[kwkarth]

Quote:

But do you really believe in manufacturers' specs? I don't - and I've a/b-compared both. And I've measured 'em. According to my sound level meter, the K240S is ~ 8 dB more efficient (which matches quite well with what I heard and still hear) - even though the K501 should be 3 dB more efficient according to the specs. Probably a different measuring method or just a simple flaw. Equipment used for my measurement was the el cheapo ratshack sound level meter, set to weighting C and 80 dB on the dial, and the Corda HA-1, set to no crossfeed with the volume knob at 12 o'clock and using the 0-Ohm-output for both phones. And I've used the same CD, same track, same timeframe for both - player was the Sanyo CDP-55A. I repeated the measurement several times, in order to make sure I don't measure nonsense... And I listened for control purpuses, too. I just don't have a fresh 9V-battery at hand right at the moment (it's almost 3 o'clock in the morning over here), otherwise I'd have reapeated the measurement with the Porta Corda, which I also have...

Yes, Lini I do believe the manufacturer's specs, and I question your measurements. Did you measure the actual power being delivered into the respective headphones? What was your method of determining that? I suspect the Corda couples better to the lower impedance of the 240, having NOTHING to do with the specific sensitivity rating of the respective cans. So you need to be more careful and accurate in making your measurements before you make statements like what you did my friend. Your current method is flawed. Sorry.

 

[kwkarth]

Lini,
If you want to do this right, going by manufacturer's specs, the 240s is rated for 91db/mw @ 55 ohms, and the 501 is rated for 94db/mw @ 120 ohms.

For the 240S, 1mw will be being dissipated when you measure 0.23v being dropped across the voicecoil.

For the 501, 1mw will be being dissipated when you measure 0.35v being dropped across the voicecoil.

So, if you want to conduct this test accurately, get out your AC RMS voltmeter, measure exactly 0.23v (using a 1kHz sine wave input) at that point, the acoustic output of the 240S will be 91db.

Using the same technique for the 501, adjust the output until you measure 0.35v across the voice coil of the 501's and you should then measure 94db of acoustic output.

Both headphones will be receiving exactly 1mW of power and your measurements should concur with manufacturer's specs.

Cheers!

 

[stuartr]

jpelg, I am a CT head-fier, and you would be more than welcome to come out and try my amps, but you will have to wait until late summer, when I am returning. I have a headroom supreme, and I love it. It was 350, and it has a really great combination of benefits. One, it sounds excellent off the bat. Two, it is very flexible -- it has three levels of gain, and a 3 level switch to brighten dark headphones, it is built like a tank, and it is "portable". I say this in the sense I bring it on planes and roadtrips with me without a problem, but it is not something you are going to drag around with you if you are walking. It has a very nice crossfeed feature. The upgrade path is extremely good if you should ever feel like doing it.
I do not have the 501's, but I want to buy them once I am back in the US. I am envious of this sale that you all had a chance to take part in, though I am sure I will find something similar eventually.
Cheers,
Stu

jpelg -- what part of CT are you from anyway?

 

[jopi]

I'm using a Little to drive my 501s. Sounds great, but I haven't heard anything else.

I like the upgrade path of the Little (better power supply, premium module), that's why I've decided to go with it.
I figure you'd need a pretty good source before you could justify a better amp than the Little.

 

[Neruda]

Quote:

Originally posted by OneMalt I don't have the 501s but my RA-1 drives my HD600s and ER-4 just fine so I'm guessing there wouldn't be any problems with the K501s.

The RA-1 will not be capable of adequately powering the K501s.
Quote:

I've just got the impression, that an opamp-based headphone amplifier like the Grado RA-1 or the Corda HA-1 won't do the K501 full justice - I prefer listening to the K501 with my integrated amps. A more powerful amp with discrete transistors like the Sugden Headmaster would probably be a better match.

what he said.

