Subwoofer crossover setting question

john22614

I just bought a new PSW1000 to go with my LSI9's and LSIc. I'm running a Yamaha rxv630 as a pre to an Anthem MCA 3 amp....and all is good. I'm using the LFE out from the AVR to the sub with a Y splitter. The crossover on the AVR is set at 90hz and can't be changed. The 9's and Lsic are set to "small".


I have noticed, however, that using a splitter to the sub allows me to adjust the crossover in the sub setting all the way up to 140HZ. When I do this.....it sounds good. As you know, the PSW1000 is a high quality musical sub....but I'm wondering....am I over doing it? The volume of the sub is set ata modest amount....in the "just there" range. Does this setting give me better quality bass than say 90hz which would allow the 9's to handle the 90 - 140 range on their own? Am I violating some sacrid code of bass management by setting the sub crossover this high and defeating the sound of the 9's in this range?

I really value the opinions expressed on this forum and love my Polk speakers....very interested what you all think on this issue.

Thanks, John

phuz

If it sounds good to you, keep it that way. If not, try different things.

IMO, having the sub set that high is bad because in that range you will start to loose the non-locality of lower frequencies. In other words, you'll be able to hear that the sound is coming from the location of your sub. Sub placement relies a lot on the fact that sub bass frequencies are non directional. One generally wants anything from 90 or 100hz up to be coming from the front, or at least shared between the sub and front.

I'd keep the crossover point at around 90hz or lower.

Also, try not to double filter. Use either the crossover on your receiver or on the sub. Not both.

aaharvel

try the double filter. 90hz from your Yamaha, 80hz from the sub. I double filter and that's the best option for my system. Running the sub full range sounds awful, and running monitors full range as "large" makes little sense.

Welcome to Club Polk.

MacLeod

Not crazy about the double filters. You can run into phasing problems that way and it can cause the sub to not blend well with the midbass drivers.

Its been my experience that a good 24 db/octave slope works best for blending.

I agree with the localization of the sub at higher frequencies. Generally anything above 80 starts getting easier to point out where the sub is. If I had the choice between 80 and 90 Id go with the 80 - lower if it were possible.

phuz

MacLeod wrote: »

Not crazy about the double filters. You can run into phasing problems that way and it can cause the sub to not blend well with the midbass drivers.

Its been my experience that a good 24 db/octave slope works best for blending.

I agree with the localization of the sub at higher frequencies. Generally anything above 80 starts getting easier to point out where the sub is. If I had the choice between 80 and 90 Id go with the 80 - lower if it were possible.

Well said. Those LSi9s will sing at 60hz and even lower. Use the sub as a sub and keep it out of your midbass range.

You might want to ditch the splitter as well. LFE isn't meant for that.

Experiment more, and let us know what you find out and what you like!

john22614

Hey guys.....I really appreciate you comments.....first of all....setting it back to 90 elimonated the localization that is noticeable even though the sub is up front between the 9's and has such clear, crisp bass.....in addition, i really like the sound of the 9's down to 60 also....so, after a little more tweeking....i will update you on what i think. Will try without the splitter and drop it down to 80 and see how that sounds. This is my first real venture into the world of hi quality hi fi, and i am over the top crazy about my system.

john22614

MacLeod......what is a 24 db octave slope? I'm doing all of this by ear...mostly because i have to tame the sub 'cause i share a wall with another townhouse....i can play it at a moderate volume i estimate a few db's below the mains and get away with that.....afraid if i calibrated with the meter i'd end up with complaints. I turn it up 'till it is clearly but mildly noticeable and leave it there. Sounds pretty good actually, but doesn't dominate.

MacLeod

Im a car audio guy so Im not very familiar with the gear you guys run and what tuning features they have so you may not have this ability. Car audio gear tends to have tons of options and the processor I use has 8 channel independant crossover settings, time alignment settings, phase settings, and 31 band EQ. So for each driver I can adjust all those things where as home audio gear (as far as I know) doesnt have that wide an array of options. However the science behind tuning is the same.

Im horrible at explaining these things but here goes. A crossover doesnt cut off at a certain frequency but rather "turns down the volume" on that frequency a certain amount per octave. The db denotes how steep that attenuation slope will be.

A 12 db/octave slope means that the crossover is attenuating response 12 db for every octave. So if you set the crossover at 1000 Hz, 500 Hz will be 12 db quieter and 250 will be 24 db quieter and so on.

So the steeper the slope the faster it rolls off the response for that channel.

The thing with too steep a slope is that it rolls off the response at an "unnatural" level so instead of a nice smooth roll off thatll blend in well with the nice smooth roll off of the other speakers (subs to midrange to tweeter) you get a very sharp drop and that can cause it to not mix well with the other speakers and not only cause it to sound wrong but also cause issues with imaging and even phasing.

There is no magic setting as there are just too many variables but generally even crossover slopes (6db, 12db, 24db) just always seem to work better and cause less issues than the odd ones (9db, 18db, 30db).

john22614

MacLeod....

Thanks for the explanation.....sounds reasonable. Here's what I've settled on (at least for now....you know how this stuff can grab you)....anyway, I removed the splitter....kept all other speakers at small, keeping in mind that my AVR LFE is fixed at 90HZ.....set the sub at 90 and increased the gain a bit because the volume appeared to drop a little without the spiltter.
Set the phase at O (sub is up front between the nines) and also set it at full range on the back as opposed to 80Hz........and now, all is good....everything blends together nicely and sounds great. Thanks to all for helping someone who is fairly new at this and happy 4th!