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Is a DAC enough to drive 250 Ohm headphone?

post #1 of 32
Thread Starter 

Currently, I'm driving my T70 (250 Ohm) direct out from Centrance Dacport LX (This version is without amp).

Although Dacport LX isn't an amp (albeit there labelled Class A, which I'm not sure what does it refer to), it's loud enough and even in Foobar 2k, I've to set the volume control to -10db.

 

I wish to hear for scientific advice as I'm not sure whether using an amp will improve its sound.

 

Loud enough = Good enough, therefore there are nothing that an amp could possibly improve?

 

Thanks!

post #2 of 32

You HAVE to have an amplifier to hear anything out of your headphones.

 

The DACport LX has an amplifier in it, and I believe it is actually the same amplifier as the regular DACport, but with the volume knob basically fixed on "1". If it isn't clipping or distorting, you should be fine.
 

post #3 of 32

An amp could improve frequency flatness. It's very hard to say, based only on the specifications. 

 

The Dacport LX is intended for use with an external amp. It's a top-line product. I would have thought that anyone who had bought it would want the reassurance of combining it with a top-line amp, which will also open up the range of phones available to use with it in the future.

 

The only way you'll know for sure is to try it. Borrow a quality amp or arrange to listen to one in a shop. If you don't hear an improvement, and you may well not, then you don't need one unless you buy some different phones, when you'll have to try listening again.

 

Be warned, you may find it hard to hear a difference other than volume, which is often mistaken for quality. It's a hard call to make. If you don't mind spending the money, then it may just be easiest to buy an amp. The sound may not be any better, but you'll be able to give up wondering about it.

 

I don't like the spec. on the Dacport amp. 10 ohms is too high for some 'phones.

 

w

post #4 of 32
Quote:
Originally Posted by Eisenhower View Post

You HAVE to have an amplifier to hear anything out of your headphones.

 

The DACport LX has an amplifier in it, and I believe it is actually the same amplifier as the regular DACport, but with the volume knob basically fixed on "1". If it isn't clipping or distorting, you should be fine.
 

 

I don't think the LX has a real headphone amplifier.

 

It's just that it may yet do an okay job with such headphones.  Beyerdynamic T70 are high impedance as well as pretty high sensitivity (~108 dB SPL / 1 mW).  They don't need much current at all, especially if you're not listening that loud.  That may be well within the capability of an audio op amp or whatever is handling the line output, even if it was not designed or intended at all to be used with headphones.

 

Plug in a HiFiMAN or Audeze planar magnetic, plenty of low-impedance dynamic headphones, and the DACport LX would probably have much bigger problems.

 

 

That said, it could be that currently, loud peaks are being clipped.  Likely there's some high output impedance, which would make some difference for those headphones.  It's 250 ohms nominal, but they go above 600 ohms at the resonant midbass hump.

post #5 of 32
Thread Starter 
Quote:
Originally Posted by Eisenhower View Post

You HAVE to have an amplifier to hear anything out of your headphones.

 

The DACport LX has an amplifier in it, and I believe it is actually the same amplifier as the regular DACport, but with the volume knob basically fixed on "1". If it isn't clipping or distorting, you should be fine.
 

 

Meaning I do not really need an amp, or that an amp wouldn't really matter on the sound quality? I'm not sure if there's any distortion due to me using foobar volume bar as the volume control, but from my ears I cannot discern anything bad coming out (maybe I got used to the distortion, if there is, and without me realizing).

post #6 of 32
Thread Starter 
Quote:
Originally Posted by wakibaki View Post

An amp could improve frequency flatness. It's very hard to say, based only on the specifications. 

I'm not really certain if I understand frequency flatness. Does it mean every frequency plays equally loud from the amp? (Flat FR)

 

 

The Dacport LX is intended for use with an external amp. It's a top-line product. I would have thought that anyone who had bought it would want the reassurance of combining it with a top-line amp, which will also open up the range of phones available to use with it in the future.

I got an amp before (Govibe Peak). Just that it went for repair due to me hearing some faint hiss when turning the volume knob. Was told that it's due to my country's unstable electric current. Well, that's another matter. For now, I just drive it direct out. Actually, I felt I did HEARD some improvement when trying for 20 mins using Govibe PortaTube amp. Felt that the soundstage is wider. Therefore, it makes me wonder if there's any noticeable/significant improvement to use an amp.

 

 

The only way you'll know for sure is to try it. Borrow a quality amp or arrange to listen to one in a shop. If you don't hear an improvement, and you may well not, then you don't need one unless you buy some different phones, when you'll have to try listening again.

 

Be warned, you may find it hard to hear a difference other than volume, which is often mistaken for quality. It's a hard call to make. If you don't mind spending the money, then it may just be easiest to buy an amp. The sound may not be any better, but you'll be able to give up wondering about it.

Yup. I'm pondering about that too. Loudness=/=improvement. I realize that and therefore I hope there's a scientific explanation to using an amp for improvement.

 

 

I don't like the spec. on the Dacport amp. 10 ohms is too high for some 'phones.

