Over this past weekend I ran a car audio amplifier test, in the Audio Video studio, for some of the guys from the Speed and Sound forum.
The test was to have two parts.
Part 1 do amplifiers sound different. If, with a statistically high degree, it could be shown that amplifiers do sound different, we would move on to part 2, which was to try determine the differences.
The procedure was as follows
A mono signal was fed to the left and right inputs of a pre amp. the outputs of the pre went to the 2 amplifiers and each amp drove a single speaker. The two speakers were located next to each other towards the front, centre of the studio. Switching amplifers was as simple as moving the balance control to the left or right.
10 tests were run, there were five A/B tests and five AA, or BB tests per session, using 10 Dolby True HD tracks, at three power levels.
Low, to see if the noise floor of the amplifiers was audible.
Medium, an average listening level
High, to listen for distortion.
As I was running the tests I didn't take part.
The amplifiers were level matched using a 50 Hz sine wave (5.26v on the one amp and 5.27 on the other was the closest we could get)
There were seven participants.
All they had to do was mark off on a sheet of paper if they heard a difference or not.
A correct answer would be a yes to an A/B test and a no to an AA, or BB test.
Once the testing was finished the results were tallied.
And the result was ......... 58 % or in other words not statistically high enough to prove that amplifiers sound different.
Of note though was that one of the participants used hearing aids but his results were similar to the average (I don't know exactly how he scored as no names were put on the sheets) and one participant scored 6/10 low level and 10/10 and med and high level.
We didn't move on to part 2.
All participants however still said that they heard differences and the concensus seemed to be that if money were no object they would take the more expensive amp.
There is a chance that the person who scored the top could have heard the left and right speaker, but I know the guy and he can hear a pin drop in a hurricane, so I'll give him the benefit of the doubt.
Next time if funds allow I'll buy a few relays and resistors and a friend will make up a switch box that will allow me to use a single speaker.
The test was to have two parts.
Part 1 do amplifiers sound different. If, with a statistically high degree, it could be shown that amplifiers do sound different, we would move on to part 2, which was to try determine the differences.
The procedure was as follows
A mono signal was fed to the left and right inputs of a pre amp. the outputs of the pre went to the 2 amplifiers and each amp drove a single speaker. The two speakers were located next to each other towards the front, centre of the studio. Switching amplifers was as simple as moving the balance control to the left or right.
10 tests were run, there were five A/B tests and five AA, or BB tests per session, using 10 Dolby True HD tracks, at three power levels.
Low, to see if the noise floor of the amplifiers was audible.
Medium, an average listening level
High, to listen for distortion.
As I was running the tests I didn't take part.
The amplifiers were level matched using a 50 Hz sine wave (5.26v on the one amp and 5.27 on the other was the closest we could get)
There were seven participants.
All they had to do was mark off on a sheet of paper if they heard a difference or not.
A correct answer would be a yes to an A/B test and a no to an AA, or BB test.
Once the testing was finished the results were tallied.
And the result was ......... 58 % or in other words not statistically high enough to prove that amplifiers sound different.
Of note though was that one of the participants used hearing aids but his results were similar to the average (I don't know exactly how he scored as no names were put on the sheets) and one participant scored 6/10 low level and 10/10 and med and high level.
We didn't move on to part 2.
All participants however still said that they heard differences and the concensus seemed to be that if money were no object they would take the more expensive amp.
There is a chance that the person who scored the top could have heard the left and right speaker, but I know the guy and he can hear a pin drop in a hurricane, so I'll give him the benefit of the doubt.
Next time if funds allow I'll buy a few relays and resistors and a friend will make up a switch box that will allow me to use a single speaker.
