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do my hd650's need an amp - Page 2

post #16 of 41
Quote:
Originally Posted by Maxvla View Post
If he moves the 'source' to a DAC the laptop is a fine transport. There are a number of affordable DAC with amp combos out there. Even a fairly inexpensive one will be a night and day difference from the laptop's headphone output. (for the OP's benefit. I know you (Mule) know this )
Indeed, DACs are wonderful! If the OP has the money to buy a decent DAC (KECES-151 is what I'm going to shamelessly plug once more) and an amp (Gilmore Lite, perhaps?), then by all means, his eyes and ears will light up bright than a Christmas tree as soon as he listens through that.

The beauty of the HD 650 is that it scales wonderfully. That's a fragment of a sentence, but I have nothing else to add onto that.
post #17 of 41
Good lord yes, they do need an amp! With some headphones, amping is an option, or in many cases none is really needed at all. The HD650 is certainly not one such headphone. They have a fairly high impedence (300 ohm) so it takes more power to drive them to perform to their potential, which thusfar to me seems near limitless
post #18 of 41
Thread Starter 
Thanks for everyone's advice & feedback so far.

I'm using flac files, and the HD650, but I guess everything in between these two is not designed purely for reproducing high quality audio.

OK, I can see the consensus now - I should upgrade my source, and get an amp - sorry for my wallet.

I'm not against getting an external DAC/AMP in future, But............this is the science section, and I'm failing to see a scientific explanation, of why I need an amp, other than to increase the volume?
post #19 of 41
I'm no numbers guy, but we do practice the science of trial and error. Trying a HD650 without an amp is an error.
post #20 of 41
Quote:
Originally Posted by dallan View Post
The problem is that the distortion is compounded without an amp because the laptops output has to work harder to drive the 650s thus distorting. In addition, the hd650s are feed at a lower impedance than they want and being very hard HPs to drive are underdriven as well.
You mean higher impedance ? The lower the impedance, the easier is the driving. A power amplifier for speaker has an impedance nearly equal to zero, and it has more than the ability to drive headphones through its speaker output.

If the output impedance of the laptop is too high, the frequency response will be affected. Data for the HD650 have been removed from the headphone.com database. But if we assume that it is similar to the HD600, the impedance of the headphones is 300 ohms with a peak of 550 ohms at 100 Hz.
If the output has a 300 ohms impedance, which is very high, the problem will be a 1 dB boost at 100 Hz.

The power ability of the output is another problem. Not enough current, and the signal gets clipped. We must take into account the impedance of the laptop, the impedance of the headphones, and the sensitivity of the headphones.

Grado SR60 are 32 ohms at all frequencies. HD650 has a nominal impedance of 300 ohms, like the HD650.

The sensitivity of the headphones are strange. Sennheiser says 103 dB for 1 Volt, and Grado says 98 dB for 1 mV... which would mean 158 dB for 1 Volt !
The impedance is ten times lower, which means that the power is ten times higher, but all the same, the numbers given in the technical specifications seem wrong.

Anyway, we don't know the impedance of the laptop, nor its maximum power output, and not even its maximum voltage output.

Quote:
Originally Posted by spc100 View Post
I'm not against getting an external DAC/AMP in future, But............this is the science section, and I'm failing to see a scientific explanation, of why I need an amp, other than to increase the volume?
Outputs produce a distorded sound if the volume is too high. With an amp, you'll get a clean sound even at high volume.
If you don't get any distortion at maximum volume with the laptop and the HD650, then you don't need an amp.

Problem : hiss and poor frequency response (and maybe a bit of distortion in the DAC if the internal resampling is poor).
Solution : USB DAC.
Problem : an USB DAC has no headphone output.
Solution : USB soundcard with headphone outpout.
Problem : will the headphone output of the soundcard be powerful enough for the HD650 ?

But keep in mind that differences between headphones are way, way bigger than differences between DACs.
I don't know the Grado SR60 (according the Headphone.com measurments, they should sound close to the HD600, that themselves sound close to the HD650).

Compare the difference between HD600 and SR60 on this graph. Pay attention to the vertical scale in dB : Products - HeadRoom - Right Between Your Ears

And look at the RMAA results that you posted above about your audio chipset.

Differences between Grado and Senn are 5 dB. Differences between the chipset and a good DAC are 0.5 dB.

The major problem are output power and noise. Inherent distortion (except distortion caused by the volume) is a minor problem.
post #21 of 41
Quote:
Originally Posted by spc100 View Post
I'm not against getting an external DAC/AMP in future, But............this is the science section, and I'm failing to see a scientific explanation, of why I need an amp, other than to increase the volume?
Listening enjoyment is now and always will be a very personal and subjective experience. There are so many qualities of what many of us consider "good" sound that defy numerical and scientific analysis.
It bears stating again that the benefit of an amplifiers ability to exert more control of the headphones drivers through increased current, that is well below it's capability (headrom), is something that is not easy to quantify with charts and graphs and will only increase listening enjoyment.
post #22 of 41
Quote:
Originally Posted by spc100 View Post
I'm not against getting an external DAC/AMP in future, But............this is the science section, and I'm failing to see a scientific explanation, of why I need an amp, other than to increase the volume?
Quote:
Originally Posted by Pio2001 View Post
If the output impedance of the laptop is too high, the frequency response will be affected. Data for the HD650 have been removed from the headphone.com database. But if we assume that it is similar to the HD600, the impedance of the headphones is 300 ohms with a peak of 550 ohms at 100 Hz.
If the output has a 300 ohms impedance, which is very high, the problem will be a 1 dB boost at 100 Hz.

The power ability of the output is another problem. Not enough current, and the signal gets clipped. We must take into account the impedance of the laptop, the impedance of the headphones, and the sensitivity of the headphones.

