I got the Alpine cda-9835 and had the challenge of figuring out how to adjust it. There are parametric eqs and digital crossovers to adjust. There is just too much to tune by ear for me. I didn't see anyone talk about how to adjust this thing other than 1) by ear or 2) pay someone else to do it. I didn't want to do either, so I got down to measuring my system and making informed adjustments.

I figure others may be interested, so I here is what I did.

System:
- one s2k
- one alpine cda-9835
- one pair Vifa D26NC55 tweeters
- one pair Peerless 850518 woofers
You can see some details of these speaker's install here
https://www.s2ki.com/forums/index.php?showt...Peerless+850518
- one alpine MSP-T220 subwoofer amp
- one super cheapo profile bs10 subwoofer in the passenger footwell
You can see a picture of the subwoofer install in Modifry's thread here.
https://www.s2ki.com/forums/index.ph...pic=139485&hl=
- One custom made microphone amp with panasonic microphone element
Here is a similar microphone amp:
http://www.gti.net/wallin/audio/preamp/preamp.html
- one copy of speaker workshop found here
http://www.speakerworkshop.com/
- One misc laptop
- one good external sound card found here
http://www.esi-pro.com/viewProduct.php?pid=10&page=1
- One alpine ainet auxillary adapter

Step one:
Get the axilliary input installed so I can inject the test signals from the sound card.

Step two:
Hook up a car battery charger so the 9835 doesn't drain the battery. It will do it in several hours otherwise.

Step three:
Mount the microphone. That was easy, I just stuffed the microphone amp between the driver headrest and the rollbar. I bent the microphone wire so it was about where my head is normally.



Step four:
Get a test response with speaker workshop. I must say I have a love - hate relationship with speaker workshop. It is quite non-intuitive to use, but it works and it is free. It compares very favorably with expensive spectrum analyzers I have compared it to.

Step five: identify what you want to change and change it. There are lots of things to change on the 9835, so that is not too hard. Speaker workshop will

Step six: go back to step four until you can't find anything you want to change that you can change.

Step seven: don't forget to save your eq and crossover settings to presets. I forgot and got to figure out what was I did all over again after I looked at another preset.

Here is a picture of the whole test set up.

 

One of the big reasons that I bought the 9835 was for the digital crossovers. I took my old passive crossovers out and wired the tweeters and woofers directly up the the head units. I used 24 db / oct crossovers as I couldn't see a bit of difference between 6, 12, 18, and 24 db / oct crossovers in speaker workshop. I couldn't really hear a big difference between those, so I went for 24 db / oct especially for the tweeter to keep out of band energy away from each speaker.

I could, however see some peaking at the crossover frequency. Seeing that, I put the tweeter / mid crossover at 2 khz, where there was already a drop in the response.

Here are some response plots for the flat eq, and the eq settings I settled on.


Passenger side. Before on left, after on right


Driver side. Before on left, after on right

All data measured from driver headrest mounted mic. 1/8 octave smoothing.

OK. So for all that data, is it perfect? Nope. In 5+ hours of testing, adjusting, testing, ... I only really got the mids and tweeters to the point where I thought that was all I could get out of it. I really need to deal with the sub / mid transition, still. The difference in audible sound quality between the before and after adjustments above is big. The difference makes it obvious that some things that are wrong with a speaker / system can be patched with an eq. Music sounds less like a car stereo and more like music. It is really striking how many more details I hear in the music than I have heard in a car before. The subwoofer peaking is audible with the right music. More work left there. I was using an Alpine head unit with time alignment before on these speakers, so the soundstage that was so amazing before is the same. Still very good.

I learned several things that I did not expect:
- While there are five bands of parametric adjustment, there are significant limitations including
-- equalizer bands are centered on 1/3 octave spacing -- not that flexible
-- very limited q adjustment in eq bands
-- two bands cannot be centered on adjacent bands. Seriously, wtf?
-- Each band can only be centered in part of the audio range.
-- I do enough digital filtering at work to know that this range of limitations if just stupid.

