I was able to perform some measurements when boards are installed inside the chassis to replace the USSA-5.1 boards. This way I use the same PSU. This was also done this way for the USSA-5B.
So this is the USSA-3B THD profiles into 8 ohms at 1.1A bias:
USSA3B_THD_1KHz_1Wrms.jpg
USSA3B_THD_1KHz_6Wrms.jpg
USSA3B_THD_1KHz_10Wrms.jpg
USSA3B_THD_1KHz_20Wrms.jpg
I was able to get <= 0.1% THD at 30Wrms with +/-24vdc PSU.
I have adjusted for extra H2 to impress the gallery
I could have put even more if wanted
Fab
So this is the USSA-3B THD profiles into 8 ohms at 1.1A bias:
USSA3B_THD_1KHz_1Wrms.jpg
USSA3B_THD_1KHz_6Wrms.jpg
USSA3B_THD_1KHz_10Wrms.jpg
USSA3B_THD_1KHz_20Wrms.jpg
I was able to get <= 0.1% THD at 30Wrms with +/-24vdc PSU.
I have adjusted for extra H2 to impress the gallery
I could have put even more if wanted
Fab
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Hi Claude
I have 3 x USSA-5 versions and 2 x FSSA versions
....
See this post for USSA-5.1:
USSA-5 PCB GB
All 3 USSA-5 versions thd profiles are in the consolidated USSA-5 manual.
For the FSSA, the THD profile is kind of similar too but the numbers are much lower, see my web site for values.
The THD profile is more a side effect result of the other characteristics that I target..
H2 higher level is just the flavour of the moment in the magical search of a single criteria for good sound...
Fab
I have 3 x USSA-5 versions and 2 x FSSA versions
....See this post for USSA-5.1:
USSA-5 PCB GB
All 3 USSA-5 versions thd profiles are in the consolidated USSA-5 manual.
For the FSSA, the THD profile is kind of similar too but the numbers are much lower, see my web site for values.
The THD profile is more a side effect result of the other characteristics that I target..
H2 higher level is just the flavour of the moment in the magical search of a single criteria for good sound...
Fab
That THD profile brings a tear to my eye, nice Fab!
Thanks Vunce! I hope it is an happiness tear...
Fab
LOL!
Yep, H2 sounds nice I must admit, although apparently I seem to prefer 4x less of that flavour than the usual audiophile - albeit still a tad more than H3 in my case.
Thanks a lot Fab, I will browse and see all that... just as side note, I don't have sadly the USSA-5 manual.
Joyeuses Pâques
Claude
Yep, H2 sounds nice I must admit, although apparently I seem to prefer 4x less of that flavour than the usual audiophile - albeit still a tad more than H3 in my case.
Thanks a lot Fab, I will browse and see all that... just as side note, I don't have sadly the USSA-5 manual.
Joyeuses Pâques
Claude
Some pictures to show the real thing...
I use ceramic insulators for the output.
During the investigation of the second board I tried the 2SC5200-O/2SA1943-O and then put back the MJL transistors. In the exact same circuit with same polarisation the latter transistors pair gave lowest distortion supposing a slightly better linearity. It could also be the difference in HFE too but I doubt it...
I started to listen to the amp since yesterday and still in break- in. Burn-in was done on Saterday.
Fab
I use ceramic insulators for the output.
During the investigation of the second board I tried the 2SC5200-O/2SA1943-O and then put back the MJL transistors. In the exact same circuit with same polarisation the latter transistors pair gave lowest distortion supposing a slightly better linearity. It could also be the difference in HFE too but I doubt it...
I started to listen to the amp since yesterday and still in break- in. Burn-in was done on Saterday.
Fab
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