Help with C5 Corvette system

eRiCdWoNg · 27th July 2003, 03:52 PM

I have a 15" Adire Audio Tumult I put into my C5. So far I have used a Sonotube enclosure. I find that if I put the sub directly behind the seats it sounds like poop. below is a picture of the under construction stage setup with a different woofer. There is alot of cancellation between the midbasses up front and the sub right at the X-over frequency (I run 24db/oct Linkwitz Riley alignment at about 90 Hz), the effect is most noticeable especially if the top is down. Reverseing the phase of the woofer in relation to the front speakers doesnt do a thing, so I'm thinking that the woofer is about 90 degrees out of phase. I use a real time anaylzer with pink noise to do A-B response comparisons.

If I put the woofer in the extreme rear of the car it sounds much better. However I still want to stow the top.

Is there any sort of time delay/phase shifter I can buy/make to rectify this? I might turn to a different enclosure design that I can position in the rear of the car as well.

tsmith1315 · 28th July 2003, 03:18 AM

Right behind your head isn't a very good place for long sub-bass waves to originate. Unfortunately, the car dictates the location and it would be a crime to interfere with lowering the top on that car!

You could try an all-pass filter to help with phase correction. A first order allpass would delay phase slowly from 0º to -180º asymptotes with -90º at resonant frequency.

For a cheap delay look for Princeton Technology's PT2399 IC. It has ADC/DAC built in, all you need is a few external components. The only datasheet I found on the device was minimal, but did have a complete delay schematic. +5V single supply was shown which would limit the input signal. I have no idea if higher supply voltages are acceptible.

Tim

27th July 2003, 03:52 PM	#1
eRiCdWoNg diyAudio Member Join Date: Jul 2003 Location: maryland, USA	Help with C5 Corvette system I have a 15" Adire Audio Tumult I put into my C5. So far I have used a Sonotube enclosure. I find that if I put the sub directly behind the seats it sounds like poop. below is a picture of the under construction stage setup with a different woofer. There is alot of cancellation between the midbasses up front and the sub right at the X-over frequency (I run 24db/oct Linkwitz Riley alignment at about 90 Hz), the effect is most noticeable especially if the top is down. Reverseing the phase of the woofer in relation to the front speakers doesnt do a thing, so I'm thinking that the woofer is about 90 degrees out of phase. I use a real time anaylzer with pink noise to do A-B response comparisons. If I put the woofer in the extreme rear of the car it sounds much better. However I still want to stow the top. Is there any sort of time delay/phase shifter I can buy/make to rectify this? I might turn to a different enclosure design that I can position in the rear of the car as well.

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28th July 2003, 03:18 AM	#2
tsmith1315 diyAudio Member Join Date: Jul 2003 Location: Doerun, GA	Right behind your head isn't a very good place for long sub-bass waves to originate. Unfortunately, the car dictates the location and it would be a crime to interfere with lowering the top on that car! You could try an all-pass filter to help with phase correction. A first order allpass would delay phase slowly from 0º to -180º asymptotes with -90º at resonant frequency. For a cheap delay look for Princeton Technology's PT2399 IC. It has ADC/DAC built in, all you need is a few external components. The only datasheet I found on the device was minimal, but did have a complete delay schematic. +5V single supply was shown which would limit the input signal. I have no idea if higher supply voltages are acceptible. Tim