Tube Vs. Solid State

Discussion in 'Power Amps' started by shaizada, Nov 23, 2016.

  1. TraverS

    TraverS Rando

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    Phase shift may have something to do with stage dept as I've read some academic papers about detection of sound direction from phase shift.
     

  2. tomchr

    tomchr MOT - Neurochrome

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    Depends on the frequency range. At LF (where the human head is acoustically small) we judge direction by the time difference between left and right ear. At HF (where the head is acoustically large, thus casts an acoustic shadow) we judge direction by the level difference between left and right ear.

    Tom
     
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  3. Hrodulf

    Hrodulf MOT: Sonarworks

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    Below 80Hz location is extremely hard and mostly is done by overtone perception. You can mess up below 80Hz location by making low frequency content reach ears before overtones, which happens with crappy subwoofer placement.

    Overall sound location is a very tricky business because you have only two ears in a roughly the same plane. Therefore technically by earholes alone you shouldn't be able to distinguish between front and back sonic events. Which is why you have eyes. Sound location without visual cues feels strange, because it requires a certain level of self deception. Then you have the pinnae which colour incoming sound depending on direction. And miniscule head movements, which introduce differences depending on tonal and time changes.
     
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  4. murray

    murray Friend

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    I have found recently through persevering to get good IEM insertion that my left ear hole is on a completely different axis from my right hand one (which I suspect is the "normal" one). While I now get a much more balanced sound, it has left me wondering how asymmetric ear hole alignment might affect such things as sonic location. (just idle curiosity)
     
  5. Hrodulf

    Hrodulf MOT: Sonarworks

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    Your brain must have learned to compensate for that. Otherwise you'd be bumping into stuff, walking sideways or tilting your head constantly.
     
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  6. Armaegis

    Armaegis Friend

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    Soundstage with headphones is mostly a hack too, unless it's a binaural recording. There's just no way that any of the phase/time differences will be aligned properly otherwise. Mixing/mastering with headphones is great though, if you're doing some heavy notching and need to be mindful of keeping all the tracks aligned.
     
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  7. Derf

    Derf Acquaintance

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    Maybe unrelated to the conversation at hand, but I figured it would still be the most appropriate place to ask: Can anyone explain why a tube/OTL (I have no idea what "Output Transformer-Less" even means) is generally considered to not be the best match with planar headphones (at least compared with SS)? For instance, a ZDS is known to have good synergy with HD650 which is 300ohm, but less so with planars, some of which have an impedance well below that. I'm assuming there is far more at play then just the issue of impedance or driving things to a listenable level.

    Apologies for the silly question.
     
  8. Hrodulf

    Hrodulf MOT: Sonarworks

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    Orthodynamics usually are pretty current hungry headphones and OTL amps aren't too good with supplying current. That's about it.
     
  9. FallingObjects

    FallingObjects Pay It Forward

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    It's not a silly question, I think. It's actually a pretty difficult concept. Going off the assumption that you don't have much knowledge in electricity, so please pardon me if this is an erroneous assumption.

    Electrons behave fairly similar to water, on a superficial level. You have your voltage, which is similar to water pressure; how much is trying to try to get through a pipe of any given diameter. Your amps is how much water is actually flowing through the pipe at any given moment, and your resistance which is... well, resistance to flow. Your actual flow rate is a result of the voltage and resistance. Thus we end up with our electrical equation; V = I * R, or Voltage = Current (amps) * Resistance (ohms).

    tl;dr- Water pressure = Voltage, Resistance = Ohms, actual flow rate of water = Amps.

    Some headphones have very high resistance, but don't require much flow to move. Think of a toy paper windmill that's sitting behind a bush. So you need a lot of pressure to get around the leaves, but any wind that gets past is gonna make that thing spin quite quickly. These are basically your HD800-ish dynamic headphones; high resistance, but it doesn't take much to get them going once you get past it. Sometimes the bush is there for a reason, because if you had the windmill sitting in the open bad things would happen.

    tl;dr- Dynamics have high resistance, but are 'easy' to get going with the excess capacity. So they require a lot of pressure, but not much flow.

    Then you have your planars, which I can't pull out a good analogy for from my butthole, but let's say hydroelectric dams. It takes a LOT of water to get them going, but they're designed to be really efficient with what they get.

    tl;dr- Planars like lots and lots of flow, but don't have much resistance. OTL's are good with pushing at high pressure, but don't have high volume of flow.
     
    Last edited: Jan 1, 2017
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  10. Derf

    Derf Acquaintance

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    Ah, I remember the water analogy, but couldn't quite remember how it went. Thanks for taking the time to explain.
     
