Ok, *why* do I need a headphone amp for HD650?

Discussion in 'Computer Audio' started by alfbaxter, Aug 10, 2010.
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  1. beeman458
    You'd need to have soundproofed listening room or something to do that with the HD650s.  They will get pretty harsh at quite moderate volumes if they don't have enough juice.
     
    Maybe I'm lucky.  Not intending to be argumentative in that I to listen at very low levels, I find that the although the 650's aren't as full as one might want, considering low level listening volumes, overall, the sound is pretty darn good  Using a Xonar STX sound card, I listen at volume control levels of 4 or 5/100.  To me, not a speck of harshness.
     
    ???
     
    And FWIW, yes, I do crank it up on the occasion, to between 10-20/100.
     
    (Okay, my head finds loud music a distraction.)
     
    [​IMG]
     
  2. maverickronin
    Quote:

    Maybe its just relative.  The HD650s are so very smooth with some muscle behind them.  The first day I got them I listened to them all day at work from my Bithead and thought it was great until I got home and plugged them into my Maverick D1.
     
  3. beeman458
    To me, when the 650's are new, they're so tight, they're disappointing in their sound signature.  After a couple hundred hours of use, they loosen up and their qualities begin to shine through.
     
  4. tvrboy
    OMFG... the signal to noise ratio on headfi is terrible these days! OP, there are a million threads on why volume does not equal sound quality. Sure, you can get the volume high using a sound card or DAP. But things like bass control will improve with a desktop amplifier. For many cans, a desktop amp is necessary to get acceptable sound quality (as opposed to just playing loudly). I'm sure you have heard speakers that play super loud but still sound terrible. That is the same case when you are trying to drive a HD650 with an underpowered amp. Amps are not snakeoil and nobody is trying to cheat you. There are easily measurable and audible differences between amplifiers. The only people who say desktop amplifiers are a waste of money are newbies who don't have experience with a wide variety of equipment. Sorry, just cause a HD650 + ipod is the best YOU have ever heard doesn't mean it's the best possible combination. Newbies often confuse the best of their experiences with the best experiences possible!
     
    You don't have to spend $2000 on an amp. You can buy used or new amps in the $250-350 price range that will work just fine. Let me give you a list of some to look up: 
     
    Gilmore Lite (used)
    Schiit Asgard
    Matrix M-Stage
    Audio-GD C2C
    Sheer Audio HA-006
    Eddie Current EC/SS (used)
    M^3, dynalo (DIY designs)
     
  5. AlfBaxter
    @tvrboy: thanks for your reply, but it wasn't me who said iPods could drive HD650! I use an Auzen Prelude straight out of the line-out. I also didn't mean to imply that amplifiers are a waste of money. I started out neutral on that issue.
     
    The purpose of this thread wasn't to find out whether people think HD650 sound better amplified - as I said, I posted anticipating that most people on here would think they do. What I was looking for was some sort of objective justification for the common subjective impression that HD650 need amplification - something of the form *this* is what an amplifier can do that a soundcard can't do. Otherwise there's always a chance the subjective impressions are due to placebo effects. Although I found many threads *repeating* the claim that HD650 need amplification, and the claim that there's a distinction between driving headphones loud and driving them well, I couldn't find anything explaining *why* they need amplification, or what good driving is, and why soundcards can't do it.
     
    I am now convinved, in any case, that there's quite a bit that amplifiers do other than drive headphones to a sufficient volume level. I'm also convinced that plugging HD650 directly into a soundcard isn't a good idea. I posted a couple of things I found above, about the effects of high output impedance sources on headphones. In the case of my Senns, it seems (due to the fact that their impedance varies with frequency) I need a low output impedance source to maintain constant voltage over the headphones, which in turn smooths out the frequency response. That's the kind of thing that convinces me that the differences people with amplifiers hear are not due to placebo.
     
    Took the plunge and ordered a Matrix M-Stage from coolfungadget. Thanks all for helping to convince me to buy one - I'll let you know how it works out.
     
  6. beeman458
    I'm also convinced that plugging HD650 directly into a soundcard isn't a good idea.
     
    ???
     
    People (reviewers) rave regarding how well the HD650 does with a signal supplied by an ASUS Xonar STX.
     
    ???
     
    The STX has a headphone amp on board and requires a separate, 12v molex power supply.
     
    ???
     
    I posted a couple of things I found above, about the effects of high output impedance sources on headphones.
     
