iPod replacement for vehicle use with DAC embedded - what do you recommend?

Aug 31, 2016 at 4:30 PM Thread Starter Post #1 of 5

sdaughtry

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My Dodge Challenger's stock stereo can control an iPod via a USB port embedded within the center arm rest (as do most newish vehicles). Even though I use a 5th gen iPod (which has a decent DAC, according to the Internet), the head unit / Harmon Kardon speaker set up can only do so much - the tweeters are pretty harsh and bass response is on/off. I believe a better quality DAC would help - I don't want to chunk the head unit/amp/17+ stock speakers.
 
That leaves me with 2 options:
 
1. A portable DAC that plugs in between the iPod and the USB input jack that would hopefully smooth out the highs and improve low-end clarity
2. A different portable music player that has a much improved DAC
 
This afternoon I looked at different iPod types of devices on the Internet - the problem with every single one of the manufacturer web sites is NONE of them talk about iPod control compatibility. Because I don't have to use an AUX port my steering wheel controls can skip tracks forward/backward and pause/play the iPod... and if these replacement devices have that functionality they become a non-starter from me. I am not going to open my center console while driving 80MPH to press a button on the box...
 
Surely others have gone down this route - what did you find that worked and improved the sound quality of the music being sent across the USB port?
 
Sep 1, 2016 at 12:42 AM Post #2 of 5
Quote:
Originally Posted by sdaughtry /img/forum/go_quote.gif
 
1. A portable DAC that plugs in between the iPod and the USB input jack that would hopefully smooth out the highs and improve low-end clarity
 

 
Actually the best way to deal with the tweeters is to install new ones, and more importantly, that they're angled with proper toe-in, which unlike in a home audio set-up you now have to account for the dispersion pattern and reflections off the windshield. Ditto with the sub. A fully custom system with a DSP that can split the frequencies into different analogue preamp channels feeding separate amplifier channels can give you a lot of control over relative gain as well.
 
Now since you don't want to do any of that, the DAC isn't a better solution for your problems either, unless you're somehow able to use a DAC with a frequency response that cancels out some of the issues in you cabin and the stock audio system, ie, a non-oversampling DAC which is very midrange-focused. The easiest solution really is to use EQ (something that even a fully custom system has to use to round out the system, because there are a lot of other considerations and compromises that would still be done despite all that work). Doesn't the iPod EQ work? If not, doesn't the stock receiver have one? Just cut on the bands at 3000hz and above to tame the tweeters, experiment on how much on each, short of using an RTA to take a measurement from where your head is (which is also something that is built into most aftermarket DSP units, and why people invest in custom systems).
 
At the same time fiddle with the balance controls. One of the main problems with tweeters in cars, apart from reflections on the windshield, is that you don't own a Maclaren F1. One tweeter and one midwoofer (if not also one midrange) are closer to you than the other speakers. With a custom DSP you get a lot of control, most especially on time alignment which allows you to delay the output on some of the drivers so the sound from all of them will arrive at your head at the same time, as well as the relative gain, with preamps on the DSP unit and gain controls on the amp. One thing however that basic receivers and DSP units have in common is a balance control. Bias the sound towards the passenger side so the relative loudness from the driver's side is reduced. At the same time bias the sound towards the front as the speakers all around you aren't representative of a 2.0ch set-up with a band on stage (ie sound isn't supposed to come out behind you; in a large concert the rear speakers face towards the rear, and you should ideally be closer to the stage than these if you're between them) so the sound doesn't come from freaking everywhere causing a lot more time alignment issues than you're already dealing with for not having a Maclaren F1 (which, if you could buy it, already has a BMW sound system in the back anyway).
 
Quote:
Originally Posted by sdaughtry /img/forum/go_quote.gif
That leaves me with 2 options:
 
1. A portable DAC that plugs in between the iPod and the USB input jack that would hopefully smooth out the highs and improve low-end clarity
2. A different portable music player that has a much improved DAC
 
This afternoon I looked at different iPod types of devices on the Internet - the problem with every single one of the manufacturer web sites is NONE of them talk about iPod control compatibility. Because I don't have to use an AUX port my steering wheel controls can skip tracks forward/backward and pause/play the iPod... and if these replacement devices have that functionality they become a non-starter from me. I am not going to open my center console while driving 80MPH to press a button on the box...
 
Surely others have gone down this route - what did you find that worked and improved the sound quality of the music being sent across the USB port?

 
One other problem - you lose system integration either way. You won't see your iPod's content on the receiver's screen where it's a lot safer to glance or look at from the corner of your eye and hit Next/Prev Track on.
 
One thing that people do in serious audio set-ups is use an integration DSP, which takes high level (ie speaker output) signal from the stock receiver or amp, runs it through an ADC, which allows it to apply the processing on its DSP. Still, even if you did add this, best case scenario is that your receiver has line level (RCA) output to go into the DSP unit, and then feed the amps from it, but then the whole point in this DSP unit is getting control on each amplifier channel, so you'd have to get amplifiers with the right total number of amp channels. And in serious car audio set-ups you'd need seven channels of amplification just for stereo - 2xtweeters, 2xmidrange, 2xmidwoofer, 1 subwoofer.
 
