17 replies to this topic

[meekee]

Is it possible to listen to CD Recordings from a Vu+Uno HDD via the Toslink connector to an external audio dac? Media player shows that it is playing but I have no sound,  I have tried various Images with the same result, am I missing package files? this setup works fine with audio from sat tv.

[Erik Slagter]

Everything you play (including TV shows, music etc.) that's available on the analog output ports, is also available on the s/pdif/toslink connector.

 

It may be that your DAC requires PCM (no AC3 etc.) or certain PCM parameters.

[meekee]

Thank you Erik I have sorted it out I was trying to play  .ogg audio files I am now using .mp3 audio files. Is it possible to play .ogg files? which audio coding sounds best in your opinion? thanks meekee

Edited by meekee, 19 November 2013 - 17:09.

[Erik Slagter]

Both ogg and mp3 are decoded by gstreamer and output as PCM. How they sound is merely a matter of encoding parameters, not quite whether they're mp3 or ogg.

[meekee]

Thank you Erik I am testing a Beresford Bushmaster Dac MK 2 and I am trying to find the best format for the audio it sounds very good.

[dAF2000]

Thank you Erik I am testing a Beresford Bushmaster Dac MK 2 and I am trying to find the best format for the audio it sounds very good.

 

Are you "more of less" an expert in DAC's? I was thinking about buying a Beresford DAC because they are quite cheap and I read they are quite good too.

[Erik Slagter]

I think if you're going for no-compromise, you should use a lossless format, like FLAC, ALAC or even PCM.

 

I have no idea whether the various enigma receivers can output S/PDIF at higher quality than 48 kHz, 16 bit audio.

[meekee]

Thanks Erik.

Hello dAF2000 no I am no expert on Dacs the Bushmaster is the first Dac that I have owned. I am well pleased with the audio many other people have commented how good it sounds in comparison with much more expensive Dac's. I have it running with my Roksan Caspian Bi-Amp, Vu+Uno and a cheap Cambridge Azure 340C I bought in a boot sale for £30 the Cambridge sounds stunning as a transport.  I paid £180 for the Bushmaster I would recommend it to anyone, the best bit of kit I have bought for a long time. But do not forget to burn it in as it sounds miles better. meekee

Edited by meekee, 21 November 2013 - 11:05.

[Erik Slagter]

I do agree there really is difference between various DAC's. I've have had two DAT-recorders in the past and both had an execptionally good DAC, it was a pleasure to listen music with them (especially the portable one, used as a walkman, completely uncomparable to any "normal" walkman or discman).

 

What I'm worried about is the analog link between the output of the DAC and the input of the amplifier. The link may pick up all sorts of noise and distort the signal.

 

A few years ago I bought a Class D amplifier with digital inputs (PCM), hoping that it would skip the analogue phase, but it appears it converts the signal to analog after the DSP and from there it converts it to PWM for the Class D amplifier. Also the sound quality is absolutely less then my previous (Rotel) analog amplifier.

 

What you (or at least I) would want is a Class D amplifier that converts PCM to the required PWM signal within the digital domain, which really can be done. Then there is no analogue signal within the amplifier at all (until the output coil where the loudspeakers are directly connected to). This would also eliminate the need for a DAC, dithering, filtering etc. If anyone can find me such an amplifier I would greatly appreciate

Edited by Erik Slagter, 21 November 2013 - 11:37.

[Sjaaky]

@Erik: Do you really want to go that far? I for one would settle on a tried and true amplifier design, rather than an experimental design which should sound good in theory, but might lack in practice.

I think you might benefit from a good DAC connected to the analog Rotel, with a good quality and short interlink.

 

And really, how big a problem is the noise and distortion problem? My stb's are connected using the hdmi input of my denon avr1910, when I put the stb to mute, I can only hear some noise on the couch when I put the volume above 85 (scale 1 to 100). Just to compare, when I play loud music, I barely reach 70. For Brava HD, I might reach 75, but the noise is usually in the recording itself. I never had a party at my house though. I actually limited the receiver to 80 to prevent a run-away press on the volume-up button causing hassle.

