[jmciver]

A few more pics of the amp rack installed in the car. The thin black cable you see coiled up roughly in the center of pics is the USB interface cable that plugs into the amp.

Power, ground, remote turn on and the subwoofer RCA signal cable (not pictured) are run to the trunk under floor storage area.

[jmciver]

It's alive!! And tuned……!!

After taking care of a few more odds and ends for this project, I got the system buttoned up, powered up and DIY tuned this weekend. I was really surprised and pleased with the results.

After loading the starter tune from Audiotec (verifying key parameters like high and low pass filter settings, etc), I did what no professional does and listened to it with some test music because I was impatient . It actually did not sound that bad, and I even played around with some of the DSP sound effects a bit which made it better IMHO. But it didn't sound that great either (who am I kidding, it actually sounded like crap which became painfully obvious after I was done with the initial tune )…. My starting basic benchmark was the HK system in my X7 with Bavsound Stage 1 speaker upgrade. My X7 was also coded to add the B&W DSP sound profiles, both of which are an upgrade over the stock HK system IMO as well. As expected, the starter tune from Audiotec was way off my "benchmark".

After a ton of research and way too many hours watching YouTube over the past several weeks, I got on to the tuning. It was actually pretty straight forward. I probably spent 3hrs on it, including the setup. I used a RTA microphone, the UMIK-1 from MiniDSP, plugged into my iPad. On my iPad, I used an app called SoundTools which had a very simple RTA feature. I used the same app on my iPhone as a Pink Noise generator for the tuning. I plugged my iPhone into the car with a USB cable. I did not use a CarPlay or BT connection to minimize any possible sound degradation from wireless streaming during the tuning process.

After that, I connected my laptop to the car (with the Audiotec DSP tuning software), shut all doors, turned on the pink noise with volume at approx 75%, and started tuning. The RTA pic below shows the final curve I went after and was able to achieve. The front left, right, center, and underseat woofers were tuned to the house curve shape you see below. The rear door and rear deck speakers were tuned "flat" as they primarily support the sound stage fill. I was shocked by the results when I was done …

How "good" a system sounds will always be subjective. But the difference between the final tune and the starter tune was really night and day. I also installed the URC remote from Match, which allows you to switch between two tunes on the fly - which really allows you to hear the difference.

The tuning process and house curve I used was nothing new - I picked it up from my research. But it definitely works. I am far from a professional, and I am sure a pro could get it to sound even better. But I am very pleased with the results. Next step is to get the trunk sub installed for some more bass. The Audison underseat woofers actually sound very good, IMO, now that the system is tuned. But I bought them (over the Earthquakes) with the intention to add a trunk sub.

So I have s few more odds and ends to finish up (including adding the trunk sub), but I am very happy with this project so far ….

[jmciver]

So after a bit more tweaking of the tune (actually a lot more tweaking ), I think I have a better sounding system than my first tune attempt, even though I was surprising pleased with my initial results. I actually have it tuned so that when the factory EQ is completely flat, I have enough bass and treble to my liking (well almost, at least until I install the trunk sub). But using the factory bass/treble/EQ is really not necessary to me, and I generally prefer a bass heavy setup in my cars.

While not hard, there is definitely a learning curve to car audio tuning. After some more research, for my subsequent tuning sessions, I used an audio analysis tool called Room EQ Wizard (or REW for short). REW is a free, yet powerful tool used for all types of acoustical analysis and audio system/speaker tuning - of which I only scratched the surface when using it. I used REW on my laptop, along with the Audiotec tuning software, on my laptop. I used a signal generator app on my iPhone, connected to my car via USB, to play pink noise for my tuning. And of course, the UMIK-1 was the calibrated measuring microphone mounted to the headrest area in the car.

The attached pic is the final result of my tuning (a screenshot from REW). The blue curve is the target curve I was going after (also called a house curve). It is the Harman curve, which is a very popular (and proven) curve used in automobile audio tuning based on the general acoustic characteristics found in every car (as opposed to a room in a house or studio). The green curve is the actual frequency response, using pink noise, from all of the speakers in the car with the final tune complete (without any sound effects turned on). The four major “dips” you see on the curve are the result of frequency cancelations (mostly due to the acoustic environment inside the car), and the result of phase shifts with all the speakers playing together. It is possible to correct some of these issues using various methods, and after some research and a lot of trial and error, I was able to get rid of some others. But it is impossible to get rid of all of them (but I acknowledge that a more experienced tuner could probably still do better than I did - I am still an amateur after all ).

