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In Reply to: RE: It works ... posted by hahax@verizon.net on February 07, 2021 at 21:15:05
as the HP filter in the 'Loki' appears to:
a) be 1st order (the blurb says "shallow slope"), and
b) operates at 20Hz
... it is not doing a great job of reducing LF excursion on the LRSs.
A far better approach (if the OP doesn't want to go to an active filter) would be a 12dB line level passive filter on the inputs of the amp driving the LRSs - this is made from a small cap and a resistor (on each channel). Values depend on:
1. the input impedance of the amp, and
2. the desired roll-off frequency.
Andy
Follow Ups:
I understand the difference between a tone control and a crossover. I will give a passive HP crossover a try. I made a simple one for my son's small Pioneer mains and it works well in his 2.1 system. The Loki is there so I used it. I have time to experiment. Thanks for the advice.
Gsquared
a pair of Harrison Labs FMOD in-line 70Hz high pass attenuators would do an excellent job of rolling off your LRSs (and I suggest will be exactly right with your current 60Hz sub setting).They seem to be 12dB.
Andy
Edits: 02/09/21
Thanks for the suggestion. I almost went for a set of the cable FMODS. That would have given me the flexibility to use 50 or 70 HZ and may have worked out for my system with the (now in need of repair) ProAcs. I like the packaging of the in line units better.I will let you know how it works out.
Gsquared
Edits: 02/09/21
That will be interesting to know. :-))
Andy
Has anyone tested these Harrison Lab filters? I remember reading in a car stereo magazine several years ago that did a review of them. It turned out that the advertised 12dB/octave slope tested at being only 6dB/octave.
-
Edits: 02/10/21
.
I use a set of 100HZ in my trunk to roll off my car stereo's tiny rear fill tweeters.
Gsquared
100Hz?
If they're tweeters , I wouldn't have thought they actually go down to 100Hz.
Andy
They are actually advertised as 3-1/2 in two way full range marine speakers, but they puke up any input signal below 100Hz. They only add a little fill so the sound is not all from the footwell.
Gsquared
Edits: 02/09/21
The Harison Labs FMOD inline high pass antenuaters works great. I use them for the same purpose. No extra cables, no power supply needed.
I see they offer, say, a 70Hz HP attenuator ... but isn't the amplifier's input impedance (Zin) relevant to the component values in the HP filter?
Or do you supply your amp's Zin to Harrison Labs and they then send you the appropriate FMOD for the specified Zin?
Andy
In the Fmod's the components are scaled to low impedance values so the attached load resistance does not alter their operation, much.
As long as the source is low output impedance and the load is equal to a greater than a nominal input resistance, they will work as advertised.
The low-pass ones have an insertion loss though, which needs to be understood.
Dave.
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