Basically, if you want to avoid all that work, you're really down to using whatever EQ and Balance/Fader controls are built into the receiver.
 
Sep 1, 2016 at 1:04 AM Post #3 of 5
The Challenger SRT has a 19 speaker configuration with a single amp - the head unit controls everything from stereo / backup camera / suspension + traction control settings and more.. yanking it out would be a nightmare. The speaker sizes in the dash and rear kick panels are a weird size (7x90mm), which makes it REALLY hard to find replacement speakers. More info on this configuration: http://www.harmankardon.com/content?ContentID=dodge-challenger

The stock stereo doesn't sound horrible - it does have very good imaging. I don't want to throw $4k into a new head unit/amp/19 speakers (if not more)... I've done enough custom stereo upgrades in the past 20+ years (and taken a beating when the car is traded in - some dealers don't even want a car with a custom stereo).

Seeing how a headphone amp + DAC made a phenomenal difference for my Desktop PC's Focal 2.1 speakers and Sennheiser HD600s I figured maybe doing something similar with my iPod in my car would help improve it's sound quality. The iPod setup is similar to most cars - plug in the standard USB cable into the bottom of the iPod, plug it into the USB port built into the car and control the iPod via the head unit/steering wheel controls.

The Dodge head unit has a pretty crummy 3 band EQ... and no separate subwoofer volume control or ability to alter crossover points.

I've read up on the Apogee One (http://www.apogeedigital.com/blog/blog-how-to/listen-audiophile-quality-music-car-apogee-one-ios-device), but if you plug into the head unit via the AUX port you lose the ability to navigate through the iPod via the head unit/steering wheel controls..... which creates a distracted driving scenario.
 
Sep 1, 2016 at 1:45 AM Post #4 of 5
  The Challenger SRT has a 19 speaker configuration with a single amp - the head unit controls everything from stereo / backup camera / suspension + traction control settings and more.. yanking it out would be a nightmare. The speaker sizes in the dash and rear kick panels are a weird size (7x90mm), which makes it REALLY hard to find replacement speakers. More info on this configuration: http://www.harmankardon.com/content?ContentID=dodge-challenger

The stock stereo doesn't sound horrible - it does have very good imaging. I don't want to throw $4k into a new head unit/amp/19 speakers (if not more)... I've done enough custom stereo upgrades in the past 20+ years (and taken a beating when the car is traded in - some dealers don't even want a car with a custom stereo).

Seeing how a headphone amp + DAC made a phenomenal difference for my Desktop PC's Focal 2.1 speakers and Sennheiser HD600s I figured maybe doing something similar with my iPod in my car would help improve it's sound quality. The iPod setup is similar to most cars - plug in the standard USB cable into the bottom of the iPod, plug it into the USB port built into the car and control the iPod via the head unit/steering wheel controls.

The Dodge head unit has a pretty crummy 3 band EQ... and no separate subwoofer volume control or ability to alter crossover points.

I've read up on the Apogee One (http://www.apogeedigital.com/blog/blog-how-to/listen-audiophile-quality-music-car-apogee-one-ios-device), but if you plug into the head unit via the AUX port you lose the ability to navigate through the iPod via the head unit/steering wheel controls..... which creates a distracted driving scenario.

 
Because your using a digital (USB) input into the car stereo, your stuck using whatever DAC feature is built into the car stereo.
The output from a DAC is analog, so it can not be feed the analog signal into a USB (digital) connection.
 
If the Car's audio amplifier is a separate unit, you might be able to replace it with several aftermarket amplifier units.
 
Sep 1, 2016 at 2:07 AM Post #5 of 5
Quote:
Originally Posted by sdaughtry /img/forum/go_quote.gif
The Challenger SRT has a 19 speaker configuration with a single amp - the head unit controls everything from stereo / backup camera / suspension + traction control settings and more.. yanking it out would be a nightmare. 
---
I don't want to throw $4k into a new head unit/amp/19 speakers (if not more)... I've done enough custom stereo upgrades in the past 20+ years (and taken a beating when the car is traded in - some dealers don't even want a car with a custom stereo).

 
You don't yank it out. I never mentioned yanking out the headunit, and you don't even need to yank out the amp. That's even if you do a custom sound system. That's why there are integration DSP units now. The key word there is integration. You don't yank out any of the active electronics in a car precisely because, in the mid-2000s, at minimum you had to deal with not having a DIN-sized slot for an aftermarket receiver, and that entire panel has entertainment, climate control, and even suspension systems controls on it. The idea behind an integration DSP is that instead of being fed a digital signal from a high end receiver - such as the flagship Pioneers that have a 1DIN receiver and a 1DIN DSP - you will just take the speaker amp output from the stock system, hook that up to the integration DSP, run the signal through an ADC, then its own DSP chip so it can do the processing, then back through its own DAC, and then through separate preamplifier channels. At minimum you will add amplifiers, but never have to yank out what the factory put in the car.
 
