805 + SVS sub: Your help/comments please

[audioqueso]

So I just purchased my SVS sub to accompany my Nautilus 805s, the PB12-ISD. This thing is huge. Well, I've been playing around with the placement and settings, but somehow seem a little disappointed. My room size is 18x30, but I have my actual sitting position set up more like 18x20. I have used a SPL meter to set my freq range as neutral as possible, but because of the room dimension (and all tiles), the bass can easily disappear. I have my sub settings at 180 degree phase, 65Hz cut-off, and the gain at the 3rd notch (4th notch is 50% gain). My 805s are at full range. I've attached my best and current readings to aid my topic.



As you can see, my sub seems to favor from 28Hz to 38Hz. This is good for movies, but I want a more musical feel. There isn't much in music (aside double bass and organ) that usually plays that low. I want a better 35Hz to 55Hz because for my music, that's where it's at. If I raise the gain, I get too much of 28Hz to 38Hz, and that sounds bad if it's too much in music. But if I lower the gain to eliminate the 28-38, then I lose the 35-45 range as well. For those with a 805 and sub, how have you come along in a nice blend? Thanks in advance.

[scottielee]

bass traps in corners are the first things i can think of. have a look at these:

https://www.rpginc.com/residential/cinemusic-products.htm

https://www.realtraps.com

https://www.asc-hifi.com

does your processor has bass management? i would try adjusting it if available.

i personally use the digital equalizer that came with my velodyne dd-12. here are my system response charts: https://www.htguide.com/forum/showth...ighlight=dd-12

[greggz]

Are we talking about a stereo setup or a HT setup?

If we are talking HT, the make sure you have your speakers set to small and your processor crossed over at 60Hz.

If we're talking good old analog stereo, then my guess would be that the crossover on your sub is set too high.

You are sending a full range signal to the 805s. The 805 is a ported speaker. All of the bass that comes from the port is out of phase with the bass that comes from the mid/bass driver.

You correctly have your sub set to 180 degrees out of phase. But with your crossover set at 65 Hz that means that your sub is producing "out of phase" bass in the frequency range handled by the "in-phase" mid/bass driver and therefor causing cancellation.

[greggz]

The more I look at your graph the more I agree with my assertion that your sub's crossover is way too high for stereo. The port on the 805 is tuned to somewhere around 40Hz. That hump you have in the 30 to 38 Hz range is out-of-phase bass being heaped on top of out-of-phase bass and then that sharp drop you see in the 40 and 50 Hz range is cancellation occurring from out-of-phase bass encountering in-phase bass.

I'd lower the crossover to 30Hz and take new measurements. There will probably be a dip somewhere near 40Hz. Gradually increase the crossover and take new measurements until you see the dip go away. You may even be able to bump up the gain some when you remove that "double bass" issue you have right now.

Remember a sub's crossover isn't a brick wall. Bass begins to taper off at the crossover point (typically a -12dB slope).

What you are looking to do in a stereo setup is to augment (not replace) the bass from your speakers (in HT you literally transfer all the bass duties from the speakers to the sub). You want to get the sub's crossover set so that it starts tapering off the bass as your speakers are starting to be able to produce bass. On the 805's the -12dB point is going to be somewhere around 30 to 35Hz. This is where you'll want your sub's crossover set.

The analogy I would use is a baton pass in a relay race. Done correctly, its a seamless transition with no loss of momentum between one runner who is accelerating and one who is decelerating.

[audioqueso]

HT and Music, but my problem is with music. HT is find since the bass seems to favor betwen 28Hz and 38Hz. My xo is set to 65Hz. I think I will measure my 805s first to see what it looks like. Also, my processor xo is at 80Hz. The bass management is minimal. And unfortunately, I do not have any EQ to lower my freqs that are a little bit too strong. My guess is only because of THX, cause for music that xo is way too high for me. I'll try it out again. Thanks.

[audioqueso]

Well, I played around with my settings and xo's, and at the end I had my sub at 45Hz and at around 40% gain.

Here's my freq response. The bold blue is my 805 + sub response when played together. So far my best settings.



But as far as sound, I don't like these setting. On paper it looks good, but in audible response, the bass was disappointing. The deep notes would play, but overwelming, and if I lowered the gain on the sub, I would not get any bass. I'm wondering if a 12" sub is what I really need. It sounds great with movies, but I'm more concern about music. I'm wonder if two small quality 8" would sound better. What should I do next?