    The STX sound card has three impedance settings (0db, +12db, +18db) to accommodate individual headphone requirements.
     
    ???
     
    The point of my above is, the STX is both a DAC and a headphone amp, in every sense of the word.
     
    ???
     
    The question marks indicate that based upon readily available information, in the case of the STX, I don't understand the context of your comments.
     
  7. caliskimmer
    I have the Zero Dac and it drove my Sennheiser HD 650s really well before I had to sell them. However, it had some issues even after I soldered a new volume pot on. Without an amp, you just won't get the full potential of the HD 650s
     
  8. AlfBaxter
    @beeman: when I said plugging directly into a soundcard isn't a good idea, I meant plugging directly into the line out, as I do. I should have been clearer when I made this claim.
     
    The Xonar STX has a headphone amp built in, as you say. What's more, if you look here: http://www.stereophile.com/budgetcomponents/asus_xonar_essence_ststx_soundcards/index5.html you'll see that the output impedance of the headphone amp is measured at 10.7 Ohms, which is much lower than the impedance of the HD650. (By contrast, the output impedance of the line-out on my Prelude is around 300 Ohms.) My earlier post highlights the importance of the source having a much lower output impedance than the input impedance of the headphones/speakers it is driving, and so what I say there actually supports your view that the STX will drive HD650 just fine.
     
  9. beeman458
    @beeman: when I said plugging directly into a soundcard isn't a good idea, I meant plugging directly into the line out, as I do. I should have been clearer when I made this claim.
     
    Oh.  Cool.  Important note to self, don't plug into the "line out" jack.  I got it.
     
    [​IMG]
     
     
  10. beeman458
    Stereophile writes:
     
    The line output impedance was a moderately low 99 ohms at all frequencies; the headphone output impedance was 10.7 ohms at all frequencies and settings. All the outputs preserved absolute polarity; ie, were non-inverting.
     
    You write:
     
    you'll see that the output impedance of the headphone amp is measured at 10.7 Ohms, which is much lower than the impedance of the HD650.
     
    Me?  I think.....Huh!  10.7 Ohms vs 300 Ohms.
     
    ???
     
    Okay, forgive me, I'm not an EE.  What's the above trying to tell my ignorant butt?
     
    ???
     
     
  11. Dalamar
    Amplifiers are a waste of money, no headphone amp should cost over $100, and at $100 it out to be extremely low output impedance, zero THD/IMD, and high SNR.
    $200 is enough to get a good speaker amp that puts out roughly 100 watts = which is what, well over a few thousand times what headphones use?
     
    If the amp is short on voltage - the headphone's max volume MAY be limited, but it won't affect sq. If it's short on current, it will clip, and clipping is audible - same with speakers. As long as your source impedance is below your headphone impedance, it's all good.
     
    The mere $200 Essence STX with its dime a dozen TPA amplifier is capable of driving every headphone at a listenable volume. Near perfect RMAA measurements (any improvement won't be audible), plenty of power, and there are no headphones with an impedance lower than its output.
     
    High end audio is full of scams, and BS. Use common sense. There is ZERO logic in something that uses a few milliwatts of power to require some retardedly priced amplifier.
     
  12. Uncle Erik Contributor
    Dalamar, have you ever priced out components for an amp? Digikey, Mouser, Newark, and others show you the price discounts for large orders. It's not easy to find the required components with even volume discounts of 1,000 units or more. Pull up some of the designs at Headwize and price them out. Sure, some amps are overpriced, but $100 won't cut it. If you could find a way to profit from a quality $100 amp, you should. You could make a lot of money.
     
  13. grokit
    Man I am starting to hate threads like this; there's so much ignorance and trolling masquerading as advice, it's really hard for any decent information to get through the static. OP, if you want to hear the potential of your HD650, get yourself a decent impedance-matched amp; you could also change the title of your thread to something a lot less inflammatory for help in finding one. If you don't, just plug them in to your iPod/DAP or soundcard without an amp and convince yourself that as long as your headphones don't clip that what you are hearing is "topnotch sound", even though you would perhaps be better served by a set of Triports at that point because that is what they are made for.
     
  14. beeman458
    Man I am starting to hate threads like this; there's so much ignorance and trolling masquerading as advice, it's really hard for any decent information to get through the static.
     
    Ahhh, come-on, how do you really feel?
     
    [​IMG]
     
  15. FallenAngel Contributor
    This is getting terrible and so poorly off track.  Oh, and there's another person on my ignore list... ignorant and determined, what a combination.
     
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