I did an interesting little experiment over the weekend. I downloaded a cheap, but well reviewed SPL meter ap for my iPhone and Ethan Winer’s test tone tracks (
http://realtraps.com/test-cd.htm). Basically these tones cover the bass frequencies from 20hz to 300hz. I used these tones because my own ears told me that I had an issue with certain bass frequencies and I don’t have any real bass traps in my room.
I used the included pink noise to set the volume to 70db and then played the test tracks and recorded the levels. While this SPL meter on my phone is hardly a precision instrument, it did show me my peaks and valleys.
To adjust, I moved my absorbers, diffusers around and watched the SPL digital display while playing the offending frequencies. I was not able to change the offending frequencies by more than 1 db. Then I used the equalizer within Audirvana to try to tweak the three problem areas.
I was not able to do much with the lower frequency problem areas, but I was able to take care of one at about 200hz. I just played the tone and adjusted the slider down until I got closer to 70db. I went from 79db down to about 74db.
Then I sat down and listened. The changes were easily noticeable. Imaging improved a little, but the detail I could hear now was significantly better and the recordings (just about all of them) sounded more real. An example is being better able to hear vibrato in the end of a verse where the singer’s voice tails off. Not only that, but the tail of that passage is longer than I could previously hear. I suspect that this peak I had was actually hiding some of the detail present at or around that frequency.
So now I am able to say without hesitation that this was my best bang for the buck audio tweak. I think the SPL ap was $1.99. I did probably spend 2-3 hours doing this exercise.
Here’s the catch. I changed speakers and it was all out the window. I changed output tubes and to a lesser degree, there was a change as well. So I will have to re-tune for speakers. I am not sure I will re-tune for tubes. Luckily, Audirvana has settings you can save as separate files.