- I now need to consider the right amplitude vs left amplitude vs a mono sub. I didn't consider this before the measurements, but there is a good 4 db difference between the right and left channels due to different distances, etc., but there is a 0 db difference right vs left on a mono sub. AFAIK, threre is no adjustment for this in the head unit.
- It would be very nice to have separate eq and volume for every driver. Oh well.
-- The right and left responses just aren't identical, so separate adjustments would be *very* nice.
- This head unit has so much more capability than any other head unit I have used it is just silly. That it is so good just points out more intensely how much better the eq adjustment could be. I thought the crossover was pretty good.
- I have measured the stock speakers and saw +/- 20 db swings in response over a small frequency range, so these speakers do better than that.
- Don't forget earplugs when testing the system. Loud white noise can get pretty irritating after an hour
- This set up is not the equal to my home set up in measurement or listening, but it is closer than I would have guessed before I started.
- Overall, I am pretty happy with this project and think some more improvement can be had with another testing / adjustment day.
- It doesn't sound the same (it sounds much worse) with the windows and top up. I will have to post the data showing the delta. It isn't small. Luckily, the 9835 can use eq presets, so some day I will have to re-eq for the top up.

 

Sounds/looks very interesting... look like a lot of work though.

You do know with the 9835 you can go to the Alpine website plug in the distances' on Alpine's online program and it will setup a program that you can burn to a CD and you can just pop that into the HU and it will program itself right...??

Either way how did it sound and was it worth all that trouble to set up a mic setup?

 

You must have been typing at the same time as me...

 

I figure that the time alignment stuff could be automatic, but the eq on non standard speakers will be on a case by case basis. Not sure what value this is, but here are the settings I ended up with today. I really like to subtract, not add with an eq, but with limited eq adjustment, I had to max things out more than I would like.

eq:
+6db 100Hz, width 1
-3db 800Hz width 1.5
+6db 2kHz width 1.5
+6db 10kHz width 1

xover:
sub 63 Hz 0 db 24db/oct
mid 63 Hz -3db 24db / oct
mid 2 kHz -3db 24db / oct
tweet 2 kHz -9db 24db / oct

time alignment
2.8 tweet left 1.5 tweet right
2.2 mid left 0.9 mid right
0 sub left 0 sub right

I need to think about the sub alignment some more. 0 can't be right ... The mono sub with stereo inputs aspect has me scratching my head a bit.

 

I'm surprised at the timing alignments your using... I haven't set up the EQ or xover in mine yet but from having setup my last time correction adjustments those just seem a little high on the left hand side??...

Very cool though.
How much did it cost to set this test equipment setup, up? I would mind giving this a try and compare it to how I usually tune. Can you give me a cost breakout and were to get the products you used?
Thanks

 

The alignment on the left was a few tenths lower by the numbers, but the stereo image sounded like it came from left of the center of the steering wheel. I would play with the balance, but it just "smeared" the stereo image. Increasing the delay on the left got everything in line.

On equipment, it wasn't much.
- Sound card was a little over $200. While this sound card performs very well, I think any decent sound card would do the job. I did a loopback on my laptop's internal sound card, and it wouldn't do. So, you need something decent, but what I have is likely overboard. I have a ESI waveterminal 24. Just do a search on nextag.com for waveterminal.
- Laptop. It is convenient to use a laptop, but not really required. It just saves lugging a desktop to your car and eliminates possiblities of ground loops (I couldn't test with the ac adaptor plugged into my laptop -- it hummmmmed). No computer, let's say $700. You have to have a computer to be an admin , so let's say $0.
- Microphone. I would estimate $50. You could build the one in the link in the first post for that much, including shipping on parts. You can get everything from digikey or radio shack (except mic element). You need a decent mic and preamp. Maybe you already have a good mic. Make sure your preamp is good. My sound card has no mic input, so a preamp is mandatory for me. The page I linked to in te first post for the mic has a walkthrough to make this preamp out of pretty reasonable parts. If you don't feel up to making your own preamp, then loop at audio express for the mitey mike 2. The preamp and mic will run about ~$250. I'm sure there are cheaper alternatives, but people have good success with the mm2.
http://www.audioxpress.com/bksprods/kits/kd-4.htm
- Speaker Workshop - priceless. Doh! I meant free. Where? Link in first post.
- You need a way to inject the test signal into your system. The easiest way for me was an ainet accesory adapter ~$40, I think. If you are using all external amps, it is easier, just plug your sound card in.

I really recommend this setup. It is nice to never have to wonder how your system measures. There are all sorts of other ways to measure a system, some of which I have used, but this is by far the biggest bang for the buck I have run across. I use a stand alone spectrum analyzer at work, and to be honest, the only thing it does significantly better in the real world than this system is show measurements in real time.

 

Hey John, looks like we have a new project next weekend.

I'll warm up the soldering iron...

Jake

 

Yeah that's what i'm thinking too... I'd like to give this a try and see how close my tuning is..

 

Thanks Otter!