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Re: Driving headphones at high peak levels

On 10 Dec 2014 at 9:57, Bob Carlyon wrote:

> Hi Bob,
> Thanks very much for your suggestion. It sounds great,
> although I am slightly nervous about using an unbranded
> product for clinical research; having said that I may as
> well order one and try it out, as they are very cheap
> even in the UK. As a matter of interest, though, what was
> your "second best" for driving low impedance headphones
> at high levels. Mike Stone recommended some Sennheisers
> that produce 112 dB/V at 1 kHz and that are 50 ohm, so
> if I can drive these without loss at 1.5 V maximum then
> I would be in business! 
> Thanks again

"Second best" (out of only 5 USB devices so far) would be 
the Creative X-Fi (US$85), which can deliver 1.14 Vrms into 
a 100 ohm load.  It's output impedance is 35 ohms, however, 
so no hope of driving 1.5 Vrms into 50 ohms.  Just for 
completeness I'll try to test it today with a 50 ohm load, 
as well as the cheapie no-name device.

The separate headphone amp is starting to sound like a 
safer bet.  Unfortunately, I haven't tested any.  Note that 
standard 5 V, 100 mA USB power is theoretically capable of 
driving 1.5 Vrms into 43 ohms without clipping, but to 
actually drive 50 ohms at this level may require more 

Best regards,

Bob Masta
            D A Q A R T A
Data AcQuisition And Real-Time Analysis
Scope, Spectrum, Spectrogram, Signal Generator
    Science with your sound card!