Welcome! Need support, you got it. Or share your ideas and experiences.
In Reply to: RE: LRS happiest not working too hard posted by G Squared on February 07, 2021 at 12:23:06
What frequ are you rolling off the LRSs at?
I am using the Loki's 20Hz control to reduce the bass to the LRS and using my Rythmic sub's crossover to bring the sub in at 60Hz. The sub has a parametric eq that I use to tame a room node as well. The integration is very convincing.
Your Rythmic sub comes in @60Hz (great sub btw - I have one in my 2nd system, with some standmounts!) - ie. this is the sub low-pass frequency.
But the high-pass frequency on your LRSs ... is 20Hz?
If so - I suggest that's completely useless ... as the LRSs don't go down to 20Hz.
With the sub LP filter set to 60Hz ... you need an LRS HP filter @ 60Hz - or maybe even 80Hz.
It works. The attenuation is gentle and wide enough.
If I assume that the control attenuator is "linear," then based on the position of my control I am cutting approx. 3 db at 60 Hz from the LRS amp's input. That seems about the right. The results are good to my ear.
Aah, OK - I'm sure it does have some effect. LOL!
When I do things ... I like to do them well - so they are optimal, rather than just 'working'.
You would seem to have a different approach to life - which, of course, is not a problem. I was merely trying to help you get a better result than what you have now.
It sounds like the preamp high pass takes enough energy out of the Maggies to significantly reduce their excursion and improving the Maggie dynamics.
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.
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.
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.
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.
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.
I use a set of 100HZ in my trunk to roll off my car stereo's tiny rear fill tweeters.
If they're tweeters , I wouldn't have thought they actually go down to 100Hz.
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.
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?
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.
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