Bit Ten and MM6501s

pentoncm

Just picked up the car last night from the installer. They made custom door pods for my Polk MM6501s and set up the Audison Bit Ten. The pods have the tweeter mounted right below the woofer aimed up and to the opposing window just before the headrest.

Observations
1. The system just set up with the active network was a huge improvement over the db set up. Highs were much clearer and mid bass was a big step up as well.
2. Setting up TA was very easy. I will need to fine tune here in the future.
3. Installer commented that the signal coming out of the Bit Ten looked identical as it was going into the Bit Ten; it is an extremely clean processor.
4. I was up till 3 last night starting to tweak the 31 band equalizer. Basically set up a L/R combined eq to get the tonality in the ballpark. Then I went L/R independent cutting more midbass on the driver side and cutting more tweeter frequencies and upper mids on the passenger side. I'm just getting started here though.

pentoncm

Any comments on whether to use butterworth or linkwitz-riley crossover setup? The bit ten has a visual display and the difference is that if you set a crossover at 60Hz for instance, butterworth starts cutting at 60Hz, L-R cuts before 60 hz.

arun1963

For now now I'd just choose one and focus on the other areas. You can come back to it after you've set up the rest of the sound and then see which does better.

If you had the setup installed, I would go in and check all the basic settings like xover points for each driver, slopes, TA settings etc just to make sure that the guy who installed it got the basics right.

On the eq you've got the right idea. Maybe get an spl meter and do the pink noise test one driver at a time. You'll get to know which frequency is hotter from which side and by how much. See whats happening an octave above and below the xover point one driver at a time and then with both playing.

Get a good reference sound and try to identify what needs to be corrected in your sound. Get ready for a few thousand hours of seat time to get it really dialed in . You'll have a lot of fun, if you really get into this stuff. You have all the tools.

pentoncm

They setup all the levels, for the input into the Bit Ten, it is really picky, and they O scoped both of my amps. I actually was in the car with the installer to set up the actual output levels of each channel, crossovers, and we measured speaker distances together. So the Bit Ten has you measure each speaker and you select which seat you are in. It automatically does the math and shows you that the sub is set at 0ms delay, the driver seat with most ( i think its currently in the 2.25ms range) and passenger (in 1.6 ms range). I have yet to fine tune the TA settings; you enter to the closest inch and then you can fine tune by .02ms after that.

I'm going to use my wife's droid audiotool app to run RTA on some pink noise. Pink noise is included on the install disk. Audiotool was reviewed by sound and vision mag and it was the best one they had come across. The sensitivity of the mic on the droid falls off dramatically after 8 kHz or so though. But I have heard of people buying nicer mic's and plugging them into the droid to help out with accuracy. It does go to 1/6 octave resolution which is a plus. The JL RTA app sucks in comparison.

I will post a pic later today of the custom door pods for the MM6051's, by the way when i HPF them at 35Hz they sound sub like, definitely an impressive speaker for $200. I can post a pic of the Bit Ten computer interface also.

pentoncm

To update about the difference between butterworth and L-R filter types.
Butterworth is -3db at the crossover point, L-R is -6db at the crossover point.

I called polk and they recommend using L-R filters at 24db/octave because it theoretically gives you a flat response at the crossover point.

I have my system set up so that the mids and highs are crossed 24db/octave at 60 Hz and 3000 Hz with L-R. I tried the sub at L-R -24db/octave but it didn't seem to blend well with the mids. So I now have the sub on a -24db butterworth filter and it seems to be the right combination.

pentoncm

Just so everyone knows a little more detail about the Bit Ten.

The Bit Ten is $400, the DRC (remote control) is optional and costs $200. I would highly recommend it. Although the remote doesn't let you tune, it lets you switch between two presets, adjust balance, fader, and sub level. The balance is nice so that you can balance it to one side and then the other while driving to compare how each sounds respective to the other. The fader is useful because I use it as tweeter level control. Without these I think tuning would take a lot longer. Without the remote you would have to use an amp remote knob for sub level. I like having all of the gains on everything optimized and then control everything digitally. Also, between songs the processor is dead quiet so I am glad I went this route.