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Discussion Starter #1
This is for the 2018 Hatchback, but likely similar for all generation 3 models. Sorry in advance for the long post.

First some simple questions. I would appreciate informed first hand responses instead of the typical "I read somewhere..."

Question 1: What is the efficiency of the non-Bose woofers without any additional amp. xxdb at 1w/1m is the general reading, or if you personally made an A/B comparison, what was the results. Ie: I installed the Infinity model xxx and they were slightly quieter at equal volume than the stock. Also include for subjective impression of bass response. I will get to the reason further on. If you used a phone SPL meter or RTA to support your findings, please add them in.

Question 2: What is the TRUE RMS rating at 1% THD for the non-Bose stock HU? I have looked almost endlessly, and have found no facts. There are youtube videos of a guy testing actual amp power, but no stock units. As near as I can tell, 13 watts RMS at 1% THD, but only found opinions.


Now for my reasons and possible ways to create a very simple budget upgrade that yields excellent improvements:

Many have noted that aftermarket speakers improved the sound, but often had less bass. I have not heard comments on volume differences though. By knowing the true factory SPL rating, you will know in advance the volume improvement potential (if any). Obviously for those adding big amps, this is irrelevant, but this forum is for stock head unit only. Many of us just want to fix the major shortcomings without breaking the bank or turning this into an extreme project.

I ran some pink noise frequency response tests on the base unit, and the problem is clear: There is a 20db drop in the octave or so around 5kHz. 20db drop basically means you don't even hear that octave. To isolate the problem, I tested the woofer alone, and after 5kHz, it just goes wild up and down.

Solution A: This can be tamed with a simple 0.25mH-0.35mH coil connected to the woofer. Same bass, just no wonky. And you keep the higher efficiency and the hassle and cost of changing it. If someone can provide a wiring diagram (does it go first to the dash, then the door?), the coil can be installed in below the tweeter without ever taking a door panel off!

The tweeter tests makes the woofer seem like great quality. A 6db slope strait up to 10kHz and then back down the other side. A pyramid shape if you will. We have all heard of single note subs. Very common. Well, Mazda has a single note tweeter. It is absolutely useless and no hope for using this tweeter. Sad thing, Mazda has used this same garbage tweeter and mediocre woofer ever since the Mazda 3 came out. Our old 2006 was the same. Shame, shame.

Solution B: Perhaps the best fix is simply a 3.5" replacement mid/tweet with a 10uF cap to keep the impedance curve safe (although a have no FRD or ZMA files to test it in Xsim). Once I start the project, I will test if the tweeter polarity needs changing to be in proper phase with the two 6db slope crossovers.

Combine Solutions A and B are easy, inexpensive, and may yield the best bang for the buck.

Solution C: My last possible solution is to use the highest efficiency component system possible. Has anyone tried the Hertz K 170? They claim a 93.5db at 1w/1m efficiency. If this is true, then the 13watt at 4ohm non-Bose head unit powering the Hertz K 170 would have more sound output than the highly rated 88db Alpine S-S65C teamed with the Alpine KTP-445A Power Pack Amp that is rated 45watts. Remember that each 3db of output requires a doubling of amplification. Be careful on the SPL ratings. If it states 88db at 2.83volts, if it is a 4ohm speaker the power is really 85db at 1w/1m. And the Infinity REF-6530cx is rated at an impressive 93db, however it is at 2.83v at 3ohm, equal to approx 88-89db at 1w/1m. Not nearly what you expected.

Food for thought. Please chime in if you have fact based answers to my questions. Sorry again about the long post.
 

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2018 Mazda 3 GT called Coffee.
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Searching is fun for all!
CK
Here's what I had done.
CK
The installer at Al & Ed's was also able to keep all of the original controls working properly with the Audiocontrol processor. I can use all of the HUD and steering wheel controls, as before, and the Bose AudioPilot and CenterPoint still work too.

Here are the components that were used to replace the Bose speakers (except the center dash speaker).

