High pass filters with a powered sub

[risabet]

Recently I purchased some 65Hz high pass (they also have them @ 85Hz) filters from Audio Concepts Inc Audio Concepts. and placed them between the preamp and the amp to roll off the bass to the amps/main speakers (65Hz @ 6dB/octave). I was not expecting the improvement that I am hearing in imaging and openness in the high frequencies and midrange. I am also noticing a tightening of the low bass with a better ability to follow complex bass lines in both popular and orchestral music. This is a very positive addition w/o any apparent veiling or losses audible.

The sub is rolled out at the lowest freq possible i. e. 50Hz @ 12dB/octave. Frequency is variable but the slope is fixed.

Because it is a simple capacitor the phase shift is a nice 90° and isn't audible to me and didn't require a change in speaker position. For those who can't get a sub to work with their mains (Roberto ) this is a cheap, $40 including shipping, tweak to try, you may be surprised.

Why? I think for two reasons:

1. The woofers in the Clarity's aren't all that good in the bottom octave, distorting and muddying up the higher frequencies it is asked to reproduce, Clarity x-over @ 450Hz, and

2. The OPT core in the amps is less saturated w/o the last octave and 1/2 of the bass to pass thus allowing more efficient usage of the trafo at higher frequencies.

Those of you with CLSs/subs and no active x-over might want to give these a try. Getting the lowest frequencies out of the speakers and main amps may be a very good and cheap upgrade. It certainly is for me.

 

[zaphod]

i'm confused. you roll off anything below 65Hz from going to the mains. but you have your sub set to handle 50Hz and down.

what have you got against the frequencies from 51 to 64Hz? i must have misread what you wrote.

 

[DTB300]

Recently I purchased some 65Hz high pass (they also have them @ 85Hz) filters from Audio Concepts Inc Audio Concepts. and placed them between the preamp and the amp to roll off the bass to the amps/main speakers (65Hz @ 6dB/octave).

The sub is rolled out at the lowest freq possible i. e. 50Hz @ 12dB/octave. Frequency is variable but the slope is fixed.

I have been playing around with my mains having an 80Hz/6dB High Pass. My sub has variable xover points and slopes for both low pass and subsonic. After many changes with the setup of the sub, I have found a very good configuration, and as you, I too like the change I am hearing. Clearer mids and highs. There is not an issue with my amp by any means with the low end and its reproduction. But I agree that any amp will benefit to a different degree when the low end demands are relieved from it. Even though the CLS does a good job with bass, they sound even better when the very low bass is removed from them.

I wish ACI would make some other ones instead of just the 65 and 85. Ones at 100 and 120 would be a great addition.

i'm confused. you roll off anything below 65Hz from going to the mains. but you have your sub set to handle 50Hz and down.

what have you got against the frequencies from 51 to 64Hz? i must have misread what you wrote.

Zaphod...really great to see you back on the site!!!

Others here can probably explain better than I...But each of the Xovers are not like a brick wall where the sound stop, but has a drop off of 12dB and 6dB in this instance. Hence there is music still occurring from the sub and mains in the region you ask about, and this combination actually adds up both signals and causes the gap to be either flat or sometimes a bump - depends on the slops and xover points. Go to Marchand Electronics site as they have some great stuff to read on Xovers.

Dan

 

[risabet]

i'm confused. you roll off anything below 65Hz from going to the mains. but you have your sub set to handle 50Hz and down.

what have you got against the frequencies from 51 to 64Hz? i must have misread what you wrote.

Nothing, I like them all There is an overlap between the 65Hz rolloff and the 50 Hz rollin, so to speak. That combo gives me the smoothest response in that transition area but there is some experimenting to do to be sure.

 

[onlyMLsub]

high and low pass filters Abyss

Hi.....new here. you can see from my user name I am only using a ML sub. Have had it nearly 2 years. Great tight bass.

I am trying to research the roll off and crossovers people are finding with the Abyss sub, and came across this thread.

I am considering doing something similar to risabet by using inline high pass filters. My speakers (devore) have a freq response of 36Hz to 40kHz. I was considering using a high pass filter...likely a 50Hz to free them up from the lower frequencies.

ACI has 65 or 85Hz but Harrison Labs has a range of passive inline filters....
http://store.hlabs.com/pk4/store.pl?section=9


My Abyss low pass issue.

But the other thing I found is my in room testing of the Abyss by itself (test tones and Radio Shack meter) I found that the Abyss's low pass crossover settings seemed to have little effect. Sure room conditions come into effect but essentially I had the Abyss Low pass set to 30 Hz and was getting readings from the meter at 120Hz about -10db. I was expecting something at about 50Hz to bleed through but

So I am thinking about adding inline passive filters as well to limit the Abyss output.

Anyone have any thoughts on this?

cheers, e

 

[risabet]

Hi.....new here. you can see from my user name I am only using a ML sub. Have had it nearly 2 years. Great tight bass.

I am trying to research the roll off and crossovers people are finding with the Abyss sub, and came across this thread.

I am considering doing something similar to risabet by using inline high pass filters. My speakers (devore) have a freq response of 36Hz to 40kHz. I was considering using a high pass filter...likely a 50Hz to free them up from the lower frequencies.

ACI has 65 or 85Hz but Harrison Labs has a range of passive inline filters....
http://store.hlabs.com/pk4/store.pl?section=9


My Abyss low pass issue.

But the other thing I found is my in room testing of the Abyss by itself (test tones and Radio Shack meter) I found that the Abyss's low pass crossover settings seemed to have little effect. Sure room conditions come into effect but essentially I had the Abyss Low pass set to 30 Hz and was getting readings from the meter at 120Hz about -10db. I was expecting something at about 50Hz to bleed through but

So I am thinking about adding inline passive filters as well to limit the Abyss output.

Anyone have any thoughts on this?

cheers, e

It appears that the Abyss is rolling off at about 6dB/octave so 30Hz is flat, 60Hz is 6dB down, and another octave or 120Hz is about 12dB down. Keep in mind that the Rat Shack meter IS NOT linear at all frequencies so any measurements are suspect w/o the correction table Correction Table