[holycow]

So I just got done installing a budget system in my GFs Saturn Vue and I need some help setting the built in HPF and LPF on the amp. The system sounds great, but i think I could dial it in better with a little help. First, here is what I am running in the car

front stage - 10 year old polk audio 6 1/2" coaxial door speakers
sub - 10" Alpine type E
box - .9 CU sealed
amp - profile H1000 80x4 (80 - 80 - 160)

I have the high pass filter turned on for the front two channels running the doors, and the low pass filter turned on for bridged 3 and 4 running the sub. But, where exactly should I set the filters? I have the sub current set at 90hz, and I have the coaxials set somewhere around "middle".

LPF options = 50hz - 120hz
HPF options = 80hz - 1.2khz

So, any ideas where I should set them for optimal performance? I want to make sure frequencies the speakers cant handle are filtered, but I also want to make sure that I am not cutting them off unnecessarily.

Thanks!

[Greg]

It's helpful to know the frequency response and power handling capiblities of the drivers. But given the age, that info may not be readily available. Start by getting a test tone CD. Order it or download it and burn your own.

Next, shut off the sub, set the HPF to 50hz. Play the CD and see how the Polks sound in the lower frequencies. Pay special attention to the what frequency the Polks begin to drop off. Most 6.5 don't play well below ~60hz or at least start to taper off around 60hz. Also listen for door rattles in the lower frequencies. This is good chance to isolate and resolve those.

Once you have a rough idea how low your 6.5 can play, then shut them off and repeat the process for the sub. The sub will comfortable play much higher than you'd want, so what you looking for is where the sub sounds best, and the sound is not localized to the rear. For most subs this is closer to 60hz, but sometimes lower. Going higher can make the bass sound bloated as well as become directional. You don't want to be able to tell where your bass is coming from or it will detract from the sound stage.

Next is the question of over lapping or underlapping the x-overs. With some basic sense of where the drivers should crossed, turn them all on and see how the Polks blend with the sub. If the bass is too bloated you can move the Polks up, or the sub down. Or both. Underlappying is would be something like setting the Polks to cut at 60hz and set the sub to cut at 50hz. Since the filter is not perfect, it will taper off from both crossovers providing balance in the middle. Many crossovers allow adjustment of the slope, which gives you another tuning aid to play with. I couldn't find info on your amp, but it looks like the HA1040 which has a fixed 12db slope. This isn't a very steep slope so you may benefit from underlapping, especially with the Polks. Just FYI, a slope of 36db/octive is the highest I've seen, allthough many only go up to 24db/octive. Do this if you are having a big spike right around the cross over frequency. If midbass is too weak you can over lap the sub and 6.5

Once you have the crossovers set they way you like do some tuning with the gains. There is alot of theory about the best way to set gains, and really you set them before and after the x-over tuning. I just do it by ear using one some louder undistorted source material. Find the ceiling for the sub and the Polks, then adjust the "higher ceilined" drivers down to match the lower.

Once you have it the way you want, listen to a bunch of different source material and plan to do a little fine tuning later. Also remember that what sounds good sitting in a parked car will not sound right with a bunch of road noise. Do a road test on the freeway before settling on the settings. You might find the bass lacking at freeway speeds.

[holycow]

Greg.. thanks, a great source of knowledge as usual! I just read somewhere else that most (in general) 6.5" mid drivers don't like to play below 90hz, and the average 10" woofer doesn't like to play above 100hz. Sounds like this is a generic overlap point to start with. I just set my passes here (around 100hz for both) and it sounds good. But... I think I am getting a little too much mud out of the rear. Should I drop both to 80hz, or should I just drop the sub to 80hz and leave the polks at 90? The front sounds pretty good right now. With the sub at 80, and the fronts at 90, im missing 80-90hz. Naturally there is intentinionally recorded sound at those frequencies, so waht to do? drop both to 80?

Thanks for chiming in again, I appreciate it!

By the way, In my STI, I went with front stage only and it's the only way to go!

[Greg]

I just read somewhere else that most (in general) 6.5" mid drivers don't like to play below 90hz, and the average 10" woofer doesn't like to play above 100hz.
I don't think that is true of all drivers. But certainly could be true of some. There are some 6.5 that do OK down to to 60hz, and others that just can't take it. CDT makes some deep playing 6.5s that make you may not even need a sub. I have my Lotus referance drivers (6.5) cut at 60hz (24db) slope and they are doing fine. The biggest problem I have is the door card is rattling like heck even after adding loads of RAAmat (Dynamate like product)and Ensolite (close cell foam sheets). When I add the sub, I probably move the crossover up a bit to let the 6.5 be more deticated to the mid range/mid bass.

While a sub can probably play above 100hz, you probably wouldn't want to. Much above 60hz and bass gets a bit bloated. Plus its easlier to tell where the sound is coming from.

Sounds like this is a generic overlap point to start with. I just set my passes here (around 100hz for both) and it sounds good. But... I think I am getting a little too much mud out of the rear.
I think lowering your crossover point to the sub will help with the mud. Be careful as the sound will intially feel more "empty". Turning up the gains on the sub, or turning down the gains on the Polks may help, if needed.

Should I drop both to 80hz, or should I just drop the sub to 80hz and leave the polks at 90?
I'd first figure out how low you safely play the Polks. Again power rating and frequency response might provide some guidance. Barring that info, you'd need to do it by ear. I'd be nervious pushing a driver unless I knew its power rating. What's the model number? Crutchfield or Polk may still have manual laying around.

