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In Reply to: RE: Subwoofer placement suggestion given restrictions (kenster) posted by Presto on July 04, 2012 at 13:35:11
Good questions.
Kester in a 2008 posting in response to a question I had talked about his preference to having a subwoofer firing directly up as opposed to straight forward or downward (I hope I'm stating this correctly). His advise about the benefit of getting the sub off the floor was spot on. Definitely tightened up the bass. But for me to do upward firing of the sub given that is not designed for that orientation requires building a frame to hold it so that I can make the electrical connections. So positioning the sub at an upward angle would be the easiest thing to do - but is there any benefit from that? To answer your other questions, I think I have too much of the bass sound from the left, not bad, but not correct. And still more of a flabby sound than I prefer or think is correct from an instrumentalist point of view. Cross over points between the monitors and sub I think are OK. So to improve the performance, is the solution: a) tweaking the location of sub b) Modifying the design of the speakers (see other posting) c) I'm at max performance of these speakers. If I want better sound simply buy better speakers. Option-A costs no money. Option-B maybe $200. Option-C $2K+.
Follow Ups:
Configuring the crossover properly is more important than how you "aim" the sub. Since the sub's frequencies are so low, the radiation is omnidirectional and orientation should be irrelevant.
So, let's have the specifics of the setup.
Bass frequencies are omni directional making the "aiming" of the sub irrelevant. What is wrong with your setup that displeases you?
The word "displeasing" would be incorrect to use. It seems as if I'm getting a little domination of the bass from the left side, where the sub currently resides. And the bass seems to be a little uncontrolled, not as tight as maybe it should be. Monitors sound good.I'm wondering if I re-locate the sub it might tighten up the mid and lower bass. It is a fairly well sounding system. I'm just wondering if I make a simple change I can get more out of it (in other words, my current location of the sub by an outside observer is just plain dumb. If I put it somewhere else I would immediately notice an improvement). Or as asked in a related posting, is my answer in doing a simple mod to the sub to enhance it's performance (i.e., rope calk enclosure and speaker frame, remove amp from back of enclosure, etc...). In other words, the sub is simply performing up to its level of design and build quality. It is a $400/$600 sub, not a $2,000 - $3,000 sub. Sub has a 10" cone with a 250 watt amp.
Setup: Coming out of the AGI preamp I split the signal through a Y connection. One side of the Y goes to the Main Amp which drives the NHT Classic 3's full range. The other side of the Y goes to the NHT SubOne Subwoofer Controller. I've previously sent the pre-amp signal to the Controller and had it split the signal to Main Amp for the Monitors and to the Sub, but the Monitors didn't blend in as well with the Sub. The setup sounds better when the Monitors are allowed to see the full signal (others may wish to differ on this). The Subwoofer Controller has been set will a low pass setting at 80, 90, 100 Hz. Changing the setting doesn't seem to have a noticeable difference. 0 dB gain to Sub.
Which brings me back to following. The simply changes of taking the grills off the Monitors and elevating the Sub off the carpet by 14" made the system sound cleaner and tighter. So, is there something simple in there a simple re-orientation of the Sub that would provide further improvement.
Edits: 07/05/12
Tough call. Repositioning may reduce the problem but given the omni directional qualities of bass, I think that maybe your crossover setting is set a tad to high. The higher a sub has to play the more the localization effects come into play. I would try the easy thing first by playing with the crossover. If that doesn't help, reset the crossover to where you ahd it and then play with placement.
Hi Charlie,
It appears that the most likely culprit for the problems or "displeasure" you're describing is that the subs Low Pass setting is too high in this particular sub location. What is the range of Low Pass settings on the controller and can you select the Low Pass slope as well?
If the available Low Pass settings are not low enough, one can insert line level crossovers such as the FMODS available from Harrison Labs before the subwoofer controller to produce a much lower Low Pass frequency.
There are other ways to "clean up" the bass by mechanical means but lets start with the crossover first and let's leave the sub located where it's currently at.
Cheers
Kester, thank you for the input.
Low Pass feature on NHT Sub Controller is variable down to 40Hz. I'll start to try incremental settings below 80Hz. with approximately 5Hz steps.
