Took some measurements

[canaris]

This is for my 4 Tempest IB..I had the microphone at 2 feet from the woofers.


My soundcard was emitting a slight hum so the meter was exibiting 78 db before I even started to take the measurements..


This is with no eq.



This is with eq.





Does this make any sense?

[Wayne A. Pflughaupt]

Don’t know what’s more impressive, the response or the extension!

If you don't mind, it would be good if you could rescale your graph to the standard we use on this particular Forum - at least the dB scale and the upper frequency limit (you can keep the lower frequency limit).
http://www.hometheatershack.com/foru...eady-post.html

Nevertheless, I'm sure it will still look imprerssive!

Regards,
Wayne

[brucek]

Does this make any sense?

Can you tell us what type of meter/microphone you're using that has a calibration file below 10Hz? Best to limit the lower horizontal extension to 10Hz if that's as far as your cal file goes.

You should also try and clear up the hum problem. Some sort of ground loop perhaps. If you are using a laptop, many people switch to battery to reduce any hum.

brucek

[Otto]

canaris wrote:

This is for my 4 Tempest IB..I had the microphone at 2 feet from the woofers.

Looks good. Have you done any measurements at the listening position?

My soundcard was emitting a slight hum so the meter was exibiting 78 db before I even started to take the measurements..

78 dB seems pretty high for hum. I'd try to get rid of that...

Does this make any sense?

It looks like your frequency response in the range of 65 Hz was boosted quite a bit to get the "after" plot. What are your filter settings?

[canaris]

I used a regular digital Radio shack meter on a tripod...

I unplugged my eq from my HTR and plugged my soundcards 'out' into to it... I used my PC with 20 foot RCA cables...


How accurate is this Room EQ?

My settings are:

20 +2
30+2
40+3
50+3
63+3

[brucek]

How accurate is this Room EQ?

REW itself is extremely accurate. The inaccuracies usually come from the SPL meters.

Hopefully, you created a soundcard calibration file, (which eliminates any errors caused by poor soundcard response), and are using the correct calibration file for the meter you have. I would include those long cables in the loopback when creating the soundcard cal file, as to eliminate their response also from the mix.

The accuracy between meters is somewhat questionable, so that's a variable.

brucek

[Otto]

canaris wrote:

How accurate is this Room EQ?

My settings are:

20 +2
30+2
40+3
50+3
63+3

REW is pretty good. Although I wouldn't expect it based on your filter settings, you have more than 30 dB of gain in the 50-80 Hz region. Something's wrong...

[SteveCallas]

Does this make any sense?

No, a 75db rise from 50-4hz measured from 2' away means something is wrong. I had a similar (though not nearly as potent) thing happening to me with my first set of measurements, the soundcard calibration file - though I made one - was not being applied correctly, and my card had a naturally rising response down low. Double check that your calibration file is being applied correctly.

[Ilkka]

LOL, talking about a slight house curve...!

There's definitely something strange going on. Check your sound card and mic calibrations. Also check that you are recording the correct channel (the one where your SPL meter is plugged).

Also your filter setting don't correlate with your measurements.

[Sonnie]

Yeah... if you scale that to our standard 45db to 105db... 15Hz to 200Hz, I think about 1/3 to 1/2 of the response will be missing.

Anything below 10Hz there is really meaningless.

[canaris]

Thanks guys..I will take some more measurements..as soon as I can ..and repost them.