High Pass Filters

[keenween]

I just ordered some 85hz high pass filters from ACI. I thought I might start a thread for people who have tried these and want to share their experiences.

My system is:
SB3 -> BPA-1s -> RS-450s & ERTs
-> RDES & UFW12.

I am inserting a passive controller (VPC3) after the SB3 with two inputs/outputs and so my new system will be:
SB3 -> 1 VPC3 1 -> 85hz HPFs -> BPA-1s -> RS-450s & ERTs
CDP -> 2 VPC3 2 -> RDES & UFW12

I am was pretty happy with the existing system, I'm just hoping to lighten the RS450s load with the HPFs and squeeze out a bit more clarity and dynamics. I think this may have a similar effect to upgrading to higher wattage amps.

[billnchristy]

I have always been curious about these but scared too since most of them are called "crossover simulators" I never quite understood what that meant.

If it doesn't work out, Behringer has a 2-3way electronic crossover for like $150.

[keenween]

Here is how to design one:

https://www.t-linespeakers.org/tech/filters/passiveHLxo.html

[CloudStrife]

How does an active crossover send separate signals to each driver?

[billnchristy]

You have to amplify each driver seperately.

[keenween]

The 85hz filters I ordered arrived. I have installed them. I can't really give too much at this time. I don't think I notice a decrease in performance. My system has been handicapped for sometime and I have been really busy...so I almost feel like I have to relearn what it will provide. So I figure I will keep them in for a few weeks and then remove them and do some testing to see what difference, if any, I think they make.

[billnchristy]

Cool.

I will be able to design and build high/low pass active filters soon too if anyone needs help with that.

[keenween]

Cool.

I will be able to design and build high/low pass active filters soon too if anyone needs help with that.

Very cool. Its hard to find ones for the low dollar.

[billnchristy]

Which is a shame considering how simple they are really. :thumbsup: I guess it is because they do such a valuable job.

[keenween]

The 85hz filters I ordered arrived. I have installed them. I can't really give too much at this time. I don't think I notice a decrease in performance. My system has been handicapped for sometime and I have been really busy...so I almost feel like I have to relearn what it will provide. So I figure I will keep them in for a few weeks and then remove them and do some testing to see what difference, if any, I think they make.

Well...I've had these in for a while. I can't say that I've really noticed an improvement in performance...I will be making some system adjustments soon and try the system without them again to see if I notice a difference removing them.

Some of the system improvements should make my system more resolving (fingers crossed), so I will do a repeat and try my reworked system with and without.

[Chane M&C]

So, it's been several years since I have played with crossovers so please forgive if I mis speak.

Are you talking about these? These filters have a pretty shallow slope of 6 db/octave. I don't remember how exactly how to read the ratings. If I were to guess, I would say that these indicate that the speakers should have -6db output at 85 hz with the crossovers installed. I suspect your subwoofer is also producing a lot of sound in the 85 hz region so simply crossing over your main speakers might not make any noticeable impact.

I think before you spend money on high pass filters like this, you might want to ask what you are trying to achieve. The solution might involve more than just installing some in line filters.

As an example... some speakers have a natural roll off that make them have little usable output below 100hz. Speakers like this, mated with a decent subwoofer might sound perfectly fine without high pass filters. In other systems, you might have a lot of output below 100hz from your main speakers. In those cases, you might need a high pass filter with a pretty steep crossover slope at 12db/octave or better.

Disclosure: Very little experience in tweaking sub/satellite systems in the home.

[snock]

I am just trying to understand your setup - Is the SB3 acting as your preamp I guess?

I have used similar devices before (F-mods i think) and the effects weren't terribly obvious but you have the piece of mind you aren't pushing your mains too hard. will you be performing sweeps of the before and after?

[billnchristy]

I do believe an active filter box could be made that would do the job and do it in a very small amount of space.

A calling card box sized unit could have a self contained PSU and allow in/out and even thru if you wanted to test the difference.

You could probably make a wall-wart powered unit about the size of a cigarette pack.

Note that these would be set frequencies though I suppose a variable freq. one is possible but would add a lot of complexity.

If anyone is interested I would be willing to build one for parts cost just to try it out.

[keenween]

So, it's been several years since I have played with crossovers so please forgive if I mis speak.

Are you talking about these? These filters have a pretty shallow slope of 6 db/octave. I don't remember how exactly how to read the ratings. If I were to guess, I would say that these indicate that the speakers should have -6db output at 85 hz with the crossovers installed. I suspect your subwoofer is also producing a lot of sound in the 85 hz region so simply crossing over your main speakers might not make any noticeable impact.

I think before you spend money on high pass filters like this, you might want to ask what you are trying to achieve. The solution might involve more than just installing some in line filters.

As an example... some speakers have a natural roll off that make them have little usable output below 100hz. Speakers like this, mated with a decent subwoofer might sound perfectly fine without high pass filters. In other systems, you might have a lot of output below 100hz from your main speakers. In those cases, you might need a high pass filter with a pretty steep crossover slope at 12db/octave or better.

Disclosure: Very little experience in tweaking sub/satellite systems in the home.

The link you have is correct, thats what I installed...and already spent the money on. The speakers I'm using (RS450s) are +-3db to 38hz and do have usable output below 100hz. My concern wasn't so much with sub integration, it was more just reducing the signal load the 450s would have to reproduce, and possibly having a better output.

[keenween]

I am just trying to understand your setup - Is the SB3 acting as your preamp I guess?

I have used similar devices before (F-mods i think) and the effects weren't terribly obvious but you have the piece of mind you aren't pushing your mains too hard. will you be performing sweeps of the before and after?

I have the VPC3 as my preamp, its a passive unit...pretty much just volume control...check it out here: www.ciaudio.com

I haven't found the effects to be terribly obvious either...but it does make me feel better when I'm watching super basstastic movies.

I will perform sweeps although I haven't yet. I actually haven't done much work to ensure proper integration of my sub yet...I'm waiting for my other one to arrive, and then they will be out for upgrades...and I'm in an apartment right now anyway so I like to keep the bass down. However, playing subless the filters have stripped the lower frequencies that much was obvious. It was hard to hear an increase in performance from the upper ranges. I've removed them and played subless as well. I again don't notice much from the upper registries, I more realize how much I enjoy the bass from the sub.

I hope all that makes sense...