Ok, we have Kelly here claiming that the HD600 do not 'even begin to reach their potential' with sub-$1000 amps.

Surely whether an amp can show the potential of the HD600 does not depend on the *price* of the amp??

The demands of the HD600 are not extreme. 300ohms is higher than most other phones, but not by orders of magnitude...

In terms of efficiency it is not much different from your Grados and Philips and such...

So the Senns require good voltage swing. *How* good does it need to be? The Corda, with its 30V power supply, has 15V going through each of its opamps. Now tell me what 15V would sound like going through the HD600... (granted, it may not reach 15V even with the 300ohm without first clipping, but nevertheless this is an indication of the maximum voltage swing...

There are not that many headphone amps with such a high input voltage. The MicroZOTL, with its collosal 1W output, runs off a 12V battery...

The other question of course is output power. Just how much headroom is required here? Is 150mW out of the EMP enough? Is 250mW out of the RA-1 enough? What about 500mW? 1W@4ohms? (MicroZOTL) 1W@32ohms? (Wheatfield HA-4)... 5W@8ohms? (McCormack MID)

(Hmm, what is the output power of the Corda and Porta Corda?)

The RKV has an input voltage of 40W and converts that into 3 watts per channel, it also has a 0ohms jack and is designed to drive headphones of 200 to 1000 ohms impedance (this would include everything Beyerdynamic and Sennheiser makes and to my knowledge, indeed, every high impedance headphone except the K1000).

Another amp said to be good with the HD600 is the Cary SEI, which is 15WPC output.

For what its worth, the HD600 doesn't sound horrid out of my Corda HA-1--in fact, on an absolute scale it sounds pretty damned good, they just don't sound as good as the Beyer DT931/Corda HA-1 and it doesn't sound anywhere near as good as the HD600 does with a bigger amp. I strongly suspect this to be a power issue. That there is some correlation between power and price should not be surprising but if you come across a used Cary SEI for $100, I'm sure it would drive the HD600 all the same.

What I don't get is why you need so damn many watts. Headphone sensitivity is measured in dB/mW, and the value is usually around 100!

Let's take the 'wimpiest' amp, the EMP and MG Head with 150mW / channel...

Assuming 150mW / channel is at 8 ohms...

V = sqrt(0.15W * 8ohms) = sqrt(1.2V)

For 300 ohms, P = sq(V) / 300ohms = 1.2V / 300 ohms = 0.004 W = 4 mW.

Bear in mind that this is a pessimistic estimate as voltage swing ability ought to improve with increasing headphone impedance.

Now, I don't think I can stand listening to the Senns at the 1 mW volume level, so anything above 1 mW is just reserve power...

According to Sennheiser, if you feed the HD600 more than 200mW they will fry. That is the max power handling of the HD600. Over most of the frequency spectrum of the HD600 that will translate to around 7-8 volts and about 20-25 mA of current. However, the impedance in the midbass is higher than 300 ohms, so that would require more voltage swing than the rest of the spectrum. Bear in mind, however, that at these limits you are around 120 dB SPL. As I noted in an earlier thread, my normal listening volume is well below 1 volt, and even 20 dB peaks above my normal volume require less than 3 volts. In my case I could get by with a 9V battery powered amp, but I use 12V in my DIY amp just to be safe. It is always best, if possible, to feed the opamps their spec'd voltages, which are usually +- 15V. A standard opamp based design like the simple cmoy, combined with a decent +- 15V power supply will have zero trouble handling the HD600 at every sane and insane volume you could think of. You can build such an amp for $50. Based on my experience, it will drive the HD600s with confidence, and give you the signature HD600 sound.

The costs of the higher-end amps are better components and more complicated designs, all in the quest to squeeze out the best performance from the highest number of headphones (usually) at that price point. The same DIY cmoy I mention above would fail miserably with Grados at high volumes because it would not have the current capability necessary. For many, just powering the HD600s well is not enough. They want to squeeze every last ounce of goodness that is possible given their budget. I can easily tell the difference between my Corda and my DIY amp, and that difference is more than worth what I paid for the Corda. I wouldn't doubt that the Headroom amps are worth the price of admission too.

I do think that anyone that believes HD600 require a $1000 amp to sound better than other similar priced headphones is wrong. If I preferred such a headphone (say the DT-931 or SR-225) on a $50 amp I'm quite certain I would prefer it on the $1000 amp too, as long as both amps were built to drive both headphones well. Given that both amps have the power necessary for both headphones, the better sound of the $1000 amp will affect both headphones equally well. This is based on my experience with various DIY amps, my Corda, and the 7-8 headphones I own or have owned, all with various different impedances and sensitivity. If both amps don't drive both headphones well, then it is that particular headphone/amp combination you should be ragging on, not the headphones in general. You can build an amp for under a $100 that will drive nearly every modern headphone well--without clipping, without distortion, with the voltage swing and current capacity necessary for even insane volumes.

