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Discussion Starter · #1 · (Edited)
Hello everyone

I just finished my sub-woofer system project for my HT (you can see the enclosure design and construction here: http://http://www.hometheatershack.com/forums/ported-subwoofer-build-projects/70000-stereo-integrity-ht-18-alfa-74-project.html

Basically I have a vented enclosure (500L) tuned to 18Hz. I also have an SI HT18 sub-woofer and and an iNuke 1000 amp is driving the sub-woofer.

I was one of the lucky members that won an UMIK mic from minidsp, and also I got a minidsp 2x4 balanced for the fine tuning of this system.

I had some free hours this weekend and started playing with the REW, umik mic and the minidsp. But I'm pretty new to this world and although I read a lot of information, threads, etc, I'm still not sure if I'm in the right way. Can somebody take a look and give me feedback and advice?
 

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Discussion Starter · #2 · (Edited)
here is my first measurement of the system, only the sub-woofer was running and also the signal was fed directly from the PC to the minidsp box. No eq, nor crossover was used.

There is a drop between 21 and 22 Hz, I'm not sure if this ok, since the enclosure was designed for 18Hz tuning.

Also, there are 2 peaks, one at 27hz and the second the 51Hz.

See the plot:
 

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Discussion Starter · #3 · (Edited)
This is the second measurement, this is very similar to the first one, in this case, the signal was fed from the PC to the Yamaha receiver and from the Yamaha (through the sub connection) to the minidsp box, again, without any eq, crossover or adjustment.

Here the Yamaha receiver is applying a crossover point ans you can see the difference between the 2 plots:
 

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Discussion Starter · #4 · (Edited)
And finally, I began playing with the REW EQ block and generate the EQ file that I load later in the minidsp eq advance settings. I did several iterations until I got the plot bellow (of course measured with umik mic and REW). This seems to be a lot better, but I still have a valley at 21Hz. I'm not an audio expert but it sounds good to me. I still need to continue with the fine tuning process and integrate it the rest of the speakers, but so far, what do you think given these plots?

Any feedback will be appreciated

Thanks
 

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Rescale your y-axis to 45-105 dB for a more standard appearance. This scale has a drastic impact on the appearance of your FR. This should also give you 5 dB increments instead of 10, which is too large.

In the last graph, which looks decent 25-80(will be able to tell better when you change scale), do you have your main speakers going? If not, I think you should run your eq with mains running to see how they interact from 80-100 Hz....you can play with phase and crossover to flatten this area out.

Looking pretty good for just getting started!(wow, I typed "d a r n" in between pretty and good, and it got filtered out...sorry for attempting to use such a vile and offensive word......:scratch:..........I agree in keeping out excessive profanity and offensive content but.....really???
 

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Discussion Starter · #7 ·
Rescale your y-axis to 45-105 dB for a more standard appearance. This scale has a drastic impact on the appearance of your FR. This should also give you 5 dB increments instead of 10, which is too large.

In the last graph, which looks decent 25-80(will be able to tell better when you change scale), do you have your main speakers going? If not, I think you should run your eq with mains running to see how they interact from 80-100 Hz....you can play with phase and crossover to flatten this area out.

Looking pretty good for just getting started!(wow, I typed "d a r n" in between pretty and good, and it got filtered out...sorry for attempting to use such a vile and offensive word......:scratch:..........I agree in keeping out excessive profanity and offensive content but.....really???
hello Bear, thanks for your advice, I already change the plots.

The last graph is only the subwoofer, without any other speaker.
 

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Discussion Starter · #9 ·
here is my first measurement of the system, only the sub-woofer was running and also the signal was fed directly from the PC to the minidsp box. No eq, nor crossover was used.

There is a drop between 21 and 22 Hz, I'm not sure if this ok, since the enclosure was designed for 18Hz tuning.

Also, there are 2 peaks, one at 27hz and the second the 51Hz.

See the plot:
Hello every body

I had some time last nigth and continue playing with REW, umik and Minidsp, but it was not possible to improve the response.

I have a theory, but I'm not sure a/bout it.

I didn't use any filling material inside the enclosure, so, i was thinking using something like delcron, and see if this would help to push down the valley to lower frequencies.

Besides, i was also thinking about the peaks at 27 and 52 hz, and i think these are due room modes. Would it help if i add acoustic panels? I don't want to do extreme adjustments with the mini dsp.

What do you think?

regards
 
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