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Gain, what it is, what it isn’t?

Discussion in 'Amp Tech Center' started by peteb, Jan 5, 2019.

  1. peteb

    peteb Friend of Leo's

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    711083AC-F486-42DB-9D97-01DC102F3575.jpeg This is what I get for gain right off the schematics:

    Overall
     
  2. peteb

    peteb Friend of Leo's

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    This is what I get for gain right off the schematics:

    Overall pre amp gain

    Bassman, 31.7 / .00385 = 8,234


    Hot rod deluxe, 11.5 / 0.004 = 2,875
     
    Last edited: Jan 13, 2019
  3. peteb

    peteb Friend of Leo's

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    Gain in the pre amp


    Bassman:

    55 * 0.52 * 43 * 1.0 * 1.0 * 0.89 * 7.4 = 8,100


    Hot rod deluxe:

    45 * 0.07 * 19 * 0.13 * 25 * 0.87 * 15.5 = 2,623
     
    Last edited: Jan 13, 2019
  4. peteb

    peteb Friend of Leo's

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    Stage——————59—————-HRD
    one———————55—————-45
    1st interstage——0.52————0.07
    Two———————-43—————19
    2nd interstage——-1.0————-0.13
    Three———————1.0————-25
    3rd interstage———0.89———-0.87
    Phase Inverter———7.4————15.5
     
  5. peteb

    peteb Friend of Leo's

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    Now let’s compare only the gain and not the attenuation

    Bassman

    55 * 43 * 1 * 7.4 =


    Hot rod deluxe

    45 * 19 * 25 * 15.5 =
     
  6. peteb

    peteb Friend of Leo's

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    It’s totally close, I can’t tell which gas more gain
     
  7. peteb

    peteb Friend of Leo's

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    Now let’s compare only the gain and not the attenuation

    Bassman

    55 * 43 * 1 * 7.4 = 17,501


    Hot rod deluxe

    45 * 19 * 25 * 15.5 = 331,313
     
  8. peteb

    peteb Friend of Leo's

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    Results

    Comparing overall gain in the pre amp


    Bassman has 3 times the gain over the HRD 8K to 2.6k



    Comaparing only the gain and ignoring the interstage attenuation


    HRD has 19 times the gain over the 59, 332k to 18k
     
  9. peteb

    peteb Friend of Leo's

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    These results are hard to make much sense of.


    Maybe it shows how the HRD has a differen gain structure than the 59 Bman or how the gain has a different character.
     
  10. peteb

    peteb Friend of Leo's

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    After a little bit of reflection,


    I think the bassman having 3 times the gain of the HRD, is a more believable result than the HRD having 19 times the gain of the bassman.


    I can’t totally explain it, it is more of a feeling....
     
  11. Silverface

    Silverface Poster Extraordinaire Platinum Supporter

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    SECONDED!

    There are all sorts of fair tests, but none will have anything to do with reality - which is why "comparing gain from schematics" is nothing but a meaningless exercise in math.

    Note that on the schematics they don't use the same input frequency. That alone makes the calculations unequal. Maybe. Or they could be very fair. But you don't know, because they are not fixed test standards - they are variables.

    They have different EQ circuits. Do the setting used for each on the schematics compensate to a "level playing field"?

    Again - if you don't know, there's no fair comparison.

    Last - and most important to anyone that uses a guitar amplifier - NONE of this has anything to do do with actual sound quality, or whether the higher gain of one or the other would be a good thing or a bad thing.

    Because it can be neither. It's subjective.

    So this is all theoretical and based on "unequal" specifications with mathematical results that can be manipulated - there is no fair test.

    And I'll repeat this request - none of this has a bit to do with the thread topic. That was opened and SHUT on the first page!

    PLEASE start a new thread - those who want to tweak theoretical numbers and work with calculators (and there's nothing wrong with that) will have a thread they can enjoy and understand.

    And those of us that don't - and I am one who has no clue what your numbers mean - and don't care - can move on to other threads concerned with practical tech issues and how they actually affect sound.

    Which is one of the major problems with ,most of the results you seem to get every time you try to "compare" or "test" anything. And if the results don't math your "feeling" or desired answer.....

    ...well, here we are closing in on page ELEVEN.

    :confused:
     
  12. clintj

    clintj Friend of Leo's

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    All in favor?

    Sent from my Pixel 2 using Tapatalk
     
  13. elpico

    elpico Tele-Afflicted

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    This is a rhetorical question right? I'm guessing you don't really want someone to ruin the fun by providing an answer. I mean, we're so close to breaking the 200 post mark! :lol:
     
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  14. Lynxtrap

    Lynxtrap Tele-Holic

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    We can't stop now!
    Luckily, answers haven't stopped this thread so far.
     
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  15. elpico

    elpico Tele-Afflicted

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    Mystery fuel...

    [​IMG]

    ?????
     
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  16. peteb

    peteb Friend of Leo's

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    The result that makes the most sense is comparing the over all gain in the preamps, per the schematics.



    It makes sense that the bassman has 3 times the gain of the HRD, and here is why



    The schematics specify the HRD controls at 50% and the bassman has them full clock wise, that’s going to make a difference.


    And



    Using their out out voltage at the speaker for the power test, the bassman is tested for 56 W and the HRD only 33 W,
    That’s going to make a difference





    The result is what we all expected


    They test out for similar gain in the clean power test because the constraints are very similar, and yes, Silverface, they both test at 1K Hz.



    I would expect different results when the amps are fully cranked up








    I think that covers it



    Thank you



    Over and out
     
  17. Lynxtrap

    Lynxtrap Tele-Holic

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    If tested at different settings, what's the use of the comparison?
     
  18. Bendyha

    Bendyha Friend of Leo's Silver Supporter

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    upload_2019-1-14_19-59-4.jpeg
     
  19. elpico

    elpico Tele-Afflicted

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    Mystery hint #2:

    One of these circuits has two gain stages before the PI and the other has three. Which is which? Will three stages make more gain than two? Pick your horse, place your bets!
     
  20. Lynxtrap

    Lynxtrap Tele-Holic

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    #200. I can settle with that.
     
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