[sfgiants2010]

What would you say the cutoff is where you would need something more powerful than an e6? HD598? HD600? HD650? HE400?

 

[ultrabike]

Quote:

What would you say the cutoff is where you would need something more powerful than an e6? HD598? HD600? HD650? HE400?

An HD598 with an E6 or an incredibly transparent NoAmp might be fine. HD6x0 and HE400 benefit from something more powerful than an E6.

 

[sfgiants2010]

An HD598 with an E6 or an incredibly transparent NoAmp might be fine. HD6x0 and HE400 benefit from something more powerful than an E6.

But can they be driven to sufficient volumes? The consensus in this thread seems to be that that's all an amp needs to do, as long as it is neutral of course.

 

[ultrabike]

Well, my HD558 can be driven to deafening levels out of my laptop, Total BitHead, and miniscule Sansa Zip. AFAIK, the HD558 and HD598 have roughly the same impedance (~50 ohms) and efficiency numbers.
 
The HD6x0 have much higher impedance (~300 ohms). The E6 might struggle delivering power to these cans without clipping due to voltage swing limitations (not necessarily power.) From the numbers I've seen the E6 struggles with ~150 ohm loads....
 
The HE400 might require quite a bit of current given their planar magnetic nature.

 

[sfgiants2010]

Well, my HD558 can be driven to deafening levels out of my laptop, Total BitHead, and miniscule Sansa Zip. AFAIK, the HD558 and HD598 have roughly the same impedance (~50 ohms) and efficiency numbers.

The HD6x0 have much higher impedance (~300 ohms). The E6 might struggle delivering power to these cans without clipping due to voltage swing limitations (not necessarily power.) From the numbers I've seen the E6 struggles with ~150 ohm loads....

The HE400 might require quite a bit of current given their planar magnetic nature.

Why do the HE400 require so much power with such modest specs (35ohms and 92.5 db/mw sensitivity)? Same with the Mad Dogs, because people say they are as power hungry as LCD2's, when they are only 50 ohms and unmodded can be easily run off of nearly anything.

 

[scuttle]

Quote:

Why do the HE400 require so much power with such modest specs (35ohms and 92.5 db/mw sensitivity)? Same with the Mad Dogs, because people say they are as power hungry as LCD2's, when they are only 50 ohms and unmodded can be easily run off of nearly anything.

 
Two interesting questions. Re the HE400's
 
 

http://www.head-fi.org/t/604583/hifiman-he-400-impressions-and-discussion-thread/1605
 
 
Well I feel like a fool, but also very optimistic.
 
I tried driving them directly from the Clip+, and it turns out a Sansa Clip+ can pump vastly more juice than an iBasso D-Zero, which I've now realised is only good as a cheap portable DAC.
 
Higher volume straight out of the Clip at a given volume setting as opposed to through the D-Zero maxed out, and the sibilance is gone, replaced with a comfortable serving of bass.  I'm enjoying them as much as my UM3Xs, which is saying a lot compared with their previous unlistenable status..  Battery life takes a huge hit straight to the face though - I'd estimate 3hrs rather than the usual 10+
 
 

 
..So they're not that impossible to drive. As Ultrabike says, they may need a more current than normal, which would explain why they drain power packs fast - power is current SQUARED times resistance. So needing twice the current will cut battery life by a factor of four, which is what seems to be happening to that Clip. 
 
Also - although I make this mistake myself - isn't real headphone sensitivity per V, not mW? I can't see how you could give a constant linear ratio for db/mW, given that db's are a log scale. This means that compared to a headphone of the roughly the same sensitivity but 70ohms - eg HD25s - a 34ohm HE400 will need twice as much current - meaning four times as much power. (Which figures seem to fit the quote pretty well.) 
 
As for the Mad Dog's: I am astonished! Are you sure this is true?

