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Discussion Starter #1
Here are my first graphs.
Are these any worse, or much worse from the average bears?
One is just the sub, and the other is sub + mains.
The sub is about to get a couple passive's screwed onto it's sides, in short order.
I just wanted a before and after plot to start!
But, I can't help but feel those large divits are from the room, where there is very little I can change. (according to the boss)
My one question right now is, will the passives on either side of the sub cabinet change the ROOM response much? Maybe since they are propagating 90* to the left and and right of the driver? I realize the passives do not do much above 50hz anyway...
 

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I hope you can at least change your sub's position. As it stands now, your response is hopelessly beyond the help of equalization.

The sub is about to get a couple passive's screwed onto it's sides, in short order.
I have no idea what you mean by that...

Regards,
Wayne

P.S. due to the rules here, I had to change the title of your thread.
 

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Adding passives will decrease the output of the sub and it does not address model room issues. It will make your amp in turn work harder, and lower the tune of the enclosure. Decreasing the output above the tune will add more dips/peaks to deal with. That is my non pro answer, but I hope that I am at least close to making since. Not the speaker educated type.
 

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Discussion Starter #4
Here is the passives reference.
It better not lower the output!
http://www.hometheatershack.com/forums/diy-subwoofers/15971-about-go-into-sub-surgery.html

Sorry about the title.

The room is the bottom half of a small raised ranch. Across the middle ceiling is a 4 foot wide by one ft tall duct/ main house beam. I really think that is setting up a weird room mode.

But if you look at the position of the sub in the corner, and picture passives mounted on the each side, I was wondering if maybe they would affect the room mode/node. I am thinking though, that the wave is so long, that it won't matter much.
 

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Discussion Starter #8
Yes, sorry. Passive radiators. The cabinet is going to be about 2.9 cubes with them in (3.1 now) and each radiator will have about 1600 grams on it, tuning the cabinet to about 18hz. It should give a bit more low end punch/headroom.
Here is a graph I just did about 5 feet away from the first one. Not a normal listening position however.
 

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Discussion Starter #11
I moved the mic to about 4 feet in front of the listening position.

Here is another curious problem:
Looking at these two plots, can you tell which one has better phase with the mains?
I ask because I have a rather weird amp, an audiosource amp7, a tripath digital amp, that is said to have an inverting output. I then hooked up the sub inverted, to match it. In what I thought was "in phase" wiring, the output seems higher down low, where the mains don't have much response. (Actually, in this case, just one main). But the plot looks better (I'm guessing) with them wired out of phase...

I'm so confused...
 

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I moved the mic to about 4 feet in front of the listening position.
Is there anyway you can move the sub or seats??? ...you stated on the first post that the Boss doesn't agree, but maybe if you show this graphs :innocent:

But the plot looks better (I'm guessing) with them wired out of phase...

I'm so confused...
I'm not an expert on REW, but I got a similar dip on the front row (rear looks good) ...it can be the room :huh:
 

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Digital,

I can't tell much of a difference in the graphs when you add the mains. Have you calibrated your mains to the same relative level with your sw? If it weren't for the big 25-40hz suck out you'd have a nice FR. Can you move the subwoofer to a different location?
 

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Discussion Starter #14
What freq should I match the mains at?

Or to put it another way, how do you match the mains?

EDIT: The post 11 above shows both graphs with the mains on, just regular (?) and inverted sub hookup.

I really appreciate all the tips I can get. I have been playing with this thing now with *many* different combos, bassis settings, etc.
 

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Do you mean passive radiators? If so, they act as ports with greater mass.

Kal
A / in my posting is short for with, but can sometimes mean or. It's easier than to type with or not with a driver and motor. In this case I wasn't sure which one was being discussed earlier and thought maybe a passive radiator was meant, but I was reffering to a passive. I wasn't sure exactly what a passive radiator was so thanks. :T Where is the pick of the passive radiators? They are the same thing? Ones I have seen looked flat without a cone. :scratch:
 

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What freq should I match the mains at?

Or to put it another way, how do you match the mains?

EDIT: The post 11 above shows both graphs with the mains on, just regular (?) and inverted sub hookup.

I really appreciate all the tips I can get. I have been playing with this thing now with *many* different combos, bassis settings, etc.
Do you have an SPL meter? You use the test tones in your reciever, or you can use REW to set the level of the mains and the SW to the same level, or close anyway, at the listening position.
 

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When dialing in a crossover....

First measure the response of the sub. Then measure the response of the main speaker. Repeat until the volume of the sub matches the volume of the mains.

Go to the all measured tab and note where the sub and main responses overlap - this is the acoustical crossover frequency (which might be different from what the electronics are doing). Note the frequency and the magnitude.

Now measure the system with both the sub and main at the same time. If you have proper phase/polarity, then you will see +6dB at the acoustical crossover frequency.

Make sure you're not using any smoothing when going through the exercise...also make sure you don't have any one driver significantly louder than the other.
 

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Discussion Starter #18


This was the result of playing quite a bit with it. To me, it seems almost too good to be correct. I turned the sub so that it faces the corner. Changed the sony to "small" in the speaker menu.

My receiver is an older 30es model. It has terrible documentation, I have no idea where they cross things at, it looks like about 60hz, but even with small selected I can get significant output on the mains at 40 hz?

I don't know what the new receiver will be, this one sure has worked great over the years, on every day, used and abused. I think one thing that really helps it live is having outboard amps though. The next one though WILL HAVE excellent bass management if nothing else.

I appreciate all the tips guys, great info here!

Edit: This was with 1/3 octave filter on. It may have hid a little sin, namely a very narrow dip at 38hz. I have to find some bass traps and play with them. WAF might be a problem.
 
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