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Help with headphone compatibility
MagR
post Apr 14 2013, 10:28
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Hi

Ive ordered an O2 amp with ODAC which I should get in a couple of weeks. This is the open source amp and DAC by NWAVGuy who recommends this forum for objective advice.

I already own Sennheiser HD650s which this amp will have no problem driving looking at the specs and reading user reports. I want to know your thoughts on this amps abilities to drive two other headphones I am interested in to experience their different sound signatures.

Firstly the AKG K701 I keep reading this headphone is hard to drive but the specs Ive found dont seem to bear this out. The impedance is 62 ohms which is quite low compared to the HD650 at 300ohms. The sensitivity is 105 db per volt which is similar to the HD650s 103db per volt and equates to about 97db per milliwatt. I dont understand why people are saying the AKGs are more diicult to drive than the Sennheisers as these specs suggest it should be the other way round. Has anyone got any experience with this headphone and the O2 amp?

The second headphone I am interested in is the Beyerdynamic DT880 600ohm. NWAVGuy says this needs at least 5 volts to drive and the O2 can put a maximum of 7 volts into 600ohms. It looks like this is ample to handle this headphone on paper but I want to know if anyone has any experience of actually using this combination rather than relying on hearsay. What I dont want is to regularly run the amp right up to its limits in case it gets a bit ragged. The music (and games in particular) I own vary quite considerably in volume hence amp requirements. Can anyone with experience confirm whether this amp has enough power for this amp in practical use?

My final question relates to the Beyerdynamic DT880 above. Im drawn to the 600ohm version as the reports Ive read suggest this sounds the best and has the best treble. There is also a 250ohm version (the original impedance I think) which is much easier to drive. Does anyone have any direct experience of the actual sonic difference between the 250ohm and 600ohm versions? If it is marginal then the 250ohm seems a safer bet as the O2 should handle this more easily.

Thanks in advance

Mag
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skamp
post Apr 14 2013, 14:56
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QUOTE (MagR @ Apr 14 2013, 11:28) *
Firstly the AKG K701 – I keep reading this headphone is hard to drive but the specs I’ve found don’t seem to bear this out. The impedance is 62 ohms which is quite low compared to the HD650 at 300ohms. The sensitivity is 105 db per volt which is similar to the HD650’s 103db per volt and equates to about 97db per milliwatt. I don’t understand why people are saying the AKG’s are more diicult to drive than the Sennheisers as these specs suggest it should be the other way round.


Your calculation is incorrect: the AKG K701s are indeed 105dB/V, but you have to take their impedance into account (62Ω):
dBV - (10 * log10(1000/Z)) = 105 - (10 * log10(1000/62)) = 93dB/mW

The Sennheiser HD 650s are 103dB/V, 300Ω = 98dB/mW
The Beyerdynamic DT 880s are (reportedly) 96dB/mW.

NwAvGuy says the O2 can drive all those cans just fine.

This post has been edited by skamp: Apr 14 2013, 14:57


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