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Attenuators for Twin Reverb

Discussion in 'Amps and Cabs [BG]' started by Max3000, Aug 5, 2018.


  1. Max3000

    Max3000

    Jul 9, 2018
    Anyone know of any attenuators that would allow me to play a fender twin reverb (65 reissue) at louder volumes but straight into a DI and then into an interface(or just straight into an interface) instead of out into the air where it can annoy the hell outta my neighbors/roommates? Any help would be very very very greatly appreciated
     
  2. Wasnex

    Wasnex

    Dec 25, 2011
    The Aracom PRX150 will do what you want...but it ain't cheap. If you configure the Aracom properly, you can run without speakers, or you can configure the box to run with speakers at various levels of attenuation. I own the DAG version. In my opinion, these sort of devices sound/feel best at relatively low levels of attenuation, but you can lock down a 100W amp as much as you want.

    The Aracom has a line out, so you might be able to forego using a DI. FYI, my brother loves the sound of a Countryman Type 85 on the output of his vintage Twins, but he runs with the speakers connected instead of using a loadbox.

    Aracom Amplifiers Crank it up! Power Rox PRX150-DAG Power Attenuator

    Also kinda cool, you can use the Aracom as an impedance matcher. For example if you want to run a 16 ohm Marshall 4x12, simply configure the input of the Aracom to the Twins 4 ohm output transformer, and then configure the output of the Aracom to match the 16 ohm speaker load. I have done this with my Dual Showman Reverb and a Marshall 1960AX and it worked really well. The DAG version works with 2,4,8,16 ohms on input or output and will handle 150 watts.

    The Pro version is a bit less expensive, so it has a few less features. See attached manual.
     

    Attached Files:

    Stumbo likes this.
  3. coreyfyfe

    coreyfyfe Supporting Member

    Nov 19, 2007
    boston, ma
  4. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    Rugmaster likes this.
  5. If I understand your need, you want to be able to crank up the amp, but have the speakers be relatively quiet?
    You want that cranked amp overdrive sound without filling the room with high levels of sound? FWIW, this is why they make pedals. That being said.
    The following are based on the above understanding. Some of what I will offer will be quite out there, so for what it’s worth advance at your own risk.

    If you attenuate between the instrument and tha amp input, it just seems that you will have more noise to deal with.
    And that won’t really cut the speaker level very much.

    To be able to crank the amp but not the speakers, you may have to attenuate between the amp output and the speakers. This is a Twin Reverb right? A combo amp right? If not you have easy access to the cable between the amp and speakers, otherwise a combo requires getting inside to open up the speaker leads.

    A Twin Reverb? It has two speakers? It has an open back cab?
    If you were to reverse the leads on one speaker so they were opposite polarity and out of phase with each other, you might achieve some level of speaker cancellation. If this works well for you, install a switch that lets you select in-phase, out of phase.

    Disclamer: These ideas are not for tech noobs or those who otherwise have no idea what they are doing in making these changes. Any experiment in this area should start out at very low levels and gradually increase while listening for problems.
     
  6. Jim C

    Jim C I believe in the trilogy; Fender, Stingray, + G&L Supporting Member

    Nov 29, 2008
    Bethesda, MD
    Isn't the main tone issue with a resistive dummy load is that it does not replicate the non-linear speaker load?
     
    Old Garage-Bander likes this.
  7. It also won’t replicate the tone of a speaker cone moving in a box.

    It kind of depends on what the OP is really trying to accomplish.
    Does he want the amp to provide all of the tone, sans speakers?
    Or is he counting on pushing air to be a part of the equation?

    I guess it helps to know if he want’s to use an output from the effects loop, or mic the cab?
     
  8. nshuman

    nshuman

    Sep 4, 2012
    WWWJWWW
  9. That’s a pretty cool box.
    Even right down to the upside-down labels on the back so you can read them while leaning over the top.
     
  10. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    Some units do have a reactive load that emulates a non-linear speaker. The Two Notes Torpedo Live unit that I referenced above does.
     
    Old Garage-Bander likes this.
  11. And within reactive loads, the reactance may be different than that of the speaker.
    This partly due to the reactance of a speaker that changes with and is affected by movement of the voice coil.
    In other words, a speaker may exhibit dynamic reactance where a fixed reactance will be just that, fixed.
    How much of a difference does all of this make when considering the affects of reactance on tone?
    Hard to say without seeing some hard numbers.

