Bose speakers replaced, impedance matched, my project explained

[madnorwegian]

After nearly nine years of driving around with one rear speaker out, I finally did a speaker replacement. A helpful soul here measured the 6x9s to 2.6 Ohm and the tweeters to 4 Ohm. Looking at the schematic it became logical to me that the 10-speaker Bose system has ~2.7 Ohm 6x9s, 2.7 Ohm rear door speakers, and since the midranges and tweeters are connected in parallel on their own channel, the midrange is also 4 Ohm. This was measured out correctly after dismantling the system.
I chose Infinity Primus PR6512is 2-way speakers for the back doors, they are 2.7 Ohm impedance and these channels are supposedly full range. In fact, I think they have a high pass around 120 Hz as there isn’t much bass. I used speaker adapter rings sold for the Q50 rear doors, M37 wasn’t listed, but they were the right ones. For wiring I used a pair of Metra 72-7401. Polarity is correct with these. Used the included adhesive foam to mount speakers to adapters, then used a 3mm thick, 10mm wide speaker mounting foam on the adapters before mounting on the doors with the factory fasteners. This upgrade alone turned out to be brilliant.
For the front door 6x9s, I chose Infinity Primus PR9610cs components (2.7 Ohm) and I only used the woofers from the set. Again, the included foam up against the original plastic fittings, the drivers fit with some finangeling, take the adaptors out of the car to make it fit. Had to adjust the mounting holes in the drivers a little, just opened up the holes and mounted to the factory adaptors with the original fasteners - made it fit with a little force. Then 10mm wide foam on the back of these before mounting back in the doors. The wiring adaptor is not the same as the back. I used HSTECH PC2-28. I had to reverse the leads in these to get the correct polarity.
For the mids, I chose Kenwood Excelon KFC-X2C, they are supplied with bass blockers at 800 Hz and they are 4 Ohm. Terminated them to wiring harness by Red Wolf for QX60 and altima tweeters. Worked like a charm and polarity is correct. I used the two screws that mount the original tweeter to the plastic with a couple of new holes, very little plastic to work with, but got them mounted right in the factory locations.
For tweeters, I used Hertz DT 24.3, they are supplied with bass blockers at 3.5 kHz. I cut the plastic grill material in the original holes and press fit the tweeters into the holes from the back, then let a little super glue seep in to the fit from the back. Mounted the bass blockers with included double-stick tape directly underneath the tweeter connectors and reused the plugs from the old tweeters. Positive is the tweeter lead with a stripe.
So how does the Bose amp with the factory subwoofer sound with this modification? Unbelievable. Higher sound level and lots of front door bass. I turned the treble down one or two steps and bass at zero and this is bliss.
The Kenwoods have plenty of highs, if I were to do it over, I would have left the factory Bose tweeters in their place and saved $50. The Kenwoods are flat from 800 Hz to 20k Hz. The whole job took me two days, I worked pretty slow and used the shop manual for every step in removing the door panels, didn’t break a single little plastic piece. I can play to max volume now without any sign of speaker breakup, although sometimes I get a buzz from the subwoofer area. Next project is to tighten up the baffle between cabin and trunk and find what’s buzzing back there.

[Ilya]

Nice!

[madnorwegian]

So I have proven that the Bose amplifier is indeed adequate, more than adequate for me anyway, just have to match impedance. I can play louder now than what I can physically tolerate. I kept the center and the sub, and I think I can improve the sub enough to make it awesome. Not bad for a $310 budget.

[Q70sGuy]

I was hoping to find someone else who did something like this as I’ve been exploring it myself. I find the Bose 3inch speakers to be absolutely terrible and the 6x9s as well.

Are you saying the tweeters at the top of the door are good enough?

Please do the sub and update us, it’s one of the weakest parts of the system but I’m worried the Bose amp doesn’t have enough output to properly power an aftermarket sub and I’m not that knowledgeable in all that.

