Caps in active networks....

[Mighty Favog]

Are they as/less/more durable than passive networks?

 

Since there are different components that make up an active network, are there still some parts that need servicing over time like passives??

 

[Mighty Favog]

Crickets??

[Don Richard]

If one uses a DSP crossover there is less chance a bad cap will shift the crossover point. A bad cap in the power supply would probably affect both channels, caps associated with one channel would affect that channel. Generally, digital either works or doesn't. 

 

ESR is a factor that affects passive crossovers. Caps in electronic crossovers have DC biasing the caps so ESR is less of a factor.

[John Warren]

Dielectric material used to make the capacitor is important for low distortion and noise levels.  High-K dielectric materials allow large capacitor sizes in small packages which is a good thing for PC board layout but not so great for distortion and noise.  The capacitance of high-K materials will vary as a function of both signal voltage and temperature causing distortion.  Low-K materials are less sensitive to these effects but physically much larger for a given capacitance and voltage rating. 

 

In an existing design, changing from a high-K to low-K is usually not possible because of space and mounting constraints.  This is the case for all small signal circuits, not just active filters. 

 

 

 .  

 

 

 

[djk]

" Caps in electronic crossovers have DC biasing the caps so ESR is less of a factor. "

 

Really?

 

I'd like to see a schematic showing DC bias in an electronic crossover, I've seen one in a car stereo crossover, years and years (and years) ago.

[Don Richard]

11 hours ago, djk said:

I'd like to see a schematic showing DC bias in an electronic crossover, I've seen one in a car stereo crossover, years and years (and years) ago.

 

The electronics in an active analog crossover are connected to circuitry powered by DC. The audio signal, which is alternating current, rides on the DC from the power supply and does not pass through zero. The current passing through coupling and time constant caps is low. ESR is of little consequence in low-current circuits, but more important where current is high and goes through a zero crossing such as caps in a passive crossover.

 

 

[djk]

" The electronics in an active analog crossover are connected to circuitry powered by DC. "

 

Of course you mean ±V, the signal is referenced to 0V (ground).

[babadono]

@Mighty Favog Were you asking about analog or digital? Or both? I would think that maybe the electrolytics in the signal path of an analog type if there are any might degrade with time. In a digital unit I would think by the time any might degrade that technology would move so far forward you would buy a new unit for the technology advancement.

[Mighty Favog]

I'm pretty much asking about an analog active unit. 

[djk]

" I'm pretty much asking about an analog active unit.  "

 

As was I.

 

The only electronic crossover I have ever seen that ran on a single-ended DC voltage (that puts DC bias on the caps) was the old A/D/S AX2 (circa mid '80s).

 

Lead attachment is still a problem with the caps over time, and any device with copperweld leads (as most small film caps and film resistors were).

 

Carver and Hafler bought NOS parts to save money, they failed much sooner than other companies products (due to copperweld failures).

[Don Richard]

On ‎7‎/‎1‎/‎2017 at 3:27 PM, djk said:

The only electronic crossover I have ever seen that ran on a single-ended DC voltage (that puts DC bias on the caps) was the old A/D/S AX2 (circa mid '80s).

 

http://www.marchandelec.com/xm26.html