The All Purpose Advice Thread

Discussion in 'Advice Threads' started by purr1n, Sep 26, 2015.

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  1. Ardacer

    Ardacer Friend

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    Mkay, I'm at work so I'll try to be brief and concise.

    Power spent driving the headphones is voltage drop over output impedance times current + voltage drop over headphone transducers times current. If the impedance of the headphones is constant with frequency, then it forms a simple voltage divider that causes the headphones to be a bit quieter and nothing much else. Planars usually have constant impedance over frequency. If it's dynamic though, this changes, so you basically have voltage dividers with different ratios depending where you are at frequency, causing unwanted colorations.

    So. Transducers themselves have something called sensitivity, this means how loud they get with input power or voltage. This is actually the same thing, cause the sole drivig force of power is voltage. The only thing that dictates power, relatively speaking, is voltage, cause the current is a result of it. Now, line outputs from, say, dacs, have a fixed voltage of anout 1v or so. For some iems, this could be way too loud. For some other full sized headphones, you'd hear something quiet.

    Another thing to consider is that, to perceive something as double the loudness, you need a 10 db boost which is about 3x the voltage, or 9x the power. And this is true for both speakers and headphones of any kind. So... gain and power can and is often overrated.

    Now, you want to be able to achieve at least 110 db, to be able to listen comfortable at around 70-ish db and still get those dynamic peaks. To see just how much power, or voltage, or gain (same thing in the end) you need, you take the transducers sensitivity and impedance, and calculate the required voltage and power to achieve this.

    Once you know this, you can see how much gain you need - how much you need to boost that line level voltage from dac or other sources. Also, you check the amps data to see if it's capable of outputing as much power you need into your impedance. Higher is easier to drive cause it needs less current, and also those colorations as a result of output impedance (in dynamic driver case) are less of an issue.


    So basically, without enough gain, you can have all the power available in the world, but you just won't ever use it.

    With enough gain and not enough power, you won't be able to go past some level of loudness anyway, and you're stressing your amp as more of the signal drains its max power.

    With too much gain, you can clip your amp, which can be dangerous for both the amp and headphones, if you overdo it.
     
    Last edited: Jul 3, 2019
  2. Ardacer

    Ardacer Friend

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    Now, as to how much power the amp can deliver cleanly and nicely, that's a whole other can of worms.
     
  3. ergopower

    ergopower Friend

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    Gain is a measurement of voltage difference only. Power is voltage x current, so they're not the same thing.
    In general, a higher impedance transducer needs more voltage and less current to produce a given loudness; a lower impedance transducer needs less voltage and more current to produce the same output.

    Power = voltage x current
    Power = current^2 x impedance
    Power = voltage^2 / impedance
     
  4. Joao Paulo

    Joao Paulo New

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    Hello, I have a Woo Audio WA22.

    I'm willing to make a upgrade. My eyes is turning to the EC Stduio Jr.

    Someone did listen those amps ? How was the comparasion ? Is the Studio Jr. vs Studio a huge gap upgrade ?

    Thanks

    Joao
     
  5. Biodegraded

    Biodegraded Friend

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    @purr1n requires us to have tattooed somewhere visible on our bodies:

    V = IR (Ohm's Law; I = current, R = resistance); and P (power; watts) = VI

    The other equations given by @ergopower and the practical results described by @Ardacer follow directly.
     
  6. gixxerwimp

    gixxerwimp Professional tricycle rider

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    Just got my NBM from @Zampotech. Is it normal for one tube to be much brighter than the other in a pair? As you can see, the left driver tube is super bright. The left power tube in the back is very slightly brighter than the right one, but not enough difference that would cause me concern.

    20190706_180315.jpg
     
  7. Cakecake

    Cakecake Guest

    My PC is about 30 ft from Yggdrasil. Any recommendation for a long USB cable?
     
  8. zonto

    zonto Friend

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    That is too long of a run without an active repeater in the chain (source). Something like this: https://www.amazon.com/dp/B004HJDUW0/

    At that distance I’d run something like an Eitr to a digital coax made from RG6 cable (like Belden 1694A) or an optical cable (likely from Lifatec).
     
  9. Taverius

    Taverius Smells like sausages

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    30ft :eek:

    That's twice over usb spec (5mt max) it's a crap shoot over what will work and you might need to stick a wyrd in the middle just as a repeater.

    It might be easier to just use an allo usbridge, or a USB-AES converter.
     
  10. gixxerwimp

    gixxerwimp Professional tricycle rider

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    @Zampotech explained:
    So there's nothing to worry about.
     
  11. Cakecake

    Cakecake Guest

    ugh, what do ppl use for source? dedicated laptop or something other?
     
  12. bixby

    bixby Friend

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    Never a laptop, too noisy unless maybe running as a roon core via ethernet to another end point. Desktop is usually much better. Allo bridge with Roon, as @Taverius, has mentioned is an excellent endpoint.
     
  13. LetMeBeFrank

    LetMeBeFrank Won't tell anyone my name is actually Francis

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    Raspberry Pi 3 with HiFiBerry Digi+, all in with a memory card and case should be around $100. Software I use is Volumio (free) but I think you can do Roon if you have that.
     
  14. Taverius

    Taverius Smells like sausages

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    I don't remember which pi software is best for roon - you can add it to volumio but it's a pain and there's an easier one, I just forget the name.
     
  15. captkirk

    captkirk Khan's BFF

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    DietPi maybe? I recently picked up an DigiOne Sig Player running DietPi as a Roon endpoint and have been thoroughly impressed with it's performance.
     
  16. LetMeBeFrank

    LetMeBeFrank Won't tell anyone my name is actually Francis

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  17. Cakecake

    Cakecake Guest

    Can I use my phone as remote for this pi roon thing?
     
  18. LetMeBeFrank

    LetMeBeFrank Won't tell anyone my name is actually Francis

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    Yeah you can control Roon or Volumio with a phone, tablet, laptop, etc.
     
  19. Ksaurav402

    Ksaurav402 Friend

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    Yes, you can. You just need the Roon app which is free and it will connect with roon core and can work as remote
     
  20. aamefford

    aamefford Nothing like chamberpot coffee

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    This what I use as well. Works fine.

    We need to talk. This is what I want for the headphone rig. I’d move my digi + downstairs to the speaker rig.
     
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