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line-level high pass filters in subwoofers: high quality?

skyfly

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Are line-level high pass filters in subwoofers of high quality?

Subwoofers have circuits that generates intense noise: high-power D-class power amplifier and high-power switching mode power supply.
 

dougi

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If you are worried about noise etc, measuring the performance is a good idea. They will be designed with a target load impedance so the frequency of filtering will depend on what you connect it to, so it is a good idea anyway. I know this from experience in using a Velodyne's HP output which, from memory seemed to be designed for a 47kohm load. Connect it to a 10kohm load amp/measuring device and the filter frequency was then more than double the intended 80 Hz! Apart from that it measured fine.
 
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skyfly

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If you are worried about noise etc, measuring the performance is a good idea. They will be designed with a target load impedance so the frequency of filtering will depend on what you connect it to, so it is a good idea anyway. I know this from experience in using a Velodyne's HP output which, from memory seemed to be designed for a 47kohm load. Connect it to a 10kohm load amp/measuring device and the filter frequency was then more than double the intended 80 Hz! Apart from that it measured fine.
I did not expect that a subwoofer has a passive line-level high pass filter.
 

DonH56

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Are line-level high pass filters in subwoofers of high quality?

Subwoofers have circuits that generates intense noise: high-power D-class power amplifier and high-power switching mode power supply.

Every sub I have seen with a line-level high-pass filter uses a standard op-amp (active) design so they are fine. I suppose it depends upon what you call "high"; the ones I have seen specs for (a small sampling) run around 100 dB or so for THD+N so not SOTA but very good (much better than most components not all that many years ago). Certainly much lower distortion than your speakers. ;)

As for "intense noise", class D amps and SMPS' operate a decade (10x) or so higher than the audio band, so all that noise is up where we can't hear it.
 

aac

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If you are worried do it digitally first (before converting to analog).
If you can't and want it analog: Neumann subwoofer kh805/810/870 has 119 dBA SNR, so I guess it is pretty high quality.
 

Frgirard

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Are line-level high pass filters in subwoofers of high quality?

Subwoofers have circuits that generates intense noise: high-power D-class power amplifier and high-power switching mode power supply.
Proofs. My ex kh810 does not have noise.
 

voodooless

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Are line-level high pass filters in subwoofers of high quality?

Subwoofers have circuits that generates intense noise: high-power D-class power amplifier and high-power switching mode power supply.
Even if it were true, what do you think a line level high pass would actually accomplish?
 

Ultrasonic

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Even if it were true, what do you think a line level high pass would actually accomplish?

Presumably providing the audio signal for the main speakers.
 

voodooless

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Presumably providing the audio signal for the main speakers.
So we’re talking about high pass filtered pre-out’s of a sub amp then? That might make some sense. You can do a simple test: hook it up, if you don’t hear any noise, noise it not an issue.

But in general there might be other problems: if you can adjust the frequency (or slope) independently from the low pass, the adjustability might not be good enough to get proper integration. In general it’s better to do most of the integration upstream.
 
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