Keego
New Member
Hi All,
I joined the forum recently and have found it to be a gold mine of information in so many different departments. I'm hoping to get some help improving the performance of my Lux power amp. it is a push-pull amp with KT66's as outputs and a 6an8 driver section. I believe originally the design had 6L6's as outputs. I have a reasonable understanding of how my amp works, and have done a lot of work on it over the years, re-capping, new output transformers (one original failed), new improved individual bias circuit, balancing pots for 6an8's etc., and I am very happy with the sound, apart from some harshness in the upper mids, which I am fairly sure is being caused by the amp, as it is present on phono and cd sources (passive preamp to power amp).
I managed to find a circuit diagram online, and have uploaded it here if anyone wants to have a look. The NFB circuit seems a little unusual as there are electrolytics in the signal path, which I believe is not the greatest idea from a sound point of view. Also, there are no stoppers on the output tube grids, and I recently put some carbon comp Allen Bradley 1.5k's I had kicking about on the grids, and to me the top end sounded noticeably smoother as a result.
Just looking for advice on any improvement I could make without radically altering the circuit, because as I said I'm very happy with the overall sound, just looking to get it as good as it can be. Here is a link to the circuit diagram online if the jpeg is unreadable: http://music.geocities.jp/hoppyfather/page131.html
Thanks,
Keego
I joined the forum recently and have found it to be a gold mine of information in so many different departments. I'm hoping to get some help improving the performance of my Lux power amp. it is a push-pull amp with KT66's as outputs and a 6an8 driver section. I believe originally the design had 6L6's as outputs. I have a reasonable understanding of how my amp works, and have done a lot of work on it over the years, re-capping, new output transformers (one original failed), new improved individual bias circuit, balancing pots for 6an8's etc., and I am very happy with the sound, apart from some harshness in the upper mids, which I am fairly sure is being caused by the amp, as it is present on phono and cd sources (passive preamp to power amp).
I managed to find a circuit diagram online, and have uploaded it here if anyone wants to have a look. The NFB circuit seems a little unusual as there are electrolytics in the signal path, which I believe is not the greatest idea from a sound point of view. Also, there are no stoppers on the output tube grids, and I recently put some carbon comp Allen Bradley 1.5k's I had kicking about on the grids, and to me the top end sounded noticeably smoother as a result.
Just looking for advice on any improvement I could make without radically altering the circuit, because as I said I'm very happy with the overall sound, just looking to get it as good as it can be. Here is a link to the circuit diagram online if the jpeg is unreadable: http://music.geocities.jp/hoppyfather/page131.html
Thanks,
Keego
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