.
Turns out they're 2 ohms (which matches my Bose tweeters... 2003 CTT) so I tried replacing one of them (while I looked for the other one) to do a comparison.
Actually I first bought a pair of alleged Burmester tweeters out of a Mercedes S550 on eBay (2 for $25) but they turned out to measure 4 ohms so I decided not to use them.



I didn't want to wait anymore so I went ahead and replaced just the left tweeter. I lucked out and the MB Quarts fit perfectly in the Bose bracket. A little hot melt glue and it was a done deal.



I did find the correct Torx driver eventually. Also, despite my best efforts, I broke both of the tabs that hold this cover in place. I'm not ashamed. I'll put some double sided Velcro down there... it's fine.



I reused the capacitor from the Bose tweeter which is bipolar at least. I don't think the Porsche engineers and Bose would put in a garbage cap to save a few cents.



I had a good listen for a week or so with just the left front tweeter swapped. To my surprise, it sounded like the original Bose tweeter (right side) had more midrange coming from it somehow. At first I thought this was related to the crossover frequency and the tweeter impedance but I checked again and they are a good match.
Anyway, my next idea was to replace the midrange speakers with some Infinity KAPPA-20MX's. I found these by using the Crutchfield website and buying "last season's" equivalents of whatever they were peddling.
They are 2 ohms also.
I also just replaced the left side to do a comparison.
I'll give my 2 cent review at the end.. here are some pictures in the meantime.


The cheap tools I found on eBay were too thin so I used two of them sandwiched around a chisel to make easy work of the panel pop things.
I ordered two set of these tools from different sources and the second set I received later are a bit more beefy.



Not much new to see here.







The Infinities came with a nice mounting bracket that nearly matched the original speaker. I just had to move the holes out a bit.
I inherited this old hand drill that I think was as perfect for the job now as it was 30 years ago.




And that's pretty much it. I couldn't believe the speakers didn't come with any connectors and I didn't feel like looking for some I had so I just soldered the wires and crimped them up.




As far as the review, what I'll say is I don't think the Bose speakers are that bad. I think they might have some kind of peak, which makes them sound fuller or louder in some circumstances, but it is a coloration (not flat) that at other times makes them sound harsh. This is just a theory though. One day I'll get my hands on a proper spectrum analyzer.

I think if I replaced the other side and readjusted the EQ, the results would be a huge improvement.
But I'll say again that I'm not ready to bash the Bose.

One thing to mention though is I damaged my right ear as a young lad with an errant firecracker (only for very high frequencies). So I think the left MB Quart tweeter is winning me over on both sides of my head since I'm sitting in the driver's seat.
I really do love the detail from the MB Quart tweeter.
I do recall hating the sound of my Bose tweeters after Malibu got me to thinking about them... It's hard to tell what is personal bias and what is real and it's hard to do a direct comparison since most of my good music with high hats or cymbals is mixed to the right or left channel.
But to repeat, moving my whole head from the left side to the right while playing certain test songs, the Bose don't sound horrible.

This is equally true for the midranges. I just may leave the current setup in place. It may sound crazy, but the combination of the Bose on the right and my improvements to the left are an unexpected complement.
I mean. it's not exactly a studio environment... sitting way to the left right next to a glass windshield with speakers near your knees.

As far as the larger woofers, I have no plans on replacing them, as IMO they can't be improved on with the same factory amp.
They are tuned, sealed, bass speakers, and (in my case... not sure of other's options) they work excellently at their job.
I have received many compliments on the bass they produce while listening to bassy songs. And that from the front. In my experience I've never had bass from front door speakers.
One last comment on that... bass is low tech IMO as far as fidelity. It's either there or no. Since I have it, I'm not thinking of changing anything.

I'm only on my first week of test drives to work and so far I'm very happy. Its all very subjective, of course.

thesteve

Quick update.

I couldn't find the other MB Quart tweeter, so I went and ordered a pair of Infinity Kappa 753T's. 3-ohms and a good match to the KAPPA-20MX's I bought not long ago (mentioned above).
They sound great and are a perfect fit.










I trimmed the wires that were included because I got it in my head from Crutchfield descriptions that the wire gauge/length influenced the impedance, which I wanted to keep low.
Probably didn't make a difference, but I get free butt connectors from work so...

The included cap is a high quality 4.7 uF rated at 100V. Beyond overkill, but hey, who knows, I may upgrade the amp in the future. Better more than less.

I also finally swapped out the right-hand-side midrange. Before I did, I tried to take some comparative measurements.
I bought this calibrated USB mic from Dayton Audio and installed some freeware software that folks from Audiokarma.com turned me on to.



The software is called REW (room eq wizard).

