Axiom Home Page Forums General Discussion Technical Questions blind testing of speakers

can someone at Axiom tell me within how many dB's 2 different speakers are adjusted for equal volume before doing critical blind or double blind listening tests?

I believe they use a special switcher so the speakers are exactly set the same, plus other criteria. Keep in mind, placment will play a huge roll.

Would that be like a big 'ol drum roll Randy?

J.B.

It is very important to get the SPL of each one exact. With careful set up you can get them within fractions of a decibel. As SirQuack mentioned the positioning can also play a roll so if the results are close the positions need to be exchanged and the test repeated to ensure your results do not change.

Myself, I prefer lots of butter on mine. (I've been on a strict diet. How could I not think of food.)

Jacques, the "roll" that using different frequencies plays when calibrating for equal speaker volume is also interesting. Primarily electronic components such as receivers and players have so little variation in frequency response across the 20Hz-20KHz range that using one frequency(e.g. 1000Hz)to set levels equal will result in audibly equal levels for the entire range. Speakers, on the other hand, have much larger variations which often occur at different frequencies for different speakers. For example, if speaker A was 2dB louder at 1000Hz than was speaker B, lowering A by 2dB would result in equal volumes at that frequency, but if B was 2dB louder than A at say 2000Hz(certainly a common possibility)then the 2dB adjustment previously made because of the 1000Hz measurement would result in 2000Hz now being 4dB louder in favor of B.

Using pink noise, which contains the entire frequency range in a way roughly similar to music, rather than a specific frequency when setting levels can result in a better average leveling result when comparing speakers with music selections. It would be interesting to hear Ian's comment on what Axiom uses in equalizing levels.

Huge roll?


or Huge Roll?


Yes, that is a roll of toilet paper.

Sorry JB.

what i would like to know is what fraction of a decibel are those speakers usually adjusted to.