Electronics > Beginners
Crossover frequency of a 2.1 speaker system
poot36:
The 10" sub is in a sealed enclosure that is attached to a ported enclosure (with a piece of pvc pipe in the port for tuning that I think is around 4" long) about 2 to 3 times the volume of the sealed enclosure. I built this enclosure based on the sub specs and what frequency (I think it was around 30Hz) I wanted to achieve a vary long time ago based on some books about subwoofer enclosures. I have no clue if it is correct or not. The sub is made by Pyramid has a orange fome surround and is rated for 150 Watts peak and 50 Watts RMS 4? coil. This would have been a good 10 or more years ago. I still have the warranty card and I think that it has some more complete specs on it if I can find it. I will measure the enclosure and try to find more specs on the sub.
poot36:
Well here is the measurements of the sub 33" high 12 14/16" wide and 21" deep. The top sealed section is 10.5" high and the bottom ported section is 22.5" high. This is using 11/16 thick MDF on the sides and top and bottom. The front and back are probably the same thickness as the MDF but are plywood. I think that the board that is inside holding the sub is melamine (basically coated mdf) of the same thickness as the MDF. The port is 2 3/4" deep and 2 1/16" inside diameter. I found the warranty card stating the model of the sub is wc1020, it was purchased at London Drugs and the date of purchase was Dec 27 1999! The sub box was built some time after that date though (I think a few years). I think that these are the specs but I am not sure Vas (liter) 105,1 Fs (Hz) 31 Qts 0,492. Does this make sense for a sub box? I have found a pdf file with some more complete specs but it is in a different language. I have attached it to this post.
poot36:
If I remember correctly it was a bandpass design with a cutoff frequency of around 1000Hz. I am not sure if this makes sense for a sub though. Maybe it was 100Hz?
poot36:
That is not really a option/problem. Here is my current speaker setup. Wii U sends sound to 2 stereo speakers in my playstation 3D monitor over hdmi and sends analog audio to a 1970s kenwood stereo receiver that currently drives the sub from the right channel and two 4" or 5" Craig branded speaker + tweeter units from the headphone jack on the receiver to limit the volume to them also the audio comes out of the stereo speakers in the game pad. I do not want to connect the small speakers to the standard outputs on the receiver because that would result in it trying to drive an unequal or to low ohm load (the sub is 4 ohms and the speakers are as well). This setup works but I wind up with the sub been louder then the rest of the speakers and trying to output frequencys that it was not designed for. My current plan is to use the line level stereo output from the active cross over that limits the low frequencys and input that into the kenwood amp and then use the passive cross over amp for the sub channel. My only problem with that is the way the active cross overs sub section increases its output level as the frequency goes down. This causes the passive cross overs amp to clip due to the overvoltage (it has a 300mV max input level). If I can find a way to fix this problem with the sub circuit on the active cross over I believe that it would work well (I think).
poot36:
Right now I am just using the Kenwood for the Craig (actually Curtis) speakers + sub. The Sony Playstation 3D monitor has its own speakers in it that are in use. Here is the flow chart Wii U -> hdmi -> 3D monitor, Wii U -> analog -> Kenwood -> Curtis L+R headphone jack + sub R speaker out on rear of amp, Wii U -> wireless -> gamepad speakers. There are 3 sets of stereo speakers in use with this setup. Here is what I want to achieve Wii U -> analog -> active crossover -> L+R out -> Kenwood, Wii U -> analog -> active crossover -> sub out -> passive crossover just used for the amp section -> sub. The problem that I have with this setup is the sub section of the active crossover increases in output amplitude as the input frequency goes down and ends up overloading the input to the passive crossovers amp section. How would I go about modifying the active crossover sub section to get a flat output amplitude regardless of the input frequency? I know that the L+R outputs on the same board do this although they are only one op amp in the signal path not two like the sub circuit. I have attached a picture of the setup sorry about the mess. The PS3 and Xbox 360 connect to the 3D monitor directly through hdmi and I use the headphone output on the monitor to listen to them but it is not very good because of all the hiss from the crappy amp in the monitor.
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