 

[ultrabike]

Quote:

Why do the HE400 require so much power with such modest specs (35ohms and 92.5 db/mw sensitivity)? Same with the Mad Dogs, because people say they are as power hungry as LCD2's, when they are only 50 ohms and unmodded can be easily run off of nearly anything.

 
The HE-400 is not 35 ohms, is about 50 ohms:
 
http://www.innerfidelity.com/images/HiFiMANHE400.pdf
 
According to the above, the power needed for 90dB SPL is 0.33 mW, or 94.8 dBm. An amp should probably be able to drive a headphone to about 115 dB to cover large dynamic range recordings. To do so, and amp should be able to provide about 104mW peak for the HE-400 case...
 
That is 10^((115-94.8)/10) mW
 
The max output of an E6 into 33 ohms is reportedly about 59mW and into 150 ohms about 24mW (Voldemort's numbers.) I could have made a mistake in my calculations, but it seems the E6 might have some difficulty there.
 
The E6 might be able to drive them to 90 SPL (33 mW peak) though.
 
Using the E6 to drive the HE-400 probably works, but the power requirements might result in occasional clipping whenever music hits a spike and therefore a little distortion.
 
---
 
BTW, the HD598 sensitivity (using IF sheets) is about 98.9 dB/mW (sensitivity), which means that to hit 115 dB SPL it requires 40mW, which might be in the realm of the E6...

 
---
 
BTW number 2, the Mad Dogs (using IF sheets) is about 92.8 dB/mW (sensitivity) which makes them a bit harder to drive than the HE-400. LCD-2s are about 96.2 to 90.7 dB/mW (depending on serial number and revision). HE-5LE are about 83 dB/mW and HE-6 77 dB/mW 

 
---
 
BTW number 3, sensitivity is not flat across the audible spectrum, those numbers are likely average. If pairing a somewhat borderline weak amp with a demanding headphone with peaky sensitivity vs frequency numbers, distortion might kick in... depending on the phone and the music it is playing.
 
----
 
Whatever the numbers, it all comes down to what is audible. I would check the options out there and see if they make a difference.
 
EDIT: changed dBm to more correct dB/mW.

 

[stv014]

Quote:

Originally Posted by ultrabike /img/forum/go_quote.gif
 
An amp should probably be able to drive a headphone to about 115 dB to cover large dynamic range recordings.

 
That really depends on the dynamic range of the music, and the loudness preferences of the listener (of course, snobs will never admit that they are listening very loud). With less dynamic (and more popular) music, even ~100 dB peaks could be enough, and that is more than 30 times less power. On the other hand, I have seen people on these forums, who find devices capable of 120 dB peaks with their headphones "too quiet". But it also looks like many think their amp is "underpowered" if they need to set more than about 50% volume, even if it would in fact work fine without clipping at 100% volume.
By the way, many dynamic headphones struggle to produce much more than 100 dB SPL in the bass range without heavy distortion. Listening at extreme volume is not only harmful to hearing, but may also not be "high fidelity".
 
Quote:

Originally Posted by ultrabike /img/forum/go_quote.gif
 
The E6 might be able to drive them to 90 SPL (33 mW peak) though.

 
It can drive them to ~110.7 dB SPL, and the Mad Dogs to ~108.5 dB SPL. There is also some random variation between headphones, so in practice it may be a couple dB more or less.

 

[stv014]

Quote:

Originally Posted by ultrabike /img/forum/go_quote.gif
 
He did go all an about the allegedly mighty and apparently unloved NJM4556 indeed, and those numbers are apparently from a cMoy with that opamp installed. NwOpAmpGuy claims those numbers are w/o gain. The prufeshional genier dood does not seem to provide 33 ohm power numbers for the cMoy w gain (same NJM4566 amp), but it is supposed to give about the same juice to 150 ohms and a bit more into 15 ohms (all at the expense of distortion of course.) JDS Labs cMoy uses the OPA2227 instead so numbers are probably different with it.

