Biasing with a SRS UNIT (anyone?)

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by Mooncusser, Sep 21, 2006.

  1. Mooncusser

    Mooncusser Member

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    HI guys,

    Have any of you biased with an SRS unit?
    Could you give me your thoughts, opinions or just the lowdown on this unit if you have heard of it, or tried it out?
    I appreciate your time and efforts,
    Mass
     
  2. Bruce O'D

    Bruce O'D Member

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    I haven't used the SRS personally, but it's the same current draw concept as most other DIY bias kits (e.g. Groove Tubes Bias tool, which is alot more expensive). SRS gives you the option of having it read mA directly or getting a shunted adapter for reading mV (1mV=1mA) if you don't have a meter capable of reading current. It's only method I've ever used. Might not be as "balls-on accurate" as using an oscilloscope, but it's close.
     
  3. Blue Strat

    Blue Strat Member

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    What's an SRS unit?
     
  4. Mooncusser

    Mooncusser Member

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    Bruce O'D,
    I have a REALLY good meter...................
    What I was wondering is this:
    Is the SRS a cheaper alternative to the Weber Bias-Rite BR-4 octal unit, without imposing a multitude of time and steps?
    As I said, the SRS is much cheaper, but ya know how sometimes you get what you pay for.
    BTW...I have a really old oscilliscope. I just don't know how to use it.
    Thats why I am trying to find a good cheap method si I can change out my old tubes.
    Thanks,
    Mass
     
  5. Mooncusser

    Mooncusser Member

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    SRS is a company that produces biasing eqiupment of sorts.
    Very much like a GT bias probe.

    Take care my friend,
    Mass
     
  6. wixedmords

    wixedmords Member

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    I have 2 Mass. A single 9 pin unit and a double 8 pin unit.

    Great for biasing, but you will still need to get plate voltage.

    EDIT: There are also instructions on the web somewhere to build just about the same thing. Off hand I cannot remember where they are.
     
  7. Blue Strat

    Blue Strat Member

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    Do they have a website? A Google search didn't locate them.
     
  8. Bruce O'D

    Bruce O'D Member

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    True, but that's easily measured across two of the pin sockets.

    http://www.srs-webstore.com/pages/biastool.html
     
  9. HandOfTheHost

    HandOfTheHost Member

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    I've got one and it works pretty well. I can change tubes and know that I'll get the bias close. If anything, I wish I had the dual bias tool so I wouldn't have to swap it over to the other tube(s) to check them.
     
  10. Mooncusser

    Mooncusser Member

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    I wonder is it just worth the $$ to get the Weber Bias Rite BR-4 Octal unit?
    I feel ridiculous, though.
    I have an old oscilliscope, but haven't the faintest idea how to use it. It is very old, but works.
    I'm not sure if I want to risk damaging my amp if I use it incorrectly in some way.
    The Weber and the SRS seem so straight forward.
    Take care,
    Mass
     
  11. Bruce O'D

    Bruce O'D Member

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    In addition to the oscilloscope, you also need a signal generator and a dummy load for the amp. Here's an excellent analysis of why this type of biasing is not recommended:

    http://www.aikenamps.com/CrossoverNotchBiasing.html
     
  12. Mooncusser

    Mooncusser Member

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    That was interested reading there.
    Thanks for that.
    I am glad in a way, because I really didn't want to get into a signal gen. and a dummy load anyway.

    SRS is preparing a qoute for me on their BiasTool mA, plus a BiasTool PVT.
    I'll see what the $$ looks like and compare it with the Weber.
    Thanks for all the info!
    Best regards,
    Mass

     
  13. Lution

    Lution Member

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    Hey Mass, what did you end up getting? I'm also looking at the SRS or the Weber unit.

    -Lution
     
  14. Mooncusser

    Mooncusser Member

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    I am trying to decide to go with a Weber Bias Rite Octal unit, or the SRS.
    The Weber units seem to cover alot of ground and applications quickly and easily....kinda leaning twords the Weber to tell you the truth.
    Have you visited the Weber Bias Rite site yet?
    Check it out.let me know what you think.
    https://weberspeakerscom.secure.powweb.com/biasrite/br_page.htm
    Take care,
    Mass
     
  15. Lution

    Lution Member

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  16. Mooncusser

    Mooncusser Member

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    I just checked it out....nice unit!!! Get a good MM to go with that rig.
    I'll look into it later when I have more time to see if he offers a quad octal set as well as the dual.
    Talk to you soon,
    Mass
     
  17. Lution

    Lution Member

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    just an update. That Amp-Head Dual Bias Tester worked perfectly!

    very nice product.
     
  18. Mooncusser

    Mooncusser Member

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    I am really glad to hear that...happy for you.
    I love when things work out.
    So, did you find the unit easy to use?
    What amp did you use it on, and was it your first shot a biasing?
    Peace,
    Mass
     
  19. Lution

    Lution Member

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    It was very very easy to use. I used it on a used Bogner Shiva I picked here from a TGPer last week. It was my first time. I was very very careful!
     
  20. GDking

    GDking Member

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    I ordered a weber bias rite 2 and a half weeks ago and it still has not even shipped! Even though the website says 3 days on them if in stock. I asked if they were in stock when I ordered and they said yes. If it does not ship by friday I am cancelling the order and getting the same one you did.. The salesman gave me some runaround on how they had a sale and thats why they are running late etc. Woulda taken less time to just ship the thing as it did to write me the letter.

    On a different note I have a few questions for you.

    Do you have a 6l6 or el34 shiva? I have the 6l6 version and if you have the same would you mind telling me the formula you used?

    I can find the plate voltage with the bias rite but I am not sure what formula works the best I have seen quite a few different methods to doing it.

    I would REALLY appreciate it since you are happy with it..
     

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