Very Quickly - what does HRM mean?

Discussion in 'Amps and Cabs' started by Goodwood Audio, Dec 23, 2009.

  1. Goodwood Audio

    Goodwood Audio Member

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    I see it in threads all the time. Especially threads about $$$$$ amps.
     
  2. riffmeister

    riffmeister Gold Supporting Member

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    It means it sounds like a HaRMonica.
     
  3. dividedsky

    dividedsky Member

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    from wiki (dumble page):

    In some newer models (1990s to present), the overdrive stages are followed by a passive tonestack (treble , middle and bass), which is adjustable using trimmer potentiometers inside the amplifier. This is known as the "Hot Rubber Monkey" (HRM) modification (these amplifiers are voiced for the overdrive channel to be used with the preamplifier boost engaged). Most players use three tones: clean, clean with boost on, and overdrive with boost on.
     
  4. PedalFreak

    PedalFreak Supporting Member

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    I was told once it was Hot Rod Marshall. As I believe that circuit was more Marshally than Fender.
     
  5. Goodwood Audio

    Goodwood Audio Member

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    while I have no doubt this is accurate, I'm pretty sure I still don't understand it
     
  6. Flyin' Brian

    Flyin' Brian Member

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    In most amps the tone controls are before the overdrive stage. In HRM models the tone controls are after the overdrive stage.
     
  7. fusionbear

    fusionbear exquirentibus veritatem Gold Supporting Member

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    I'll try to explain:

    HRM:

    Guitar> Cable> Amp> >First gain stage>Treble, Mid, Bass> Recovery stage> OD gain stage> "HRM" Internal Treble, Mid, Bass, OD Trim> OD Level>Master

    Hope that helps...
     
  8. Goodwood Audio

    Goodwood Audio Member

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    Ahhhh.
    So HRM means the builder has added internal EQ based on what he thinks is required POST Gain?
     
  9. nater9

    nater9 Member

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    Well, the internal EQ's are tweakable by you, not just the builder's ideas. Not sure if that's what you meant.
     
  10. Goodwood Audio

    Goodwood Audio Member

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    yeah it is. so it's like having eq pre and post OD. Damn that would confuse me.
     
  11. peterdjp

    peterdjp Member

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    These amps are cascaded gain single channel not true two channel amps. The idea is you use the regular TMB to dial in the perfect clean tone then you can go in and use the trimmers to adjust your lead tone to perfection.
     
  12. aeolian

    aeolian Member

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    Pre gain tonestacks don't really behave well into a high gain preamp. Hence the Boogie graphic eq,s, the Dumble HRM trimmers, and the post preamp tone controls on the Zinky Superfly. Turning up the bass usually doesn't add a lot of bottom, it just makes for a flubbier distortion. Mk Boogies are really sensitive to this. You don't turn the bass up more that to 2 or 3 or it gets really ugly. The post preamp graphic eq was set up so that it could be left on all the time, turned off, or brought in only on the lead channel. Which allowed you to have a more Fender like clean tone while killing an overly buzzy lead tone. Or to have some bottom end on the lead tone.

    The post OD tonestack on Dumble like amps also allows one to tweak the tone of the OD making the switch back and forth from clean to OD more usable for some folks tastes. Especially those wanting a more sparkly clean tone and a very smooth, non-buzzy OD tone.

    It does homogenize the sound a bit and some folks prefer not to have it to get more clarity and dynamics out of their OD sounds.
     
  13. Goodwood Audio

    Goodwood Audio Member

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    Ah ok. It seems this type of control is inherent in amps that I'll probably never use. I'm more into NMV class A designs.
    Thanks for the info guys. Always good to know this stuff.
     
  14. Purplexi

    Purplexi Member

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    So, it doesn't mean Hot Rod Marshall?? I'm not prepared to accept the rubber monkey at this juncture.
     
  15. Structo

    Structo Member

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    It's what Howard Dumble named it.
    Hot Rubber Monkey is the correct name.

    As mentioned before, it is for fine tuning the overdrive tone.
    The clean stage feeds into the overdrive stage.
    The clean stage has front panel TMB controls and will also affect the OD stage.
    The HRM trimmers are located on a small daughter board inside the amp.
    You simple dial in your front panel TMB then adjust the trimmers inside for the OD tone.

    But this can be tricky depending on what volume you set it up for.
    Several boutique builders of D clones are now putting the HRM controls on the front panel so they are readily available for adjustment.
     
  16. NFB

    NFB Senior Member

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    It is a really bad word.
     
  17. rockon1

    rockon1 Member

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  18. leodiditright

    leodiditright Supporting Member

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    Taking the chassis off the cabinet everytime you're feeling to tweak the trim pots is a real joy....no?:D:D

     
  19. Julia343

    Julia343 Member

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    Okay, so how is this any different from a good EQ in an effects loop?
     
  20. Baminated

    Baminated Member

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    good question !
     

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