 

Yes, 10 Ohms Output Imped and that's why I go for higher impedance phones (250 Ohms or more).

 

w

post #7 of 32
Thread Starter 
Quote:
Originally Posted by mikeaj View Post

 

I don't think the LX has a real headphone amplifier.

 

It's just that it may yet do an okay job with such headphones.  Beyerdynamic T70 are high impedance as well as pretty high sensitivity (~108 dB SPL / 1 mW).  They don't need much current at all, especially if you're not listening that loud.  That may be well within the capability of an audio op amp or whatever is handling the line output, even if it was not designed or intended at all to be used with headphones.

 

Plug in a HiFiMAN or Audeze planar magnetic, plenty of low-impedance dynamic headphones, and the DACport LX would probably have much bigger problems.

So, here you mean I can get away with T70 because it's sensitive enough? But when directly plugging in the orthos into Dacport LX, I may have bigger troubles (like distortions)? From what I was told, orthos need a lot of driving power because of its low sensitivity, therefore it requires an amp. Well, I'm not sure if it's voodoo or fact, just hearsay.

 

 

That said, it could be that currently, loud peaks are being clipped.  Likely there's some high output impedance, which would make some difference for those headphones.  It's 250 ohms nominal, but they go above 600 ohms at the resonant midbass hump.

Could you explain what's "loud peaks are being clipped"? I wish to know this issue and ways to solve it regarding to my current situation. Well, I saw the graphs too, 250 Ohms it said but when I saw the graphs in Headroom, the midbass region just rocketed until a peak I can't even see clearly. What does that mean in terms of the headphone performance btw? 

 

Thanks!

post #8 of 32
Thread Starter 

That said, I heard a lot of complaints regarding T70 as being measurement terrible headphone. For one, I have encountered Tyll's measurement and felt that he kinda dismissed T70 as a "bad" headphone, at least that's how I perceive. And I went to GoldenEars measurement, and they rate T70 as harsh and bass light. 

 

Refer: http://en.goldenears.net/9989

 

Frankly, it's my first "expensive" (I'd prefer not to use high end) headphones, and I have no technical knowledge to understand what the complaints are about. I studied the FR graphs, noticed the peak around 8-9kHz, and also a minor peak around 12-13kHz. Tested with Sinegen. Felt that the signals are louder at those particular areas. But then, how does it translate into performance?

 

I learnt a lot from head-fi about the audiophile jargons like soundstage, bass impact, and etc. To me, T70 does sound bad with piano, making it kinda harsh to listen. Therefore, I do hope that from this experience, and backed with more scientific knowledge on how to interpret graphs, I can make a better decision on buying a better open can headphones. 

post #9 of 32
Quote:
Originally Posted by autumnholy View Post

That said, I heard a lot of complaints regarding T70 as being measurement terrible headphone. For one, I have encountered Tyll's measurement and felt that he kinda dismissed T70 as a "bad" headphone, at least that's how I perceive. And I went to GoldenEars measurement, and they rate T70 as harsh and bass light. 

 

Refer: http://en.goldenears.net/9989

 

Frankly, it's my first "expensive" (I'd prefer not to use high end) headphones, and I have no technical knowledge to understand what the complaints are about. I studied the FR graphs, noticed the peak around 8-9kHz, and also a minor peak around 12-13kHz. Tested with Sinegen. Felt that the signals are louder at those particular areas. But then, how does it translate into performance?

 

I learnt a lot from head-fi about the audiophile jargons like soundstage, bass impact, and etc. To me, T70 does sound bad with piano, making it kinda harsh to listen. Therefore, I do hope that from this experience, and backed with more scientific knowledge on how to interpret graphs, I can make a better decision on buying a better open can headphones. 

 

 

Quote:
Originally Posted by autumnholy View Post

Currently, I'm driving my T70 (250 Ohm) direct out from Centrance Dacport LX (This version is without amp).

Although Dacport LX isn't an amp (albeit there labelled Class A, which I'm not sure what does it refer to), it's loud enough and even in Foobar 2k, I've to set the volume control to -10db.

 

I wish to hear for scientific advice as I'm not sure whether using an amp will improve its sound.

 

Loud enough = Good enough, therefore there are nothing that an amp could possibly improve?

 

Thanks!

According to Centrance, the output stage can drive headphones but is not recommended as it is a line out output stage. You are recommended to get a proper amp as it is a low impedance buffer. Having a proper headamp can lower distortion and prevent any non-linearities during listening. You can try out a cheap O2 or if you are feeling richer a sheer audio Dynalo, a lovely cube or sicphones amp if you can wait for end this month.  

 

The mids looks pretty bad to be honest on the T70, which is maybe why you find the piano sounds bad. 8/9khz contains your treble region and to some(like Tyll) are very sensitive to treble peaks and it may be fatiguing to wear for long periods as a result. 

post #10 of 32
Thread Starter 
Quote:
Originally Posted by firev1 View Post

 

 

According to Centrance, the output stage can drive headphones but is not recommended as it is a line out output stage. You are recommended to get a proper amp as it is a low impedance buffer. Having a proper headamp can lower distortion and prevent any non-linearities during listening. You can try out a cheap O2 or if you are feeling richer a sheer audio Dynalo, a lovely cube or sicphones amp if you can wait for end this month.  

