First Galaxy 140 results.

[Chrisbee]

Hi

Had a quick spin with REW with my new Galaxy 140 this morning to see how it performs.

Sub is a 4 x 15" AE1B15 True Infinite Baffle line array (as seen in my signature).

I am getting a low readings warning from REW on calibration but I continued to calibrate to 80dB and ran a few sweeps.

Listening position: Galaxy 140 SPL meter. 80Hz crossover with BFD boost +16dB @ 20Hz. C weighting ticked. No meter or soundcard correction files.



Here's the 140 without C weighting or correction files.



Now I just remembered that I could use the ECM8000 correction file with the 140 but there isn't a correction file in the downloads area.

[Chrisbee]

Two more graphs using ECM8000 calibration files:

C weighting ticked.



C weighting not ticked.



They look the same to me.

All measured:

[PeteD]

How does this look compared to what you thought you had with the RS meter? I don't recall the dip in your response and I thought you had a house curve dialed in with the +16 dB of boost, no?

Pete

[Sonnie]

Make sure you have the CM-140 set to "Fast" and that should eliminate the low reading warning.

[Chrisbee]

Sonnie wrote:

Make sure you have the CM-140 set to "Fast" and that should eliminate the low reading warning.

Thanks Sonnie,

I set to Slow from habit. I'll have another try tomorrow.

Pete,

The RS meter showed the same dip at around 16Hz.
I think my usual filter set looks slightly more humped around 40Hz now.
More quality time with the BFD is indicated.
Perhaps I'd better wait until Sonnie posts a 140 calibration file.

[brucek]

C weighting ticked

C weighting not ticked

They look the same to me.

As they should. The ECM8000 calibration file extends from 10Hz to 46KHz.
The C-Weight curve will only compensate outside the range of a calibration file.

The C-Weight curve is not to be checked when you use the ECM8000 calibration file because it will try and compensate below 10Hz, which would be meaningless for the ECM8000 as a flat mic.

No meter or soundcard correction files

Why no soundcard file. You need to compensate for its response. If you don't the results aren't accurate.

brucek

[Chrisbee]

Thanks, brucek

You have a way of cutting through the swirling mists of doubt to bring clarity where none formerly existed.

I once did a soundcard calibration but it was so flat I decided it wasn't worth worrying about. (Soundblaster Live! and a 1 foot long cable)

As I use a 10 meter cable between the SPL meter and the soundcard and another out to my preamp I had better include those in the soundcard calibration. 60 feet of cable might have some visible effect in REW. We shall see.

[Chrisbee]

IB, 140 (fast) ECM8000 cal file, soundcard cal, BFD active.
REW still complaining about -20dB low readings on test.



Here's the soundcard cal image. (violet) The ECM8000 cal curve is also shown.(black) Do these look reasonable?

[brucek]

Your soundcard cal file is not good. The upper end ringing can be caused by too high a level used when setting up for that test or from soundcard features turned on. The low end response isn't very good, but not uncommon. You need to get a good soundcard file cal file before proceeding.

Once you get one, take a measure of the loopback cable (before removong it). It should measure perfectly flat because the soundcard cal file is inversly compensating for its poor internal response. Once you get a flat response on a loopback cable, you're ready to take measurements.

brucek

[Chrisbee]

Thanks, brucek.

By careful adjustment of level I have managed to improve my Soundcard calibration. I have reduced the Live! mixer to 2 speaker (rather than 5.1) and set input to Line-in rather than default input. No effects. No bass or treble. The bass response is further extended but the ringing persists. This is with my two foot long cable using two solid RCA to mini-jack adapters. No other programs running except REW.