 

[TimSchirmer]

agreed. Personally, I am just having someone build me a Mosfet with OPA627AP's with lots and lots of gain.

 

[TimSchirmer]

holy crap, they do have the Art DI/O for a mere $159.99

 

[r4z0r]

The Art D/IO was on sale for 129.99 a while ago..

I should have grabbed one then! Damn, that's twice I've missed deals at Musiciansfriend.com!

 

[dcg]

Consider yourself lucky.

www.fullcompass.com has them for $122 shipped.

http://www.head-fi.org/forums/showth...ght=ART+DI%2FO

 

[Cousin Eddie]

To NickG and anyone else trying to get the deal on the K-501's, keep trying. They go in and out of stock. Right now they're back in stock again.

 

[lini]

kwkarth: <Lini hitting his forehead with his flat hand> Oh, blo... he.., you're right, of course. What I've conducted was a 'relative real world sensitivity test' - not a 'relative real world efficiency test'. How embarassing... <sigh>

I can at least partly blame it on AKG, though, because they list their dB/mw-ratings as sensitivity on their site - not efficiency, what it should be then, right?

So what I've actually been talking about, was a sensitivity problem, people with opamp-based might run into - not a power requirement problem. Thanks for your patience and for the input.

Nevertheless, I think it's worthwhile to compare the K240S and the K501 soundwise. In case you should do that, it would be nice if you could also do a 'relative real world efficiency test', 'cause I don't have the right tools at home to do that. And I'd actually prefer that to the standard measuring method with a 1 kHz sinusoidal wave, as impedance is not constant throughout the headphones' bandwith - and I don't exspect anyone of us listening to 1 kHz sinus waves, anyway.

Greetings from Munich!

Manfred / lini

 

[kwkarth]

Hi Manfred,
the use of the word "sensitivity" by AKG for the spec is appropriate as long as they define the parameters as they do. Namely; db/mw @ specific impedance. So you need all of the spec for it to be valid. Also, I believe the db measuremebts are specified with A weighting rather than C weighting as well.

So we're not dealing with a sensitivity issue here but rather an impedance matching issue if you will. Most small portable amps are designed for low impedance cans out of convenience and necessity because one is usually working with a limited voltage on the B+ rail, namely on the order or 3 volts or so. With a mains amp, we have more flexibility as it is no problem to design for a B+ B- of +-15v or 30v rail to rail. This greater rail swing enables an amplifier to more easily/properly drive higher impedance headphones.

I'm very much looking forward to hearing the AKG 240S at the HeadRoom Tour this summer.

Thanks for all of your information!

Cheers!

 

[kelly]

It's very interesting to me that the AKG fans don't seem to have issue with admitting that they're not really great with the lower end opamp based amps compared. The Sennheiser guys totally wig out when you say that about the HD600.

From my audition, I felt that the K501 was still too bass shy, even with the Max. I wodnered if it might pick up with the bass monster RKV, but Vertigo indicated that he didn't care for that combo when he had my RKV. I'm led to believe that the K501 won't have enough bass to satisfy me under any circumstances. *sigh* But they sound really good otherwise(!).

 

[kwkarth]

Hi Kelly,
The 501's will never sound as full in the upper bass as the 600's. Some like myself view that fullness as an added coloration and there are others who don't, hence the preference of one can over the other by each camp. Most folks concede that the mids and highs are more cohesive on the 501's and I find that particular characteristic so compelling, I am willing to overlook their shyness in the bottom octave. (Please Mac, don't chime in here saying that there's no bottom octave, cause it ain't true.) Anyway, the bottom octave on the Senns is better than the bottom octave on the AKG's. I personally feel that the midbass on up is better on the AKG and that's why I perfer them for most music, but again, remember, that's my preference. Your mileage may vary...

Cheers!

 

[kelly]

kwath

Do you also think the bass on the K1000 is bloated? Because I feel the K1000's bass is a lot better than the K501's.