 

The mids looks pretty bad to be honest on the T70, which is maybe why you find the piano sounds bad. 8/9khz contains your treble region and to some(like Tyll) are very sensitive to treble peaks and it may be fatiguing to wear for long periods as a result. 

 

low impedance buffer... err, what does it mean?

So having an amp can lower distortion, and using digital volume control may distort sound signals right?

 

Yup, I could've tried that oxygen amp. There's a diy version sold by a forumer over here. But the look is really...well, I think I fancy look too!

 

How does the mids look pretty bad? I thought I enjoyed it rather honestly. How do you read from the FR graph?

 

 

Thanks!

post #11 of 32
Quote:
Originally Posted by autumnholy View Post
Currently, I'm driving my T70 (250 Ohm) direct out from Centrance Dacport LX (This version is without amp).

Although Dacport LX isn't an amp (albeit there labelled Class A, which I'm not sure what does it refer to), it's loud enough and even in Foobar 2k, I've to set the volume control to -10db.

I wish to hear for scientific advice as I'm not sure whether using an amp will improve its sound.

Loud enough = Good enough, therefore there are nothing that an amp could possibly improve?

What is your budget for audio quality improvement?

See if you can plug the Beyer T70s into an A/V receiver, compare sound quality.


Edited by PurpleAngel - 9/18/12 at 12:09am
post #12 of 32
Thread Starter 
Quote:
Originally Posted by PurpleAngel View Post

What is your budget for audio quality improvement?

 

Currently looking for value buy more than expensive upgrade. Budget around $300+/-.

But I'm uncertain if spending on amp will really affect the sound quality (positively).

 

Therefore, I'll need to go into more reading and understand how the full audio system work so that I'm not putting money into things which I was told I need but in fact don't affect significantly on the audio quality in terms of money spent.

post #13 of 32
Quote:
Originally Posted by autumnholy View Post

 

Currently looking for value buy more than expensive upgrade. Budget around $300+/-.

But I'm uncertain if spending on amp will really affect the sound quality (positively).

 

Therefore, I'll need to go into more reading and understand how the full audio system work so that I'm not putting money into things which I was told I need but in fact don't affect significantly on the audio quality in terms of money spent.

Low cost ($96) single tube headphone amplifier, lots of voltage for driving 250-ohm headphones.

http://www.ebay.com/itm/Indeed-MK-2-Class-A-Hybrid-Tube-Headphone-Amplifier-Electro-Harmonix-6922EH-New-/290678335270?pt=US_Home_Audio_Amplifiers_Preamps&hash=item43adc76726

Here is one for $79

http://www.ebay.com/itm/Class-A-Hybrid-Tube-Headphone-Amplifier-6922EH-Pre-AMP-/110661860034?pt=US_Home_Audio_Amplifiers_Preamps&hash=item19c3f5fac2

post #14 of 32
Thread Starter 

 

But why tube amps? Does it make the headphone sound better?

post #15 of 32
Quote:
Originally Posted by mikeaj View Post

 

I don't think the LX has a real headphone amplifier.

 

 

LOL, okay then...

I wonder how it amplifies his music, and drives his headphones?

 

Quote:
Originally Posted by autumnholy View Post

 

low impedance buffer... err, what does it mean?

So having an amp can lower distortion, and using digital volume control may distort sound signals right?

 

A "buffer" means what I said earlier, that it has a fixed gain/volume. It was designed to be paired with an external amplifier with a dedicated volume control. It is made to drive up to "line level" which is a standard voltage/current typically sent between stereo components (e.g. a DAC into an amp).

However, a headphone out can also be used to send line levels: http://www.sweetwater.com/expert-center/techtips/d--10/26/2000

Maybe you have plugged in your ipod into a car stereo or speaker setup through its headphone out? This is the same thing.

 

Now what you are talking about is doing the opposite: using a line level to drive a pair of headphones. Usually the difference is that line level outs have very high impedances (sometimes thousands of ohms), much too high for most headphones. However the DACport LX has only 10 ohms, which is exactly why they call it a low impedance buffer. It just so happens that a low output impedance is a requirement to be a decent headphone amp, since most headphones don't have that high of an impedance. Thus, you're DACport LX can drive headphones.

 

If you're DACport LX was distorting or coloring the sound, I don't see how putting an amp in front of it would fix anything. It might make it worse..

Some people in this thread think the LX actually sounds better without an external amp: http://www.head-fi.org/t/615548/do-the-dacport-and-the-dacport-lx-really-sound-different

This is due to the volume potentiometer adding flaws in the signal, or something like that.

 

Anyways, if you really want to put your mind at ease, borrow an amp or buy a cheap cmoy or FiiO and see if you like it more. Do a blind listening test with the volume levels matched as best you can.


Edited by Eisenhower - 9/18/12 at 12:52am
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