    But yes, I would think a reactive load that can somewhat simulate a speaker at at least one point in the reactance curve would be better than a purely resistive load.
     
    Wasnex and beans-on-toast like this.
  12. Jim C

    Jim C I believe in the trilogy; Fender, Stingray, + G&L Supporting Member

    Nov 29, 2008
    Bethesda, MD
    Is this non-linear load related to the output power and frequecny based on X brand speaker?
     
    beans-on-toast likes this.
  13. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    There are more sophisticated circuits than these, but you will get a dynamic response with an L-R-C network. Some load boxes have a speaker motor as part of the circuit. I have a unit that has this. BTW, Weber sells speaker motors for those that want to build load boxes.

    Of course, there is the option of emulating a speaker digitally. They can really refine the response that way.
     
    Last edited: Aug 6, 2018
    Old Garage-Bander and Jim C like this.
  14. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    Not sure about specific speakers. In the documentation they list a number of different cabinets, so indirectly they do. Two Notes has a very good reputation for their cabinet emulations.

    These are the bass cabinets that they have built in, there are also guitar cabs:

    • 2Notes CSB : Two notes Custom 1×15”
    • Alu XL : Hartke® XL 4×10”
    • AZ Ben : SWR® Big Ben 1×18”
    • AZ Work : SWR® WorkingMan 4×10”
    • Calif Low : Mesa/Boogie® 2×10”
    • Fridge : Ampeg® 8×10”
    • Heaven Bot : David Eden® 1×15”
    • Heaven Top : David Eden® 4×10”
    • Marco : Markbass® 2×10”
    • Voice V125 : Vox® V125 2×12”
    They also emulate power amps and mic type and placement. Of course, you can dial in your own. There is a more expensive studio version that offers more functionality.
     
    Old Garage-Bander likes this.
  15. seventhson

    seventhson Supporting Member

    Aug 12, 2005
    Seattle, WA
  16. seamonkey

    seamonkey

    Aug 6, 2004
  17. ficelles

    ficelles

    Feb 28, 2010
    Devon, England
    THD Hot Plate. The best imo.
     
    Element Zero likes this.
  18. Wasnex

    Wasnex

    Dec 25, 2011
    The Aracom is one of the best attenuators you can buy. Their marketing materials mention patent pending tech used to emulate speaker reactance. Despite their proprietary technology, as attenuation in increased, the sound becomes less resonant, dull, and lifeless. However from comparative reviews I have read, the degradation with the Aracom is less severe than with many similar devices.

    IMHO, the sound is still very usable, I just find the unattenuated sound superior in all areas except volume. I keep the Aracom around because I have some vintage non-master 100 watters with the bright caps intact. The Aracom allows me to play these amps at a reasonable volume level. It's also useful if I want to crank any of my 100 watters into output distortion.

    I believe what you have written captures part of the puzzle...I think there's a bit more, but I am not an engineer so consider this uniformed speculation. I agree there is a bit of an organic interplay between the speaker and the amps output transformer, and this interaction is unique for each amp speaker combination due to the variable reactance of the speaker.

    To go one step further, the speaker is driven, but also drives the output transformer. Consider the speaker's mechanical compliance and the voltage that is generated when the cone is moving. The speaker is both a motor and a generator.

    The more attenuation that is used, the more the interaction between the amp and speaker is suppressed, partly because the output transformer is isolated from the speakers variable reactance, partly because the signals coming back from the speaker are attenuated to the point of insignificance, and partly because the speaker cone is moving less so the signals are smaller to begin with.
     
    Old Garage-Bander likes this.
  19. Ross W. Lovell

    Ross W. Lovell

    Oct 31, 2015



    My God, I'm such a dinosaur.

    I've used a Tom Sholz Power Soak for close to 30 years now.

    I have one for my Twin and another on my Bandmaster Reverb.

    I was told that it would kill my output transformer.

    Both amps retubed about every 5-7 years.

    I did finally lose the transformer on the Bandmaster, but it is the original one from 1971, so I'm guessing it wasn't the Power Soak.

    Power Soak is just a bank of resistors that are progressively switched in by a knob.
     
    Last edited: Aug 5, 2018
  20. Primary

    Primary TB Assistant

    Here are some related products that TB members are talking about. Clicking on a product will take you to TB’s partner, Primary, where you can find links to TB discussions about these products.

     
    Apr 11, 2021

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