If you are using top quality opamps and experience bad results with what you build, it's all on you.
Find your problem and get good measurements.
Theoretically, active crossover is reducing bandwidth demands on rest of signal chain, making job of power amplifier and transducers easier.
Regards,
Andrew
I wish they would do that in the UK. Emigration is off the cards for the forseeable future
Problem is, I have tried many opamps. Well, I'm following Scott Wurcer on the discrete opamp thread. But for an active xover, there will be many components
I have several exotic opamps, all have at least 1000v/us slew rate. But I couldn't find a model to design an xover circuit. I have checked all Analog Device stuff, also all opamps in LTSpice library to find one that is close, but couldn't find one. Anyway, I will build 4 SSA amps (final version for 1 pair lateral fet output) tonight and will see if my opamp based active using whatever regular opamps I have on hand (only up to 60V/us) can outperform my passive crossover speaker.
I meant low quality thd
Leading us to 'that means there is good quality THD.......WTF?'
I'd like to bring this up again, as it seems to have been met with little interest.
How important is this? In an active setup, each driver is exposed to all the noise and distortion of the amp that is connected to it. Not so in a passive crossover. How much of a difference does this make? And to what extent is it balanced out by not running a full signal into each amp in an active crossover?
Well the IMD of the amplifier, or any of the non linear distortion products for that matter, should be significantly lower then any of those produced by the loudspeaker. It is obviously system dependent, but if you've got a well designed set of amplifiers, for the job they are asked to do, then any non linear issues, passive or active, should be off the audible radar.
Noise on the other hand, with an active system, isn't quite so trivial. If you're using some very sensitivty compression drivers, hooked up to suitable horns, then the in band sensitivity is going to be very high. Passively you might have 10-20dB of resistive attenuation before the driver, whereas actively you will have none. You will need a very well designed system to ensure that the active version doesn't produce any audible hiss, not so much for the passive version. Of course if you've got a treble section pushing the mid 100's then you could resistively attentuate it, in an active setup, and still only need flea power to make your ears bleed.
Noise on the other hand, with an active system, isn't quite so trivial. If you're using some very sensitivty compression drivers, hooked up to suitable horns, then the in band sensitivity is going to be very high. Passively you might have 10-20dB of resistive attenuation before the driver, whereas actively you will have none. You will need a very well designed system to ensure that the active version doesn't produce any audible hiss, not so much for the passive version. Of course if you've got a treble section pushing the mid 100's then you could resistively attentuate it, in an active setup, and still only need flea power to make your ears bleed.
There are some amps noisy enough to be audible through HF compression drivers, they are not a good choice for active use.
To the degree a HF driver is attenuated, it would reduce noise and distortion.
That said, the same amp used with a passive crossover with a high frequency bypass capacitor to extend a compression driver's HF response would reveal the usual "white noise" spectrum, concentrated in the upper range.
As far as distortion, any decent amp operated in it's linear range has a tiny fraction of the distortion of the best drivers when run hard, and distortion such as amplifier zero point crossing distortion, evident at low volumes, is objectionable with active or passive crossovers.
At any rate, if amp distortion and noise sound bad, in my experience it will sound bad with a passive crossover or an active crossover.
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