Quote:
Originally Posted by myinitialsaredac View Post
... voltage swing, etc.etc. Basically it can better control the drivers in the hd650s which are producing your sounds. It can do this with less strain (distortion), faster, and more accurately to the original as well as a plethora of other factors.
Quote:
Originally Posted by Pio2001 View Post
If you feed it with the laptop output, all you may get is a higher maximum volume. The noise and distortion of the laptop will be faithfully amplified.

Speed, transient response or accuracy, regarding the ability to deliver current, are not a problem in a laptop output. The problem is the DAC quality, that is usually very bad.

You'll enjoy the HD650 all the same, but hiss and noises might be quite annoying.
Some of the quotes above are the scientific explanation if you will, regarding proper (as in optimal) driving of the headphones. I'm fairly sure your laptop's output is really not up to par for driving the hd650. Some of the posters have lightly touched on issues of proper amplification (ie. current delivery/voltage swing/impedance mismatching). Looking into that more in depth, I believe you'll find your answer. Proper amping isn't just about "wow I can make them louder," it's more about the ability to provide the more optimal method of driving the headphones. Just like you could take an outstanding amp that is designed for cans like audio technicas/grados and find it to be at a mismatch with cans like the hd650/k240 lp.



Your point about the noise + distortion of the laptop being amplified when connected to an amp is completely right. So that will also be a problem to take care of.
post #23 of 41
Quote:
Originally Posted by Pio2001 View Post
If you feed it with the laptop output, all you may get is a higher maximum volume. The noise and distortion of the laptop will be faithfully amplified.

Speed, transient response or accuracy, regarding the ability to deliver current, are not a problem in a laptop output. The problem is the DAC quality, that is usually very bad.

You'll enjoy the HD650 all the same, but hiss and noises might be quite annoying.
QFT.

laptops soundcard are the worst source of audio one can possess.

first get a USB based soundcard/DAC ..and then get an amplifier.

there are cheaper options also. visit Amps section
post #24 of 41
Thread Starter 
So, I got the hd650, and they play fine from my laptop hp out.

The hiss is almost completely eliminated presumably due to the higher impedance. I can detect a hiss by comparing plugged in and plugged out. buf it they are on my ears for a while i cant really detect the hiss.

this lack of hiss, makes them much more pleasurable than my sr60.

They are too loud for my ears when vol is at max. I am normally using it at < 50%.

I must point out that I may not have a very critical ear, so your opinion may differ from mine.

If i get a chance to trial a higher quality sound out, or a headphone amp I will.
post #25 of 41
Then, if hiss and volume are OK, you don't need an external amp.
post #26 of 41
Quote:
Then, if hiss and volume are OK, you don't need an external amp.
Actually wong, just because there is no hiss and it goes loud enough doesn't mean it's driving it sufficiently. Hiss is to do with sensitivity of the phones, and what the noise floor of your amp is. Being it's a soundcard in a laptop it'll have lots of hiss. For example horns are far more sensivitive than standard speakers, and will show up amp hiss.

As to volume speakers or phones can play loud but there may be a some lot of distortion.

I would not even consider using large Sennheisers with laptop headphone out, at the most PX100/PX200's. With HD line I'd use USB DAC/headphone amp. Even a pair of HD 5xx didn't sound great with a decent amp on a DAP, really needed portable amp.
post #27 of 41
Thread Starter 
Hiss is present with sr60s but not with hd650.

I think I read that higher impedance tends to reduce hiss.

(presumably the hiss with the sensitive low impedance phones is caused by low power electric noise, but with the high impedance phones I *guess* the weak electric signal is not powerful enough to overcome the high impedance of the hd650 and product a noticeable sound)

How does one determine if they are distorting. they are definitely not distorting the way one can enable distortion on an electric guitar.

I have used them with hp out from my laptop, and I think they sound good.
post #28 of 41
I would say its a good idea to get an amp, but its all up to you. If you are more than happy with it unamped stick with it, otherwise pick out an amp from a dealer who offers returns and test it out. If you cant tell a difference, send it back an consider yourself lucky
post #29 of 41
There's definitely no need for an amp if your system sounds good to you as it is. You're saying that you're not an audiophile -- so don't let you talk into becoming one, unless you have indeed corresponding ambitions.

Stating that the HD 650 will be better «controlled» by the amp -- the latter fed by your laptop's HP out -- is a bit of a generalization. There are just two things that would justify such speculation: 1) high output impedance, 2) limited current supply. Other than that, the amp would just add a different flavour -- and certainly higher coloration and lower signal accuracy compared to the direct connection. Your now experience with the latter seems to indicate that your laptop's soundcard has no such problems.

It has been said that the amp would be an easier load for the HP out than the HD 650. I dispute that. The amp's input impedance would be around/above 10 kOhm, whereas the HD 650's is 310-480 ohm.



It's not really clear which load is easier for the HP out. Definitely it doesn't make much sense to expect a huge quality gain from feeding a high-quality amp with a mediocre audio signal. So if you really want even better sound from your HD 650 (an excellent choice, BTW), I recommend a DAC/headphone amp combo (--> Meier-Audio, HeadRoom...).
.
post #30 of 41
Wait a minute... is this is a speaker output, or a headphone output ? Both are possible, though speaker output are quire rare.

Speakers output are the same mini-jack as headphone output, but are capable of feeding small unamplified PC speaker. I once compared headphone output and speaker output from an SB64 AWE gold soundcard with an AKG K-400 (very difficult to drive properly). The speaker output was much louder than the headphone output.

In this case, if you have no hiss, the speaker output has more than enough power to drive your HD650.
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