First graph - Is this to good??

[bcon2010]

Hi all,

I created my first graph in my new room with no treatment applied yet.
using an rme fireface800 soundcard/pre, spl meter and a Audio technica 4040 mic to measure.

Now maybe im reading the graph wrong or doing the measurement wrong (ive read all the help setup so i think its ok) but this graph doesnt look too bad with no treatment, I think??

what do you guys think? I still plan to put in superchunk broadband absorption to get the reverb time down
but do you see any major problem areas i should focus on (110hz and 240hz?)

cheers
bryan

[brucek]

what do you guys think?

A couple of points.

You're being extremely kind to yourself with respect to the vertical scale you're using.

You have a 180dBSPL vertical axis range, where the standard accepted practice should be 60dBSPL. The scale that we use is 45dB-105dB. That is 30dB above and below 75dBSPL measuring target.

You also have not loaded a mic calibration file. This is necessary to account for the response anomalies that every mic has.
A quick look at a review of the 4040 mic shows:
In tests, the 4040 gave me bright but smooth highs, flat or slightly scooped low mids (or high lows), and solid lows beneath the scoop. These results are borne out by the mic's frequency plot, which shows appreciable boosts (3 to 5 dB) at 6.5 and 12 kHz, a mild dip between 60 and 100 Hz, and a relatively flat low end extending down to at least 30 Hz (at which point the plot is cut off). Also notable were the mic's exceptionally good transient response and relatively open cardioid pickup pattern..

So, your bottom end may well be better than you show. It would be good if you had a cal file for your mic.

brucek

[bcon2010]

new it was too good to be true, thanks brucek!
where do i find a cal for my mic (its actually a AT 4033a not a at4040)
would i have to make one?

Here is the graph looking not so go with a different scale lol
and here is the graph for the mic.

thanks again

[brucek]

where do i find a cal for my mic

You would create it yourself from the graph, although as you can see, it stops at 30Hz, so you have no idea below that.

brucek

[bcon2010]

cheers, my speakers (dynaudio bm6a) only go to 41hz so i think this mic will be fine until i get a sub.
would it be easier to get an ECM 8000 as the frequency response on the AT mic isnt that accurate.

[brucek]

would it be easier to get an ECM 8000

Yeah, the ECM8000 is a decent measurement mic (at a fairly reasonable price) and we do have a generic calibration file down to 5Hz on our download page that is quite suitable for home use.

brucek