| 4 Pi Pro's and pp6BQ5's [message #35762] |
Tue, 02 April 2002 06:07  |
Sam P.
Messages: 307
Registered: May 2009
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Grand Master |
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in my fisher 500-S are a match made in heaven. Driven into the aux inputs by my sand preamp...absolutely ZERO hum...this is a 40+ year old tube receiver...only cap changes were the voltage doubler ones...replaced with minature ec's that fit inside the original cardboard "can".
MIDRANGE/vocals sound BETTER than the sand amps. I think the tube amp can't supply extra current, so the zobel is acting to suppress the woofs rising response better. OR the 14 year old monster cable interconnects are well broken in, contributing considerable "magic":)
Regarding tube friendly Z characteristics, the Fl peak is only 22.5 ohms/26Hz, Z min. near Fb is 6.3 ohms/48Hz, Fh was 20.5ohms/80Hz. Calculated system tuning was 48Hz...I'm not cutting the tubes again...ended up at 3.0idx1.5long...the 2.5cu.ft. net enclosure volume acts like about 3.3cu.ft. once the 1.2cu.ft. of 'glass was added, according to boxplot and ausberger(sp). Aside from the normal zpeaks, everywhere else the Z stays between the absolute min. of 5.8ohms/195Hz. and 9.0ohms/1500Hz. From 3kHz to 20kHz, the Z stays between 8.2 and 7.1 ohms.
NO HUM! Who stole the hum??? Sam
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