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  Topic Review (Newest First)
03-21-07 08:14 PM
Malice
Re: calibration confusion!

Without a BFD and REW I'm sure by now I would either have had to have sold my sub, or at least have sold the missus. The sub without EQ and SWMBO were not destined to share the same floor space!!

Bob
03-21-07 07:49 PM
blue_max
Re: calibration confusion!

Thanks John,
I think you are quite correct - although this is 'old' now. I have had another crack and found it also works better with the phase at 180. I added a house curve, increased the subs level and hammered down the peaks a little more heavily. This one was just to get some filters in to sample what could be achieved. I must say, initial real-world results are quite impressive - I am really beginning to appreciate what the bfd is doing for me. It is quite an expense on top of the sub, including all the extras, such as soundcard and cabling, not to mention the learning curve, but it has all been very worthwhile. In fact, I am only now getting the value out of my expensive subwoofer!

If I ever get the luxury of a couple of hours to myself, I would love to have a real good play and share my results with you guys. REW really is an excellent piece of software. Being able to see what is going on is a revelation.

Graham
03-21-07 06:40 PM
JohnM
Re: calibration confusion!

Did you go through the "Optimise PK Gain & Q" step after assigning the filters? If you dd, you may want to manually tweak (increase) the bandwidths for filters 1, 2 and 3 to get a smoother corrected result, use "Adjust PK Gains" afterwards to get the levels correct.
03-19-07 09:35 AM
brucek
Re: calibration confusion!

Quote:
It seems that I am going to have to increase the sound level on the sub. Is this via the subs volume control?
Yes. Also, if you want more of the plot considered for filter recommendation, then before pressing the Find Peaks button, manually lower the set target thumbwheel to include more of your plot above the target line.

Quote:
add a few filters to push up the dips by 3db or so - is this correct?
Adding gain filters is not a great idea. Your dips seem to be sharp and likely you won't hear them. Better to raise the sub level as you've already figured out (and then cut a bit more on the new peaks)...

brucek
03-19-07 09:22 AM
blue_max
Re: calibration confusion!

Success!!!

Thank you brucek. I changed back to line-in and it all seemed to work. The 200 figure in your previous post was there and still is, so I don't really understand what had changed. Maybe just changing the input back to line-in made it register in some way?

Malice, you were right about the midi connections needing reversing - never would have thought of that, so thanks!

Anyway, Just to confirm, here are my graphs.

before filters.



with filters applied (not manually adjusted).



and with the filters and the main speakers.



It seems that I am going to have to increase the sound level on the sub. Is this via the subs volume control?

Then I can add a house curve and add a few filters to push up the dips by 3db or so - is this correct?

Many thanks for your help and thoughts on this.

Graham
03-18-07 08:27 AM
brucek
Re: calibration confusion!

Quote:
all the way up to the measure panel when I was asked to check the levels. That is where I get the -53 reading and the warning it is much too low. The check of levels in the setting panel was fine.
Ahhh, there's something you failed to mention - that the Check levels was OK (in Check Levels) and not in the Measure routine.

That's because the Check Levels routine in the Measurement screen and the Check Levels routine in the Settings screen use different values to generate the pink noise.

The Check Levels routine in the the Settings screen uses the fact that you have the Check/Set levels with Subwoofer pull-down selected to generate its test noise.

To double check and verify that the end frequency of the sweep that you have selected in the Measurement panel matches that subwoofer setting, its' Check Level routine uses the end frequency as the pink noise hi-limit cutoff. So if you had 20KHz as the end frequency to measure for your sweep, you can see how the pink noise would be different (between the two Check Levels) and as such the low level signal you're experiencing.

Set the End Frequency in the Measurement panel to 200Hz..................

Attachment 2634

brucek
03-18-07 05:20 AM
blue_max
Re: calibration confusion!

Quote:
brucek wrote: View Post
Are you using a standard RCA connector on the Radio Shack meter?

Can you plug the Radio Shack meter into the AUX or CD input of your receiver with a standard RCA to RCA cable and sing... it's a microphone. Does it work?

brucek
Hi brucek, yes it is standard rca connectors. I can't sing : ), but CAN get sound out of the mic. To be honest, I was able to meet all the criteria of the software - and it was as expected - all the way up to the measure panel when I was asked to check the levels. That is where I get the -53 reading and the warning it is much too low. The check of levels in the setting panel was fine.

Tis a mystery.

Graham
03-17-07 08:20 PM
brucek
Re: calibration confusion!

Quote:
virtually no input volume
Are you using a standard RCA connector on the Radio Shack meter?

Can you plug the Radio Shack meter into the AUX or CD input of your receiver with a standard RCA to RCA cable and sing... it's a microphone. Does it work?

brucek
03-17-07 07:56 PM
blue_max
Re: calibration confusion!

Quote:
brucek wrote: View Post
I assume you're using stereo connectors on the line-in and line-out plugs?

brucek
Yes, the double ones like the pic in the help files. I'm just using the red (right) channels.

I am determined to get to the bottom of it. It's good to have you on my side though.

Graham
03-17-07 07:44 PM
brucek
Re: calibration confusion!

Quote:
virtually no input volume
I assume you're using stereo connectors on the line-in and line-out plugs?

brucek
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