Hello everyone,
I have assembled all of the parts needed for my build, the amp, the power supply, and two sets of woofers, mid-ranges, and tweeters. Now my big task is building the crossovers and deciding the configuration I want for that. I went to the electronic store, and I got the impression that multi-amping might be the way to go, since I can use lower cost, and lower power electrical components. My question is however, how do I deal with stereo sound for this project? Do I need a crossover for both the left and right speaker? Also, my amplifier has four channels, so could I devote one channel for each woofer, and then another channel for a combo of each mid and tweeter? That would work well since I would only need my one amplifier. Or would you all recommend I get another four channel amp so each signal, low, middle, and high would all have their own channel?
Thanks, I hope I posted in the right place.
I have assembled all of the parts needed for my build, the amp, the power supply, and two sets of woofers, mid-ranges, and tweeters. Now my big task is building the crossovers and deciding the configuration I want for that. I went to the electronic store, and I got the impression that multi-amping might be the way to go, since I can use lower cost, and lower power electrical components. My question is however, how do I deal with stereo sound for this project? Do I need a crossover for both the left and right speaker? Also, my amplifier has four channels, so could I devote one channel for each woofer, and then another channel for a combo of each mid and tweeter? That would work well since I would only need my one amplifier. Or would you all recommend I get another four channel amp so each signal, low, middle, and high would all have their own channel?
Thanks, I hope I posted in the right place.
If you want to biamp, that is fine, but I don't buy your reasoning. A crossover may have more expensive parts, but there are not many of them. Biamping requires an amplifier for each frequency range. One for woofer and one for tweeter. You can indeed biamp with one channel to woofer and one to mids and tweeter, but then you are back to needing a crossover to separate the mids and highs in the speaker.
You will need an electronic crossover to splits highs and lows from your preamp into the respective power amps. yes those caps and resistors and inductors would be cheaper than ones in a speaker crossover, but they will be much more numerous, and you will need to build a separate chassis and power supply for them, something a passive crossover doesn't need.
If you have stereo, then yes, you will need a crossover for each channel, the left speakers and right speakers are separate things.
You will need an electronic crossover to splits highs and lows from your preamp into the respective power amps. yes those caps and resistors and inductors would be cheaper than ones in a speaker crossover, but they will be much more numerous, and you will need to build a separate chassis and power supply for them, something a passive crossover doesn't need.
If you have stereo, then yes, you will need a crossover for each channel, the left speakers and right speakers are separate things.
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This is the schematic that I am planning on using for the crossover. Won't I need some really high power rated inductors and capacitors in order to handle the few 100s of watts of power going to the speakers?
You'll need Zobel networks across the woofer and maybe the midrange to compensate for the inductance of their voice coils. A rule of thumb for Zobels is a resistor equal to the woofer impedance in series with a capacitor that's as many microfarads as the driver diameter in inches. So, with a 15" 8 ohm speaker I'd try an 8 ohm resistor in series with a 15 uF capacitor. There's probably more accurate ways to determine the values, but that's consistent with some Altec crossovers I've seen inside, and with some measurement I did on a real crossover and woofer.
Given the size of the inductors and caps for the 250 Hz crossover, an active crossover looks more attractive. Passive components could easily add up to over $200. But, you might be able to scrounge magnet wire from old electric motors or transformers, then wind your own coils.
A passive crossover between the mid and tweeter makes sense, though. I really don't like the idea of connecting an amp directly to a tweeter; one loose cable and a blast of 60 Hz hum could destroy the tweeter. I believe some pro tri-amping setups put a capacitor in series with the tweeters just to be on the safe side. If you're talking real high power, you'll want a protection device in series with the tweeter. Car dome light bulbs could be suitable, or maybe taillight bulbs.
Given the size of the inductors and caps for the 250 Hz crossover, an active crossover looks more attractive. Passive components could easily add up to over $200. But, you might be able to scrounge magnet wire from old electric motors or transformers, then wind your own coils.
A passive crossover between the mid and tweeter makes sense, though. I really don't like the idea of connecting an amp directly to a tweeter; one loose cable and a blast of 60 Hz hum could destroy the tweeter. I believe some pro tri-amping setups put a capacitor in series with the tweeters just to be on the safe side. If you're talking real high power, you'll want a protection device in series with the tweeter. Car dome light bulbs could be suitable, or maybe taillight bulbs.
I am not too familiar with active crossovers. Is it something I would be able to make myself? If I cannot do the multi-amp setup and still go with the passive crossover I think I will be able to wind the coils up myself. I have a lot of electronic test equipment so I'll definitely be sure that the inductances are what I am shooting for. Also for that resister in series you were talking about dangus, wouldn't that be a huge resistor to handle a decent number of watts of power? Also, I bought a 350W power supply and a 4x100W amplifier board, it didn't seem like that huge amount of power compared to other setups, but am I mistaken?
Did some more research, I forgot that capacitors and inductors are passive devices (makes sense for a passive crossover) and at least for the capacitors I shouldn't have to worry about too much power flowing through since minimal energy should be dissipated in the cap. Best bet too go with big though probably not massive.
The Zobel resistors don't have to be very big. The Altec N1209 crossover used 10W wirewound resistors. Capacitors were rated 100V AC. (I replaced the dead ones with 250V caps from Solen.) According to Some Guy On The Internet those crossovers were rated at 125 watts.
With inductors, it's usually a good idea to keep the DC resistance low both to reduce losses, and because resistance will alter the response of the circuit.
Active crossovers can be made using opamps and resistors and capacitors. Look up active filters in an op-amp textbook. Plans and information:
Linkwitz-Riley Electronic Crossover Sometimes you can find car audio active crossovers cheap second-hand; high-end car stuff is worthy of home use. Or, try music stores and pawn shops for (semi)pro audio active crossovers.
It would be helpful if you explained just what you're trying to create here. Is this going to be an all-in-one boombox, or what?
With inductors, it's usually a good idea to keep the DC resistance low both to reduce losses, and because resistance will alter the response of the circuit.
Active crossovers can be made using opamps and resistors and capacitors. Look up active filters in an op-amp textbook. Plans and information:
Linkwitz-Riley Electronic Crossover Sometimes you can find car audio active crossovers cheap second-hand; high-end car stuff is worthy of home use. Or, try music stores and pawn shops for (semi)pro audio active crossovers.
It would be helpful if you explained just what you're trying to create here. Is this going to be an all-in-one boombox, or what?
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Ok I just finished drawing out a schematic for the speakers. The woofer and the mid has a zobel network in it, and from what I can tell the zobel network on the tweeter would hardly do anything. Parts-express doesn't even advertise its l(e). Just as a check here is a link to where I found the equation for the zobel network capacitors. TA Speaker Topics - Neutralizing L(e) with a Zobel
Anything else I might need to add or consider? If it looks good I might try and purchase components for the crossover tomorrow.
On another note, with the inductors, how worried should I be about inductive coupling?
Ok I just finished drawing out a schematic for the speakers. The woofer and the mid has a zobel network in it, and from what I can tell the zobel network on the tweeter would hardly do anything. Parts-express doesn't even advertise its l(e). Just as a check here is a link to where I found the equation for the zobel network capacitors. TA Speaker Topics - Neutralizing L(e) with a Zobel
Anything else I might need to add or consider? If it looks good I might try and purchase components for the crossover tomorrow.
On another note, with the inductors, how worried should I be about inductive coupling?
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