The best results I got were in my living room, just comparing the Bose midrange and the Kappa. Actually the best info I got was from my ears in a direct comparison.
I used the pink noise test tone out of an old Denon receiver and just compared the two. The Kappa was so much better sounding. Total no-brainer. Much fuller and truer if that's an audio word. Also 10 dB louder surprisingly.

The scale is off on this... I had a better looking pair of graphs. Anyway, the Bose on the top shows weird peaks, especially between around 2 or 3 kHz.
The Infinity was just much better fidelity-wise.




I had high hopes of trying to use the software inside the Cayenne, but in all honesty there was a bit of a learning curve and even more patience required to get good results. I played around with things for a while, but daylight was fleeting so I took a few pictures, some worthless videos that I'll spare you from being bored by...
I never hooked up an extra pair of RCA cables to any inputs in the back of my stereo, but I found some work-arounds.
One was using CarPlay and a pink/white etc. noise generator app on my phone.
Then I realized I could connect to my laptop through Bluetooth which provided a direct feedback connection. There are other tests you can do through the software that require this. Pretty cool stuff.





I really liked the Microsoft lock screen du jour, so here is a pic of my new to me second laptop that I recently treated myself to.




I put in some ear plugs and filtered out the bass to try to compare the Bose to the Kappas before replacing the right-hand-side speakers.








The end results are, I love the Kappas. I had to tweak the EQ a lot more... I think there's a chance the amp is set up from the factory to play better to the characteristics of the Bose speakers... either way, now I find I can set the EQ and leave it there.
Before, what would sound good for one song would sound harsh for another. And volume was always an issue. I found myself turning the volume down a lot due to ear fatigue.
I think the sound is a lot cleaner now. And with the power rating I have from the Infinities, I'm only limited by ear safety and the amp.
I have lots more to say but I just wanted to put this out.

Oh, btw lots of bass as I eluded to previously. The factory lower doors do a great job of that. Midrange is from the midrange speakers.
My Carplay ended up on a Swedish House Mafia track as I pulled into my driveway. I noticed my neighbor pulled back her blind to see who the heck was disturbing the peace before I shut things down for the night.

Malibu955

I love seeing these kinds of experimentation with the audio systems in the cars. The entire Burmester swap was one big experiment for me too, and I'll most likely be continuing to tweak it more. I found that there was a huge difference once both sides were swapped out vs. just one.

I will say that swapping out to the Burmester midbass speakers in the doors yielded a noticeable improvement in detail for me. Not just volume of bass, but instrument detail. I would give some thought into replacing the Bose drivers with something else at some point if you're ever so inclined. On the other hand, if it sounds good, then run it.

I'm sure the Bose amp is set up for the characteristics of the Bose drivers, although not entirely sure how in-depth it goes. I'm not sure there is any crossover capacity built into it since the tweeters have a cap. On the other hand, I'm pretty sure the tweeters and midranges share a common wire back to the amp, so there may be some passive filtering going on in the amp from the midrange to the midbass speakers. I'd really like to get my hands on a 2018+ Burmester amp with the built-in active crossover, but I have yet to see one come up for sale (and the other Burmester amps I've seen on eBay are too expensive right now to buy one just to see if it will work. I also need to do some research into the MOST protocol to see if there are any standardization of commands).

Anyway, nicely done and thanks for the info about that Dayton mic. I'll have to look into that.

957austin

I always thought using a JBL MS-8 amplifier to replace the Bose amp would be a great choice because it has 8 channels and a Logic 7 DSP to recreate the surround sound similar to the original system. It does automatic equalization and time correction using an external microphone which is pretty cool.

Ob917

I love these car audio posts. Eventually I’ll pull all the Bose stuff out of my truck and replace it all with some quality audio gear.

thesteve

Yeah I held off posting anything until I figured out better what was going on. I was tempted to just declare victory since I paid some money and spent time on things... but I would have put the old Bose mids back in if they sounded better.
Well maybe not, but I mean I would admit failure and try again.
I actually listen to mostly classical music during the day (morning drive) and think the real ear candy is in the details of music and realism... accurate texture. I'd prefer my bass was farther away and less obtrusive actually. I dial it down so that it blends in.
Now that the front sounds better (and the level is slightly down actually overall from before I think) I can hear the rears slightly and I like it (since I have no fader). So now my attention is on the rear door speakers and next steps. It's kind of a bug.

I was looking at 6-1/2" speakers yesterday. It was a lot simpler to find the front Kappa mids since the choices were so limited, but I think there are a lot more variables at play with the bigger mids in the rear since the enclosure is part of the equation.
For those I might look into a Burmester upgrade, since the application is such a close match. But for the rear speakers, I would mainly want lower frequency presence I think.

