External HD VS Flash Drive Sound Quality Question

Audiolabyrinth, I've done as you requested.

Regards,
-- Al

Hoping for folks who know the definitive answers; I have my own guesses, but that's all they are.

IMO the only folks who would know the definitive answers are those who have carefully compared a variety of recent generation drives from different manufacturers, some of which utilize wall wart power supplies and some of which utilize power from the USB bus, and have compared them using an Oppo BDP-95 or another similar Oppo player. In other words, just about nobody.

IF any of the alternatives you described make any difference, IMO it would be the result of coupling of electrical noise from the drive and/or its cable and/or its power supply to unrelated circuit points within the BDP-95, and possibly to points elsewhere in the system. And/or effects within the BDP-95 that may result from the fluctuating current drawn from it by the drive, in the case of a bus powered drive.

Noise effects don't have a great deal of predictability. And I see no reason to expect much if any consistency between experiences that may be reported with computer setups and what can be expected with your Oppo.

Personally, I'd just follow the advice RW offered in his last paragraph.

Regards,
-- Al

Geoff, he's not talking about playing CDs. The spinning disc he's referring to is the one in the hard drive mechanism. The data being read from the hard drive gets clocked, processed, and reclocked multiple times through all kinds of digital circuitry before it ends up being converted to analog. The jitter that matters is jitter in the timing of digital-to-analog conversion.

Regards,
-- Al

Was what you read based on experience connecting an external USB hard drive to an Oppo player, or to some other kind of player, or to a computer, or to connection of a computer to a USB DAC? Those are all very different situations from a technical standpoint.

Also, if you hear a difference between playback from the new hard drive and from the flash drives, I would see no reason to necessarily attribute the difference to the cable. I would think that a more likely explanation would be that the design of the player is such that the player itself sounds different when it plays from one medium compared to the other. Due for example to differences in internal noise coupling that may affect either analog circuit points or jitter at the point of D/A conversion.

Regards,
-- Al

What made me think of the question when I posted is that with 2 piece cd players I've always heard HUGE differences between digital cables.

There are many reasons why large differences can be expected between digital cables that connect CD transports to DACs. Not only the type of cable, but even the length of the cable can make a major difference. See this paper for starters.

Basically, in those applications the effects of impedance mismatches between the cable and the components it is connecting, the introduction of noise due to ground loop effects or RFI pickup (both of which are cable sensitive), and other ways in which the cable may affect waveform integrity can ultimately have very significant effects on jitter at the point where D/A conversion is performed within the DAC (to a greater or lesser degree depending on the jitter rejection capability of the particular DAC).

None of those factors have any relevance to transmission of digital data from a USB hard drive to your Oppo, as long as nothing involved is defective. The technical considerations are completely different, and vastly less critical with respect to their potential effect on sonics.

Regards,
-- Al

It's definitely putting out a lower (digital) volume level than discs or flash drives. No idea why. Not a big deal, I'd say I'm turning the volume control 1-2 clock markings higher

If so, I'd expect that the reason is not that the hard drive is "putting out" a lower volume than the discs or flash drives, but that for some reason the player is treating the data that is received from the hard drive differently than the data that is received from the other media. Perhaps shifting the data within each sample by one bit location, at some point in the data path, which would probably result in a 6 db change in volume.

Regards,
-- Al

I'd appreciate an explanation I can understand as to why Power cords & digital cables make a dramatic difference with transports, but not with an hd.

I attempted to explain that, with respect to digital cables, in my post in this thread dated 8-4-13.

Basically, differences in digital cables connecting transports and DACs can directly affect the signal that is received by the DAC in such a way as to affect jitter (timing fluctuations) when the digital signal is converted to analog within the DAC. Jitter at the point of digital to analog conversion has directly audible effects. A lot has been written on that subject.

None of that has any relevance to the connection between between a USB hard drive and your Oppo.

As far as power cords are concerned, if I recall correctly you are using a bus powered drive that does not have an AC power cord or power supply. So the drive receives 5 volt DC power from the Oppo, while a transport receives 120 volt AC power. A transport is a physically large component containing extensive amounts of circuitry and parts that generate electrical noise, which can be fed back into its power cord and pollute the AC that is received by other components. Again, none of that has any relevance to the situation of a bus powered USB hard drive.

Now, I am not saying that it is impossible for the cable connecting your hard drive to the Oppo to have any audible effects. But if it were to, it would be in ways that are subtle, indirect, unpredictable, and much less audibly significant than in the transport to DAC situation. What I am basically saying is that the fact that you have found cables to make major differences in the transport situation should not create an EXPECTATION that differences will occur in the hard drive situation.

Regards,
-- Al

A question: When you change between listening to the flash drive and the external hard drive are you removing one and then connecting the other to the same USB connector? Or do you have one always connected to the rear panel USB connector, and the other connected to the front panel USB connector? If the latter, when you reach a more definitive conclusion I would suggest that you reverse which connector is used for which drive, and see if the same results still occur.

Regards,
-- Al