Sorenza 20 clean channel hiss

Discussion in 'Amplifiers' started by Tim foshee, Jun 24, 2018.

  1. Tim foshee

    Tim foshee Fosheti

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    Yes I bought a Sonzera 20 from zsounds. My amp has a loud hiss on the clean channel. I absolutely love the tone of the amp but the hiss is awful. The amp also has way to much gain. I put a couple of low gain preamp tubes in and it helped calm the amp down some but didn’t help the hiss. I’m going to call customer service Monday and talk to them about it. I hate to send it back because I love it so. I think the hiss is probably in the circuit board
     
    #1 Tim foshee, Jun 24, 2018
    Last edited: Jun 24, 2018
  2. elvis

    elvis Hamfisted String Banger

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    Sorry you have a problem. You may want to consider that the problem may not have been there when it left the factory. Shipping can be rough.

    I always find it odd that people make a single problem out to be a company reputation issue. PRS doesn't have a reputation for zero failures. They have a reputation for taking care of their customers. A single phone call would probably do the trick. If your image of them is dented, it must have started as a belief that none of their products should ever have a problem, and that they have 100% control of the product until the moment you open the box. Regardless of price point.

    Hope they take good care of you. If so, I hope you give them credit for it.

    Good luck!
     
  3. Em7

    Em7 deus ex machina

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    First off, hiss is the price that one pays for using tube technology. Hiss is thermionic noise. A vacuum tube works by heating a cathode to the point where it emits electrons (the heater within a tube is what makes it glow). Extreme amounts of hiss are almost always the result of having a less than perfect tube in the first gain stage. A 12AX7A contains two triodes, so the tube closest to the input jack usually contains the first two small signal gain stages. It is important to install the quietest tube that one can find in this socket because the noise picked up in the first gain stage is amplified several times before it is fed into the power tubes. Sadly, NOS (new old stock) tubes from a reputable source still rule in the noise department. Some of the quietest small signal (preamp) tubes that I have heard are old Telefunken 7025s. A 7025 is a low noise 12AX7A. NOS Telefunken 7025s are difficult to find and command a premium price. In a pinch, a MESA SPAX7 in the socket closest to the input jack should quiet an amp down. Mesa selects these tubes be as quiet as possible because noise and microphony can get out of hand in a high gain circuit. Another thing that you can do is buy a bunch of 12AX7s and swap until you find a really quiet one.
     
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  4. LSchefman

    LSchefman Hears Tones

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    To what Em7 said, I’ll add that Tube Depot has an option for a “low noise, low microphonic” tube selection, where they test the tubes. I always have them do that when I buy NOS tubes; they put the test results right on the box. Makes tube installation easier, because I don’t have to keep experimenting.

    I’d agree that it’s probably a tube issue. I’ve installed plenty of new production, as well as NOS tubes over the years, and every so often, there’s a noisy one that can drive me nuts until I find the culprit.
     
  5. Tim foshee

    Tim foshee Fosheti

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    No it’s not the tubes. I already replaced them all. No change. Probably a bad cap or saudering job in the circuit board. None of my other amps are making noise like this so it’s not the outlet.
     
  6. Tim foshee

    Tim foshee Fosheti

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    It’s just the clean channel. The lead channel has a much lower sound floor
     
  7. LSchefman

    LSchefman Hears Tones

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    Well, Tim, I tried.

    Call PRS customer service, they’ll take good care of you.
     
  8. Tim foshee

    Tim foshee Fosheti

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    Thanks man, I’ll get it figured outwe musicians always do
     
    elvis, Dirty_Boogie and bodia like this.

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