The Corda has no problem driving the HD600, so I'll give my HD580s (not my HD600s though ) to kelly if I prefer the DT-931 to the HD600 on the Corda and yet like the HD600s better than the DT-931 on the Max. I'll definitely do the comparison this summer when Headroom comes to town. And I'm not joking either, I will give them to him (and buy some DT-931's for myself of course). If Headroom doesn't have a Corda or won't let me hook mine up, I'll do the comparison on the Little vs. Max.

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If you listen to a lot of compressed music this may be true Dynamic music has large peaks so you do need extra headroom, and remember that a 10 dB peak would require 10 times the power and a 20 dB peak would require 100 times the power.

So did I do my calculations wrong?

Is the power rating for the EMP and MG Head given for 8 ohms or 32 ohms?

If at 8 ohms, is taking the voltage swing at 8 ohms and applying it to 300 ohms too pessimistic?

Or do the EMP and MG Head really not have enough power to drive the HD600?

It's nice that you can feed opamps 15V. But will they really be able to swing 15V on the HD600? I don't think so So how many volts can a diy cmoy actually swing?

Hmm...

BLOGGS!!!

DAMNIT!!

*Deep Breath*

OK, now bloggy, take your math equations and burn them, they don't mean anything. You wan't to hear the HD600 at it's maximum get a damn good source and a damn good amp. Quit trying to prove thousands of audiophiles wrong. It's just not going to happen. You're living in a world of delusion even more elaborate than my own and that''s really saying something.

The EMP does NOT drive the HD600's to half their potential IMO. It has little to do with your math "equations". ASK AN ELECTRICAL ENGINEER IF THERE IS A MATH EQUATION FOR HOW A COMPONENT WILL SOUND!!!!!!!! HE WILL POINT AT YOU AND LAUGH!!

He will laugh as I laugh. NOW. *Deep Breathe* Are you going to drop this subject or are you going to make me sic Mike Walker on you? I think he's for hire, he'll torch anyone for 5 bucks and a bag of espresso beans.

aiotron,

I think you are just being an elitist snob. If you had enough formulas and equalizer settings, you would be able to get the same sound out of the HD600 from anything.

For me at least half the fun in this hobby is now derived from the 'math equations' and mulling over the electronics principles and only the rest from the listening. So I'm afraid I'll be bugging you for a long time to come

I just wish I studied electronic engineering myself.

And I'm not trying to prove anybody wrong.

Joe

edit: damn, and kelly has to squeeze in his post before mine Well I think you're just freakin' hilarious

Trying to find out the difference between the $1000 amp and the $100 amp is not the same as claiming that there's no difference...

And of course, even if 2 amps have the same power output, they may well have very different output quality. Obviously.

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OMG, for once good old ai0tron says something that makes sense. Quick! Someone buy me a ticket for that $325 million Big Game lottery in the USA.

This discussion and the various threads that spawned it are fascinating to me.

While I appreciate reading about the wattage/current/voltage issues of various amp designs, I'm not an engineer or techie, so I can't add anything substantive on that level. I can, however, offer my personal, subjective, and totally anecdotal experience as a "dirt-cheap audiophile"---someone with filet mignon taste on a Hamburger Helper budget.

I am now the proud owner of a beautiful little CHA-47 that I purchased recently from Erix (who built it). Definitely a sub-$1000 amp. In fact, it cost me $85, plus $3.50 extra for one mail exchange to repair a grounding problem. The amp is wall-wart powered only, and I'm using a Ratshack regulated 12V, 800mA converter ($16). I also bought the Markertek mini-to-mini interconnect ($15).

I listen to all styles of music from the iTunes mp3 Player on my Mac Pismo Powerbook, mainly from 196K ripped CDs and 128K internet downloads. I suppose my preference for compressed digital music will cause some of the more snobbish audiophiles to turn up their noses in disdain, but I have to reconcile my left-leaning radical politics with my right-wing audiophile yearnings, and mp3s are the chosen format of the musical revolt. But then, that's another thread discussion entirely.

Knowing that the CHA-47 was designed specifically with Grados in mind, I bought the amp to go with my Alessandro-Grado MS-1 headphones ($99, but equivalent to the $150 Grado SR-125). I also hoped that the amp might bring out more of the fabled potential of my Sennheiser HD-580 cans (from uBid, NIB for $118 shipped---a deal that was just too good to pass up).

