Hello,
I would like to make an active crossover for a pair of speakers I have. They are stereo two-ways with a 1" tweeter, 6.5" woofer, and I also have a sub I need to make a mono sub out for. I know opamps and ckt design, but not power supply design - I always just hook my stuff up to some supply we have around in the lab at work.
What is the max power consumption for an opamp like an OPA2134 or NE5532? What size components should I look at for an active crossover box? 15VA transformer? 50VA? Bridge rectifier current/voltage ratings? Going for +/-15V regulated supplies using 7815 type of LM317 type regulatos.
Also, should I strive to make my cap values as large as possible and my resistor values as low as possible in the filters to lower noise?
Thanks for any help.
I would like to make an active crossover for a pair of speakers I have. They are stereo two-ways with a 1" tweeter, 6.5" woofer, and I also have a sub I need to make a mono sub out for. I know opamps and ckt design, but not power supply design - I always just hook my stuff up to some supply we have around in the lab at work.
What is the max power consumption for an opamp like an OPA2134 or NE5532? What size components should I look at for an active crossover box? 15VA transformer? 50VA? Bridge rectifier current/voltage ratings? Going for +/-15V regulated supplies using 7815 type of LM317 type regulatos.
Also, should I strive to make my cap values as large as possible and my resistor values as low as possible in the filters to lower noise?
Thanks for any help.
Also is a transformer with dual 15VAC secondaries at rated load (18VAC no load) good enough for +/-15V regulated DC supply lines, or should I go for an dual 18VAC secondary (~21VAC no load) and just regulate it down to 15? Lose more power in the regs but certainly no worries about supply lines drooping below regulator set point.
Thanks!
Thanks!
Go for 317/337s, put the big caps before the regs, and unless you are using silly amounts of op amps, 500mW per rail should be fine.
And for your second question, 15-0-15 would be fine as long as it's not so undersized that it droops when loaded.
So 2x15VAC @ 1amp in parallel (15VA) transformer would be plenty? This could be a (very) overkill active xo (8th order filters, response shaping filters, all kinds of stuff).
Figure 10 mA draw for each OPA2134 or NE5532 (data sheets are your friend). Sounds like you'll be drawing around 150 mA per channel, or 4.5VA.
Assuming you'll still have 20V after the rectifiers (15VAC * 1.4 - 1.2V), 15VAC input ought to be plenty. I'd beef up to maybe a 30VA transformer to keep the losses lower and give the regulator plenty to play with. PSU Designer is a useful tool that doesn't take much to learn.
Assuming you'll still have 20V after the rectifiers (15VAC * 1.4 - 1.2V), 15VAC input ought to be plenty. I'd beef up to maybe a 30VA transformer to keep the losses lower and give the regulator plenty to play with. PSU Designer is a useful tool that doesn't take much to learn.
Mkay, time for some more questions - thank you guys for the answers so far 🙂
I would like this to have the volume digitally controlled. I envision source -> active xo box + volume control -> amps -> speakers. My part is the active xo box + volume control.
I would like to take the source (analog input), put it through whatever necessary op amp based active xo functions are needed, then have a digitally controlled analog volume control on the output. I will be using something like these for the digitally controlled volume controls:
http://focus.ti.com/docs/prod/folders/print/pga2310.html
So, I will need the +/-15V supplies for the active filters and analog side of the volume control IC's, and a +5V supply for the logic side of the volume control IC's, the MCU to control them (probably a PIC16F), and whatever other 5V stuff I need (switches, selectors, etc).
QUESTION: I have the +/-15V regulated supply lines for the analog portions of the circuit. Can I just regulate the +15V down to +5V for the digital logic side? Or will switching noise on the 5V digital side make it back through the regulator to the +15V line and / or ground connection? If so, how do I isolate them? I would like to isolate them without having to use some sort of isolated switching DC/DC converter. I've seen how noisy some of those things are (ugh).
Thanks for any advice!
I would like this to have the volume digitally controlled. I envision source -> active xo box + volume control -> amps -> speakers. My part is the active xo box + volume control.
I would like to take the source (analog input), put it through whatever necessary op amp based active xo functions are needed, then have a digitally controlled analog volume control on the output. I will be using something like these for the digitally controlled volume controls:
http://focus.ti.com/docs/prod/folders/print/pga2310.html
So, I will need the +/-15V supplies for the active filters and analog side of the volume control IC's, and a +5V supply for the logic side of the volume control IC's, the MCU to control them (probably a PIC16F), and whatever other 5V stuff I need (switches, selectors, etc).
QUESTION: I have the +/-15V regulated supply lines for the analog portions of the circuit. Can I just regulate the +15V down to +5V for the digital logic side? Or will switching noise on the 5V digital side make it back through the regulator to the +15V line and / or ground connection? If so, how do I isolate them? I would like to isolate them without having to use some sort of isolated switching DC/DC converter. I've seen how noisy some of those things are (ugh).
Thanks for any advice!
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