a good attenuator?

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by dave6, Aug 1, 2005.


  1. dave6

    dave6 Member

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    i have a marshall jmp 100w head and a specific pedal that i get a killer sound out of. the only problem is the "tone" doesn't happen until around 7 or 8 on the volume.

    i have NO experience with attenuator's AT ALL. i have never even plugged into one. can someone help with a good choice...??

    thanks so much,

    dave:dude
     
  2. CAFeathers

    CAFeathers Member

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  3. hasserl

    hasserl Member

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    I believe you are correct. I've seen Ted also state this on his amp bbs.
     
  4. AndyZ

    AndyZ Member

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    What I've been using for 25 years on non master Marshalls is my old (professional Music Products) PMP Super Sink. It was one of Riveras very first products he made. It does say Rivera Research on it. It's an attenuator and heat sink. It also has a line out which you can use if you want to feed another rig. e.g. wet rig for FX. Unfortunately, they don't make them anymore, but they pop up on eBay from time to time. One of the best I've used!
     
  5. Blauserk

    Blauserk Silver Supporting Member

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    I use a Komet Airbrake; Dr. Z makes one that is available used for pretty good prices. In my experience, the Airbrakes are extremely transparent attenuators. But I have no basis for saying they could handle that kind of power--I'd e-mail Dr. Z and check if you're interested.

    Something else worth considering is doing the "RICH mod"--an extremely well-regarded master volume modification that supposedly lets you tame volume without coloring the sound appreciably. Do a search either here or the LP Forum to learn more.
     
  6. CAFeathers

    CAFeathers Member

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    Hmmm, I was not aware of that. It is good information to have.
     
  7. mmorse

    mmorse Member

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    I have a weber minimass that I've used on my 50 watt. With heavy attenuation, it smells like it's burning up and sucks treble so bad as to make is virtually unusable IMO. Plus, I'm afraid it might blow and take out my 2204. For a little attenuation it's not bad. But then again, if it's not cutting much, why bother.

    If you are not adverse to modding your amp, +1 on the rich mod over an attenuator.
     
  8. slowburn

    slowburn Supporting Member

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    but a weber minimass should be good for attenuating 20watt amps or less, right?
     
  9. skyeking69

    skyeking69 Member

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    I know the THD is ohm specific... are there any that can ajust to
    4/8/16 ohm ?
     
  10. samtheman

    samtheman Member

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    I have "rich" and "one wire" mods my plexi RI 50w Marshall, and I also use Hot Plate, -4db att and my tone is amazing. Mods are good itselfs, but HP is "fine tuning" my tone.

    sam
     
  11. aortizjr

    aortizjr Member

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    I have the THD 8 Ohm and really like it. To me it sounds just like having the volume turned down, well and the speakers moving less.

    You could probably swith the Ohm's with like a Weber Z-Matcher or something.

    Just remember though, that a Marshall amp at 7, even attenuated to the max (right before off/dummy load), it is still going to be damn loud.

    My Sovtek has nice power-amp distortion, but at that point, even with the attenuator it is still way too for alone practicing. So what I do is use the attenuator as a dummy load. Run the out into a Behringer GDI, then run that through my DAW. Not dreamy, but definitely good enough.
     
  12. gkelm

    gkelm Supporting Member

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    You can get Webers with those features, but that's part of the beauty of the Z Air Brake...takes whatever impedance you throw at it. I think the Z is more transparent as well.

    If you do a couple searches in "amps and cabs" you'll find LOTS of good info already logged.
    Greg
     
  13. DavidE

    DavidE Member

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    There's SO much to wade through. I was just going to get a used airbrake, but the new version of the Weber Mass offers a LOT of options for $225.

    What do you mean that the airbrake is more transparent than the Mass?
     
  14. gkelm

    gkelm Supporting Member

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    For me? The Z did not seem to color, or weigh down the tone. That's been my experience...others may have heard it otherwise. I'm very happy with the Z.
    Greg
     
  15. John Phillips

    John Phillips Member

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    Not quite. It's really an 8-ohm attenuator that will work with other impedances due to tube amps being fairly tolerant of mismatches. It's actually a purely resistive load that's close to the average impedance of an 8-ohm speaker, and not far off for a 16 at most frequencies. It will also work for most 4-ohm amps because it's just about within the safe mismatch range. It is NOT a good idea for a 2-ohm amp.

    I really wish manufacturers would be honest about this sort of thing, not simply make claims that it's "universal" or whatever, since it isn't.
     
  16. gkelm

    gkelm Supporting Member

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    To their credit, I don't think Z advertises "universality"...on the other had, if that's true, I suppose they ought to state something to that effect (2 ohm prohibition) on their website. I'm pretty much an 8 ohm'er. Good thing I don't own, or even know of, a 2 ohm amp that I'd ever want. :)
    Greg
     
  17. Robal

    Robal Supporting Member

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    A vintage Super Reverb is not a shabby amp, is it? ;)
     
  18. gkelm

    gkelm Supporting Member

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    Well, you got me there! :) But a Fender is not an amp i'd be interested in attenuating (well, maybe a tweed!).
     
  19. tweber

    tweber Member

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    Yes, that's been a real issue, unfortunately. Dr Z himself NEVER suggested or promoted his Airbrake as a universal impedance device.
    Some guy named Perry Roper, who bills himself as "Dr Z Internet Relations Specialist" made claims about the Airbrake (the Fischer design) "automatically" switching impedances and therefore safe to use on virtually any impedance. He caught heck for that on the 'net, but never really reversed his position. It is, as you say, basically a fixed impedance attenuator like most other resistive attenuators on the market. By design, the plan is to have a low enough load impedance that the reflected impedance back into the plate circuit will quench any flyback pulses that can damage the output transformer or cause arcing at the output tube sockets.

    Unlike some other attenuators, I have never heard of an airbrake causing a meltdown, so I would say it is very effective in its design to work at a 2:1 mismatch. It is a very transparent attenuator.
     

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