[madnorwegian]

I guess I was like you and waited years to see if anyone would try this. I am an engineers, so I finally used my masters degree for something good This is all about impedance matching.
The rear door speaker upgrade alone was worth the effort. Then when I moved to the front doors, the 6x9s really came alive, and the little Kenwood 2.5" midranges are insanely good. Yes, if I did this again I would try to leave the original tweeters alone. I don't think I've heard them break up, and the Kenwoods are mid-tweeters and dominate the whole frequency range from 800 Hz and up to 20k Hz.
Might have to let my sub rattle through winter, it's getting cold here in WI. I'll report on it once I get it done. There was another post in this forum where someone had performed this baffle improvement if you can find it. As for the Bose amp driving an aftermarket sub, I will say I believe that's impossible unless you can find one with impedance of 1 Ohm or below. Too bad nobody makes a replacement for these, I think there would be a pretty big market for a 1 Ohm shallow free air subwoofer. The Infinity 6x9s in my doors really improved the bass though. I run Bass at zero, treble at minus one and that sounds fantastic.

[Q70sGuy]

That’s what I was worried about regarding the sub, they all have a minimum wattage need and I doubt the stock amp has at for any of them…

However the bass volume felt ok for me, I just find it’s quite weak with really low frequencies and muddy at really high volume. Does your 6x9 improve that range too?

I have a spare set of four way 6x9 kenwoods but I believe they are 4ohm so don’t think they would work. Sad because they are the clearest sounding speaker I ever heard.

[madnorwegian]

One option is to use the Bose amp sub signal to a high level input on a 1 channel amp, then you could use any sub that handles infinite baffle in the factory spot as long as it's shallow enough - or go with a box in the trunk.
My 6x9s really improved the bass, they seem to hit down to about 40 Hz. Your 4 Ohm speakers won't work, the amp just won't drive them, you'll have very little sound coming out of them. The 2.7 Ohm Infinity components I have go for about $85-95 on eBay with shipping, I think it's 1 or 2 generations old. The 6.5s in the back go for $50-55 with shipping, same thing, older generation. Most people don't know that as speakers go to a new generation, they generally lose quality, they become cheaper to manufacture. The Kenwoods came from Amazon for $59. Find them on eBay, put them on your wish list, then wait a few days. Most sellers will send offers of 10-15% off now and then. There are also other 6.5 and 6x9 2 Ohm speakers out there if you search. The mids and tweeters are 4 Ohm though, and you'll be hard pressed to mount anything larger than 3" where the mids sit, the factory Bose ones sit up against the steel on the door and there's factory foam there to keep them from making noise against the steel.

[Q70sGuy]

Thanks for the info ! I was trying to find the pr9610cs and I just wondered why it says the impedance is 2.7 but it also claims « true 4 ohm architecture » https://th.infinityspeakers.com/PR9610CS_.html

Unfortunately in Canada they’re pretty expensive even though they’re cheap on eBay the shipping doubles the price. Regardless I was curious why they say it’s 4 ohm and 2.7 ohm

[madnorwegian]

The 2.7 Ohm being "true 4 Ohm architecture" I think is just marketing talk. They claim that factory speaker wires are so thin that it adds up to 4 Ohm total. I don't know about that, and it means nothing because what's important is to match the impedance of the speaker itself, the rest of the system remains the same. The speakers are indeed 2.7 Ohm, and measured R across woofers came to 2.6 Ohm, same as the Bose 6x9s.

[Q70sGuy]

Thanks for explaining, confused the hell out of me lol.

[HeyJoeQ70]

Absolutely brilliant work! I was hoping to do something like this with my 2017 Q70. It looks like the part numbers for the amp and the speakers are all different starting around 2014. I wonder if the amplifier power ratings and the ohm loads for the speakers actually changed, though. On the 6x9's in the doors, did you wire in the crossovers for the woofer or are you driving them direct?

[DoN_BLaZe34]

This is great work and info, thanks for sharing!

I do wonder if these would work on the 16 speaker system as well.

[madnorwegian]

@HeyJoeQ70 That's a difficult question with the new part numbers, but I don't see any logic in changing the wattage and impedance just because the name of the car changed from M37 to Q70. For the 6x9s, there were no crossovers mounted by the speakers. It's possible that there's a low pass in the amp, but they sound just great even at the highest of volumes.
@DoN_BLaZe34 I fully expect this to work with the 16 speaker system, pretty sure it's the same speakers, just more of them. I would double check by looking at eBay auctions for the two different speaker sets. Pretty sure you'll find they are the same 6x9s and 6.5s and 3" mids.

[DoN_BLaZe34]

Thanks. Do you have the foam and Q50 adapters you used?