The second attachment is my tune file if anyone with a F30/F80 wants to give it a listen. Keep in mind that my tune file was tuned for a sedan so the time alignments (i.e. the distance from the speakers to the driver’s seat headrest) is based off of a sedan, so a coupe or any other car would be different. Also, my tune, specifically the crossovers, are based on the BimmerTech Alpha One speakers and the Audison APBMW S8-2 under seat woofers. So other brand speakers would have slightly different acoustic characteristics, especially the underseat woofers. But if you are starting from scratch with a UP10DSP in a F30/F80 sedan I would like to think this will sound better than the generic, non-EQ’ed tune on the Audiotech site, regardless of speaker brand installed in your car . Prior to uploading the tune file, just be sure to change the .pdf extension to .afpx first.

This has been a fun journey and I am still not done yet as I have to get/install my trunk sub and integrate it with my tune (although the bass with the Audison’s is better than expected). But there definitely is some satisfaction with listening to what I was able to accomplish - and actually liking it .

[Billfitz]

That's a good looking plot. When using REW or the like set the resolution/smoothing to 1/6 octave. That's the best that one can hear, so there's no point chasing every tiny bump or dip that doesn't show up on a 1/6 octave plot.
This is a 1/6 octave plot of my not quite but almost stock Hi-Fi system.



Were it not for the dips at 175 and 400Hz it would be reasonably close to yours. With the Hi-Fi system there's no way to correct those, and the meager 7 band EQ of the H-K system isn't much better. This is why every time someone asks how to improve their system I always say start with the amp. Audio is the same as computing, garbage in always results in garbage out, and advertising claims not withstanding no magic speaker will fix problems with the signal or the listening room. A good DSP can.

[jmciver]

Thanks! My graph is 1/12 smoothing. My first tuning attempt with REW I used 1/6 smoothing with decent results, but decided to try 1/12 smoothing after a bit more research (or to be technically correct, I took the measurement with no smoothing and 100+ averages, then applied 1/6 or 1/12 smoothing before EQ'ing the curve). But it is definitely easy to let the OCD kick in when trying to smooth out a frequency response .

This experience has definitly taught me that audio tuning is a bit of an art, even though it is founded in science. For example, after tuning the left and right front channels individually, both with pretty good curves and just a few unfixable dips, when I combined the two curves together, I had a huge cancelation dip at 200 Hz at -15 dB. The only way I could get rid of it in my final curve was to shift the LPF cutoff for the underseat woofers up to above 300 Hz (which the Audison's can handle). And the end result (surprisingly) sounded better, to my ears anyway….

The first plot below is my final curve (with house curve overlayed in blue) set at 1/6 smoothing. The second plot is the frequency response of my left underseat woofer, before and after EQ'ing (also in 1/6 smoothing).

[MEN54]

Originally Posted by jmciver

Thanks! My graph is 1/12 smoothing. My first tuning attempt with REW I used 1/6 smoothing with decent results, but decided to try 1/12 smoothing after a bit more research (or to be technically correct, I took the measurement with no smoothing and 100+ averages, then applied 1/6 or 1/12 smoothing before EQ'ing the curve). But it is definitely easy to let the OCD kick in when trying to smooth out a frequency response .

This experience has definitly taught me that audio tuning is a bit of an art, even though it is founded in science. For example, after tuning the left and right front channels individually, both with pretty good curves and just a few unfixable dips, when I combined the two curves together, I had a huge cancelation dip at 200 Hz at -15 dB. The only way I could get rid of it in my final curve was to shift the LPF cutoff for the underseat woofers up to above 300 Hz (which the Audison's can handle). And the end result (surprisingly) sounded better, to my ears anyway….

The first plot below is my final curve (with house curve overlayed in blue) set at 1/6 smoothing. The second plot is the frequency response of my left underseat woofer, before and after EQ'ing (also in 1/6 smoothing).

I have a question, I have 2017 BMW 330xi with Hi-Fi, I have upgraded Tweeters, Mids front and Rears and two under seat Subwoofers and also installed Match PP86DSP DSP Amp, I feel I need more bass, can I add Match PP 7S-D Compact trunk Subwoofer and not loosing existing underseat subwoofers?

[Billfitz]

You may, but I don't see a pair of 6.5 inch drivers being any better than the pair of 8 inch drivers under the seats. For that matter if you installed SWS Earthquakes they wouldn't even be as good, not by a long shot.

[MuchenTuchen]

Hello guys, sorry if I‘m hijacking this thread. I want to go into the speaker (mid and tweeter) itself again. I read several times, especially from Billfitz (really great and helpful input), that the hifi speakers are good, but need a little tweaking with a real crossover. I‘m not sure if I want the hassle of building my own crossovers. Is there any aftermarket speaker which can be recommended? When I would upgrade to the HK speakers, would I also need to build a custom crossover for better quality or is the existing crossover in the HK speakers already good?

