modifying my room. Ethan, please jump in

[Hans Hitmachine]

Alright...this is what I did: I placed one dynaudio BM6a in the recording room and one of my Avenson omni microphones. These are not officially test microphones, but they are very flat so I think they should do the job. I got this program off the internet (TrueRTA)to measure the room accoustics. I played pink noise through the speaker and placed both the speaker and the microphone in different positions. I even walked around with the microphone while somebody else was monitoring the curves on the screen.

It starts off at rounf 18Hz at around -100 db and then rises to 60Hz at -70 Db (the dynaudios are flat down beneeth 40 Hertz, so that causes the rise from -100, ). Then it drops a little and stays relatively flat upto 20kHz.
There's a slight drop at 2kHz. Banana shaped at low levels and just a small gap at higher levels. The higher the levels the more even the mid frequencies, which sounds logical to me.

The bump in the low frequencies is around 20dbv, but as we know dbv is relative; very foftly snapping my fingers causes a bump that is about three times the size of the 50Hz hill, blowing about twice its size. And it looks like only a very small rise on screen too. So is it really necessary to get basstraps?
Ethan, I checked your DIY page but your basstraps start at 80Hz and I would need something below that (around 20-60Hz).

Any tips?

Thanks,

Hans

[Ethan Winer]

Hans,

> Then it drops a little and stays relatively flat upto 20kHz <

Unless you measure to at least 1/12th octave resolution, you are not getting accurate results at low frequencies. I use ETF which resolves to 0.7 Hz, and that's the kind of accuracy you really need for this. You can use the demo of ETF to see your room's true LF response. ETF also shows decay time and modal ringing which TrueRTA does not. ETF is here:

www.acoustisoft.com

> There's a slight drop at 2kHz. <

Okay, the above was for low frequencies, but for higher frequencies there's a whole new set of problems. There, the problem is comb filtering off nearby surfaces that skew the response quite a bit. You can get a better sense of the real response by measuring at several different nearby locations, maybe four inches apart from each other.

> I checked your DIY page but your basstraps start at 80Hz and I would need something below that (around 20-60Hz). <

The bass traps my company sells are effective down to 40 Hz, and most rooms need the most absorption from about 80 Hz up to 300 Hz. That's where the bass "fullness" range lies. Not that bass trapping below 80 Hz won't help, but it's not nearly as critical as the higher bass range where the clarity of bass instruments is directly affected. So even though my DIY traps do the most above 80 Hz, they'll still make a huge improvement in any room.

--Ethan

[Hans Hitmachine]

Thanks!

I will read this very carefully and try the program you suggested.
I'll post my results later on!

Thanks very Much, Ethan and keep up the good work!