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Skeptico Saloon: An Objectivist Joint

Discussion in 'Sound Science' started by gnarlsagan, Jun 27, 2013.
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  1. StanD
    @imackler The Leckerton UHA-4 is very limited in output power, I doubt that one would get good results with either the HD600 or HD650. Their web page indicates no USB support for Android or iOS.
    I would take a look at the FiiO E18 it works with Android as well as iOS, etc. and has plenty more audio output power. It doesn't draw USB power so you won't need a powered USB Hub.
    UHA-4 Max Output Power
    16 ohms: 20 mW
    32 ohms: 40 mW
    100 ohms: 50 mW
    300 ohms: 15 mW

  2. maverickronin
    @StanD, that's still 109db with the HD650s...
  3. imackler
    I'm out of my league here... But using the spreadsheet at http://www.apexhifi.com/specs.html
    There seems to be a lot of difference between listening at 110db and 115db regarding how much power is required. 110db seems like 20mw would be enough for both HD600/HD650. But Lord Voldemort recommended 115db for audiophile recordings (I listen to lots of well-recorded classical). Wow... That extra 5db requires a ton more power.Wouldn't I need 53mw for the HD650 and 63 for the HD600? 
    (For the record, I never really listen to music loud.)
    Does it look like I'm doing this right? Do you agree that I might need 115db for audiophile recordings? 
    Thanks for all the help guys! I feel like the fog is lifting. I stayed up too late leading this section of the forum...and loved what I learned! 
  4. StanD
    NOW CORRECTED: misread the decimal points during calculations.
    15 mW on the HD650 will only get you about 109.5 dbSPL. The sensitivity of the HD650 is 103 dBSPL at 1V or 97.77 dB/mW
    Close but maybe not enough headroom.
    Although the E18 has far much more power at lower impedances, at 300 Ohms it can deliver almost 27 mW taking the HD650's to around 112 db SPL, IMO not bad. If you use lower impedance cans, then the gap in power is much more favoring the E18.
    If you don't need a DAC then the E18 Amp can kick out 93.7 mW at 300 Ohms which should deliver 117.5 dB SPL for the HD650's.
  5. maverickronin
    Looks good to me.  If you like to listen  to well recorded classical with plenty of dynamic range and like it loud then indeed,  the UHA-4 probably won't cut it. for you.
    I normally listen at lower volumes so I didn't have a problem using the UHA-4 with my HD650s (when I still had them anyway...).
  6. stv014
    With 97.77 dB SPL at 1 mW, why would it be lower at 15 mW ? Also, 15 mW into 300 ohms is 2.12 V, at which 109 dB SPL seems to be correct.
  7. StanD
    Crap, I goofed up and misread the decimal point. Sorry guys. I'll go back and fix my post
  8. imackler
    Am I right to understand that unless a manufacturer tells how how much power there is into a certain load, there is no way to tell from its output into one load? For example, if they say 200mw into a 16ohm load, you can't extrapolate from that information what the output would be into a 300ohm load? 
  9. maverickronin
    You usually can't do that very reliably, at least from just one power rating.  There are to many other possible variables.
  10. stv014
    The maximum output voltage an amplifier is capable of without clipping generally decreases at lower load impedance (due to factors like current limiting and output impedance). Thus, the extrapolated output (200 mW into 16 ohms = 1.79 V = 10.7 mW into 300 ohms) in your example would be a pessimistic estimate, as the real maximum could be somewhat higher than that by an unknown amount.
  11. cel4145
    I find it interesting that this discussion is placing so much reliability on manufacturer specs that have not been independently verified, given how often they have been found to be unreliable when it comes to audio equipment. Not that I don't do it. Just saying since this is the Skeptico Saloon :)
    imackler likes this.
  12. StanD
    Sometimes even better, FiiO usually specs the Max Vp-p for their Amps or DAC/Amps. That's what I used to get the power at 300 Ohms.
  13. SunTanScanMan
    Anything change to how 'like' comments appear now on this forum?
  14. imackler
    The E12A is listed by Fiio as 10.3 Vp-p. How do I measure what the power would be to a 300ohm load? Is there a formula to use? 
    In some places, the E12A is only listed as recommended to 150ohm, but I think that may be marketing... The X3 is 8 Vp-p and its listed as up to 300 ohm. 
    Is there another spec to take into account?
  15. StanD
    I spec'd the E12 not E12A. Peak output voltage is 15 Vp-p. which  15 / 2  is the peak voltage multiply by 0.707 to get VRMS which is 5.3025 VRMS.
    VRMS = Vp-p/2 X 0.707
    Power = VRMS2/Impedance so 5.30252/300 is 0.0937216875 Watts or 93.7 mW at 300 Ohms.
    The X3 should deliver about 26.7 mW at 300 Ohms at 8 Vp-p.
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