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Is this regulated filament supply any good?
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Posted on October 25, 2014 at 01:28:16 | ||
Posts: 870
Joined: February 11, 2005 |
Hi, At one time I decided to build a Velleman Kit (K7203) to use a a regulated filament supply, also giving me the possibility to adjust the filament voltage easily over a wide range (to use different tubes). I use 4, one each for the VT25 drivers and 300B finals. It works splendidly, but I want to hear your opinion of this implementation vs a Coleman Regulator. Although noise performance is super and it all sounds great, I'm not sure this implementation addresses the following problem as addressed by Ron: "The 5,0V filament carries filament dc voltage but also the anode-current Ia. At the 2 ends of the filament there is a 5V difference caused by the heating voltage - and this makes a current-flow across the filament of MUSIC-signal! This is because the gm of the triode is different at the +5V end compared to the 0V end. This is normal, it is natural. But when you connect a voltage regulator, the feedback action of the LT1084 will try to CORRECT the Music signal flowing in the filament. The regulator thinks the music-signal is an error! so you get a bad situation where the LT1084 is trying to compensate for the Music. This is the reason why the voltage-regulator desreves its BAD reputation for making bad sound. " Is this feedback/correction problem present in the regulator I use? Thanks, NC |
Yes..., posted on October 26, 2014 at 04:12:03 | |
Posts: 870
Joined: February 11, 2005 |
I have read about this before on your blog. I think I will be gong this route one day. Thanks for reminding me. NC |
So..., posted on October 26, 2014 at 07:04:30 | |
Posts: 870
Joined: February 11, 2005 |
Remove C4, C5 and D6? A lot to contradictions in the answers of this thread. It looked so simple ;) NC |