| tube active crossover LISTENING TESTS [message #40496] |
Mon, 03 March 2003 11:00  |
Sam P.
Messages: 307
Registered: May 2009
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Grand Master |
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have officially begun:) Damn, I was having sinking spells about the hum problem, until I remembered my XM9L has the p/s center tap/ground point earthed via a 100 ohm resistor. I checked Phil Marchands web site, and sure enough in his MEGA-buck tube design, the B+ AND reg. dc filament supplies both have their negative sides earthed...via 100 ohm 1 watt power resistors. Installed them, and it is now VERY quiet. When the cd player is powered off, there is a slight buzz, which goes away completely when it is turned on. With no music playing, the HF is as quiet, maybe even slightly less hiss than the XM9L, which is really quiet. And the mighty 555, no hum or buzz.
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A final tweak was to take a black marker, and remove the "hecho in frog land" labels, the rest of the uncooperative hum vanished!!! Sam
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yep, tubes on top, the MC-240 has level controls on it's "twin" inputs, sand on bottom for punch.
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