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Here's the tweeter mounted in the measurement rig from the previous post.
Here's the frequency response - not a great graph, I saved this at the wrong size, but you get the overall idea. Good response up to about 15 kHz, at which time there's some raggedness which also shows up a little in the waterfall plot as an energy storage thing. The way this tweeter is "aimed" from the sail, I don't think much of this above-15 kHz sound reaches the driver, except maybe as reflections from sound bouncing around in the cabin. This is not a bad tweeter, though I would say that since it has just a 4.7 uF capacitor as a series crossover from the signal driving the midrange, I am guessing that the output of this driver overlaps and adds to the output of the 3.5" midrange, adding to the sense to "too much treble" in this system. I think that with a 2nd order- or even 3rd order- high-pass crossover at about 5 kHz, this driver might make a decent tweeter to compliment the 3.5 inch midrange. But as I said in the previous post, that midrange has GOT to have a 5 kHz low-pass in series with it, it should NOT be used full range.
This is the plot of harmonic distortion. On the distortion plot, frequency response is the black line; blue line is total harmonic distortion, red line is 2nd harmonic, etc.
And here's the waterfall plot
This driver has an impedance of 4 ohms (NOT 2 ohms!!!) and 1 watt of drive at 7 kHz gave 98 dB SPL at 1 meter, so it's quite efficient.
Do you plan to do the rest of the drivers in a similar way? How awesome would it be if Bose FINALLY moved to drivers with flat response all around?
The lack of a crossover may explain that brightness. I think we still need to see what the signal to each driver is as well. As great as this is (thanks!) that may actually be more important.
Do you plan to do the rest of the drivers in a similar way? How awesome would it be if Bose FINALLY moved to drivers with flat response all around?
The lack of a crossover may explain that brightness. I think we still need to see what the signal to each driver is as well. As great as this is (thanks!) that may actually be more important.
Yes I think I need to measure the frequency response of the output of the amp channels. I've got to lash up some gear / software to do this with, I don't know of a way to use OmniMic with a voltage input. Probably there is a way to do it using an audio sweep generator from my phone into the head unit using bluetooth and then use one of the USB oscilloscopes I have; it might be hard to calibrate to read in dB, but I could at least graph the relative response and be able to see at what frequency EQ is being used, what frequency the crossover is set to, etc.
I don't know if I'm going to run curves on the woofer, I'd have to buy a used one, they're about $45. If you have one to send me I'll gladly run the tests..... :-)
I'll try to make this simple; I'm not here to bash Bose or Infiniti. I absolutely love my car; it's not perfect but I love it. My girlfriend thinks I'm crazy; she calls it my other girlfriend. But I have to say the stock system is a big disappointment. It's not bad, but for a so-called luxury car with a namebrand system it's only adequate. I've always replaced the stock system in my car's with aftermarket components; I love to listen to music in my car, it's where I listen to the vast majority of my music. And I don't listen to it extremely loud; do I listen to some songs loud? Of course, but they are few and far between as I've mellowed out in my older age (59). I was psyched to finally get a car with a good stock system as I'm tired of having to replace systems. But as previously mentioned it's a big disappointment. My last car was a 2011 Subaru Legacy with a stock system and the only addition was a small sub in the trunk and an amplifier feeding the entire system. And it blew the Bose system out of the water. I really miss it........ Anyway, infiniti needs to up the ante with their stock systems because this just ain't cutting it ��
Yes I think I need to measure the frequency response of the output of the amp channels. I've got to lash up some gear / software to do this with, I don't know of a way to use OmniMic with a voltage input. Probably there is a way to do it using an audio sweep generator from my phone into the head unit using bluetooth and then use one of the USB oscilloscopes I have; it might be hard to calibrate to read in dB, but I could at least graph the relative response and be able to see at what frequency EQ is being used, what frequency the crossover is set to, etc.
So after all the outstanding work you've done, what are your conclusions?
So after all the outstanding work you've done, what are your conclusions?
I had to order some gear so I could measure the output of the Bose amplifiers to see if any EQ is being applied. I'll post those results when I finish that work, probably about another week.
So far, my intermediate opinion is that there's too much upper midrange / treble, but I have not yet figured out if it's coming from the ringing 3.5" driver or if it's EQ'd in by the Bose electronics. There's also a lower mid / upper bass emphasis that makes radio announcers sound really "chesty." I think EQ can solve that, but I haven't gotten to doing any analysis on that frequency rage. I want to get the mid / treble range right first, then see what needs to be done in the upper bass. The screechy highs are the most glaring problem, that mid-bass emphasis isn't as annoying on most music.
By having too much 4~8 kHz energy the system sounds somewhat screechy and this make it sound like the system lacks midrange presence, punch and warmth. It doesn't sound bad on symphonic recordings, acoustic jazz or small classical ensembles, those recordings have a naturally laid-back treble level and the Bose system's emphasis doesn't 'damage' the music too much while making their treble content stand out a little in the noisy auto-cabin environment, which is kind of OK. (The Bose engineer who designed and voiced this system is a violinist) But listen to anything with a lot of content in this frequency range- like techno, most pop, EDM, trip-hop etc etc and the treble is overwhelming, screechy and out of scale with the midrange.
I am trying to come up with a "solution" to improve the sound quality that doesn't require all new amplifiers and drivers. I have bought two balanced input / output MiniDSP 2x4's so I can EQ Left, Right and Center signals from the head unit to the Bose amps, but I'm not going to install those before I have a better handle on exactly whats going on electronically and acoustically. I'm not sure they are the answer, or part of an answer, or quite what. If I don't use them in the car, I will find other uses- I like to build active 2-way speakers for home use so they could be used for that.
