new sub and new to measurements

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guf

new sub and new to measurements
« on: 21 Apr 2017, 02:52 am »
I did something I was never going to do. I added a sub to my 2 channel. I use a fairly efficient, 95db larger monitor speaker that supposedly plays down into the 30’s. I just hooked up a Rythmik F12G I’m pretty impressed with the generic settings - crossover at 50, medium low volume so I can kinda hear it, Placed near a corner, and sounds good at the listening position. I have older GIK absorbing stuff, monster bass on the back wall and corner traps, first reflections, ect…Of course some will say all this is worthless with out measurements. SO I also purchased the usb mic and the REW software. Spent a day last week and did the basic figuring out how to connect and use. I am clueless on reading the data. I spent hours trying to read tutorials but its pretty overwhelming.  How do I start? Any simple suggestions?
« Last Edit: 21 Apr 2017, 05:36 pm by guf »

poseidonsvoice

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guf

Re: new sub and new to measurements
« Reply #2 on: 21 Apr 2017, 05:54 am »
I learned more in an hour reading that than I did all afternoon. Thanks so much!

artur9

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Re: new sub and new to measurements
« Reply #3 on: 21 Apr 2017, 11:51 am »
That's the first time I've seen someone say the mic should be pointed down.  I always do mine up as recommended by another very helpful forum.

jtwrace

Re: new sub and new to measurements
« Reply #4 on: 21 Apr 2017, 12:03 pm »
That's the first time I've seen someone say the mic should be pointed down.  I always do mine up as recommended by another very helpful forum.
Yes, up...

JohnR

Re: new sub and new to measurements
« Reply #5 on: 21 Apr 2017, 01:59 pm »
The question must be asked... has anyone actually measured with it both up and down to see if there is any difference?

poseidonsvoice

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Re: new sub and new to measurements
« Reply #6 on: 21 Apr 2017, 02:17 pm »
The question must be asked... has anyone actually measured with it both up and down to see if there is any difference?


John,

I have.

At frequencies below 300Hz (or whatever your Schroeder frequency), there is no difference that is material enough to mention, especially AT the listening position (i.e. comfortably far away from the sub or subs)

Most of my experiments were with multisubs (both monopole and open baffle/dipole).

But for my own preference, I have it pointed up.

I learned more in an hour reading that than I did all afternoon. Thanks so much!

You are welcome. It's a shame more don't read and apply what can be garnered from those 3 articles.

Best,
Anand.

guf

Re: new sub and new to measurements
« Reply #7 on: 21 Apr 2017, 07:39 pm »
All right. Part one done.  I think I did it right.


poseidonsvoice

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Re: new sub and new to measurements
« Reply #8 on: 21 Apr 2017, 07:51 pm »
Ok. That's a waterfall with time set to 300msec. Set it to 400-500 mSec and see the differences. You'll obviously need more absorption but that can be worked on later. But more importantly:

Let's look at your amplitude response. Try no smoothing or just 1/24th octave across 15 Hz to about 300 Hz. Try to make your vertical axis not 10 dB spacing but 5 dB to see more detail.

Best,
Anand.

guf

Re: new sub and new to measurements
« Reply #9 on: 21 Apr 2017, 08:17 pm »
Thanks so much for the help.


guf

Re: new sub and new to measurements
« Reply #10 on: 21 Apr 2017, 08:33 pm »
deleted

guf

Re: new sub and new to measurements
« Reply #11 on: 21 Apr 2017, 10:04 pm »
getting the feel of the software. thanks!

poseidonsvoice

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Re: new sub and new to measurements
« Reply #12 on: 22 Apr 2017, 01:32 am »
Ok but remove the waterfall. Go back to the 1st tab that ONLY shows the frequency response.

Best,
Anand.

guf

Re: new sub and new to measurements
« Reply #13 on: 22 Apr 2017, 01:44 am »



poseidonsvoice

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Re: new sub and new to measurements
« Reply #14 on: 22 Apr 2017, 12:40 pm »
Is this a measurement of the LF response of JUST your D.C. Berlins? Or both your mains & Rythmik sub?

I would measure just your DC Berlins to get a baseline. And try to show us the response from 15-500 Hz.

Next, Read this about SBIR: http://arqen.com/acoustics-101/speaker-placement-boundary-interference/

A picture of your room, and distances between each wall (ceiling, front wall, back wall and side walls) to the WOOFER on your Berlins will be helpful. That will help you understand the destructive interference patterns between 100-200 Hz. You obviously have modal issues like we all do, especially below 100 Hz.

This will augment what you have learned from the Hifizine articles. It may take a few reads...

Best,
Anand.

THROWBACK

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Re: new sub and new to measurements
« Reply #15 on: 22 Apr 2017, 12:57 pm »
WOW, Anand! Thanks for introducing me to Hi Fi Zine. What a great resource. I can't believe I missed it all these years. But there goes my weekend as I plow through all the back issues.

And thank you for your thoughts on woofer integration. Too late to help me get through tomorrow's audio session with the guys, but I'll pounce on the problem next week for sure. LIke GUF, I got the mic and the REW software and had a hard time getting comfortable with them. A geeky buddy of mine has figured it out, but even he has to revisit his learning curve when he hasn't used REW for awhile. 

Finally, thank you for your patient and generous responses to GUF. I'm sure there are lots of us out there who will benefit from them.

Sincerely,
Chuck

poseidonsvoice

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Re: new sub and new to measurements
« Reply #16 on: 22 Apr 2017, 02:02 pm »
Chuck,

You're welcome.

Have fun at your mini audio meet :thumb:

You have a kickin' system  :P

More reading for all if bored: http://www.acousticfrontiers.com/category/blog/acoustics/lowfrequencyoptimization/

Now get to work!

Best,
Anand.
« Last Edit: 22 Apr 2017, 03:37 pm by poseidonsvoice »

guf

Re: new sub and new to measurements
« Reply #17 on: 22 Apr 2017, 07:04 pm »
Yeah, Thanks so much for your help and with your patience. That was the data from 2 speakers and sub.  I followed the directions from the first links you sent and did individually and together.  I guess to begin I was wondering what volume and crossover setting to start with. I did 50 and mid on volume. I did hundreds of measurements last night. I guess I was experimenting and looking for the flattest response, I found moving the speaker to the other corner up front and crossing over around 80 had a smoother line. It was far from smooth but it was less jagged.
I'm super busy the next few days before vacation. This was a hard time to become obsessed with this project.
Thank you again for sharing.


guf

Re: new sub and new to measurements
« Reply #18 on: 17 Jun 2017, 11:38 pm »

ok!! Back at this. new speakers for now before I go back the old ones. Omegas ^^^

And Omegas and Rythmik.

room is 13x19. speakers are 6 feet from front wall and 7 feet apart.



poseidonsvoice

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Re: new sub and new to measurements
« Reply #19 on: 18 Jun 2017, 12:04 am »
guf,

Do you mind shrinking your vertical axis? The scaling of 5dB is fine but the scale range goes from 20dB to 105dB. A whopping 85 dB range. That's unnecessary and obscures detail. Switch it to 55-95dB ( a 40
dB range). What's the crossover point for the Rythmik? What slope? 24dB/octave? Sealed? Ported? Do you have any of the LF settings engaged on the plate amp? Have you played around with the volume control on the plate amp?

And how many subs?

Thanks!

Best,
Anand.