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What's causing hiss??


tswei

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I've got background hiss on a new-to-me tube/ss integrated with a tube pre amp stage. It is constant no matter what volume with no input from source.

Can this be a power problem? Other amps on that circuit with same setup have no hiss.

Tubes getting old?

Defective unit?

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this could simply be a situastion where the amp you have is poorly laid out and it is a noisy amp the grounding may not be well done. With regular efficiency speakers you would never tell but with a pair of speakers that are 104 db efficient you pick up the noise you did bit heat wit 92 db efficient speakers. The guys who play with speakers that have efficiency above about 106 -108db have to go to great lengths to make sure that their amplifiers are ultra quiet.Borrow a decent pro amp and see if the problem goes away. Best regards Moray James.

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With regular efficiency speakers you would never tell but with a pair of speakers that are 104 db efficient you pick up the noise you did bit heat wit 92 db efficient speakers

If you have Klipschorns, Belles, or La Scalas, a tiny bit of hiss from the pre-amp may well be transmitted. With my Khorns with a Belle center I had that problem with one pre, then replaced it with another that was low in hiss, but produced hum [:@] even with the volume control at minimum. I'm happy to say that my current Marantz AV pre-amp processor (AV 7005) is hum free, and produces hiss that is only audible from very near the speaker.

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Yeah... its most likely a bad design or implementation but be sure to check your connections before anything else. It could be something as simple as a bad solder joint or wires crossing over parts that will cause noise (hiss and/or hum). If the amp's power supply is lacking (either the transformer or capacitance), you may want to try a decent power conditioner but that may compromise the sound as well as get quite pricey. Improper grounding will usually induce a hum and tubes going bad will reveal themselves through diminished gain, distortion, a rushing sound or a sudden flash (usually upon powering up).

Often a unit that specs well and otherwise looks good on paper doesn't 'fit' in your system and the first thing you may notice is noise. I'm amazed at the level of noise I'll hear when some folks demo their system for me and they seem oblivious or just assume its something that must be tolerated. SS or tubes (in any configuration) as well as digital amps (though they seem to hum more than hiss), all can make noise but its usually reduced or even alleviated by good component matching, better connections and/or wire management.

You don't have to settle for noise and it wont necessarily cost you anything more than your time and effort. If you're hearing any noise - hiss, hum, even those little fans in some amps, you're not hearing everything your speakers (certainly most Klipsch) are offering - its not a compromise you should have to live with and you wont fully appreciate it until you hear the absence of noise through your speakers and those previously unheard micro details and textural nuances become evident. Have fun

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Last time I got an appriciable about of hiss was when I used the variable loudness control on a McIntosh C33 pre. The more the loudness was attenuated the louder the hiss got. I sent the pre into Mac and the replaced the loudness processor. All was not perfect but it did help quite a bit.

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