I can't comment on distortion, as there is little I know about it.

 

@dAF2000: For a comparison of DAC's, look at this blog: http://nwavguy.blogspot.nl/ . The guy designed his own dac. Read the story complete with measurements: http://nwavguy.blogs...c-released.html . Unfortunately it is usb only, no s/pdif.

[Erik Slagter]

Yes I want to go that far, if no one ever starts to develop something like that, it will never mature. The analogue phase is completely unnecessary. Why introduce any distortion when it's not necessary.

 

BTW some white noise doesn't bother me that much, distortion does. It will o.a. reduce the effective sample width. It's difficult to pin-point but usually it leads to a "misty" sound instead of being totally "clear".

Edited by Erik Slagter, 21 November 2013 - 13:32.

[MiLo]

The output of a class D amplifier is still analog.

It will amongst others suffer from clock jitter, skew and ordinary noise, although the latter will be completely negligible because of the 4..8 ohm impedance at the speaker side.

The quality of a DAC can easily be objectively measured, so it should be no problem whatsoever to scientifically compare DACs and pick the best.

In mixed digital/analog electronics, usually the main source of noise is crossover from the digital domain. That is also the main reason to avoid mixed analog/digital cables between equipment. Optical SPDIF was targeted at exactly that problem - the optical signal doesn't interfere with the electrical analog signals in the vicinity. In analog setups the main sources of noise on signal cables are usually related to bad implementations of the signalling, like ground loops and high-impedance connections.

In any case, keep in mind that whatever you're listening to is likely to have travelled through a few hundred metres of analog signal cables already, so if that last metre in your house really makes a noticable difference, it's likely to be faulty.

[Erik Slagter]

The difference is that the analogue cables at the studio are balanced and almost free from picking up any noise. Also they're guaranteed free from earth loops etc.

 

Yes, unfortunately there are still no microphones that output a digital signal, which is a shame, imho.

 

Also, I don't mind at all that de output of the Class D amplifier is analog. My speakers and ears are also analog, that won't change (although Philips has been doing some experimenting with "digital" loudspeakers at some point). The output impedance is low c.q. power is high, so noise or distortion won't be noticable.

 

My point is that I want to skip two unnecessary conversions from/to analog/digital, which do introduce all sorts of distortion. The amount may be small, it's still unnecessary.

[Erik Slagter]

I just found the thing I desire actually exists: http://nadelectronic...d-DAC-Amplifier

 

"Like the M2, the C 390DD has no analogue stages in the signal path, keeping music in the digital domain right up to the speaker outputs. All preamp functions are executed in the digital domain without the phase shift, noise and distortion that plagues all analogue designs regardless of price or pedigree"

 

I fear it will be costly though

[MiLo]

...All preamp functions are executed in the digital domain without the phase shift, noise and distortion that plagues all analogue designs regardless of price or pedigree...

Not a lie as it is written here, but it is misleadingly formulated.

Digital filters indeed aren't subject to the same type of signal errors as their analog counterparts. They are still subject to their own class of phase errors, noise and distortion. If well designed, they'll be less noticeable though.

So the above must be read exclusively as:
 All preamp functions are executed in the digital domain without {the phase shift, noise and distortion that plagues all analogue designs}

and NOT as one would expect,
 All preamp functions are executed in the digital domain {without the phase shift, noise and distortion} that plagues all analogue designs

Edited by MiLo, 22 November 2013 - 11:56.

[Erik Slagter]

I know that, but you're right, it's wrong to advertise it like this.

 

Still the distortion is perfectly predictable, that's something completely different than an analogue design.

 

BTW the device costs 2500 euro's...

[Rob van der Does]

BTW the device costs 2500 euro's...

So that seems to be a fair/reasonable price then?

[Erik Slagter]

I don't know. It's academic. I never have such funds available.