[greggz]

One of the complaints you will often hear as people get closer and closer to a flat response curve is "it looks great on paper but it no longer thrills my ears."

What you may be more interested in is trying to achieve a "house curve". Rather than tweaking for flat response, you tweak for different shape response curve.

It is frowned upon here to cross post to other forums. But if you were to look for postings on "house curve(s)" on another Home Theater Forum (especially posts by Wayne A. Pflughaupt) you may find an alternate approach.

Also, don't forget to look into bass traps like scottielee suggested earlier. Often times, though it may seem counter-intuitive, removing bass will actually make more bass.

Take a look at this other post of mine for a quick and dirty tip on testing how effective bass traps would be in your room

http://www.htguide.com/forum/showpost.php4?p=193966&postcount=10

Lastly, you've never mentioned your room dimensions. Have you ever used one of the room calc websites or spreadsheets to determine the modes of your room? It is possible that your rooms dimensions could be causing some of your problems.

http://www.google.com/search?hl=en&rls=DVXB,DVXB:2005-27,DVXB:en&q=room+mode+calculator&spell=1

[Briz vegas]

Very interesting discussion guys. I get a similar frequency response from my 705/Strata 5 set up (only above 25hz, the curve well and truely heads south by 20hz - but that is of no concern for music). I have a dip at 63hz (the "doof" zone) which has corrected by 50hz. This is a room problem as far as I can tell. Even when I experimented by bumping up the crossover on the sub so that it is operating in the doof zone I cannot iron out the kink in the graph. Currently I have the crossover at 45hz, the 705s running full range and using both the high and low level connections to the sub.

I did not know that the port on my 705s was out of phase with the mid/bass driver. I have my sub phase on 0 as recommended by the Rel sales guy. I may have to experiment with phase and using the port plug. Pity I had to return my borrowed SPL meter to the dealer. I am happy with the overall balance of the sound and I think that is the important thing.

By the way, I call 63hz the "doof' zone after working with noise pollution officers in our night club district. Outside the clubs our noise meters (which are worth almost as much as a pair of 800Ds - and no they do not let us take them home) showed a huge spike at 63hz. Of course we were measuring the music from the clubs, not the frequency response of their sound systems.

[audioqueso]

What you may be more interested in is trying to achieve a "house curve". Rather than tweaking for flat response, you tweak for different shape response curve.

I started looking at this. Sounds interesting, but I didn't get to fully read into it. I'll have to read some more.

Also, don't forget to look into bass traps like scottielee suggested earlier. Often times, though it may seem counter-intuitive, removing bass will actually make more bass.

lol... I'm gonna go to Home Depot today, and I can't wait to see the response from my wife. I'll tell her it's permanent and let her get upset first. lol

Lastly, you've never mentioned your room dimensions. Have you ever used one of the room calc websites or spreadsheets to determine the modes of your room? It is possible that your rooms dimensions could be causing some of your problems.

I wrote on my first post that my room is 18x30. But I have it set up so it's more like 18x20. I have the speakers facing the wall that is 30', not facing 18' wall. But I guess for my sub it doesn't matter... it's still 18x30.

[greggz]

I wrote on my first post that my room is 18x30. But I have it set up so it's more like 18x20. I have the speakers facing the wall that is 30', not facing 18' wall. But I guess for my sub it doesn't matter... it's still 18x30.

My bad, I missed that part initially. What is the height of your ceiling? How far from the back and side wall are your 805's? Where is the sub located and how far from the walls is it? And, where is your primary sitting position (distance from front wall and side wall)?

Also, anything unusual about the room (lots of glass, large openings, etc)?

[audioqueso]

The 805's are 2 feet from the back of the wall, and the sides are not close to the wall. Sub is 1 feet away from the back and side of the wall (corner). Ceiling is 8" high. And there's all sorts of obstructions since this is Miami. One wall is all glass (sliding door), the other wall is all mirror (previous owner did that, and I just didn't bother taking it down), Mexican tiles. A very cold room which is typical is south Florida.

You know, I actually listened to a sub that sounded very nice to me. Velodyne SPL-R 800. Sealed sub. I was looking for a sealed sub because I think a lot of my excessive bass is ported bass. I always preferred sealed subs over ported when it came to car audio, and just started thinking with the same mind. So yeah, I heard it today and liked it. I think I'm going to give that sub a try as well. It's smaller, looks a whole lot better (wood grain to match my 805s) and cost the same. I'll see how that goes.

Comments on Velodyne? Always heard good things, but never have owned a Velodyne.