Aiken's Reactive Dummy Load.

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by James Freeman, Apr 27, 2012.

  1. Blix

    Blix Supporting Member

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  2. James Freeman

    James Freeman Member

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    Yes, Safe.
    Go with the 300w for a 100w head.

    The damn thing is hotter than I thought when cranked.
     
  3. teemuk

    teemuk Member

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    True RMS converter. Is there one in your multimeter?

    Cranked amp -> Input signal is NOT sinusoidal.
     
  4. James Freeman

    James Freeman Member

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    No.
    I also didn't measure with a 1kHz signal tone.

    Just strumming the guitar in the gain channel with everything on 10.
    Which I know is not ideal.

    I also don't have a scope to see in what voltage the signal is not clipping.
     
  5. James Freeman

    James Freeman Member

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    Did some scoping with an Oscilloscope plugin in my DAW and my Saffire sound card.

    With 1khZ Sine wave going through a Zero Loss FX Loop (by Metro Amps),
    I got 22 Volts of unclipped pure sine wave power, that equals to 60W from 2x 6l6GC biased at around 70%.

    Then from 23V to 25V the top of the wave gets more clipped
    From 25V to 30V all hell breaks loose... the Square (once Sinus) wave distorts and looks like and evil square with big crossover and some horns.
    The Output Transformer buzzes like crazy according to my playing and the Dummy resistor gets hot like Hell.

    Thats what I call Rock & Roll. :JAM

    [​IMG]

    [​IMG]
     
  6. catalin gramada

    catalin gramada Member

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    Hello All,
    Hey
    Man have care, you work for nothing, those inductors will be quickly saturate bellow 1 A draw, so will become nothing but simple resistors.
    Better take a look at Hammond ofert for some nice, well built, cheap, inductors...maybe 15x series.
    And for resistor, think is a better ideea to use more in series/ parallel conjunction , with a Al radiator over for good heat convection.
    Hope this help
    Regards
    Catalin
     
    Last edited: May 12, 2012
  7. James Freeman

    James Freeman Member

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    Hello Catalin.
    Can you please elaborate why do you think these inductors will saturate before 1A?
    Also in one of the pictures there is a small inductor which is rated 20mH 3A.

    Also Hammond 15xx series don't have 20mH inductors nor do they have high current ones.

    Any info is good.
     
  8. catalin gramada

    catalin gramada Member

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    Hi
    You need to have a "gap" in your tor if want to be usable in AC. sometimes I used toroidal laminate core, cuted by section to have the right air gap and impregnated after in epoxy resin for rigidity. not a very practical construction anyhow. better to use classic E+I
    sorry did't know exactly for 15xx series , was just one example, but you will find one for sure if you search in their catalog
    Cheers
    Catalin

    sorry for my bad english
     
    Last edited: May 12, 2012
  9. James Freeman

    James Freeman Member

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    catalin.

    Iv'e tested the circuit with one of the inductors the 0.5mH one which is responsible for the high frequency boost.

    It Saturates. :puh
    It buzzes like crazy not even half way through the volume knob.
    The scope shows a very "shaky" pointy wave.
    Do you think the buzzing is because of loose windings?
    It sounds similar to my Output transformer buzzing.

    In other attenuators like Weber and Ultimate, the inductor is an Air-Cored
    inductor so it will not saturate; It is only for the high frequencies.
    They also LACK the big resonance Inductor and Cap, so for the resonant frequency they did not even bother.

    The only attenuator that is large enough to fit a huge inductors is Aracom.
    Maybe they did? who knows.
     
  10. teemuk

    teemuk Member

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    Yes, huge inductors, huge 200W power resistors getting ridiculously hot, huge finned heatsink chassis', etc.

    Now, imagine that all that juice usually goes to a tiny thin voice coil instead of a dummy load. :eek:
     
  11. James Freeman

    James Freeman Member

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    Understood.
    No Reactive Dummy for me.

    Well maybe just the small Air core inductor like the Ultimate Attenuator will do.

    Thank you all.

    EDIT: read further.
     
    Last edited: May 13, 2012
  12. James Freeman

    James Freeman Member

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    Eureka !!!

