Output impedance=(Load resistance*(Vunloaded minus Vloaded))/Vloaded
Set the output to 1v AC and measure the voltage. Then connect a 1k ohm resistor from the output (center conductor) to the shield. Measure the voltage again. Use those values and the value of the resistor to determine the output impedance. Use a sine wave of 50-100hz.
Set the output to 1v AC and measure the voltage. Then connect a 1k ohm resistor from the output (center conductor) to the shield. Measure the voltage again. Use those values and the value of the resistor to determine the output impedance. Use a sine wave of 50-100hz.
pair your 9887 with this ...
http://www.alpine-usa.com/US-en/products/product.php?model=PXA-H701
its available for the same price as a behringer if you look around.
Alpine 9887 is about the best unit you can put in your car right now. I tried the DVA 9965 and its not worth the extra coin in my opinion, unless you are making Mp3 dvd's.
The Clarion top of the line unit has the WORST pre amp output i have ever heard. Dont know why but it sounds like ***.
OHHH and if you are looking for something strictly for USB play DO NOT buy this unit. It will not shuffle play/remember or FF-Rew any Mp3 or USB key except the iPod. Turn off the key and you are back at the start of your USB key. I hate the iPod so much but i am gonna have to buy one. 50 gigs of music @ 320 stored on my comp :-( ....
http://www.alpine-usa.com/US-en/products/product.php?model=PXA-H701
its available for the same price as a behringer if you look around.
Alpine 9887 is about the best unit you can put in your car right now. I tried the DVA 9965 and its not worth the extra coin in my opinion, unless you are making Mp3 dvd's.
The Clarion top of the line unit has the WORST pre amp output i have ever heard. Dont know why but it sounds like ***.
OHHH and if you are looking for something strictly for USB play DO NOT buy this unit. It will not shuffle play/remember or FF-Rew any Mp3 or USB key except the iPod. Turn off the key and you are back at the start of your USB key. I hate the iPod so much but i am gonna have to buy one. 50 gigs of music @ 320 stored on my comp :-( ....
I only have a HU to do this with, is that possible?Perry Babin said:
I don't get ipods at all, don't have an interest in proprietary equipment on top of that. If something does not support anything else I see it as a big fault in that product even though I like alpine. All this "technology" and you can't even listen to the song you want that you paid for and own....and someone might wonder why I hate the music industry/patent office/liberal legal system. Fact is the rest of the world is moving on while we sit here. That is about as opposite as you can get to what built this country and why it is successful. I always try to support open source products if I possibly can. If people knew the things some of these companies have done like sony to stop technology, they would think differently. Meanwhile anyone outside the US just defeats their stupid protection stuff anyway while we are the only ones to suffer. If they had good products they would sell themselves now wouldn't they?
Sorry for the ramble but music is in such a bad situation today with little excuse.
Madmike2 said:
Have you ever used the Alpine in your own system? The menus are nearly impossible to navigate with any fluidity. I spent three hours with one and barely scratched the surface of being able to switch among mens - frequently getting lost. I built the supply for the DCX unit because I was using it in my own car after trying the Alpine. The menu is a snap and using a laptop "on the fly" helps to tweak from the driver's seat without leaning over to the headunit.
Hey, just found this thread. I don't own a DCX2496, but I've used my computer to produce similar results for active crossovers. A DCX2496 is on my "to buy" list, it seems everyone is using them!
Anyway, my plan is to try out my computer in the car, set all my crossovers and delays to my taste, them make a circuit from op-amps, as I don't want to have to run a computer just to have sound in my car.
I know crossover circuits are pretty simple with op-amps, but I've never come across a delay circuit. Does such a thing exist, and if so, are there any pitfalls going the op-amp route?
Anyway, my plan is to try out my computer in the car, set all my crossovers and delays to my taste, them make a circuit from op-amps, as I don't want to have to run a computer just to have sound in my car.
I know crossover circuits are pretty simple with op-amps, but I've never come across a delay circuit. Does such a thing exist, and if so, are there any pitfalls going the op-amp route?
MikeHunt79 said:
Thanks, I totally missed that thread until now. I only really want to adjust tthe delay on my sub anyway, so it looks like it might just be achievable with op amps.
Delay and phase adjustment are not the same thing. You can adjust phase at the crossover point to help blending between your drivers, but only time delay will correct distance discrepancies. I actually delay my entire system with respect to the subwoofer to achieve transient perfect response.
With op-amps you can delay a frequency band, but not the entire audio band, except for very short delays like 25us. Each op-amp stage can add the equivalent to 90 degrees of reasonably constant delay at the highest frequency where it is still required. Note that some frequency margin for crossover overlapping is always required.
To understand it better, you can simulate an all-pass filter with some electronics software and take a look at the resulting group delay plots.
To understand it better, you can simulate an all-pass filter with some electronics software and take a look at the resulting group delay plots.
Here we are, I have a larger one if you need. I can try to measure impedance if I can figure out how....why does it matter? Can I run a test signal in the HU and set volume to get 1v output AC on the 200? I have to order stuff so I can get a resistor then. What would you set the controls to, and do I need to do both outputs?
An externally hosted image should be here but it was not working when we last tested it.
Linear xo-2
FTW?
The Burr Brown's in the high pass are not OEM, there are extra Tants in the PS filtering and high temp high freq caps replaces the OEM electrolytics. It's got new mylars too.
- Matt
FTW?
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
The Burr Brown's in the high pass are not OEM, there are extra Tants in the PS filtering and high temp high freq caps replaces the OEM electrolytics. It's got new mylars too.
- Matt
Looks near the same as the one in the LP pa2s. The XO-2s were very nice, I prefer dash mounts but I'd use an XO anytime.
An externally hosted image should be here but it was not working when we last tested it.
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