Review of the NuForce DAC-9 - coupled to Sennheiser HD800 headphones - Page 2

Quote:

Originally Posted by Head Injury 

I'm not saying it's a perfect match. I'm saying that's plenty of power, and all power determines is peak volume, so there's not much point in quoting a power figure if you're talking subjective preference. I'd need to see some in-depth graphs of distortion, noise, phase, crosstalk, channel balance and other sorts of things to say it's a good match or not 

 I suspect the HD800 likes a lot of voltage swing but it's a difficult call considering few manufacturers publish their figures

 ~ end of the day, it might be a crude approach, but I just go about what my ears are telling me, taking note of source used,

 material and the amp in question.

 From there it's just an expressed subjective opinion that some may or may not agree with.

Quote:

Originally Posted by Gwarmi 

 I suspect the HD800 likes a lot of voltage swing but it's a difficult call considering few manufacturers publish their figures

 ~ end of the day, it might be a crude approach, but I just go about what my ears are telling me, taking note of source used,

 material and the amp in question.

 

 From there it's just an expressed subjective opinion that some may or may not agree with.

It does need a lot of voltage, all high impedance headphones do. The HD800 as measured by Tyll needs about 2.4 Vrms for 110 dB. That 152 mW is sqrt(0.152 x 300) = 6.75 Vrms (though for the headphone Tyll measured it would actually be about 7 Vrms, because he measured 320 ohm impedance at 1 kHz). Voltage swing, if you mean peak-to-peak, is 2 x Vrms divided by 0.707, but that's not really as useful.

You don't need the manufacturer to publish voltage swing if they publish power output into a given impedance. P = V^2/R, where P is power in watts, V is Vrms, and R is resistance in ohms. Likewise they don't need to publish current, since P = I x V, I being current in amperes. Even if you take a subjective approach to audio, these sorts of equations might come in handy in determining whether or not an amp will give you enough volume. Plus it clears up some of the mysticism surrounding all the different terms and how they relate.

Quote:

Originally Posted by Head Injury 

It does need a lot of voltage, all high impedance headphones do. The HD800 as measured by Tyll needs about 2.4 Vrms for 110 dB. That 152 mW is sqrt(0.152 x 300) = 6.75 Vrms (though for the headphone Tyll measured it would actually be about 7 Vrms, because he measured 320 ohm impedance at 1 kHz). Voltage swing, if you mean peak-to-peak, is 2 x Vrms divided by 0.707, but that's not really as useful.

 

You don't need the manufacturer to publish voltage swing if they publish power output into a given impedance. P = V^2/R, where P is power in watts, V is Vrms, and R is resistance in ohms. Likewise they don't need to publish current, since P = I x V, I being current in amperes. Even if you take a subjective approach to audio, these sorts of equations might come in handy in determining whether or not an amp will give you enough volume. Plus it clears up some of the mysticism surrounding all the different terms and how they relate.

 Here's a nutcracker for you ~ I've always been baffled why the SPL Phonitor sounds fairly average with the T1

 and absolutely dreadful with the DT990 in 600ohms.

 Might check some of those figures but it's a head scratcher, make no mistake ~ it's a shocker with the DT990.

 Both the DT990 and Phonitor play nice with other gear so it's definitely not a case of defective operation.

You don't like the sound of the T1 with whatever brand of coloration (if any) the Phonitor imbues. It has nothing to do with power, voltage, or current. The DT990 is quite a bit less efficient (I think about 6 dB less per mW, so it needs twice the voltage for the same volume), but as long as they're both playing at sufficient volume (and obviously you're volume matching accordingly!) then it's not a power issue.

I think we've had this discussion before.

Quote:

Originally Posted by Head Injury 

You don't like the sound of the T1 with whatever brand of coloration (if any) the Phonitor imbues. It has nothing to do with power, voltage, or current. The DT990 is quite a bit less efficient (I think about 6 dB less per mW, so it needs twice the voltage for the same volume), but as long as they're both playing at sufficient volume (and obviously you're volume matching accordingly!) then it's not a power issue.

 

I think we've had this discussion before.

 I've got figures of 102dB for the T1 and 100dB or 96dB (no specific reference to whether it's for the 32,250 or 600)

 for the DT990-600ohm. Anyway, it's something for the Head-Fi X-files..

 Volume is not the issue, it's just really congested.

The design of the amplification circuit would have everything to do with it. Amps aren't just power output, impedance and distortion figures.

Quote:

Originally Posted by Currawong 

The design of the amplification circuit would have everything to do with it. Amps aren't just power output, impedance and distortion figures.

That's certainly debatable, but this isn't the place for it 

I think it's cool that Tassie Devil has his 800s plugged directly into the analogue outs of the DAC, not using the HP out. I'd love to hear how that sounds.

Hey John,

I posted up some brief impressions when it rolled into the store here

http://www.head-fi.org/t/549887/nuforce-dac-9-dac-9-new-high-end-all-in-one-solution

No time as yet to give it a go with the HD800, the other dilemma being that this particular unit developed

a particularly nasty fault whereby it would just drop out, necessitating that it be switched off, switched back

on and the USB cable unplugged and plugged. Bit frustrating :-) The supplier is looking into it for a replacement.

Anyway, as per my micro impression in that thread ~ the DAC-9 is certainly one of the most colourful, musical

DAC's I've ever heard to be honest, it makes my Rega by comparison sound a little restrained on the straight

and narrow. For personal tastes, It would make my short list ~ however, for this unit I'm helping a local store

evaluate whether it could be a keeper for them ~ at this stage, knowing full well how so many regulars like

a neutral source, I'm a little hesitant to recommend it to the store.

Still it's a big, long thing - nice remote control, pre amp volume control and touch button LED is interesting.

Such a shame, only 10hrs or so old before it just went silent.

I understand now why you're running it out of the pre-outs or with the on board head amp ~ heaps of gain

present on these two!