Would it be possible to get some more noise level info?

[sycraft]

In particular I'd like the absolute noise level in microvolts at idle of the XPA-5 Gen 2 and the new Gen 3 and, if possible the noise spectrum of each.

You may have noticed my whining about the noise level of the XPA-5 and I'm trying to determine if a new Gen 3 XPA would be quiet enough to solve it. The combination of sensitive speakers, close placement, and me being irrationally fussy is just proving hard to solve. I decided to give a Samson Servo 120a a try since they are fairly quiet, but it doesn't do the trick its absolute noise level is around the same as the XPA Gen 2s.

I'm just trying to decide if it is worth my money to drop $1500-1900 on am amp. It's a lot to bite off for me, particularly since my speakers aren't super expensive.

Thanks for your help and sorry for being such a difficult customer.

[Gary Cook]

Signal to Noise Ratio (SNR) ie; noise divided by signal, is the common comparator. From memory an XPA-5 is around 89 db at 1 watt and 117 db at full power. Gen 1 XPA-5's have a gain of 32 db and Gen 2's are 29 db. The Gen 1's were designed for use with AVR's which commonly had low voltage pre amp outputs, hence more gain was built into the XPA-5's. More recent AVR's and dedicated processors have higher output hence Gen 2's reverting to the 29 db gain which is common in audio equipment.

My experience with XPA-2, XPA-3, XPA-5 and XPA-1L power amps is that they are silent, they really don't generate much noise internally. But due to their 32 db gain Gen 1's are more likely to amplify noise elsewhere in the system. This is why when comparing one power amp with, say, 29 db gain and another with, say, 32 db gain it isn't fair to claim that the one with the higher gain is generating noise. It may simply be amplifying louder the noise that is already there.

If you have a Gen 1 power amp it may well be worthwhile trying a 3 db attenuator on its input to see if that lowers the noise output. One channel will do for a test and an attenuator is way cheaper than trying multiple amplifiers.


Cheers
Gary

[sycraft]

The reason I'm looking at the absolute noise level rather than the ratio is because I want to compare it to my Rotel RB-1050, which is fine and does not have audible noise. Now it only has 116dBa of SNR according to Rotel, as opposed to the XPA-5 Gen 2's 119dBa. However the difference is it is much lower power, 75 watts in to 8 ohms instead of 200 watts. The Gen 3 is again different, they quote 124dBa, but 300 watts per channel. Since what is bothering me noise at idle the absolute noise level matters, and it is difficult to calculate with all the different wattages (which of course effects max voltage out) and so on.