Well, to make a long story short, to my ears the Alessandros beat the Senns hands-down on my budget-amped rig. The Senns sound darn good, but the Alessandros make me happier overall. With the Senns, I think, "Hmmm, interesting." With the Alessandros, I feel, "Wow. I love this." One is critiquing the music with my head; the other is enjoying the music with my feelings.

Do I believe that the MS-1 is objectively better than the 580? No. Not at all. I tend to trust the retail price differential and all the opinions I've read here that tout the Senns as distinctly higher-end cans than the Alessandros.

Do I think that the limitations of my set-up influence my preference? Quite possibly. The soundcard and iTunes player in my Powerbook are definitely top shelf for PCs, but it's still just mp3s played through a CHA-47, not a Thorens turntable and pristine analog vinyl LPs played through a Carver preamp.

Is it possible that I simply prefer the signature Grado sound? Yes. That is eminently possible. I haven't heard the Senns with a Corda Headamp or Slee Solo or MG Head, much less with a thousand-dollar-plus amp like a Cary, Headroom Max or Blockhead. Perhaps I'd be blown away by the airiness and detail of those with the Senns and a high-end SACD deck. But perhaps not. Maybe I'm just a Grado kind of guy (in which case I might still be happier with the SR-325 and RA-1 than with a Senn 600 and Max).

My real point is that I'm happy NOW. Yeah, I'm glad I own the Senns---it'll be fun to audition them at the Headroom Tour when it comes to Minneapolis in June. But with the Alessandros, the Markertek IC, and the CHA-47, I've got a $235 audio system that makes me very, very happy (at least for now).

Plus, I get to enjoy all the discussions here on Head-Fi, argumentative or not. LOL.

--Bill

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Glad you're happy with your music. Wish I could say the same for myself. Every time I question the received wisdom here I get treated as a fool I'm not surprised about kelly because I've recently made a harsh post targeted at him and have yet to make up with him, but why everyone else as well?

As soon as I get my replacement Porta Corda from Jan I'm gonna go listen to some music--and forget about Head-Fi, if conversations here go on in the same way as it has recently.

And you know what? I don't even have to bother about whether it can drive my HD580 properly--because my phones of choice are the Sony EX70!!

Joe

It could be that people are not interested in technical geek talk.

Power alone doesn't predict quality of sound. Neither does price.

Power and impedance issue is a complicated. It really depends on the amplifer design.

There's a couple of good threads on power over at Headwize's DYI forum. Here's a recent one.

http://headwize.powerpill.org/ubb/sh...ays=20&stime=0

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"Dude, that's crazy talk!"

Seriously, I think the EMP and the 600/580 combo is magical. Maybe you're thinking of the original, underpowered Earmax (not the Pro)?

Kelly's claims aren't really novel although I never heard enough amps to put a price tag on it myself. But I was one of the first to be quite dissapointed with HD600 performance out of entry-level amps (buried deep in ancient head-fi/headwize history). I just believe this is just do to the fact that I had other points of reference.

Of course most people who start, start out with an entry-level SennHD600 setup...this is fine as long as they either

a.
Never get a chance to audition another more synergetic combo at an equivalent or perhaps even lower price...

or

b.
Eventually upgrade their amp to something viscious.

IMHO, I think your EQ'd EX70's would not be your preferred cans of choice over the Senns if you tried a more synergetic combo.


I usually keep quiet about this topic even though I was one of the early adopters in believing the HD600s are quite UNremarkable out of entry-level amps, but stopped pushing this stance as *so* many people do go this route with Senns and they don't like to hear it. But like kelly, I think that if people want an affordable synergized combo they could do better. But if you want *decent* performance now and know without a doubt you will eventually couple the Senn HD600 with a viscious beefy and probably wallet draining amp...than do so. However if you do not plan on doing the amp upgrade (and surely not everyone has intention to obtain a viscious beefy amp) for the price you pay for that *decent* performance...IMO I think my DT931 + Szekeres combos would absolutely ream it. Unfortunately I don't know how well the HD600 would works with a Szekeres.

Oh and unfortunately I also wouldn't be able to formulate what criteria makes a *GOOD* amp for the HD600, but I can't wait to find out what amps I'd actually like the HD600's with at a headroom meet. I hate boiling down things to price tag too...however IMO I can't really think of anything in the entry-level amp area that would absolutely tickle my fancy with a HD600 combo.

Ha...there I said it again...and finally posted an incendiary opinion when I've long stopped...I'll probably regret it and stop posting such silly things again.

Joe,

One possible explanation for why so many Watts are necessary is the linearity of the power delivered. A 15 W amp may not use all of its power to drive a pair of headphones, but may have the most linear 2 mW available to drive it. Or knowing human preferences and Cary amps, may have the right non-linearities to make those 2 mW sound really nice. Not accurate, but nice.

--Andre