 
The OPA2227 is specified to have a short circuit current of 45 mA, which only allows for about 50 mW into 50 Ω, not much more than the E6. Additionally, the JDS Labs cMoy does use a TLE2426 rail splitter (or - optionally - two of them in parallel), that limits the short circuit current to about 30 mA (or 60 in the parallel configuration), which is shared between the two channels. So, the most pessimistic estimate into 50 Ω (both channels driven, only one TLE2426, one 9V battery) is less than 6 mW.

 

[ultrabike]

Quote:

 
That really depends on the dynamic range of the music, and the loudness preferences of the listener (of course, snobs will never admit that they are listening very loud). With less dynamic (and more popular) music, even ~100 dB peaks could be enough, and that is more than 30 times less power. On the other hand, I have seen people on these forums, who find devices capable of 120 dB peaks with their headphones "too quiet". But it also looks like many think their amp is "underpowered" if they need to set more than about 50% volume, even if it would in fact work fine without clipping at 100% volume.
By the way, many dynamic headphones struggle to produce much more than 100 dB SPL in the bass range without heavy distortion. Listening at extreme volume is not only harmful to hearing, but may also not be "high fidelity".

 
Yes, loudness is not a reason why I would go for something that could do 115 dB SPL. Dynamic range would though. Like you said, with most modern and heavily compress stuff 115 dB is probably overkill. But if you have a few well mastered recordings with high dynamic range, it may payoff.
 
Quote:

It can drive them to ~110.7 dB SPL, and the Mad Dogs to ~108.5 dB SPL. There is also some random variation between headphones, so in practice it may be a couple dB more or less.

 
If the requirements are relaxed to 110 dB, then E6 might pull it off. Using DR15 I guess the rms value would be 95 dB which might be decently loud (93 dB rms for the Mad Dogs.) Not too many DR20 stuff out there I suppose.
 
Quote:

 
The OPA2227 is specified to have a short circuit current of 45 mA, which only allows for about 50 mW into 50 Ω, not much more than the E6. Additionally, the JDS Labs cMoy does use a TLE2426 rail splitter (or - optionally - two of them in parallel), that limits the short circuit current to about 30 mA (or 60 in the parallel configuration), which is shared between the two channels. So, the most pessimistic estimate into 50 Ω (both channels driven, only one TLE2426, one 9V battery) is less than 6 mW.

 
You bring up a very good point. It seems not all cMoys are created equal. If going the cMoy way I guess one would need to shop for a NJM4556 (Nw's favorite opAmp) one through eBay perhaps. From what I've seen @ eBay the NJM4556 version is about $60, while the OPA2227 seems to be going for about $30 (A/C adapter not included.)
 
If needing to drive more challenging stuff and portability is not a top priority, might as well go for a Schiit Magni for $100. If portable is a must and still want to be able to drive more challenging stuff, might need to go the Leckerton UHA-6S way (a little north of $200 but not too bad.)
 
I suppose sticking to an E6 for that Pro 900 should be fine (I think it's sensitivity is 96dB/mW.) The E6 does reportedly seem to suffer from a bit of distortion at low frequencies into 15 Ohms. An E11 might be a little bit of an upgrade for ~ $60. Not sure if the distortion issue would be audible though.

 

[wburton]

can the fiio e6 drive 80 ohms?

 

[streetdragon]

can the fiio e6 drive 80 ohms?

About just as well as your inbuilt amp

 

[ultrabike]

Quote:

can the fiio e6 drive 80 ohms?

 
Depends on the headphone sensitivity. What headphone do you have in mind?

 

[wburton]

Quote:

 
Depends on the headphone sensitivity. What headphone do you have in mind?

Beyerdynamic DT770 80 Ohm

 

[ultrabike]

Quote:

Beyerdynamic DT770 80 Ohm

The E6 can probably drive the DT770-80 Ok. The E6 might be a little noisier than the internal amp of an iPoo tho, but not sho.