It looks like the "straight wire with gain" theory is being questioned

Discussion in 'General Audio Discussion' started by the skipper, Dec 30, 2017.

  1. RTally

    RTally Speaker addict Subscriber

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    Gain can be positive or negative. Even an active preamplifier, which has a powered amplifier, can output a signal having negative gain, that is, attenuate the input signal.

    I would venture to say that every preamp uses negative gain. I know if I were to apply the input signal from some of my non-TT sources directly to my amp, I would blow my speakers.
     

     

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  2. loopstick

    loopstick AK Subscriber Subscriber

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    Voltage gain. Current attenuation. Lossy. Power attenuation.
     
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  3. WobblySam

    WobblySam Well-Known Member

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    No, no, don't say that! I was betting this thread would make at least 10 pages.
    You old fuddy duddy.
     
  4. Lavane

    Lavane AK Subscriber Subscriber

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    I use a passive with a relay activated selector. it also has an extra pass through output bipassing the selector and volume control. I use the pass through for my headphone amp. the headphone amp has a set of rca outs that I use to drive another amp. Most of my other systems do have active tone contols. I tend not to need them unless the recording is lacking. I'm kinda liking the idea of the Loki in my main system since it has a bipass switch. The small footprint is also a plus for me. Tone control when you need it. It's just that simple. Having the right speakers to begin with is important also.
    20180102_114407.jpg 20171114_084745.jpg 20171114_084726.jpg
     
  5. JoeESP9

    JoeESP9 ESL's & tubes since 83

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    More so than a Loki I'd jump on a stand alone variable loudness control based on the latest data in a hot minute. OTOH, maybe that could be added to Loki.
     
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  6. c.coyle

    c.coyle AK Subscriber Subscriber

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    That would be loss.

    Hey, I take no position whatsoever on whether tone controls are good or bad. But when we start calling attenuation gain, I start thinking of Alice in Wonderland and 1984.
     
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  7. Lavane

    Lavane AK Subscriber Subscriber

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    :thumbsup:
     
  8. Lavane

    Lavane AK Subscriber Subscriber

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  9. Pio1980

    Pio1980 AK Member Subscriber

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    Attenuation, not negative gain. Line level output from a source may be sufficient to drive a power amp to full output without an active line preamplifier, in which cases an in line attenuator, a passive level control, is all that is required.
     
    Last edited: Jan 2, 2018
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  10. guitarlvr

    guitarlvr Super Member

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    Already, bought one LOVE it.
     
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  11. whoaru99

    whoaru99 Epic Member

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    Gain in basic definition is simply the ratio of output relative to input.

    6dB attenuation, -6dB gain; six of one, half-dozen of another.
     
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  12. Lavane

    Lavane AK Subscriber Subscriber

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    I'm most curious about the bass control and how it works/sounds when used.
     
  13. restorer-john

    restorer-john Addicted Member

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    Not often. The voltage may be sufficient, but the source output impedance may be too high, especially when hanging off a passive attenuator. Achieving a remotely flat response with a typical passive attenuator into a equally typical 20k input impedance power amp is impossible. HF roll-off is inevitable.

    This is correct. All active preamplifiers can output a negative gain figure. People may think they are attenuating as a whole, but internally, they are amplifying, then attenuating, bufering and produce an output amplitude that appears lower than the original source amplitude.

    However, they offer a phenomenally low output impedance due to the active buffer stage and can achieve ruler flat responses in a typical system. This is something passive attenuators simply cannot do.
     
  14. Son-of-Vere

    Son-of-Vere Super Member

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    I don't think inferior is the right word to use here. Lots of us have less than ideal conditions. I have a room full of junk here. My pro 31 band GEQ is a bit noisy. If I turn it all the way up, I can hear the hash. But at that level, I don't want to be in the room, plus massive clipping is no fun either. Keep in mind I'm for this unit, but I seriously doubt you'll see this in a $200K+ system. At this price level I would expect no need for outside processing (I include room/room treatments as part of a system at that level).

    OK, so we have a few folks here that have purchased one. Do the test. Switch to a non-noisy input, like a CD player. With no source playing, turn on the tone box and turn the volume to full. Hear any extra noise? Now turn it down, hit bypass and swing the volume to full again. Is there any difference? Inquiring minds want to know.
     
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  15. Lavane

    Lavane AK Subscriber Subscriber

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    Yes, we do!
     
  16. Pio1980

    Pio1980 AK Member Subscriber

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    Corey Greenberg, while at Stereophile, came up with a reasonably transparent buffered level controller, based on the BUF-01 device ca 1990. I'd like to find one of the advanced versions for sale. My Conrad Johnson Motif MC-9 uses just a pair of FETs per channel to provide a modest gain stage into a source follower line driver.
    My passive is an input selector Noble 10k black cube switch point pot.
    I'd like to think that any modern solid state line source could drive a 1k loading, that would make things much easier.
     
    Last edited: Jan 2, 2018

     

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  17. the skipper

    the skipper Amateur Curmudgeon Subscriber

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    Actually, that was an attempt at sarcasm.
     
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  18. Son-of-Vere

    Son-of-Vere Super Member

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    Sorry Skip, came off as a dig. I've become too use to the "/sarc" tag. Guess I should have read your sig line.
     
  19. E-Stat

    E-Stat Addicted Member

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    Goody for you. Not all do nor necessarily use transformers.
     
  20. loopstick

    loopstick AK Subscriber Subscriber

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    Speaking of transformers - the Hydraulic Jack. On one end you have a small force (voltage) and great movement (current). On the other end you have a great force (voltage) and small movement (current). In terms of direction (polarity) you can think of both the force and movement (voltage and current) as being "transformed" by a "negative" gain.

    The force and movement (voltage and current) of your hand is downward, but the direction of the transformed force and movement (voltage and current) is upward (inverted). So setting aside the logarithms of numbers greater than or less than 1.0 - you can still have a "negative" gain with an absolute value greater than 1.0, and a "positive" gain with an absolute value less than 1.0.

    OK - that's tonight's bedtime story. Good night.
     
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