Another possible low-cost solution I have sketched out is to put a second order 4 KHz low-pass in series with the 3.5 midrange in the doors, parts for this are about $10, to keep from exciting that drivers' ringing behavior. Another idea, possibly in combination with these low pass filters would be to replace the Bose mylar-dome tweeters with Dayton 0.75" silk-dome tweeters with a 4 KHz high-pass. These tweeters are low in costs, small enough to fit in the sails (I think?? Have not tried it) and are better quality than those Bose Mylar jobs, allowing a slightly lower crossover point to the 3.5" mids. The stock 4.7 uF capacitor in series with the Bose tweeter is a first-order high-pass filter at 8400 Hz- the Dayton driver can be used down to 4 kHz, although the Dayton driver is about 7 dB less efficient and so may require EQ...work in progress... )
Anyway I will be posting more info once I measure the electronics.
I had to order some gear so I could measure the output of the Bose amplifiers to see if any EQ is being applied. I'll post those results when I finish that work, probably about another week.
So far, my intermediate opinion is that there's too much upper midrange / treble, but I have not yet figured out if it's coming from the ringing 3.5" driver or if it's EQ'd in by the Bose electronics.
By having too much 4~8 kHz energy the system sounds somewhat screechy and lacks midrange presence and warmth. It doesn't sound bad on symphonic recordings, acoustic jazz or small classical ensembles, those recordings have a naturally laid-back treble level and the Bose system's emphasis doesn't 'damage' the music too much while making their treble content stand out a little in the noisy auto-cabin environment, which is kind of OK. (The Bose engineer who designed and voiced this system is a violinist) But listen to anything with a lot of content in this frequency range- like techno, most pop, EDM, trip-hop etc etc and the treble is overwhelming, screechy and out of scale with the midrange.
I am trying to come up with a "solution" to improve the sound quality that doesn't require all new amplifiers and drivers. I have bought two balanced input / output MiniDSP 2x4's so I can EQ Left, Right and Center signals from the head unit to the Bose amps, but I'm not going to install those before I have a better handle on exactly whats going on electronically and acoustically. I'm not sure they are the answer, or part of an answer, or quite what. If I don't use them in the car, I will find other uses- I like to build active 2-way speakers for home use so they could be used for that.
Anyway I will be posting more info once I measure the electronics.
Firstly, when you say measure the output of the bose amps, if you're solely referring to wattage, I can provide you those #'s.
You say you want to find a solution that doesn't involve replacing drivers and and/or adding an amp. Coming from a seeming audiophile like yourself, I'm surprised. I could've sworn that the drivers at the minimum would've needed to be replaced.
For the sake of discussion, let's say there are three main components to a system. The drivers, the amp, and the eq/processor. Are you saying that for our system, of the three, fine tuning the eq settings by adding some sort of processor to the mix, will reap the largest benefits?
playing through the factory system (with an added powered sub) using a rooted Android phone with the Viper4Android app sounds amazing with the EQ tweaked.
could never get an iPhone to sound as good, no matter what preset EQ i used.
Firstly, when you say measure the output of the bose amps, if you're solely referring to wattage, I can provide you those #'s.
You say you want to find a solution that doesn't involve replacing drivers and and/or adding an amp. Coming from a seeming audiophile like yourself, I'm surprised. I could've sworn that the drivers at the minimum would've needed to be replaced.
For the sake of discussion, let's say there are three main components to a system. The drivers, the amp, and the eq/processor. Are you saying that for our system, of the three, fine tuning the eq settings by adding some sort of processor to the mix, will reap the largest benefits?
I think/hope he is measuring the frequency response of the output signal from the amps. If they are flat then that means we can replace drivers w/o consequence.
I think it's reasonable and even ideal to find a solution without replacing everything. I do really like the sound stage the stock system makes- changing drivers would probably ruin that. And a Mini DSP or two along with some crossovers is a lot cheaper and less of a hassle than completely starting from scratch- especially if you have to get a signal flattener on top of all new amps and drivers. Only big spend would be on a better sub setup but I have priced out a really nice 600W RMS Dayton 10" PR setup for less than $500 with wiring. Combine that with that Grom Android module and you will have a modern, powerful, good sounding system for <$1000.... that is really compelling, especially compared to spending double or even triple that to redo everything and possibly get a worse result.
Yes, what I am doing is first trying to understand exactly why the system sounds the way it does, and from there trying to find a way to make it sound more like the way I want it to sound.
When I come to the step of changing the sound, I have two criteria:
1. I don't want to disrupt the appearance of the interior. No new grilles, driver pods, etc.
2. I want to spend as little as possible on the changes.
By documenting all of this, anyone else who wants to take their G37 Bose system in another direction will have some solid data from which to re-engineer their system.
The gear I bought to make the measurements isn't just for measuring the system in the car- I do a lot of audio development and I needed a few additional tools anyway.
Yes, what I am doing is first trying to understand exactly why the system sounds the way it does, and from there trying to find a way to make it sound more like the way I want it to sound.
try Viper4Android if you can (need a rooted Android phone) - i was seriously considering tearing out the amps and speakers, and then realized it sounds pretty good when the EQ is fixed. pretty sure the Bose amp does weird things to the EQ.
on the factory system to me, the highs are grating but not crisp, and the lows are muddy (i play guitar, and i'm always chasing good tone). i would highly recommend adding a powered sub either way.
there are a ton of settings in the app, and i just played around until the sound was where i wanted it.
(these aren't my settings - just a pic of the app to show some of the features):
even the stock Music app on my Samsung S8 improves the sound a great deal with some tweaking ("Tube amp" on, EQ adjustments).
unless you want to shake the neighborhood with more power, you can actually get the factory system to sound good without dropping a ton of cash and having to replace all the components ...
05-28-2017, 04:08 AM
