Hello,

I'm looking to build my first "pro" audio system for my car. By "pro audio" I mean I want to be able to tune individual channel EQs, filters, virtual crossovers, time/phase alignment, level etc manually.

For the head unit, I've built a custom setup that essentially uses an Android phone as the music player that outputs USB audio to a USB DAC, which then feeds into a preamp -> amp -> speakers. The Android phone is also hooked up to a hard drive (that has enough capacity for my lossless music library) as well as additional USB ports to connect flash drives for quick (music) file transfers.

In terms of speakers, I'm looking at coax mid-tweets on the dash (as a center channel) and doors (near the door handles) and two opposing 6.5" woofers under dash area (facing the doors); two 6x9s in the back; and a 10" dual coil sub in the trunk. These will form a matrix surround system.

Given my current setup, what can I use as a DSP, and where in the signal chain should it be?



P.S. This is my first venture into such a robust system, so I'm definitely open to suggestions/comments. However, please bear in mind that this isn't the run-of-the-mill aftermarket stereo system that simply has a global EQ and auto time alignment done. I'm looking to REALLY fine tune the system to perfection.

 

I hope our stereo guru comes in and takes ahold of your post's.He's got keen knowledge of this kind of work you want to put in.

Good Luck.

 

welcome to HAF.

there are several processors (DSP) you can use to tune your system. to narrow the list, answer these questions:

do you want manual control over settings or automatic tuning?
do you want a controller in the car or adjustment via. laptop?
do you want new or used?
what's your budget for a DSP?


i'll start by cautioning that lots of speakers don't always yield excellent results. sometimes you want to invest the same money in just a pair of great speakers. most "pro" systems are simple - one component set in the front, one sub.

what you'll need to add to your lineup are amplifiers. ideally, one amp channel per speaker so you can properly control them.

most processors are 6 channel output and a few are 8 channel.

one affordable option is the MiniDSP. it's $110 for a 2x4 model (2 input and 4 output). and you can add more to increase channel output quantity. they are separately configurable via laptop. the limitation is input voltage, 2V is more compatible with modern audio.
MiniDSP 2x4 | MiniDSP

the JBL MS-8 has auto tuning with a supplied headset. it has a built-in 8 channel amp, and 8 channel RCA outputs for external amps.
MS-8 | Car Audio DSP, Powered Digital Sound Processor | JBL US

Rockford Fosgate has their 3sixty.3 that is tuned via laptop. a concept that may work well for your setup.
Rockford Fosgate 3Sixty.3 Programmable 8-channel digital signal processor at Crutchfield.com

 

none of these are designed for true "surround sound" because you will hear the passenger side speakers as well as the driver side speakers. the miniDSP may let you tweak everything as you see fit, but there isn't DTS or Dolby Digital built-in.

think about it this way: sitting in the driver's seat you will hear both right channel speakers (center console for driver, passenger door) but you will hear them at different times because the delay for the passenger isn't the same.

even the dash speakers are heard by both occupants, but at different times.

all of these arrival times cause for a confusing sound stage with no precision.

one pair of speakers up front are able to recreate and entire sound stage across the dash with clearly defined left, center, right. and you can achieve depth as well. the result makes you think you have speakers in your dash - creating a realistic image.

to get a feel for this, take a pair of home speakers, set them equidistant from you, about 5-10 feet in front of you, and set them each at approximately 30 degrees separation from you, and toe them in so they align to a point behind you. you'll notice how those two speakers can recreate a deep and wide soundstage with a center image.


can you be happy with your plan? sure. you'll have sound coming from everywhere at multiple arrivals but a lot of people enjoy that about traditional car audio. the physical installation of the speaker and the amplification powering them are the most important aspects of the install. each speaker size requires different crossover points and youw ant to give them clean power.

 

Thanks for your insight into this. I'm going to read over this again and delve deeper into some of the things you talked about later.

As for now, I had two follow-ups pertaining to speaker selection and speaker placement.

I agree that the soundstage will be compromised based solely on my current speaker placement. That said, I'm not trying to make the entire car sound good; only the driver position (for starters at least). This is why I want to get a manually programmable DSP (given the computation requirements, I probably want to do the tuning on a laptop). To this end, the DSP will serve mainly to achieve the following:

1) establish coherence (by tuning time/phase alignment of individual speakers)
2) as a virtual crossover (individual feeds for each channel to the amp(s))
3) individual channel EQ for frequency response smoothing
4) tuning relative levels of each channel


Perhaps achieving a matrix surround might be a little outside of my tuning ability currently. I might just tune the rears as a separate 2.1 system and have them at low levels (relative to the front) just to fill in the space with sound (I'll be sure to tune the front and rear "systems" to be coherent).

As for speaker selection, what are your thoughts on the "ideal" speaker? I tend to lean toward minimal speaker correction, so I stick to flat-as-possible speakers and then correct for the environment. I only ever use global EQs for accommodating listener preferences but never as a means of correcting the frequency response.


Any thoughts?