Yeah the touch screen EQ is great but a bit frustrating to dial in. I don't have fat fingers but there just isn't enough of a fine adjustment possible with the virtual sliders. Some kind of DSP would be nice.
I did adjust the Q on the EQ lower and I think it helped. I did that over the summer though after a quick google search on my phone... I should revisit that.
That JBL device looks nice. It would be great to have that thing just get everything perfect and leave it that way.

phatz

put the phone down - drinking and driving dont mix ...needs an edit

thesteve

and seatbelts save lives - buckle up - wipers on lights on
we also would have accepted: vehicle registrations can be renewed online for extra credit

f266

I am really surprised by the Bose system. Still to this day it's the best sound in my fleet, including a new subaru with the Harman Kardon "upgrade".

thesteve

Yeah I haven't been behind the wheel much during this Twixmas week to continue my "experiments," but I agree that the Bose was/is a very good fit indeed.
Jury's still out actually if I've made an earth-shattering improvement at low volume levels. I had to with the tweeters at least... I've got my eyes on the stock amp now as the weak link.
After last night though, my ears need a rest. Still recovering. ha.

thesteve

To my surprise, my left rear woofer developed an intermittent voice coil scraping sound that was really annoying (obviously).
I was kinda happy, because it gave me an excuse to replace my factory rears. I had little motivation before this as I barely hear them the way my MOST adapter fades mostly to the front.

I found these:
https://www.jbl.com/JBL+GX608C.html
https://www.crutchfield.com/S-fNKwvJ...-GX608CAM.html
JBL GX608C

Got them on eBay brand new for around $75 (originally $199)
What makes them perfect, is they are 2-Ohms!
They also fit perfectly.







So here are the obligatory mid-install pics:





Looks like I had some water dripping down there...hmmm...



The kit came with a bunch of plastic mounting do-dads... this one above was the winner.



It almost wanted to snap right in place... No matter. A little hot melt glue did the trick.



I could have sworn I had bought some high-quality bi-polar filter caps, but I couldn't find them, so although it hurt a little inside, I stole the ones from the crossovers.
(I debated using the crossovers as-is, but I didn't see a clear place to put them... and I'm thinking the people at Bose must have done some thoughtful design stuff in the factory amp related to that.)





The 6.5" woofers fit in like a glove.
Only two of the four screws lined up, so I drilled little pilot holes and had no trouble using the original screws.
I used the self-adhesive foam gasket supplied and it was a super cozy fit. Perfect.



I'm very happy, they sound great! Although as mentioned, since my system is hard-faded at around 60/40 towards the front, I don't think there'll be a spectacular improvement.
I'll admit, I was pretty tired and just checked that they were working... I'll have a better listen during my commute tomorrow.

Steve

Edit: I just remembered (and confirmed on the schematic) that the rear woofers are just wired in parallel with the tweeters. Maybe I should have tried to use the JBL crossover. Hmmm.
I think it'll be ok though. Those doors are super hard to get off (and back on with those push clip things). I'm not goin back in there.

Edit #2: I drew up the schematic on the JBL crossover and it's all just for the tweeter; the woofer gets the full input signal. The inductor is in parallel with the tweeter.
I did some research and it looks like the parallel inductor and series cap form a simple 2nd order 12 dB high pass filter.
One of the resistors is in parallel with a thermistor and only comes into the picture if the thermistor heats up (serves to protect the tweeter).
The other one is an optional padding resistor that is bypassed by the pushbutton switch.
So I should be good. Although I'm debating whether I should have added the padding resistor (3 ohms). Still listening and making up my mind.

thesteve

If anyone's been waiting for my review, I'll just say I highly recommend this setup.
A nice surprise is that the previous condition (a product of my MOST fiber converter) where the fader seemed to be 60/40 to the front is magically gone. My guess is it's from the bright rear tweeters.
Now, while the sound stage is still in the front, it sounds like the fader is set to the middle.
If there are any Rush fans here, I played the first 5 seconds of YYZ and was in love. Incredible treble detail now. The rear tweeters really compliment the fronts perfectly. The sound is truly quadraphonic, like you don't know where the speakers are.
I'm listening to all of my old music with fresh ears. Even at low volumes, the sound is just incredible. The voice of instruments in classical music is just ear candy to me, and I retain the rich lows from the factory... I'll call them front subwoofers since they provide the real bottom end.

So this is the setup:

Infinity Kappa 753T tweeters,
Infinity KAPPA-20MX midranges,
and JBL GX608C for the rears.

These are "last year's models," so you can just as easily get the latest equivalents that are still in stock at retailers like Crutchfield, but I saved a lot of $.

If anyone wants to use the included crossover, remember you can wire the woofer as usual and just use the IN and TW OUT ahead of the tweeter.
I'm curious how it would sound with the crossover. I think it would sound better balanced for rear passengers, but I might lose the front to rear equalization effect I mentioned.