Quietest best quality Preamp Resistors for 2204 (brand and style)

Discussion in 'The Workbench' started by Yamariv, May 28, 2020.

  1. Yamariv

    Yamariv Well-Known Member

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    Hey Guys,

    What's your thoughts and recommendations if I wanted to try and quiet down the resistor hiss on my 2204 build as I play with the gain on full most of the time.

    Right now I have a mix of Metal Foil and Carbon film in there but on another thread someone had mentioned going with really expensive resistors in the first few pre amp stages. Would that be worth it, I thought there was the option of high end wire wound resistors but I looked on Mouser and there are no wire wounds that aren't below a 5w rating that I could find..eeek!

    I'm gonna be putting in a Mouser order soon and will be opening the 2204 up for a couple other minor mods and though maybe I could swap in a few nicer resistors while I'm in there if theres a chance to lower the hiss..

    All opinions and experiences welcomed! :dude:
     
  2. South Park

    South Park Well-Known Member

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    The resistors are not problem . A lot of noice is from the gain stage
     
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  3. ampmadscientist

    ampmadscientist Well-Known Member

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    Click on image to enlarge
    vishay1.png
    vishay3.png
    vishay2.png
     
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  4. ampmadscientist

    ampmadscientist Well-Known Member

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    At least 70% of the hiss noise is from 1 resistor.
     
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  5. Yamariv

    Yamariv Well-Known Member

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    Anything I could do in the gain stage you'd recommend?
     
  6. Yamariv

    Yamariv Well-Known Member

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    Wooahh! That's alot of technical stuff that just wen't over my head lol! Ok, so those are different resistors on each page? Which version would be better suited for low noise and I'll try to find it on Mouser's site.

    BTW, which resistor are you referring to, the first 68k?
     
  7. ampmadscientist

    ampmadscientist Well-Known Member

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    yes
     
  8. Yamariv

    Yamariv Well-Known Member

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    Ok cool, which resistor line you posted would be best?
     
  9. ampmadscientist

    ampmadscientist Well-Known Member

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    Any Z foil resistor is the lowest noise available anywhere.
    This produces about -40 dB noise floor as opposed to carbon resistors.

    The resistors are ordered, they make small batches. There's not going to be a lot of stock available.
    They will make 2-3 resistors but your'e going to wait maybe a few weeks to get it.
    (+1) 713-468-3882
    (+1) 713-461-2098

    txccsales@texascomponents.com

    And so it goes with aerospace grade parts.
     
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  10. thetragichero

    thetragichero Well-Known Member

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    i would use the resistors inside of a good noise gate and then put that gate inside the fx loop
     
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  11. FourT6and2

    FourT6and2 Well-Known Member

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    Go with the highest wattage resistor you can reasonably and physically fit. That will reduce thermal noise. Then, go with either metal film or thin film. I really like Beyschlag MBE0414. High quality and super low noise. PRP are nice as well. You can get PRP at https://www.partsconnexion.com/prp-1-watt-resistors.html They're a Canadian company too...
     
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  12. South Park

    South Park Well-Known Member

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    The 2204 is a high gain amp . The jacks could be loose ground loop on the input . Some preamp tubes are make noice . A lot of things
     
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  13. ampmadscientist

    ampmadscientist Well-Known Member

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    Well yeah but bulk metal is easily 15 dB lower noise floor than metal film.
    Metal film is actually pretty noisy. In fact it drives me goofy it has so much noise.
    But not "as noisy" as Carbon composition.

    So it depends on gain of the amp.
    In high gain circuits, the noise is much more amplified compared to low gain circuits.

    And so if you are building a Fender Bandmaster, you don't need low noise parts.

    Noise Gates:
    I would rather build a circuit that has no noise, compared to using a noise gate.
    A noise gate is putting a band aid on a big bleeding wound.
     
    Last edited: May 29, 2020
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  14. CROWEMAG

    CROWEMAG Active Member

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    I enjoy overly engineered things. I am interested. Would this be the correct one? It says 0.6 watts. I have always heard that if you want to reduce noise....increase the wattage of a component. I would order a couple 68K to have on hand. I am willing to pay the $27 a resistor just to experiment.

    http://webdirect.texascomponents.com/ProductDetails.asp?ProductCode=Z201_Custom_0.01
     
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  15. tschrama

    tschrama Well-Known Member

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    This has be discussed so many times....

    The only extra noise a resistor adds, beyond fundamental thermal dynamic noise, and the noise originating from electrons having discrete charge, is from de DC current through the Anode resistor.

    If you do the math, it is lower than the noise of the 12ax7 or the thermal noise of a 100k

    The only thing you can do about noise, is to lower the 68K input resistor and using extra high transductance input tube.
     
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  16. ampmadscientist

    ampmadscientist Well-Known Member

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    I will add one more.
    The hiss does not come from the tubes.
    The tubes amplify the hiss that comes from the components resistors in the circuit.

    Tube with more hiss:
    has more "gain," and amplifies the hiss more from the resistors.
    The hiss isn't coming from the tube.

    So if you are looking for the source of the noise, identify where the noise comes from instead of blaming the tubes.

    See? People keep looking in the wrong place. People make assumptions.
    You need to question if the assumptions are based in reality.
     
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  17. tschrama

    tschrama Well-Known Member

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    Tubes arent noiseless. you actually calculate the equivalent input noise of an 12ax7.. can you?
     
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  18. Yamariv

    Yamariv Well-Known Member

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    Nice! So is this the one we'd need? I'd also consider paying a few bucks and having a couple of these on hand
     
  19. neikeel

    neikeel Well-Known Member

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    It is an interesting topic that ideally deserves a proper scientific analysis to see what is evident in practice when using an ancient design primitive valve amp and having the option of ultra modern hi tech components. Personally I have not found problems with excessive hiss using the old Spanish Pihers.
    If someone had the time and resources to try several different input grids on the same amp under identical conditions it would be fascinating.
     
  20. CROWEMAG

    CROWEMAG Active Member

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    Yes sir. Custom resistance in between 25-100K. They have ranges and each range costs different. You specify what resistance you want when you go to check out.
     

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