[B]I need help tuning SonoSub![/B]

ben62670

As I thought. Lame pre for sub control. The HK would work nice with powered sub amps that have built in crossovers, but not for straight amps. Curve was very disappointing. I think my port is way to short!
10-68
15-80
20-84
20-84
25-86
30-93
35-95
40-95
45-96
50-90
55-92
60-91
65-93
70-91
75-89
80-90
100-83
110-81
120-80
140-77
160-72
180-69
200-71
220-72
240-68
260-64
300-70
Given that this is in room, in a corner I do realize that there are acoustics involved, but the low dip sucks. 10-25hz

Here is the link on the build
http://www.polkaudio.com/forums/showthread.php?t=51533

RuSsMaN

Actually, that's not bad. You are pretty flat from 30-80Hz, with a little peak in the low-mid 40's. Not to shabby for just hooking it up and measuring.

First of all, let the driver break in for a good 100 hours before trying to correct anything, to avoid the dog chasing it's tail scenario. Second, make sure you are using correction factors for your meter, and the right software. That can make a HUGE difference.

As far as the port, you need to model the driver in a good program, like WinISD to get that straight. As far as placement, the corner is probably the worst place. You excite ALL the room resonances, which makes the apparent distortion from the subwoofer seem less and while you also get reinforcement of fundamental tones from all the reflections in phase from the adjacent walls - at the same time harmonics will suffer and be weaker than the fundamental itself.

Technically, no adjacent surface for corner placement should be at a longer distance than 1/8 of the wavelength from the subwoofer at any given frequency in it's range. - Ie, the sound will travel a quarter-wave (1/4) there and back and literally mute itself.

For now, let it break in, and move it somewhere between the 2 main speakers.

Cheers,
Russ

ben62670

I am using realRTA as a tone generator, and a rat shack SPL meter. Also between my speakers is the movie screen. This sucker is almost 7 feet tall!
Thanks for the encouragement Russ.
Ben

engtaz

Good advice Russ

dudeinaroom

your computer could also be dropping the output off. burn tones to a disk and try again.

ben62670

I'm not dissatisfied with the output at all. I just stepped in my office which is about 60' away, and 2 walls. The clock on the wall was rocking back and forth pretty good. Also a door hinge was making a terrible requite. I moved it away from the corner, and it definitely helped kill the booms.
Thanks Guys

ben62670

dudeinaroom wrote: »

your computer could also be dropping the output off. burn tones to a disk and try again.

I took your advice, and inserted a test tone CD. Much better but I am not where I want to be yet. I'll let it break in for a while before I lengthen the port.

engtaz

girls over today?

tryrrthg

ben62670 wrote: »

I am using realRTA as a tone generator, and a rat shack SPL meter. Also between my speakers is the movie screen. This sucker is almost 7 feet tall!
Thanks for the encouragement Russ.
Ben

like Russ said, did you use the correction factors for the Rat Shack meter? It can be off by as much as 10+ dB's at 25hz and below.

ben62670

tryrrthg wrote: »

like Russ said, did you use the correction factors for the Rat Shack meter? It can be off by as much as 10+ dB's at 25hz and below.

I have no idea about how to go about that.:o

tryrrthg

Here are the factors from the SVS site. I had an excel file that interpolated all the frequencies in between but it must be on my old computer. But this gives you something to start from.

But you should probably make sure that TrueRTA isn't already compensating for the rat shack meter...

At 10Hz add 20dBs to the meter's readings and at ...

12Hz add 16.5dB
16Hz add 11.5dB
20Hz add 7.5dB
25Hz add 5dB
31.5Hz add 3dB
40Hz add 2.5dB
50Hz add 1.5dB
63Hz add 1.5dB
80Hz add 1.5dB
100Hz add 2dB
125Hz add .5dB

ben62670

Thanks try. I have been doing a little research, and thought that my sub was off, but it looks like I am very close. I was just using true RTA as a signal generator, and reading directly from the rat shack meter :-)