Looking for advice on an amp attenuator

Discussion in 'Amp Tech Center' started by Tenderfoot, Nov 19, 2019.

  1. uriah1

    uriah1 Telefied Gold Supporter

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  2. Tenderfoot

    Tenderfoot Tele-Holic

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    Thanks, johnDH. If you would be so kind as to send me the proposed build schematic and parts list I will give it some serious thought. Its been awhile since I did any circuit construction/soldering but my old US Navy skills as an aircraft electrician should help me get the job completed with reasonable quality.

    Cheers,

    Ed
     
  3. johnDH

    johnDH Tele-Meister

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    Hi @Tenderfoot my attenuator design is modular and adaptable, based on what you need. the basic design options are all on the thread. If you take a look at the questions below, then we can work it all out. Things to take into account are:

    1. The output power of your amp?
    2. What output taps does it have?
    3. The Ohms value of the speakers/amp tap that you want to use?
    4. Do you want the option of adding another cab, or using a different cab with different Ohms?
    5. Do you want to use it with a different amp with different parameters?
    6. Do you need a bypass switch to turn the attenuator fully off for full volume use? or would it be OK in that case to just to not connect the attenuator?
    7. What is the least and the most attenuation that you might want? The core of the design goes from -7db down to -31db, which takes a 50W amp from 10W down to about 0.03W (which still sounds great late at night!). It happens in small steps of -3.5db, ie like 10W, 4.5W, 2W etc. As an option, it can be wired to also give a -3.5db starting value, ie 50W reduced to 22W, and then 10W...etc .
    8. Do you need a line-out option to go to a mixer or IR loader?

    The answers can be yes/'all of the above' and it doesn't add much to the parts list, but the build gets a little more complex. But none of it is difficult, particularly if you can build into a generously-sized alumnium case. All the parts are 19th century technology (resistors and coils), and if you can build it to US navy mil-spec it will last for ever and maintain world-peace within your house.
     
  4. Tenderfoot

    Tenderfoot Tele-Holic

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    Thanks JohnDH for your ongoing help.
     
  5. Tenderfoot

    Tenderfoot Tele-Holic

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  6. beninma

    beninma Friend of Leo's

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    An attenuator inserted between the power amp output & the speaker is not the same as a Master Volume.. Master Volume is typically before the power amp and is used with an amp that has pre-amp that can be pushed into breakup. That's not what most Fender amps are, with a Fender you're pushing the output stage to breakup.

    In the end you are the only one who can decide.. if you have a quality local place maybe they'll let you test.

    A big negative in your case with an attenuator is it's one more box to carry around to play out if you need it.

    As soon as you get to the really nice attenuators you could go find another amp instead. Either an amp with internal power scaling or one that's just smaller to begin with.

    What about trying a compressor or something like that? A carefully chosen compressor (optical studio style as opposed to Ross/MXR/whatever style?) can fool you a bit into thinking your amp is turned up louder than it is.

    The right boost or drive pedal might get you there at a lower volume too. Seems counterintuitive but a lot of people do that with these amps to keep the volume down.
     
  7. scelestus

    scelestus Tele-Meister

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    You might need a speaker cable extension. At least on my DRRI, a short cable from the amp to the attenuator is fine but the stock speaker cable doesn't reach much farther than the chassis.
     
  8. uriah1

    uriah1 Telefied Gold Supporter

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  9. radiocaster

    radiocaster Poster Extraordinaire

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  10. Tenderfoot

    Tenderfoot Tele-Holic

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    Thanks beninma, your comments are appreciated. I demoed a Tone King Imperial II with the Ironman II attenuator and really liked it but I have been waiting a long time for Fender to release a Blackface hand wired Deluxe Reverb and sold my TK Imperial I to fund the purchase. Tried "boost" pedals and they didn't give me what I was looking for low volume sound wise.
     
  11. Tenderfoot

    Tenderfoot Tele-Holic

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    Thanks radiocaster, very interesting and first LPad attenuator build I have seen. Will keep this in mind as I saw a kit for $20US using the LPad approach.
     
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  12. Tenderfoot

    Tenderfoot Tele-Holic

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    uriah1 likes this.
  13. Tenderfoot

    Tenderfoot Tele-Holic

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    Thanks scelestus, good point on the stock speaker cable length. The one on my amp would only work with an attenuator mounted inside the amp cabinet. I'll have to remember to make or order a new one once I decide on which attenuator I will be buying. Still looking the NOS 5751 tube that I want to try first.
     
  14. The Ballzz

    The Ballzz Tele-Afflicted

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    With the John from New Zealand designed attenuators, tone is not compromised and fairly inexpensive/simple to build. With the wide variety sizes/configurations of project boxes available on ebay, etc, it can be laid out to be easily and permanently installed into the cabinet many amps, especially a combo like a Deluxe reverb! Instead of trying to build a "one size fits all" unit, to end up moving from amp to amp, they end up inexpensive enough to custom tailor (wattage capacity, how many db cut desired, etc.) individual units for each individual amp. If you actually take the time to read the whole thread over there at the Marshall forum, you'll understand why I prefer a 16 ohm version, although in Tenederfoot's application, an 8 ohm across the board unit seems more appropriate.

    Just My $.02,
    Gene
     
  15. Tenderfoot

    Tenderfoot Tele-Holic

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    Thanks for the info Ballzz.
     
  16. Tenderfoot

    Tenderfoot Tele-Holic

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    To all who have posted to this thread, many thanks. I decided to get the Z-Air Brake Lite to install in my 64 Deluxe Reverb Handwired. There were a lot of good comments and suggestions and after reviewing the information in the posts and provided links, it was decision time. It will arrive late next week and after I have had some time trying it out, I will post my initial thoughts.

    Again thanks to all for the your input.

    Tenderfoot
     
  17. The Ballzz

    The Ballzz Tele-Afflicted

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    Dr Z-Air Brakes have a good reputation. Congrats and "happy soon to be new attenuator day!"

    Keep Us Posted?
    Gene
     
  18. Tenderfoot

    Tenderfoot Tele-Holic

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    Thanks Ballzz for the congrats. I will keep you (and others interested) posted.
     
  19. Tenderfoot

    Tenderfoot Tele-Holic

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    Z-Air Brake arrived today and installed. While I'm not ready to give a final assessment at this time, I will say my initial impression is that its going to do the job I wanted. With the attenuator on position 2 (of 4) I can run the volume of the Normal channel at 3.5 plugged into the 1st input and get a good full sound without loss of treble while keeping the volume at a home use level. Without attenuation I have to plug into input 2 of the Normal channel and set the volume no higher than a little over 2 to avoid becoming too loud for home use. At this setting the sound is thin with none of the dynamics I get with the attenuated settings.

    Will post more later after using the Z-Air Brake a little more.
     
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