Another problem might be the fact that you constantly looking at the subwoofer so you know where the bass is coming from. I've had a sub/satellite system for the past 15-years or longer and I've always placed my subwoofer behind my listening position approximately the same distance from my ears as the front satellites. My subwoofer is set for 55-Hz low pass and it seems to blend perfectly with my satellites. In other words, all the bass seems to be coming from the satellites at least 90% of the time. Occasionally I hear the subwoofer behind me, but very rarely.
Good luck,
John Elison
HA! Someone said it. Visual cues due to the sub location... Excellent point! Maybe this is why some like two subs in symmetrically opposing sides of a room? :)
I still think shallow slopes/too high a point (or both) are the biggest offenders.... Mismatching sub crossover point with a speakers natural rolloff point is another source of potential integration grief. 90% of the time when I've been asked to come help out, the sub is set 20 hertz too high. Sometimes an entire octave too high. I can't see why people cross in subs over 100hz with floorstanders that go down to 50 or lower. But they do. Perhaps it's because they believe a sub will "add more bass" which it really does not do. It's supposed to add sub bass and when you crank up the Fc point to get sub bass plus BASS bass, you get severe localization effects.
Perhaps some guys don't need a sub at all, but rather an equalizer to get the "bass" they truly desire. Or just different main speakers in the first place. You can't fix the "bass" of a speaker by adding a sub - you can only add the missing subsonic frequencies. The only way to add sub AND bass is to position the subs directly beneath a standmount speaker and turn a 2-way into a 3-way. Then you can cross over as high as is practical given the drive unit sizes and spacing, as high as 200 or even 300Hz. But no longer is this "adding a sub", but instead, adding a wide range woofer to a 2-way standmount. It becomes a semantics issue at that point.
This is why I've never liked side-firing speaker designs that cross over into the 150-200Hz range to small midbass drivers.
In any case, I think the above explains where MOST guys go wrong.
Cheers,
Presto
55Hz for the low pass? That seems really low to me. Is that typical? I thought 80Hz was a good point in general. Recharging my CD player battery. I'll be experimenting with the cross over point on Saturday.
While it's true that below about 80 Hz, we lose a significant ability to detect the source direction of a sound, it's important to remember that a sub doesn't get "chopped off" at the crossover frequency, AND that our subjective impression of good bass (or "punch" or "thump") is enhanced by the boosting of frequencies in the range of about 100 Hz to 200 Hz.
As I'm not familiar with the particular sub you have, I'll just offer that, if you're crossing it at 80 Hz, you may still be getting noticeable output above 100 Hz, contributing to the localization that you mentioned. I would agree with another poster (sorry I can't see the post at the moment) that crossing much lower, such as 55 Hz, may be beneficial. Alternatively, if you need to cross higher due to limitations of the main pair, in the 80 Hz range, two subs (left and right) may be in your future.
80 is too high. It's a thumb rule for hometheatre and nothing more. How low can your speakers go? Surely lower than 80.
Every subwoofer integration I do here uses 24db/octave lowpass for the sub and a crossover frequency from 50-65hz depending on which speakers I am using the sub with. The 65 hertz situation is with a sealed box design with 7" midbass drivers. The 50Hz situation is with a ported design using nominal sized 8" "midwoofs".
Unless you're running 5" high-Fs drivers in a sealed box there would be no need to cross over so high.
The NHT may also have 2nd order (12db/octave) slopes, making it very hard to elminate localization if crossed over above 55 or 60Hz.
80Hz with a 2nd order is almost always locatable IME. 80hz with 4th order is bad enough... I like 4th order, 65 MAX.
I don't own a speaker that requires a higher crossover point and except for home theatre I don't recommend that one does! ;)
Cheers,
Presto
The NHT Classic 3 has what they call a 6.5" woofer with a very long throw. Specs say it goes down to 45 Hz.
Given the constructive insight, I will be trying much lower points below my initial setting of 80 Hz.
For those reading this, I'm going to try to complete this exercise by Sunday and do a posting. If you don't see a posting from me by than it is because I'll be in and out of town for the next two weeks.
Thanks everyone for their input.
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