SR6500s not playing as they used to.

tk421

hi, my sr's are 2 yrs old or more. i did a rest on my system (alpine 9887 with imprint, alpine PDX400 amps, active. tweet on one pr of channels, mids on the other, 2nd amp runs subwoofer)

the mids are muddy, not the nice clean midbass nor mids. tweets are ok.

have my polks run their life? or is it that i am comparing them to some mb quart 5 1/4 seps i installed for a friend (bright tweets, nice mids tho - all unequalized)

arun1963

Have you changed any settings? E.g. re-run the imprint, changed the sub/mid xover or changed the gains, eq, mid to tweet xover etc?

Are the mids muddy compared your friends set up or are they muddy compared to where they were earlier?

In any case 'mids going muddy', is not a sign of the sr's crapping out.

tk421

unfortunately... and a big embarrassed smiley goes here ... i did this:

re-tuned the imprint for two seat. then it wasnt as loud
so i stupidly screwed with the gains and made it worse.
i then turned the imprint off, manually did TA and turned all EQs to 0

i re-tuned by ear. and i immediately knew something was off. cause my tuning method is old school but proven:
- i tune using cross over and gains, not EQ
- but it's been a looong while since i've tuned like this... and i did it all before i left for work.. so it was hurried.

yet i was still able to get some tracks sounding good. but the speakers (mids) are not up to scratch. i think i need to take a look at how they are mounted in the doors. prob have an air gap or something. or maybe my xover slopes and levels are all wrong.

will have to start back by setting gains using a good fluke true rms meter and a test cd.

thoughts???

tk421

i tried my usual default settings:

midsbass: bandpass xover. highpass 63hz with 18db slope, lowpass 3.2khz with 12db slope.
tweets: highpass 3.2khz with 24db slope
sub: lowpass 63hz 12db slope for overlap. not too sure this sounds as clean. but it gives more midbass

arun1963

Put the sub on a steepest slope that you've got. Set the LP on the mid to a steeper slope 18-24db.

Cut the tweets and play only the mids and sub. Now reduce / increase the delay on the mids by equal amt, keeping the sub at 0. If there is too much delay between the mids and the sub the mids will sound hollow. If there is too little delay, you will hear the sub mask out a lot of the mid bass. You want to get it to the point where you feel the subs presence without losing the snap in your midbass. Next go the mid/tweets crossover point and do the same.

Play the mids only and play with your eq. Then do the tweets and then play both mids and tweets and blend / smoothen out using the eq. An eq is largely about cutting everything. Boosting a frequency means setting it at 0 while those around it are cut. If you're having to boost a frequency by + to +6db, theres something wrong.

Tuning by using only your xover points and slopes will not be enough. You have to use your eq. Go to post #10 in the link below. I have posted two links one measures the frequency response of a typical door mounted midbass measured 1" from the cone. The second the FR from the same driver measured at your ear level. In a car you have to use the eq and you have to use it cut the already boosted FR thanks to your environment.

http://www.polkaudio.com/forums/showthread.php?t=121057

arun1963

If you're setting things from scratch, go back and use the TA to get the mids in phase with each other. Same for the tweets. Then work on linking them. Tweets are more affected by axis issues than phase, but it doesn't hurt to set them in phase as well. I think it helps.

The alpine manual will tell you how how to time align based on measurements. Do that and it will give you a good starting point. Now leave the sub at 0 and start adding delay in equal increments to all drivers. You should feel your stage rise a bit. Add delay in like 0.1ms increments. You'll know you've gone too far when your sub falls out of phase with the rest of the drivers. Back up a bit. Now go back and play only the mids and play with the delay between them.

This bit is all done by ear so you have to make sure you're latching on to all the nuances you'd hear with each tweak. That and this is beast done over a few days so that you can walk away from one session and come back the day to see if its right.

Don't bother with a 2 seat setup in a car. The stage just isn't big enough.

MacLeod

12 db/octave is a ridiculously shallow slope for a sub cut off. Crank that baby down to at least 24 DB. With it that shallow, youre not hearing any midbass out of the mids at all. The sub is overpowering everything up to about 160 Hz and likely causing some cancellation in the process.

63 is a good cutoff, just use a steeper slope on the sub AND the mid. 24 DB/oct is usually ideal.

Also, play with polarity some. Setting the sub out of phase can help.