Friend wants to sell me his 1987x ? Or is the SC20H better choice?

Discussion in 'Marshall Amps' started by DreamerDeceiver, Dec 5, 2021.

  1. marshallmellowed

    marshallmellowed Well-Known Member

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    Oh, I know, just havin' a little fun, too tempting.
     
  2. anitoli

    anitoli Well-Known Member Gold Supporting Member

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    According to my meter with 6db attenuator reduction average of 104-108db.
     
  3. anitoli

    anitoli Well-Known Member Gold Supporting Member

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    No, power brake is ok but a Rockcrusher is way better, trust me it's what i use with my 87X and there is one more in the room too.
     
  4. tschrama

    tschrama Well-Known Member

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    I find that hard to believe. A single speaker is 100dB per Watt. If you play a 4x12 that figure rises due to acoustic impedance coupling for frequencies with wavelength longer that the distance between the speakers; say 103dB per Watt You then pump atleast 70 Watts in them. That is an extra 17dB . Total makes 120dB and this is in open space. In a closed room add atleast 6dB for 126 total. Shave off 6dB with an attenuator and you are left with 120dB.

    That is high enough for permanent hearing damage after a single hour of exposure.
     
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  5. anitoli

    anitoli Well-Known Member Gold Supporting Member

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    12 x 18 room with sound meter pointed directly at speaker cab will peak hold at the numbers i gave. Consistently every time. Maybe it's where i set the volume knobs?????
     
  6. tschrama

    tschrama Well-Known Member

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    Neh. Once the PA overdrives it doesnt get much louder.
     
  7. tschrama

    tschrama Well-Known Member

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    dBA,B,C, or unweigthed? What averaging time? Distance? Callibrated meter, which class? Do you have a callibration device?
     
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  8. tschrama

    tschrama Well-Known Member

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    Maybe you aet your attenuator at something else than -6dB? Something is significantly off for you to read those numbers.
     
  9. black knight

    black knight Active Member

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    To answer one of your earlier questions, the 1987X is made in UK. It's very well built. It seems like you're leaning towards the 1987X and IMO, is the right choice. I haven't built one of John H's attenuators yet but I only hear great things about them from those who have. You might also consider is a Fryette PS1, 2, or 100, as they afford options, not the least of which is a great "post" preamp and power section effects loop. Expensive, yes, but it will serve you well for your subsequent, several plexi purchases.
     
  10. jeffb

    jeffb Well-Known Member

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    Rockcrusher fan and owner here..

    My recommendation as well.
     
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  11. AlvisX

    AlvisX Garage Guerrilla Gold Supporting Member

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    Nothin wrong with a THD attenuator , been using one for years .....with 1987's ,go figure
    Nothin wrong with a PPIMV either
     
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  12. lespaul339

    lespaul339 Well-Known Member

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    I like the PPIMV
     
  13. GregM

    GregM Well-Known Member

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    Well if he is getting his attenuator at mates rates and as a pay when u can thing, I guess try what he will part with and find what your happy with and what lvl you can play it at, and that will mean more than any suggestion here :)
    It can always be upgraded later.
     
  14. ken361

    ken361 Well-Known Member

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    My new les paul standard and EH power tubes really made the sound come around
     
  15. DreamerDeceiver

    DreamerDeceiver Well-Known Member

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    The purchase is on hold:

    Money constraints. Even though he offered to front it to me, Id prefer to have some dough on hand at the transaction.
    We'll revisit in Jan 2022 .
    Great info guys......plus, it gave me time to research what components to obtain.
     
    Last edited: Dec 11, 2021
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  16. GregM

    GregM Well-Known Member

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    Works best with guitar and guitar lead!
     
  17. JBA

    JBA Well-Known Member

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    Speaker dB rating is on axis at 1meter. Also the lad never said his amp was cranked. Also +3 dB for two speakers, +6 for four. Also in a room a guitar speaker lands somewhere between a point source and line source. The most efficient frequencies at 1 meter on axis will occur around 4K or so so that is more on the line source side of things. Doesn’t drop as fast with distance but very directional. So where was the mic in this axis? We don’t know so 103 dB per watt even if known would be an improper assumption.
     
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  18. Gene Ballzz

    Gene Ballzz Well-Known Member

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    Get an SV20H (quite similar in operation & sounds to the 1987) and give it a MASTER VOLUME in the same part of the circuit as the SC20, by putting a JHS Little Black Amp Box in the EFFECTS LOOP. Gives the the best of both worlds. The 4-hole SV20H preamp, with the MASTER VOLUME of the SC20H!
    Easy/Peasey/Done!
    Gene
     
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  19. purpleplexi

    purpleplexi Well-Known Member

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    We have a winner ladies and gentlemen.
     
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  20. Crikey

    Crikey Well-Known Member

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    Same on thd
    Works well with all marshalls
     
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