    Its some sort of new technology.
    Here is a 20mH 500W inductor from ERSE which behaves like an Air cored one from 0Hz to 3kHz.
    That is way above the range for this circuit in its spot, and its SMALL.
    Only 30$. Good.
    http://www.erseaudio.com/Products/SuperQCoils16Gauge/ESQ55-16-20000


    Also ordered an air-cored 0.5mH 300W.
    5$ and very small too:
    http://www.erseaudio.com/Products/EQCoils18Gauge/EAC32-18-500

    Also a Metallized Polypropylene 200uF 250v Cap.
    50$ Expensive.
    But endless ripple current.
    http://www.erseaudio.com/Products/PulseXAll/MPX25-03-200-00

    I'm not giving up on this.
    Gotta' start what I have finished. :cry:
     
    Last edited: May 13, 2012
  13. catalin gramada

    catalin gramada Member

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    Hi
    Man , you have no reason to givin'up. All the parts are available, as I said if I can give you a sugestion : hammond 159zj (10mH/5amp)- buy 2 or 3 pcs. to use in series, as for caps look for engine run capacitors-they are mkp type and pretty good for low freq aplication than electrolythics
    I also ordered all parts today for Aiken's load project - everything under 100 e- including huge hammond alu box for good heating disipation
    As for line-out link ...well...I think you will be pretty dissapointed. you must use a decent speaker simulator in parallel with the load to have a usable signal for slaving , reamp ,fx...or whatever you want to route
    keep us informed please :stir thx.

    Hope this help
    Regards

    Catalin
     
    Last edited: Jan 1, 2013
  14. James Freeman

    James Freeman Member

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    Disappointed? Not at all.
    The Line-Out works PERFECTLY as expected.
    Along with the ground lift the signal is just right and dead quiet.
    Its range is from 0V to 2.5V all you ever need for recording.
    I use the Dummy line-out to record with some Speaker Impulse Responses from Redwirez.
    I like it whene I can hear myself breathe and have the amp on 10.
    Also Re-Amped from the Line-Out into the Solid State mini power amp into my 2x12 Vintage 30's it sounds excellent only a little "flat".
    Still needs the reactive part to sound natural.

    20W of SS power amp is all I'll ever need in the house.
    In fact about 3w is enough.

    My box is also Aluminium and the base of the resistor is covered with thermal paste for maximum heat transfer to the chassis.

    http://www.erseaudio.com/
    They have everything I need for the Reactive part.

    As soon as I get my components I'll post some monstrous clips.
    :JAM

    Back Panel:
    [​IMG]


    P.S
    Aiken.
    If this build will be a success , you could even build and sell it as one of your products line.
    I can tell by the # of thread views and only my posts. :aok
     
  15. catalin gramada

    catalin gramada Member

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    OK. it is "flat" but feel you have the right harmonics in your tone (sound) , compared with the speaker ? - just curious what speaker you used with amp before
     
  16. James Freeman

    James Freeman Member

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    You mean if I'm satisfied with the direct sound for recording without using IR's (speaker simulation)?

    Catalin I think you should read about "Speaker Impulse Responses".
    Google it.
    Or watch on Youtube.

    By "Flat" I don't mean the frequency response of the speaker compared to the direct sound.
    When I say flat I mean "Less Lively" comparing the Resistive Load re-amped and the natural Speaker Load (Reactive).
     
  17. Blix

    Blix Supporting Member

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    This is incorrect, for slaving into another amp and cab you don't want speaker simulation at all.
    For recording direct yes, but not for a live rig.
    I've used my CAE line out box for years going into effects,power amp and cabs, and speaker simulation would ruin the tone, as there is no need for it at all.
     
  18. teemuk

    teemuk Member

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    I think I fell in love with the look of that control panel. Kinda resembles the Orange "graphic" amps.
     
  19. VacuumVoodoo

    VacuumVoodoo Member

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    You might like/need loudspeaker sim if you feed your line out straight into PA mixing desk and receive it back in the wedges or IEMs.
     
  20. catalin gramada

    catalin gramada Member

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    K , ya confused terminology,
    I used also for live routed second amp in parallel with load ( which was a real speaker) for slaving. nice sounding overall , but not pretty sure usable for recordings ,or routed to PA mixer fx section and back , as you said
    Catalin
     

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