# New to the Shack, my first BFD graph :)



## O_ROD (Oct 20, 2006)

Hey guys, This is one of my first posts and first time using the BFD. I had a blast with it and it made a world of a difference. This site has helped out alot as well, very well done. I built a 2.1cu ft sealed Adire Shiva w/ 360 watts xover @ 90Hz. Here's how it looks before and after:










Having a hard time with the 2 valleys at around 28 and 56. Tried everything but can't get them any flatter. You can see where it rolls off at 90, Should I bother Eq'ing passed that point? Let me know what you think and feel free to post your graphs, I'd love to see em! Thanks...:T


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## Sonnie (Apr 11, 2006)

Hi O' and welcome to the Shack!

Not bad at all really... how does it sound?

I wouldn't really call those two small variances a valley... but if you wanted to try a house curve the one at 56Hz would probably disappear with the right filters.

Have you thought about trying out REW?


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## brucek (Apr 11, 2006)

> Let me know what you think


Looks good. How did you eliminate the 20dB dip at 80Hz?

brucek


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## Gard (Sep 5, 2006)

brucek said:


> Looks good. How did you eliminate the 20dB dip at 80Hz?
> 
> brucek


good question. I hope your sub has a lot of headroom. If your x is at 90hz this will probably make that sub work very hard.

Try setting your sub at 50% level. If that dip still is considerable below your target level, you could be in trouble.

The sub may get some help by the main here, so it may not be as bad as it seems. Try to figure out what causing the dip. An open door, open wall or anything. try moving the mic and see if the dip is relatively constant.


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## O_ROD (Oct 20, 2006)

I tried using the REW using my laptop but had a very hard time setting it up and getting everything working. I got alot of feedback from the RS meter as well. It looks like an amazing program, just, over my head. I kinda enjoy doing it the old fashion way, kinda sick eh? :coocoo: 

Theres only a 3dB difference during those two variances so I'm not too worried about them. I got today off so I'm gonna play around a bit more to get it purely flat. I just wish I could do a little more below 20Hz, but for a sealed box, I'm very happy.

Here's my current filter settings:
Freq. Band. Gain
20 ---- 20 ---- +7
40 (-4) -- 20 - -6
50 ---- 3 ---- -5
63 ---- 4 ---- +16
80 ---- 2 ---- +11

Sounds amazing, no more having to lower the sub output when anything in the 30's hits!
Brucek, you've done a great job with the material you've written. Nice to see your active on the boards aswell, good stuff.

Gard, I've tried finding the culprit of the few dips in the upper range. Not much luck. Doors, windows etc... Although it does seem to be consistently flat around the room now. I metered it along the wall parallel to the sub and theres some loss, but not more than a few Db. My sub would have no problem with the extra gain as I don't push the sub hard at all. What did you mean by trouble??


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## Woochifer (Oct 19, 2006)

Very nice! Of course, I'm kinda biased here because I have an Adire Rava, which is Adire's now discontinued pre-built subwoofer -- a 250W sealed design built around the same Shiva driver. (my BFD response curve is posted below) Judging from the 90 Hz crossover point, it sounds like we're also both using older Yamaha receivers. 

Generally, a sealed box with the Shiva driver won't do much below 20 Hz, but I see that you've dialed in a +7 db boost at 20 Hz. Not sure if you want that because a +7 db at your listening position might create gut-churning boominess if you sit somewhere else. Also, that more gradual tapering off in the bass might subjectively sound more "musical" since that's a natural characteristic with sealed subs. Either way though, you're already doing well with your sub.


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## O_ROD (Oct 20, 2006)

Hey Woochifer, nice to see another Shiva in the mix  

Your sub looks great, very smooth. It's funny you mentioned that boominess at other positions, I noticed it earlier today. It was driving me nuts, I'm going to move my sub to the front corner so I can use the room gain to add to the lower bass instead of using the boost and re-equalize. For a sealed sub the shiva really impresses me in the low end.

I'm actually using a Yamaha HTR-5640, good guess :hail: Maybe you can answer a question for me. My mains, center and rears are all set to "small". And bass output is set to "sub". Now does that mean all material below 90hz from all channels goes to my sub along with the LFE? Or is it just the LFE?

Just curious, I'm planning on adding a sub to the surround channels. I'm going to connect it using the subs speaker ins/outs. How do I go about testing it so I can get it level with the speakers? Connecting it to the BFD would be too difficult so I'm going t leave it out.

I was also thinking of putting the second sub on my center channel instead of the rear, since the center channel has a great deal of material in a movie. 

Thanks.