 

thanks for the reply. i'll share a bit about what i'm using.
https://www.hondaaccordforum.com/for...q-build-58960/

the best speakers i've found are what i use now - Hertz Mille MLK-165. They run $1100 for a component set (older model). The new models are also very good. They are the most neutral speakers i've heard, basically reference monitors. There are some other nice speakers in that price range, but i'm most impressed with the Mille. They hardly need EQ, woofers have better-than-normal off-axis response due to cone shape, tweeters have rear chamber absorption and fs tuning, and they are very well made. Granted, i put a ton of effort into treating the door itself and turning it into a suitable enclosure - usually 20 hours per door.

I run them active, both the head unit and amplifier have crossovers flexible enough for active. my single amplifier has a pair of Class A channels for tweeters, higher power Class AB for woofers, and a mono Class D for the sub. Audison LRx5.1k sells for $1500. It's paired with a decent head unit and with the equipment and about 100 hours of install so far. I have a very good 2.1 system. I couldn't afford to buy multiple speakers and amplifiers of that quality. In my old Accord, i built several setups using more affordable options, and i experimented with many speaker locations. All of them could reach a very good point, but nothing compares to the current setup with excellent gear.

Without a fantastic enclosure and good power, even the best speakers won't amount to anything special.

you can hear it for yourself (good headphones needed):
https://onedrive.live.com/?cid=9be58...2AB35E1D9E!410
i took those recordings while driving 70 mph on the interstate, using a Zoom H2 recorder (320kbps .mp3). nothing like being there in person, but you can get an idea.


while i'm happy with the current setup, i am adding a processor. the Alpine PXA-H800 and RUX-C800 controller to an Alpine DVA-9861 head unit, giving me fiber optic between the head unit and processor. that will give me the level of tuning you describe, with full control from the driver's seat.

 

i buddy just bought a 1997 Accord Wagon - so also a 5th gen.

we will be putting Alpine Type-X Pro components in front and rear doors. front tweeters will be in factory locations, rear tweeters on the door near the handle. we'll have a pair of gigantic Alphasonic Mayhem 12's in a custom vented enclosure with 4kW for subs and a cosmetically matching 100x4 for speakers. that build will be starting very soon.

i recently tweaked a build that is all JL Audio in a 2011 Scion tC. JL Audio ZR comps up front in stock locations, C5 coax rear in stock locations, 13W7 in a JL box, and JL HD series amps. Sounded ok. I added the JBL MS-8 and ran the ZR comps active, the put the C5 on the MS-8 amp channels. DRAMATIC improvement. soundstage is well placed in height and depth and width. the MS-8 figured out the entire system in a minute.

 

KHA, thanks for your reply.

I really like your concept of having a simply 2.1 system with proper quality components in your '14 Sports Build. People seem to always throw in as many speakers (read: subs) to "improve" their system and it almost always ends up sounding like garbage.

Back to the main topic, I'm planning on having a pair of woofers under the dash (as you've read in my other post) specifically to avoid having to spend that much time on fixing up the doors. Mine is mostly an experimental build, so I'm trying to see how I might reduce the need for door treatment, seeing how this part of the process always takes up a lot of time and effort (of course, hacking up my dash will probably take up as much time, but it'll be fun).

The speakers I'll be toying with definitely aren't as high quality as yours, but that's also part of the experiment. I'd like to spend more money on the DSP portion of things just to be able to get more experience fine tuning the audio system digitally (I have experience tuning reference/listening rooms, so I'd like to try my hand at tuning less-than-ideal environments). Also, using as high quality speakers as yours is cost prohibitive. I'm trying to stay away from the MS-8 because I want to tune the system manually.

 

In your experience with various speaker setups, what comments do you have about my proposed configuration? Repeated here:

- Coax mid-tweets in the doors by the door handles (closer to the dash)
- Coax mid-tweet center channel on dash
- Dual 6.5" woofers under the dash
- pair of 6x9" on the rear deck (for "surround" effect)
- 10" dual coil sub in a far corner of the trunk


My goal for speaker configuration is to achieve a soundstage that is as wide as possible, preferably mirror to mirror. The accuracy of the stereo image as well as the phase and frequency response will be tuned with the DSP.

 

have you reviewed my efforts in my 2001 Accord?
2001 Accord EX Sedan - it's long

you'll see many variations with budget-friendly speakers and DSP with a variety of locations used.


your best location for speakers is the kicks. if you're going to fabricate something, the kicks are the best place to do it.

i've sat in cars that had no time alignment or DSP, just analog crossovers and analog EQ, with mids/tweet pair in the kicks and woofers in the door and it did two seats at once (both driver seat and passenger seat imaged perfect at the same time), perfectly placed sound stage in height, width, and depth. MECA champion car 2001-2005. he needed EQ to make it work but impressive.

i've found that tweeter placement greatly affects stage width.

a wide soundstage is difficult and requires very discrete signals into the ears. meaning that the right channel should be strongest in the right ear and arrive at the right ear first, with arrival in the left ear occurring at a later time that corresponds to the distance between your ears. that's how we localize sounds below 3kHz - ITD. above 3kHz we localize based on IID.

your center woofers will destroy stage width and pull sounds to the middle that should be on the sides. a center works with DSP running Dolby PLII or similar. You need a DSP that eliminates hard left and hard right information from the center woofer. your proposed layout will keep most of the soundstage inside the car, near the middle. but stuff that should be stage left or stage right will still come from the middle.