[madnorwegian]

The adapters and foam I ordered from Amazon, adaptors sell by the pair, you need them. You can basically follow the shopping list in my first post, and as I recommended, keep the tweeters.

[DoN_BLaZe34]

I thought I saw part numbers for the speakers, tweeters, and wiring harnesses. Don't think I saw one for the speaker adapters and the additional foam. Perhaps I missed it

[madnorwegian]

You're right, here are links to the adapters and the foam I used:
https://www.amazon.com/dp/B0814NYLPB?re ... asin_title
https://www.amazon.com/dp/B0C2KHHDXV?re ... title&th=1

[DoN_BLaZe34]

Thank you!!! I forgot to ask about the Red Wolf tweeter harness but I think I figured that one out lol.

[Q70sGuy]

So I found the infinity’s on eBay after all at a decent enough price now looking at the mids. My understanding is that it’s a 3inch but you went with a 2.75?
Would you have replaced the in-dash speaker too by the way? I believe it’s the same as the 3 inch in the doors.

[madnorwegian]

I didn't replace the center speaker. It is about a 3" speaker, but it's not the same as the door midranges. The door midranges are 4 Ohm as they are running in parallel with the 4 Ohm tweeters. I would guess the center is a 2.6 Ohm or so, but I left it alone, it sees so little use anyway the way I listen. The Kenwood excelon midrange tweeters are awesome. Not much else will fit in those spots.

[madnorwegian]

These are the wire harnesses I purchased:
For the 6x9s
https://www.amazon.com/dp/B08R3PY3KX?re ... asin_title
For the 6.5s in the rear doors
https://www.amazon.com/dp/B01N03JC9O?re ... asin_title
For the midranges
https://www.amazon.com/dp/B08VJ7NZYY?re ... asin_title
And these are the Kenwood midrange tweeters
https://www.amazon.com/dp/B07XYCDWZV?re ... asin_title

[Q70sGuy]

Nice thanks.
FYI if anyone wants to make their own “harness” you can find the parts on AliExpress for really cheap.

If someone has the speakers out can you double check that the MALE terminals are the right ones? . I used the info from the service manual to determine the right connectors but please double check before ordering anything.

Also be aware that you need the connector and the terminals as I think they come separately.

I see the premade are also not that expensive but in Canada they’re double the price so Im hoping to get the AliExpress parts and just make my own

[madnorwegian]

I have notes on polarity in my initial write-up for all the connectors, important to make sure to reverse the leads in the connector for the 6x9s if you use the ones I pointed out.

[DoN_BLaZe34]

You mentioned your music settings previously. Have you ever cranked the bass settings any higher? I'm curious how the setup works with increased bass levels

[madnorwegian]

I have of course tested more bass, even with the fader full forward and full back. Not a whole lot of bass from the rear speakers, suspect there's a high pass in the amplifier. Lots of newfound bass in the front setup though, and turning up the bass I still get a lot of it up front, the subwoofer gets less work. Still, I have found my sweet spot to be bass zero, treble minus 1 with the new setup.

[Ilya]

Don, when you do this make sure you list the parts for the 16 speaker system. I want to do this eventually too .

[DoN_BLaZe34]

Ilya, I'm only planning on changing the same speakers that madnorwegian did. The additional speakers included in the 16 speaker setup are the speakers in the seats and then two additional speakers in the rear deck. I don't think those are worth messing with.

You're in NC, I'm in SC. You're more than welcome to come help me do this install

[Ilya]

Ilya, I'm only planning on changing the same speakers that madnorwegian did. The additional speakers included in the 16 speaker setup are the speakers in the seats and then two additional speakers in the rear deck. I don't think those are worth messing with.

You're in NC, I'm in SC. You're more than welcome to come help me do this install

Ahh! And didn't know you moved from NJ hah. Feels like so long ago we were changing the shield in the parking lot hah.

[DoN_BLaZe34]

Made the move 2 years ago. Hahaha yeah fun times in the parking lot for sure!

[Dbarry]

Ilya, I'm only planning on changing the same speakers that madnorwegian did. The additional speakers included in the 16 speaker setup are the speakers in the seats and then two additional speakers in the rear deck. I don't think those are worth messing with.

You're in NC, I'm in SC. You're more than welcome to come help me do this install

Sounds like a good plan!