The front sounds pretty good right now. With the sub at 80, and the fronts at 90, im missing 80-90hz.
The slope of the crossovers is 12db/octive. What that means is the both crossovers don't chop off the sound at 80/90hz. Instead the the crossover starts gradually attinuating (cutting) the frequency drop at 80 and 90 hz continues well past the selected crossover frequency. So there there may be a slight dip in frequency response between 80 and 90, but there will be something there.

Did a quick search for an image showing this, please excuse the roughness (not my pic). Below is a 18db/oct slope, and the crossovers are approximate 30hz (lpf) and 80hz (hpf). You can see that due to the sloping of the cuttoff, there is still only a -5db cut in middle (about 45hz). A 12db slope is very moderate so the slope would be even more gradual. This means that even at 90hz, your Polks are getting 80, 70, 60 and maybe even 50hz signal. Actually, it would be easier on your 6.5 if you could cut at a slope of 24 or 36db/oct so they don't see any of lower frequencies. Your HU may have crossover settings with a steeper slope. Worth looking into.





By the way, In my STI, I went with front stage only and it's the only way to go!
Same here. I do miss the pseudo surround sensation of the rear fills. However, it allowed me to spend more on my components and go with full active crossovers. Also I was never happy with the sound stage you'd end up with with rears, poor left/right seperation and a bit too rearward.

[holycow]

1.) Greg.. Seesh man, what a wealth of knowledge! Unfortuantely the model of the polk coax is now forever burried in my GFs doors. The only thing I remember, is that i bought them around 1995, they were the top of the line polk coax, and they are rated at 100 whatts RMS. Back in the day, I used the same line of speaker in seperates in the front, and these coaxes in the rear deck of an older civic. The seperates are long gone, but still had these coaxes laying around. They only had about a year worth of light use on them (basically still brand new).

So... 1995 ish, top of the line polk series ~100 RMS.

2.) I tried tuning the lowpass down to 60, but the only thing I would get out of the sub were kick drums... almost no bass guitar. Maybe try 70? Sorry I don't know more about it! Part of the problem, is that the circumfrance of the dial is only labeled at three places! 50 at the bottom, 90 at the top, and 120 at the max. Almost impossible to set it EXACTLY....

3.) The pioneer HU DOES have built in crossovers. The high pass I can set between 50 and 125 or so... (I have it turned off) the low pass is just the same... 65, 80, 100, 125, but it CANNOT be turned off. I have been setting the HU lowpass to match what I have set on the amp, for no other reason than it doenst make sense to have two different lowpasses running set to different cutoff levels.

[holycow]

one other things I Just thought of.... at the time these coaxes were available, polk's "cheap" line of speakers were called their "EX" series.

[Greg]

The only thing I remember, is that i bought them around 1995, they were the top of the line polk coax, and they are rated at 100 whatts RMS.
Ok, that's good info. With the amp running 80 watts per (if we can really believe that) then you aren't at risk of frying the drivers. If you are driving the drivers too distortion, the amp may clip which can fry the tweeters. Since the quality of the drivers still somewhat unknown, this will be a "take what you can get" setup. Again, I'd try shutting down the sub and see how low the Polks comfortably play. It may be that they just don't have a lot of mid bass which is regretable but common.

It would be a shame to have to cut them around 90hz and force the sub to play that high. But we do what we can with what we have. So a little bloated bass may be better than none at all. You might need to experiment a bit see what is possible, but then settle with a sub-optimal result. By the way, in case you want to enhange the mid bass using the same drivers, I'd highly recommend treating the doors with a sound deadener and closed cell foam. Sealing off the doors (as best as possible) will go a long way to help the mid bass. Right now the bass is likely seeping from the back of the driver through the holes in the door and cancelling the wave on the front of the driver. I did this with the stock stereo in the STI and was amazed how much better it sounded. Not enough to keep it though.

I tried tuning the lowpass down to 60, but the only thing I would get out of the sub were kick drums... almost no bass guitar. Maybe try 70?
This could be a problem with the calibration on the crossover pot (knob you are turning) or it could be that the Polks are just not playing low enough to blend properly with the sub.

The pioneer HU DOES have built in crossovers. The high pass I can set between 50 and 125 or so... (I have it turned off) the low pass is just the same... 65, 80, 100, 125,
Ah! This is great news. The quality of the crossover in the HU is likey much better than those on the amp. Plus, it probably has a slope adjustment. Not to mention its whole lot easier to tune in the comfort of the drivers seat instead of tipping your head in the trunk, etc. I'd set the crossovers on the amp to fully open/disabled. Then run everything from the HU.

BTW, what HU do you have? Does it have an EQ?

[holycow]

Greg, thanks again for the info. I think I have it dialed in pretty good now. I am still using the filters on the amp, but I have dropped the X-over point on both the front and rear, closer to 60hz, and BAM, it sounds fantastic.

Turned off the sub and turned up just the polks, and then tuned down the filter so that I was getting a tad more bass/kick/movemement out of the mid driver, but not so much that it was sounding like a full range... Then I boosted the gain on just the sub and turned it up so i could only year the sub, and dialed in the lowpass till the sub sounded like it was only playing what it was supposed to be playing, and got it sounding nice and tight somewhere closer to 60hz... now they both play together very nicely. Sounds stunning for a budget system! Crisp, clear, shakes the mirrors!

[Greg]

Originally Posted by holycow

Greg, thanks again for the info. I think I have it dialed in pretty good now.

Glad to help. Now you've earned your merrit badge as a tuner! Just imagine how much more fun you can have if you were tuning the crossover points for the tweeter, midbass as well as the sub. If you ever want to go with active crossovers in the STI you've already got the basics. Last thing I'll say is, I would have prefered using the crossovers on the HU. But since you've already got it sounding right, there's no need to mess with it further.

[holycow]

Yeah! Tuner Merit Badge!