View Full Version : Freq's near crossover cutoff and DX3065
08-22-2001, 02:21 AM
A couple of questions concerning the DX3565's and frequency settings.
Question #1: Does the mid/woofers 6dB crossover setting block freq's. above that of tweeters HPF of 3.5K or do the higher freq's. sent to the mid/woofer simply "bleed off" because of the mid/woofers inability to reproduce freq's. much beyond the 3.5K crossover point.
Question #2: Is boosting freq's. near the upper range of the mid/woofer eg. @2.5K, harder on the speaker then say boosting freq. @ 1K
The low frequency cut off is set to 3800 Hertz for both the first and second order slopes. Because of the "gradual" roll off from the first order slope the driver will reproduce information up to it's natural roll off point. This is at 4500 Hertz. Due to the rate of the slope, there is always present out of band information but at
a attenuated level. The sum of both the drivers and tweeter response curves will add up to a flat response. The high pass tweeter crossover frequency is fixed at 4800 Hertz at 12 dB per octave. This can not be changed
The purpose of offering a selectable low pass slope is for the installation location of the driver. If the driver is positioned next to
the tweeter, then we recommend using the 12 dB per octave slope. If the distance of the driver and tweeter is more than
6 inches apart from each other then use the 6 dB per octave slope. This is where the "overlap" due to the "gradual" slope comes into play. This will help to "fill in" the missing pieces of information because of the increased distance apart.
Hope this helps,
Kim, Polk Audio
08-24-2001, 02:18 AM
Thank You Kim for replying to my post.
I use the 6 dB slope as recommended by you and as in the installation manual because I have mounted the mid/woofers low, and in the door. The tweeters are mounted at about chin level on the front windshield/front door support frames that forms the roof and body framework. They are mounted in their swivel cups about 3 inches above the dash at each corner and aimed towards each ear respectively. I chose this location for the sound stage it provides. However I find that I can sometimes hear what sounds like the tweeters notes are being emitted off the surface of the silk dome of the tweater. I find this to be somewhat rather distracting at times. Is this effect caused by the short distance that the tweeters are in front of me (ignoring diag. distance away) and is this effect a part of the blending errors I hear. I tried changing the tweeters phase but this tended to unblend the relationship between the tweeters and mid/woofers even more so. I also tried listening with the tweeter gain set at the minus 3dB position but this setting tended only to reinforce the feeling that the sound is coming from below you instead of infront of you. This system is installed in a 93' Nissan standard cab 4x4 pickup truck.
08-24-2001, 08:34 AM
Try aiming the tweeters at each other, instead of back at you. Or even into the widsheild. This will sometimes help with the stage depth. When playing with the phase, also try just reversing polarity of one tweeter- i.e. driver's tweeter out of phase, passenger's tweeter in phase, or vice versa. Every car is different, but these things work sometimes so it's worth a try.
08-25-2001, 04:35 AM
I was not aware that doing so was safe to do. However, now that I think about it a little more, I wouldn't see why it wouldn't be. I'll give that a try.
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