In Reply to: But then should they be? posted by Al Sekela on March 15, 2007 at 13:39:00:
Hi Al,
I get the feeling you are overestimating the influence of external vibrations. I think the problem is that it is not really possible to make these FFT measurements when the amp is hooked to speakers. If you could then you would also get a convolution of the amp output with the back EMF from whatever speaker you have it hooked up to. Many speakers are highly reactive and would throw considerable energy back into the amp and therefore also the test measurement. You could simulate a speaker load, like the NHT dummy load, but again I think this throws too many other variables into the mix.Obviously a suboptimal ground could cause a noise problem making the results dubious. I was using each FFT spectrums lowest "noise" floor as the minimum value in calculating the TAD. If I had gone with the lowest value for all the amps (the Audio Research in this case I think) some of the amps would have fared very poorly with a high TAD that may or may not be reflective on their sound quality. This needs to be worked out by more experimentation. Remember, this is not my theory, I am merely seeing how useful it is in implementation.
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Follow Ups
- Re: But then should they be? - morricab 16:24:40 03/15/07 (35)
- Simple solution: - Al Sekela 15:45:45 03/16/07 (0)
- I have raised this question too - Jon Risch 18:30:23 03/15/07 (33)
- Re: I have raised this question too - morricab 03:08:33 03/16/07 (31)
- Where to draw the line to obtain data from "non" to "extremely reactive loads? - cheap-Jack 08:36:50 03/16/07 (30)
- worms, worms, worms. - jneutron 09:48:30 03/16/07 (29)
- The worms go in, the worms go out. - Dan Banquer 10:29:38 03/16/07 (28)
- Hey there Dan. - jneutron 06:38:52 03/19/07 (27)
- Re: Hey there Dan. - Dan Banquer 10:02:36 03/19/07 (26)
- Re: Hey there Dan. - jneutron 10:44:59 03/19/07 (25)
- Yo John - Dan Banquer 05:19:59 03/21/07 (24)
- Re: Yo John - jneutron 06:17:29 03/21/07 (19)
- Re: Yo John - Dan Banquer 06:48:46 03/21/07 (18)
- Re: Yo John - jneutron 07:13:23 03/21/07 (17)
- Re: Yo John - Dan Banquer 07:37:53 03/21/07 (16)
- Re: Yo John - jneutron 08:51:29 03/21/07 (15)
- Re: Yo John - Dan Banquer 09:55:39 03/21/07 (14)
- Re: Yo John - jneutron 10:05:43 03/21/07 (13)
- Re: Yo John - morricab 03:31:08 03/22/07 (5)
- Re: Yo John - jneutron 06:20:46 03/22/07 (4)
- Re: Yo John - morricab 15:25:02 03/22/07 (3)
- Re: Yo John - jneutron 06:34:23 03/23/07 (2)
- Re: Yo John - morricab 08:56:56 03/23/07 (1)
- Re: Yo John - jneutron 11:34:23 03/23/07 (0)
- Re: Yo John - Dan Banquer 11:05:33 03/21/07 (6)
- Re: Yo John - jneutron 11:46:10 03/21/07 (5)
- Re: Yo John - Dan Banquer 11:53:52 03/21/07 (4)
- Re: Yo John - jneutron 12:07:04 03/21/07 (3)
- Re: Yo John - Dan Banquer 12:17:56 03/21/07 (2)
- you have mail. Do us a favor, start a new thread - jneutron 13:20:02 03/21/07 (0)
- Re: Yo John - jneutron 12:44:01 03/21/07 (0)
- Come to think of it.................. - Dan Banquer 06:04:47 03/21/07 (3)
- Re: Come to think of it.................. - jneutron 07:03:06 03/21/07 (2)
- Re: Come to think of it.................. - Dan Banquer 07:29:38 03/21/07 (1)
- One subthread, dan..the other one..nt - jneutron 08:46:23 03/21/07 (0)
- Re: I have raised this question too - john curl 02:24:06 03/16/07 (0)