2. amps-preamps
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quiet hiss in backround?

i have a quiet hissing from speakers when no music is playing and i am sure it is there when music is on but hard to hear. it drives me crazy! i always attributed it to normal noise from my amplifier but i wonder what you folks think? is it a power issue? the amp is a krell fpb600c, dedicated line, no power conditioning (a small quiet line by audio prism (parallel power line filter) is all. is this normal?
richard_stacy

Showing 2 responses by macrojack

macrojack
1,303 posts
 
Every once in a while a tube will go out so you might want a good tube tester and a few extras around. I would guess every other year you'll need to change them all out which is nothing more than screwing out the old ones and screwing in the new ones. Yes they require more work than SS but it's not a lot.

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My tubes have pins - they aren't threaded.
macrojack
1,303 posts
 
Sure Mike,

Not much to tell. I have a pair of Audio Mirror 20 watt mono tube amps. They are self-biasing, SET amps and use a quad of output tubes every 2000 hours.

I'm using one of the better horn speakers on the market so my choice of amplifier is somewhat critical, or it would be if I was. Anymore I just turn it on and listen. By the way, I can hear a faint hiss sound in the background even when the preamp is muted. It sounds a little like the rushing sound you hear by holding a seashell up to your ear. Apparently the dbx Drive Rack PA that I use as a crossover/EQ/RTA is meant for pro amps and needs to be stepped down a bit for use with home audio. The tech advisor at dbx suggested Ebtech Line Limiters as a solution. Maybe your preamp is not an ideal match for your amp, Richard.

If you can get $6000 to $7000 for that amp, do it now. There are very satidfactory sounding products available for a fraction of that money. Same goes for the WPs.
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