Quote:
Originally Posted by sdaughtry /img/forum/go_quote.gif
 
The stock stereo doesn't sound horrible - it does have very good imaging. The speaker sizes in the dash and rear kick panels are a weird size (7x90mm), which makes it REALLY hard to find replacement speakers. More info on this configuration: http://www.harmankardon.com/content?ContentID=dodge-challenger

 
There are adapters, like how the Mazda3 came with 5x7 speakers in the doors but we were mounting 6in and 6.5in midwoofers down there. That said, it's not always a straightswap - the orientation of the adapter and the speaker dimensions on either side can still affect mounting, which is why we spent a lot on custom installers. And again adding an integration DSP will just mean you will add amps, and if you're lucky, no need to yank out the speakers ether. Still, chances are, you'd need to - speakers need to be aimed at a certain toe-in angle. The DSP unit is really the best choice you have.
 
Still, that can sound like a daunting amount of work to you, but the whole point is I'm laying out one other option that would actually address your problem, rather than simply gambling on addressing one source of it, which is the speaker's response. Oh and the thing is if your stereo has iPod controls, the DAC in the iPod is likely not in use as the signal is passed to the receiver digitally, which then decodes it. So it doesn't matter what you read about what your iPod sounds like vs, say, an iMod or an Ibasso DX50, what you're hearing is your stereo. So if your stereo doesn't sound horrible (though I'm not sure how you separate that from the rest of the system) then it comes down to the tweeter's response, reflections, relative gain, and time alignment. Just hearing one tweeter later than the other, and earlier than the midwoofers, by microseconds can make for a very harsh sound.
 
Quote:
Originally Posted by sdaughtry /img/forum/go_quote.gif
Seeing how a headphone amp + DAC made a phenomenal difference for my Desktop PC's Focal 2.1 speakers and Sennheiser HD600s I figured maybe doing something similar with my iPod in my car would help improve it's sound quality. The iPod setup is similar to most cars - plug in the standard USB cable into the bottom of the iPod, plug it into the USB port built into the car and control the iPod via the head unit/steering wheel controls.

 
Here's the thing though - do you have reflections off your windshield at home? Do you listen with one of the Focal satellites 0.5m from you and the other satellite 1.0m from you? Do you listen to the headphone with one earcup pulled apart from your head? Because these are problems that are present in a car but not at home. That's why enthusiasts scrapped the "GIGO" principle for integration DSPs - it might not have started out with the perfect DAC circuit but now the DSP can apply the corrections to deal with the above problem (plus the proper installation), on top of which, Alpine's DSPs come with a reference CD that the DSP can use to check if the system sounds right based on their lab readings, applying more EQ correction parameters to level out the sound. The problem with that of course is that most people didn't like how, basically, their Grado-like car systems were basically turned into HD600s or K702s.
 
In any case, back to your car...how do you know the iPod DAC is the problem and the stock receiver isn't horrible when, apart from how hard it is to differentiate between parts you haven't used with other gear, your iPod is feeding the receiver a digital signal? Either the receiver has no problems, or that one is one of the problems. Even if it's the latter the realities of your car cabin is a bigger problem than the quality of the DAC. If it made a lot of difference in your home system it's not simply because your initial source sucked, but also because the listening environment isn't there to screw up whatever the speakers are spitting out that it got from whichever DAC. 
 
Quote:
Originally Posted by sdaughtry /img/forum/go_quote.gif

The Dodge head unit has a pretty crummy 3 band EQ... and no separate subwoofer volume control or ability to alter crossover points.

 
But i the 3-band EQ a parametric EQ? If it is, then you can switch what frequency, and maybe the Q factor as well.

If its' a "Low/Bass, Mid, High/Treble" kind of crummy EQ then just lower the treble as far as it goes and then just dial back a bit. Don't boost the sub too much, or at all, maybe even cut if necessary.
 
What about the other controls? If it has BAL control then bias the sound to the passenger side so the tweeter nearest you isn't relatively louder. If it has FAD(er) control bias all the sound to the front, forget the rear fill - that way you get less speakers that screw up time alignment and mid-treble producing speakers that the subwoofer has to overcome.
 
Quote:
Originally Posted by sdaughtry /img/forum/go_quote.gif

I've read up on the Apogee One (http://www.apogeedigital.com/blog/blog-how-to/listen-audiophile-quality-music-car-apogee-one-ios-device), but if you plug into the head unit via the AUX port you lose the ability to navigate through the iPod via the head unit/steering wheel controls..... which creates a distracted driving scenario.

 
Again, that's one of the reasons for integrated DSPs - you still see everything on the stock receiver's display. However they can only just polish up what installation can't fix (especially with practical considerations), not correct improper speaker mounts like putting the tweeters and midrange firing straight up from the dash and onto a highly reflective windshield that, for obvious reasons, cannot be covered by sound dampening materials.
 
In the end any DAC you use will still end up with that distracted driving scenario anyway. Even a DAC designed specifically for iPod use isn't going to integrate the tagging data nor archive browsing into the car's receiver.
 

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