Specifications

I was kind of curious about getting a pair of these new amps. One thing I was really wondering about was their signal to noise ratio. I saw that is was only 100 db compared to the 119 db of the other two amps, but the model 200 rating is unweighted. I think it was soundhound who said this means that the measurement was done using the full spectrum (20Hz-20kHz?) instead of a smaller portion of it. Is this rating really something to worry much about? And since the 770 and 755 don't say anything about their being weighted or not, does that mean they were weighted?

I was thinking about getting a pair to take some of the load off of my receiver, a Marantz SR6200. It outputs 105W into 8 ohms, but doesn't list anything for 4 ohms. The reason that is important is because my speakers can take 300 watts and are 4 ohms min, 6 ohms nominal. Don't worry, I called the dealer I got the receiver from and he said this would work ok, just don't expect to crank the volume full blast. THD for all equipment I have and am considering is <0.05%. Is that number worth paying more attention to than signal to noise?

JT:

Step over to the bar, where I've got a fresh pitcher of Margaritas

The unweighted measurement is indeed full bandwidth. Now this can get confusing: 'unweighted' can mean 20Hz-20Khz or it can mean 'DC to blue light' - the term gets thrown around without much more specific information in most instances. I would assume the measurement was done 20Hz-20Khz, so let's move on. The two numbers you quote are pretty hard to compare directly, since the amps could have different power outputs, or the measurements could have been done differently. You don't know for sure. Even when the test parameters are stated, there are variables that can still creep in. "A" weighting is indeed taking a 'slice' of the audio band, favoring the mid frequencies where the ear is most sensitive. The bass end and the high end are not given as much weight.

My advise would be to try one of the 200s and see if the noise (or lack of it) meets your needs.

Distortion specs can get even more difficult to intrepret, so don't take them too literally. But if you insist ( ) generally for a solid state amp (or solid state anything) .1% to .9% is marginal - .01% to .09% is good - .001% to .009% is excellent - and .0001% means they're lying through their teeth Sometimes the distortion figure gets thrown in with a noise figure which would be "THD+N", and when this happens, things get really confusing really fast unless you're an engineer and can intrepret, and read between the lines.

Hope this helps.


[This message has been edited by soundhound (edited December 18, 2002).]