English Amiga Board - View Single Post - Queries on AGA Copper and 14-bit Audio

jarp · 19 October 2016, 20:00

All this fighting and nobody RMAA'd their Amigas? Well here you go, just for pure fun, RMAA test results played from Amiga 600 rev 1 with Furia 020 accelerator, recorded by PC and Asus Xonar STX. I used multiscan screenmode and play16 to play RMAA test signal.

8-bit (play16 verbosity=1 fast=1 filter=off output=paula8):

14-bit (play16 verbosity=1 fast=1 filter=off output=paula14):

There is clear difference in 8-bit and 14-bit output, RMAA shows it but also it can be easily heard when listening music. Led filter on / off also produces huge differences - led filter off of course being much better. High noise level can be easily heard as can be high distortion. Amiga 600 has hard filter which cannot be turned off and that makes frequency response crap. I would love to try this with Amiga 1200 which does not have it or some day de-solder the filter from the Amiga 600. Perhaps Amiga 1200 has much better noise floor also but rev 1 Amiga 600 definitely has A LOT of noise.

But there seems to be measurement errors also - RMAA says that dynamic range is 55 dB for 8-bit output but it's impossible since 8 bits allows only 48 dB, no? Theoretical limit for 14-bit would be 84 dB and RMAA says 70 dB so that is possible.

Well in any case this was just for fun. Even though RMAA measurements are poor I was hugely impressed by the quality of sound when I played back some acapella music. I was fully able to enjoy it. I mean damn, that sound chip was designed for 1985 computer and it STILL can do results which are good enough for average home audio equipment.

19 October 2016, 20:00	#123
jarp Registered User Join Date: Apr 2016 Location: Helsinki / Finland Posts: 176	All this fighting and nobody RMAA'd their Amigas? Well here you go, just for pure fun, RMAA test results played from Amiga 600 rev 1 with Furia 020 accelerator, recorded by PC and Asus Xonar STX. I used multiscan screenmode and play16 to play RMAA test signal. 8-bit (play16 verbosity=1 fast=1 filter=off output=paula8): 14-bit (play16 verbosity=1 fast=1 filter=off output=paula14): There is clear difference in 8-bit and 14-bit output, RMAA shows it but also it can be easily heard when listening music. Led filter on / off also produces huge differences - led filter off of course being much better. High noise level can be easily heard as can be high distortion. Amiga 600 has hard filter which cannot be turned off and that makes frequency response crap. I would love to try this with Amiga 1200 which does not have it or some day de-solder the filter from the Amiga 600. Perhaps Amiga 1200 has much better noise floor also but rev 1 Amiga 600 definitely has A LOT of noise. But there seems to be measurement errors also - RMAA says that dynamic range is 55 dB for 8-bit output but it's impossible since 8 bits allows only 48 dB, no? Theoretical limit for 14-bit would be 84 dB and RMAA says 70 dB so that is possible. Well in any case this was just for fun. Even though RMAA measurements are poor I was hugely impressed by the quality of sound when I played back some acapella music. I was fully able to enjoy it. I mean damn, that sound chip was designed for 1985 computer and it STILL can do results which are good enough for average home audio equipment. Attached Thumbnails Last edited by jarp; 19 October 2016 at 20:12.