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## Gard (Sep 5, 2006)

O_ROD said:


> snip...
> Gard, I've tried finding the culprit of the few dips in the upper range. Not much luck. Doors, windows etc... Although it does seem to be consistently flat around the room now. I metered it along the wall parallel to the sub and theres some loss, but not more than a few Db. My sub would have no problem with the extra gain as I don't push the sub hard at all. What did you mean by trouble??


What I meant by trouble is when you put a PEQ in your line and have to compensate for dip(s), you may be in danger of blowing/overloading your sub. To raise the level, either by level on sub or gain in PEQ, you really are using the sub very hard in that frequency. If the dip is narrow it usually isn't a problem. In your case it's relatively wide, so you need to be cautious compensating that dip. The sub need to have the headroom to play 20 db higher than your maximum listening level. Since this is in a relatively high frequency and in the x-over zone, it may not be a problem. Try adjusting the sub phase too, se if that will help you.


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## brucek (Apr 11, 2006)

> Just curious, I'm planning on adding a sub to the surround channels





> I was also thinking of putting the second sub on my center channel instead of the rear, since the center channel has a great deal of material in a movie.


If your speakers are set to small, then all the bass content is correctly redirected to the sub. Adding subs to surrounds or center doesn't really add anything and you have eliminated the ability to equalize (which is pretty **** important in a home environment).

If you need more bass, then best to get a larger sub if want more extension or a second sub (the same as the first) if you want more output and connect to the sub out only on the receiver.

brucek


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## O_ROD (Oct 20, 2006)

I wanted to add a second sub because Dolby material is full range through all channels. If I could I would have 4 seperate subs, 1 for LFE, 1 for the rear, 2 for the front. That way I could have full range sound through all channels. It doesn't have to do with overall output. I mean if you think about it, you lose ALOT of material when not using the full range of each channel. Even if you have 4 competent full range speakers, your center will still lack the full range, in most cases 60 - 20hz. and the majority of a DVD's soundtrack is played through the center. 

I'd love to hear a system set-up with 4 subs as mentioned, I think it'd be an amazing experience. I've talked to people who have done it, and they seem to swear by it.

...Or maybe i'm just :coocoo:


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## brucek (Apr 11, 2006)

> I mean if you think about it, you lose ALOT of material when not using the full range of each channel.


What material do you lose? In fact, the opposite is true.

When speakers are set to small on any channel, *all* the material above the crossover goes to the speaker, while *all* the material below the crossover goes to the sub. 

The sub is designed to handle material below the crossover far more efficiently and with better low frequency extension than a regular speaker. So in effect, you lose material when running speakers full range and you don't lose material when using a sub.

In addition, you are able to equalize a sub, where it is difficult to do so with regular speakers.

brucek


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## O_ROD (Oct 20, 2006)

brucek said:


> What material do you lose? In fact, the opposite is true.
> 
> When speakers are set to small on any channel, *all* the material above the crossover goes to the speaker, while *all* the material below the crossover goes to the sub.
> 
> ...


So, if my rears are set to small, ALL information below the xover is sent to the sub? So that would mean my 1 sub would output 5 channels of low frequencies plus LFE simultaneously at times? I'm not debating subs are more efficient in the lower range, I'm talking about using subwoofers in conjunction with speakers to handle the full spectrum seperately among 5 channels instead of sending all lower frequencies to 1 sub which already has to handle LFE.

Check out this link, it explains it better than I can:
http://www.hometheatersound.com/features/videonoise/vn_20010301.htm


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## brucek (Apr 11, 2006)

> So, if my rears are set to small, ALL information below the xover is sent to the sub?


Yes.



> So that would mean my 1 sub would output 5 channels of low frequencies plus LFE simultaneously at times?


Yes.



> I'm talking about using subwoofers in conjunction with speakers to handle the full spectrum seperately among 5 channels instead of sending them all to 1 sub which already has to handle LFE.


Not a good idea. The bass management in your receiver takes care of mixing the signals along with the LFE and sends it to the single subwoofer. It's designed to handle it.



> Check out this link, it explains it better than I can:


I won't comment on the article other than to say I completely disagree. 

brucek


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## O_ROD (Oct 20, 2006)

I appreciate your input Brucek, I'm trying to learn as much as I can about the subject. Just curious as to why you disagree with the idea, that article aside. It seems to be a logical idea.


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## brucek (Apr 11, 2006)

The article is out of date. Today, receivers and processors route all subwoofer information derived from all channels that are specified as small and including the LFE channel to a common mixer. This information is at a frequency below the crossover setting and as such is not localizable by the listener. When fed to a subwoofer it will in effect make all speakers "full range".