-Focal Speakers 6 1/2" 2 way components flax series PS165FX - Dash and front doors.
-Focal Speakers 6 1/2" access 2 way components 165AS - Rear doors and back speakers.
-Alpine Amp 4x100W + 1x350W PDR Series PDR-V75 - Under the driver seat.
-Audiocontrol Loc 8 Ch W aux-in/dash control gray processor LC8I - Under the passenger seat.
-Stinger amp power kit 6000 4 GA w/ in line midi SK6241
-Stinger Interconnect 4000 2ch 6 ft
-Stinger Hush Mat
-Dyna-Mat all doors.
CK
 

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2018 Mazda 3 GT called Coffee.
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Loud? Yeah..it can get loud and keep full clarity with crazy bass output, detail and punch.
CK
 

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Discussion Starter #4
Nobody chimed in with any input, so I went the easy way with a component speaker (Alpine S-S65C). Here are my findings that might benefit others. I did so, for they were the best I could actually hear at the BB showroom. I was unable to run pink noise to know the shortcomings. The audio industry for the US market is cloaked in deception, disinformation and sizzle.

Although the Alpines sound reasonable, I should have trusted my own research. The Mid bass is good, Low bass is absent, major drop at 3-5kHz makes clarity lacking. Kind of a single note tweeter that peaks at 10kHz. Crossover is set at 2kHz 6db slope for the woofer and 7kHz 6db slope on the tweeter, is likely the main cause of poor clarity. Overall, they have a pleasant sound and better than stock.

Stock speakers produce lower bass. This is important to realize. If you want more bass, you need to add a sub or 8" drivers.

Stock speakers are louder at the same volume setting. I was originally misinformed that the stock speakers are not efficient. Having the known efficiency of 88db for the Alpines, runing various frequencies tests with an SPL meter, I confirm the stock speakers are 91db efficiency driven at 1w/1m. This is very important to use as a comparison for the 2.83v rating that would be 94db. In short, almost every aftermarket component (except for Hertz or high end European models) will not be as loud as the stock.

Stock speakers have a 20db drop from 3kHz - 5Khz destroying ALL clarity. Stock tweeter is an inefficient one note tweeter. Awful.

In hindsight, I should have went the 3.5inch coax replacements (many brands to choose from) in the dash and added a 12db crossover to the existing woofer at around 800hz. Crossover would be a 1mH induction coil in series with a 33uF cap across the leads. This can be easily done with the connector under the dash just behind the steering column. (Also this is a great place to add a simple amp too) I would also add the 33uF cap in series to the 3.5 speaker. Simple and effective.

I hope this info helps others. BTW, still no confirmation on wattage. The consensus appears to be 12watts RMS per channel at 4ohms at 1%THD, but nothing from anyone that actually used testing equipment.
 

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Discussion Starter #5
Possibly Best Non-Bose Upgrade

After adding the Alpines and an Amp to drive them (no major improvement to bass, subwoofer in the works) I arrived at the possibly the best bang for the buck upgrade:

1. Install high efficiency 3.5" dash coax, like Hertz. ($80)
2. Install door woofers that have low frequency ability (either 8" or 6.5"), like Dayton Audio DC160-4. ($50)
3. At the joint connector C-35 below the dash just over the steering column (where amp, dash and door speakers connect) have the stock amp drive only the efficient new dash speakers and use a small sub amp mounted near the connector (A6002 Infinity or JBL, both are the same) to drive the door speakers. ($100) Set the x-over for low pass and adjust the levels and 45Hz bass boost as desired.

Totally awesome clean sound with the existing system driving it. No amps or speakers under seats, just a clean stealth system.
 

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Discussion Starter #6
Added a Kenwood KSC-SW11 underseat subwoofer. Line level converter that comes with it does not provide enough signal when connected to the rear (no amp) when the front has an amp. The Kicker 46KiSLOC maxed out fixed this and the sub sounds great. Set to sub to 60% volume and 45 hz x-over helped fill in the lower bass absent from the Alpines. When ever you fix one thing, other issues become more apparent. Bass is much better, but voice clarity is not real good. Problem is the components and poor x-over design (like the Alpines), both the woofer and tweeter produce most of the vocal range at the same time, thus losing clarity. A completely redesigned x-over using a RTA and X-Sim to test ideas made a MAJOR difference. Hindsight, my post 5 is really the best way.

FYI, most component systems are really quite poor because of the lack of coherence between the two drivers and the resultant interference when woofer and tweeter are separated too far. The only fix is 12db woofer and 18db tweeter x-over to minimize the overlap.

System sounds much better than the Bose, has plenty of punch for normal or loud rock music listening (although not the bass of a "real" sub).
 
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