[Billfitz]

There are none that I would recommend, especially as DIY is inexpensive and easy. HK speakers use the same inadequate 1st order high-pass filter with no low pass filter as the Hi-Fi.

[MuchenTuchen]

Hello Billfitz, thank you for your answer. So i guess there is no way around of creating my own crossovers :-). If I would get the HK speakers (Mids and tweeters) and add a DIY Crossover there, would they provide better performance than the Hifi ones? I can get these HK speakers really really cheap.

[Billfitz]

I don't have H-K speakers, so I haven't been able to measure them to confirm if they're better than Hi-Fi. If there's a difference they probably have a longer excursion, which allows higher output but only if there's sufficient power to make use of longer excursion drivers. A real crossover is a must. An 18dB/octave high pass filter on the tweeter is over ten times more effective in reducing unwanted midrange content in the tweeter than the stock 6dB/octave filter, greatly reducing high frequency distortion. At the same time the far lower ESR (equivalent series resistance) of poly caps versus the stock NPE cap gives better tweeter response. The lack of a good DSP is by far the #1 deficiency of the OEM audio. The lack of a good crossover between the mids and tweeters is #2.

[MuchenTuchen]

Hello Billfitz, thanks again for your reply. I highly appreciate your objective feedback. Then I guess I have to order the parts you recommended and get out my soldering Iron in the comming weeks :-).

[FastFrog]

Hi there, hijacking the highjack. @MuchenTuchen, if you happen to have read Billfitz's posts and electronic schemas, you'd probably found out that those crossovers are very easy to build.
The most difficult part -yet not such a big deal- is to fit them properly inside the door panels. (I'm about to do that myself, as I already received all the parts, including Y-shaped wires with blue connectors, allowing to achieve an OEM/clean integration with the existing stuff.)

[wildcat10]

Originally Posted by FastFrog

Hi there, hijacking the highjack. @MuchenTuchen, if you happen to have read Billfitz's posts and electronic schemas, you'd probably found out that those crossovers are very easy to build.
The most difficult part -yet not such a big deal- is to fit them properly inside the door panels. (I'm about to do that myself, as I already received all the parts, including Y-shaped wires with blue connectors, allowing to achieve an OEM/clean integration with the existing stuff.)

It would be great if you could take pictures of your crossover builds and installation and shared them with the group. Not sure I would trust myself with something like building/installing my own crossovers without more pictures and info

[FastFrog]

Yeah, I'll try to do that. Besides, I just received the central dashboard speakers + cover, rear tweeters and HK speakers covers I ordered an eternity ago, so I could do an entire post with all the setup (plus the Matchup I already installed)
But first things first, this Sunday is dedicated to my M-sport brakes retrofit!

[MuchenTuchen]

Yes, I also planned to do a documentation of this, to give something back to the community.
FastFrog : how do you stabilize and isolate the crossovers? Do you use some kind of shrink tube with a PCB board? I'm trying to figure out the best way, to not get a short circuit.
By the way, love the M-brakes, but they are so expensive

[FastFrog]

Well I first thought I would use a solid electronic mounting plate, but Billfitz said he simply used melting glue to stick the components together (not exactly sure how to call it in English, this glue you find in white sticks, that you push into a sort of "warming gun"). This ensures a soft / non-rigid setup, that I imagine less prone to vibrations against a panel or whatever.)
Then you secure the whole filter with a good old tape, and you fit it in a convenient place that doesn't interfere with the panel or anything. Challenge being that the capacitors are pretty bulky (search my previous messages on the forum, I've posted a picture of them, hold in hand)


(And yes, M-sport brakes and all the accessory hardware around are somewhat expensive. But although I have to admit I did it for the look first, it turns out I'll have a qualified use of them pretty soon, since I'll participate to a track day at the end of this month)

[MuchenTuchen]

Ok, yeah I read somewhere about the hot glue method. That's a good idea and should save some space. I'm also thinking about getting the Y cables with the „original" plugs. Where do you get them? I found some on ebay.

I would also do the M brake upgrade/retrofit for the looks, but more than 2000€ just for looks is too muche for me :-).

[FastFrog]

I bought mine on aliexpress, but they are probably similar to the ones you can find on ebay. Just pay attention to male/female setup, both options are sold.

[MuchenTuchen]

These would be the right Y-cables, correct?

[FastFrog]

Exactly.
I'm planning on cutting each "arm" of the Y in the middle and weld in one, the high pass, in the other, the low pass filter.

[MuchenTuchen]

Yes, I wanted to do it the same way. After soldering the crossovers to the Y-cables, you could reuse one of the cut plugs for the mid speaker and you would need the following plug for the tweeter. Although the tweeter cable needs to be cut anyway, because the old cap needs to be removed.