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Headphone Amps & DACs - Con-fused!
Old 22nd October 2013
Gear Maniac
gmx750's Avatar

Headphone Amps & DACs - Con-fused!

Hi guys

I'm on the market for a headphone amp, but when researching impedance and sensitivity specs on the one I'm currently looking at (Samson S-phone), some doubts arose....

I have the beyerdynamic Dt770 Pro at 250 ohm, and the samson spec sheet says that for a pair of DT801 at 250 ohm, the sensitivity is 114dB... OK.... But what does this mean?

I've read that higher sensitivity means the cans are being pushed harder, rather than what I initially thought (more volume)

I'm on a tight budget now, and my studio needs are not the most demanding, so I think something like the S phone + DT 770 will suffice....

What do you think? will I run into a wall with this combo?

thanks in advance,
Old 22nd October 2013
dont worry too much about sensitivity and stuff. just see if the headphone amp can drive your beyers and if they can , go ahead and get it. better if you can try it before purchase.
Old 22nd October 2013
Gear Maniac
gmx750's Avatar

I'm not planning on buying an amp since I already have a roland octa-capture.
I think this is enough to drive 250 ohm headphones... At least that's what I've read on other threads..
what do you think?
Old 23rd October 2013
Lives for gear
LeeYoo's Avatar

Hi gmx750.
Some info to help you decide.
Octa-capture states an output impedance of 47ohms.
S-phone is less clear, but states 385mw @66ohm.
So max efficiency (amp) is reached with ~50ohm headphones.
Both units have about the same output impedance, and will work with 32-600ohm cans.
250ohm cans are easier on the amp (maybe less distortion), at the cost of some volume. But 32ohm cans are also less volume.
"the sensivity is 114db" ??. They probably mean max SPL.
Last thing regarding max volume (SPL) is the output voltage swing the amp can deliver. Usually not clearly stated on the spec sheet.
A USB powered interface might run on a lower rail voltage.
That could make a dedicated mains powered headphones amp a lot louder.
Old 23rd October 2013
Gear Maniac
gmx750's Avatar

Hey leeyoo thanks for the very helpful reply.

I'm really not inclined towards buying a dedicated headphone amp which could possibly imply some more research on DACs and headphone amp specifics.... Not to mention the added cost it would imply...

The Octa capture runs on mains and uses USB solely for data and audio transfer... However given that the output impedance is 47 ohm I'm not sure I would get acceptable volume without a dedicated amp...

Does an amp and DAC affect the sound quality that much?

Old 23rd October 2013
Lives for gear
LeeYoo's Avatar

Hi gmx750.
Not sure what you mean with DAC research.
A headphones amp is just a bunch of analogue headphone power amps.
Nothing digital about it.
It runs off the analogue (DAC) outputs of your interface.
Headphone amps are e.g. for musician feedback (think drummer).
The inbuild headphones amp in your interface is perfectly ok for editing/mastering, where you want (have) to stay in the 79-85db max range for good mixing (Fletcher Munson curve).
If you want more headphones, just use a plug splitter.
Your interface can drive up to five 250ohm cans.
Old 23rd October 2013
Gear Maniac
gmx750's Avatar

Hey leo,

Yes that is my main goal with the DT770 : to mix and edit audio and midi.
But I also plan on using them to listen to albums like daft punk's RAM and other stuff... Maybe then I would need a dedicated amp, right..?

As far as the octa being able to drive fice 250ohm cans, how did you get to that number? it has 8 balanced TRS outs (9 if you count the front headphone output)
Old 23rd October 2013
Lives for gear
LeeYoo's Avatar

Hi gmx750.
Your cans are pretty sensitive according to the s-phone manual.
So he Octa Capture might give you already a reasonable level. Just try first.
But I think Daft Punk can never be properly listened to on headphones.
I use big floorstanders (2x12" woofer) with a 2x800watt amp for that

As for the cans. Two cans connected to the Octa Capture = 250/2 = 125ohm
Five cans connected would be 250/5 = 50ohm
The Octa Capture would still have no problems driving that.
Just saying 250ohm is easy going for a headphones amp.
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