DSL100HR Bias Help

Discussion in 'The Workbench' started by ehehat, Nov 23, 2021.

  1. ehehat

    ehehat New Member

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    Seems like it should be easy AF to bias this thing so I must be an idiot. Do I have a bad/wrong multimeter? Everywhere I've looked it says to use mV and set somewhere around 70/76mV but when I hook this thing up I get .2-.3. When I use VDC I get like .032 or some crap. What the hell am I doing wrong here? Thanks!

    Bias Points.jpg Bias Reading.jpg
     
  2. Kutt

    Kutt Well-Known Member

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    What you're doing looks correct. Is the amp out of Standby (in "play" mode) while you're getting that reading?
     
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  3. ehehat

    ehehat New Member

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    Yes, It's in "full" mode. connected to speaker cab. Same reading whether I have a cable in the input or not.
     
  4. Kutt

    Kutt Well-Known Member

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    I'm not an amp tech so my input will be minimal here, but I have the same amp and have biased it exactly like you're trying to do. My multimeter is not auto ranging, I hard set it to the 200mV setting. Do you happen to have a second multimeter you can test with to rule out if it's the Fluke?

    You probably did this but also make sure your test leads are plugged into the correct ports on the Fluke. Apologies in advance for asking the obvious.
     
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  5. ehehat

    ehehat New Member

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    No man, Really appreciate the input! I dont have another multimeter but think I may try to order something different. If I may ask.. What do you use? Again, thanks!
     
  6. Kutt

    Kutt Well-Known Member

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    I have a Klein MM100 digital multimeter. I got it at Home Depot about 6 years ago. Fluke is a reputable brand as you probably know, but there could in fact be something wrong with yours.

    Another obvious suggestion, but if you have another tube amp you could try measuring that one too. If the Fluke acts up there as well, then it's not a fluke. (See what I did there?!)
     
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  7. ehehat

    ehehat New Member

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    Ha! Nice one! Thanks for the help!
     
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  8. South Park

    South Park Well-Known Member

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    You have it on the wrong setting you need it DC not AC . You need amp meter not voltage reading .
     
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  9. ehehat

    ehehat New Member

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    Based on the pic of the dial I uploaded, what setting should it be on? I tried it on V DC and It read something like 0.032, would that then be 32mV? Or do I need to get a different meter? Thanks for your input!
     
  10. fitz288

    fitz288 Well-Known Yinzer Gold Supporting Member

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    Here's a shot of my meter on a probe when I was balancing the 6V6 tubes on my Haze.
    Mostly irrelevant, except the meter setting.
    upload_2021-11-23_10-57-8.png
     
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  11. ehehat

    ehehat New Member

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    And mine doesn't read mA. I was on Eurotubes and their how-to vid says you can use the bias points set at mV. Doesn't seem like this should be so difficult. lol
     
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  12. fitz288

    fitz288 Well-Known Yinzer Gold Supporting Member

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    I think your meter is probably good for other stuff around the house, but perhaps a better meter for your amp(s) would be a good idea.
     
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  13. pedecamp

    pedecamp Well-Known Member

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    Measure something simple like a 9v battery or something to make sure your meter is working properly. Put new batteries in your meter too. You got the amp warmed up and in play mode right?
     
  14. ehehat

    ehehat New Member

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    Yes absolutely. I'll check something else tonight. Is there a consensus that it needs to be reading DC voltage and not AC?
     
  15. WiderGates

    WiderGates New Member

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    Set your meter to V and DC,
    not A and AC, not V and AC, not A and DC.

    .032V is 32mV
     
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  16. ehehat

    ehehat New Member

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    Thank you. Are you 100% certain of this?
     
  17. WiderGates

    WiderGates New Member

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    Yes.

    My DSL100HR sounds best with 64mV per side.
     
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  18. Kutt

    Kutt Well-Known Member

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    Ah! I missed the "AC" on your picture. Yes, it needs to be DC volts. I just double checked my Klein meter as a sanity check.
     
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  19. Kutt

    Kutt Well-Known Member

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    This is the appropriate setting on mine:

    upload_2021-11-23_11-43-49.png
     
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  20. ehehat

    ehehat New Member

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    AWESOME! Thanks everyone!
     
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