Since the information is mixed on a common subwoofer output, it can be fed to a single subwoofer that can be placed in the best possible position in the room for an even response and it can be equalized to compensate for room resonances. If you attached subwoofers to rear or surround or center speakers the connection will not be equalizable (is that a word?).

The article makes statements such as this: _"Unfortunately, the product you really want for adding bass to the front and center speakers in a single subwoofer, to the best of my knowledge, doesn’t exist: a subwoofer with three input channels._ 
OK, that statement alone should make you stop reading... sheesh.

brucek


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## O_ROD (Oct 20, 2006)

brucek said:


> The article is out of date. Today, receivers and processors route all subwoofer information derived from all channels that are specified as small and including the LFE channel to a common mixer. This information is at a frequency below the crossover setting and as such is not localizable by the listener. When fed to a subwoofer it will in effect make all speakers "full range".
> 
> Since the information is mixed on a common subwoofer output, it can be fed to a single subwoofer that can be placed in the best possible position in the room for an even response and it can be equalized to compensate for room resonances. If you attached subwoofers to rear or surround or center speakers the connection will not be equalizable (is that a word?).
> 
> ...


You make very good points. When I think about it, 4 individual subs all being unequalized and pounding at the same time would sound terrible. I'm not going to even bother trying it now. But lets say for arguments sake, all 4 are flat to 20hz, any difference?

Thanks for the input.


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## brucek (Apr 11, 2006)

> But lets say for arguments sake, all 4 are flat to 20hz, any difference?


It's fairly easy to find a decent location and then equalize one sub. Some people here do two. It takes a bit more fooling around and the two subs have to be identical. 

I would suspect it would be quite a challenge to get four subs flat together in a room, but I suppose you could. They would all have to be driven from the subwoofer out, through four BFD channels, which would make for some fairly long interconnects, but it could be done. It would be uneccessary though, unless you had a massive room. I would think an IB would then be in order.

brucek


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## O_ROD (Oct 20, 2006)

I see what your saying, it's useless having that many subs.

Brucek, Gard. I took your advice on finding the culprit for the dip in the 80hz range in my set-up. I just moved the sub from the wall to the front corner and here you can now see my results. Much happier with it and now I don't have any gain which makes a huge difference when sitting in different positions in the room.










:jump:


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## Guest (Nov 13, 2006)

I currently have a sub connected by high level to the left and right surrounds and another connected to the rears. They are off at the moment and I am currently trying to decide whether to use them in the system and turn them on. They are considerably less potent than the main sub which is a Monolith.

I started to entertain the idea of having additional subs on the surround and rear channels, and setting the speaker type to Large, for the simple reason that I find my sub clearly localizable. I keep hearing that the human ear cannot localize the source but I can. I have a Denon AVR 3802 and its lowest crossover point is 80Hz, which is what I use, although I'd like to try 60Hz in an attempt to disguise the sub.

Unfortunately I am not able to park the Monolith between the front speakers because there is a fireplace in the way; the only option is in the front left or right corners. I expect that it would be less sonically visible if it were directly in front or perhaps behind my listening position. I believe that the Monolith is set up well; have spend a great deal of time equalizing its in room response, optimising the phase and setting the gain, although the quest for ideal integration continues. But is it really the case that a properly set up sub is impossible to localize? Even when serious LFE kicks in? Have you ever watched a film at your house with a friend who doesn't know about AV, let alone what your sub is, and asked them where he or she thinks the bass is coming from? I have done this a number of times and they always point to the front right speaker, which is the closest one to the sub, so its not just me who can tell that the bass is coming from the right hand corner of the room.

Although from an equalization point of view a sub per channel might be a nightmare to equalize, the idea of bass panning and rumbling around the room is an appealing one, given my super human ability to blindly point at the bass sources!


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## brucek (Apr 11, 2006)

Why don't you use those lesser subs on the front and surrounds just as you have them now except set all speakers to small with a 60Hz crossover. 

The main Monolith will handle all duties below 60Hz and will be less localizable. 

The smaller subs are only there to extend the front and surrounds bottom end to get to the 60hz cross.... You would have to play with the smaller subs crossovers to blend into the very bottom end where the mains and surrounds aren't supporting to 60Hz. You could use REW to set that up. Possibility?

brucek


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## Guest (Nov 13, 2006)

Unfortunately my amp does not allow a 60Hz crossover with all speakers to small. The lowest option is an 80Hz crossover. The lesser subs also have a different, muddier sound signature than the Monolith so I'd be reluctant to use one of these subs on the front.

My front mains are Monitor Audio B2s and an REW sweep reveals that they start to roll off at 35Hz which is lower than I expected. I will try setting all speakers to large; hopefully then the amp will give me a 60Hz crossover option.


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