  11. Kattefjaes

    Kattefjaes Mostly Harmless

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    Forgive me, but I always find this metaphor unnecessarily windy and confusing, compared to what I was taught at school at the age of 11 or so, Ohms law.

    [​IMG]

    I once sat through a rambling explanation of water leaking out of boxes, by way of "explaining" the relationship between volts, amps and ohms, as part of a lighting course. After 45 minutes, various luvvies were more puzzled than before we started. Drawing the triangle made several of them feel better in about a minute.

    I don't know, trying to puzzle the near-ecumenical peculiarity of "how much is trying to try to get through a pipe of any given diameter" vs "how much water is actually flowing through the pipe at any given moment" isn't really terribly clear.

    Sorry if that makes me sound like a bitch ass mofo, I appreciate the hell out of what you were trying to do!
     
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  12. FallingObjects

    FallingObjects Pay It Forward

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    Hey, if an explanation doesn't help, it's an issue with the person trying to communicate an idea. No issues at all, different things help more for different people and I get that.
     
  13. Xyrium

    Xyrium Rando

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    Tubes for my guitar rig, and SS for my audio rig. Tube output was meant to be clipped... :)
     
  14. Armaegis

    Armaegis Friend

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    C'mon now, the correct term is "overdrive" :p
     
  15. BenjaminBore

    BenjaminBore Friend

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    Fascinating thread. So, where does this leave hybrid amps like the Mjolnir 2?

    How do the benefits of tubes differ in the gain/pre-amp stage vs the amplification stage. I was surprised when comparing vacuum tubes to the SS "tubes" on the Mj2 at how much improvement there was in micro-detail, background macro-detail, separation, and especially micro-dynamics. How does the SS amplification stage reproduce those aspects when SS in the gain/preamp-stage was unable to? Could these perceived technical improvements actually be additive?

    (Edited for clarity)
     
    Last edited: Apr 15, 2017
  16. FallingObjects

    FallingObjects Pay It Forward

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    I know the Vali 2 has quite measurable differences in low vs high gain for most tubes, especially with distortion bumping up the mid region. Between that, and pad swapping on my Elears, it noticeably fleshed out the tone of string instruments (Where they sounded tinny before). So yeah, tubes are definitely adding in stuff that's not there; that's mostly the reason why a lot of people buy tube amps in the first place, because the change is significant enough to notice, and preferential to them.
     
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  17. Hrodulf

    Hrodulf MOT: Sonarworks

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    In most two stage amplifiers the input or voltage amplification stage is what dictates the THD profile. Hence that's where it makes the most sense to insert a tube stage.
     
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  18. tomchr

    tomchr MOT - Neurochrome

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    That depends. In an SET power amp, the output stage (output tube + output transformer) is the dominant source of THD. The THD of the driver stage is often small (0.0x %). At line level, cathode followers are commonly used. Their THD contribution is tiny (0.00x - 0.0x %) as well.

    If you want tube sound, the output stage is where it's at IMO/IME. Alternatively, a gain stage can sometimes add enough THD to be audible. Adding gain at line level isn't always the best option from a signal integrity standpoint, though.

    Tom
     
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  19. Ash1412

    Ash1412 Friend

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    Isn't that only if you want more tube distortion though? If you view "tube sound" as distortion only, that'd be great. But for minimizing distortion while still having a tube in the amp, I think using tubes for the driver stage would make more sense.
     
  20. tomchr

    tomchr MOT - Neurochrome

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    I strongly suspect that what people call "the tube sound" is the 2nd and 3rd order harmonic distortion of tube amps. That type of distortion (higher 2nd than 3rd harmonic) sounds pleasing to many and can add to the sound stage and can create an out-of-the-head experience. I suppose "tube sound" could be IMD as well, but my money is on the THD as the main driver of "tube sound".
    Now, I say "THD" which doesn't say anything about the distribution of the harmonics. I hinted at that above. I doubt an amp with 1 % THD, all harmonics equally represented from H2 to daylight, will sound like a tube amp. It'll probably sound more like a poorly designed semiconductor amp from the 1970ies. As far as I can figure, to get "tube sound", you need enough THD to be audible but not objectionable, you need low order harmonics, and you need an "ear-friendly" distribution of those harmonics. Some soft asymmetrical compression will get you there. You can do this with a few diodes and an opamp. It just doesn't glow as pretty in the dark... :) And to be fair, there's more to tube emulation circuits than a simple diode clipper.

    Whatever floats your boat. Tubes do glow much prettier in the dark, though. I loved my mesh plate 300Bs for that reason. Sadly, they had a nasty tendency to run away thermally and red-plate.

    Tom
     
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