Hello,

After numerous complaints at the state of the wiring behind my TV upstairs I decided to get busy and integrate my Mac-BeoPort solution nice and tidy.  As any good workman knows that in order to get a donkey to do some work it needs a carrot, me being the donkey and the carrot a Cambridge DACMagic to replace the crappy mac audio output.

At present I have the DACMagic wired through USB to the Mac and then unbalanced output to the BeoPort and Coax-digital to phono (via a converter) to the PC input on the BeoVision.  I intend to replace this last connection once I get the HD upgraded done to my TV then I will use digital coax in.

The sound is remarkable improvement, there is an instant clarity with the vocals standing proud from the rest of the music and a definitive improvement in the separation between Bass middle and high frequencies when played on my beolab 6000.  I only had this thing wired in since last night however I have a question which I hope someone will be able to answer regarding the connections.

Over USB the DAC only takes a 16bit input at either 44 - 48k, internally the DAC Magic up samples to 24bit.  I have not had a chance to test this yet but is it better to connect the DACMagic via toslink and set the output to 24bit on the mac or leave it at 16bit and let the DAC up-sample?  I'm not entirely certain what the macs sound engine would do to a CD or an MP3 encoded from a CD as the original recorded source would be 16 bits per sample if the output is set at 24 bits you cant create something from nothing?

I beleive the macs digital port is bit-neutral (http://extra.benchmarkmedia.com/wiki/index.php/OS_X_Audio_Playback_-_Setup_Guide#Known_Problems_for_Audio_with_Mac_OSX) however as my music is encoded at 16bit I would assume it is best to let the DAC up sample the output?

Sorry if this is a Numpty question I am just learning the way of the world at the moment.

Thanks,

Nic

I have made a little Faux Pas.  The Digital output on the DACMagic is pass through so it does not up-sample like the unbalanced phono.  Even still the quality is better than direct connection from analog out on the Mac to the BeoVision.

I am going to replace the digital / analog converter with a gold played y splitter to split the unbalanced out on the DacMagic into two one phono to mini jack for the BeoPort and a phono connection for the PC input on the BeoVision.  

I have also contacted Cambridge audio regarding the benefits of using toslink or USB, I await their reply.

Update:

From trawling the forums it seems that using a toslink cable with the DACMagic is the preferential way to go.  I have read reports of muddy bass using the USB and this is certainly something I have experienced.

I shall give it a go this evening.

Regarding the bit rate, I'm still not much clearer on which setting to choose, 24bit 88k or 16 bit 44k.  I shall let my ears do the work on that one.

Nic

Latest update,

I ditched the USB cable for the toslink as an experiment, the sound changed and initially i preferred this.  After playing around a while it seems that the default output for digital output is 24bit 48k.  In this setting the bass is much warmer however after playing around for a while I found that the for me the most natural sound was the 16 bit 44k settings.

This makes sense as this is the settings which the music was encoded at, any different setting and the Mac has to up sample the audio.  As the DACMagic does this it is my opinion that the audio out should be as neutral to its encoded / recorded state then let the DAC with its fancy hardware deal with any conversion.

I still prefer the clarity of the Toslink to the USB (still awaiting Cambridge's technical appraisal for the best connection) however this could just be my ears deceiving me but I swear the Bass is less more natural sounding.

One thing I did have to do was to re-balance the treble and bass settings for my Beosounds when used connected direct to the Mac I had the bass and the treble turned up.  Reducing this improved the sound no end.

So impressions wise, I am very pleased with the DAC it has made a huge difference to the clarity I get from my B&O.

Next job upgrade to Snow-Leopard and install the latest BM-link.

To bore you more I now have the definitive answer from the people at Cambridge regarding the best way to get a quality signal out of your mac.  This is pretty much what my ears told me last night but its nice to hear it from the horses mouth.

"Optical is the preferred output if compared to USB, as it suffers from less jitter. You should not need to set the Mac's optical output to 24 bit unless you have specific 24 bit files that you wish to output. The up-sampling in the DacMagic is superior to the up-sampling in the Mac, so it is better to just let the DacMagic do it all, rather than adding an extra stage of processing into the equation."

So in summary: 

Connect the DACMagic to your mac via the optical toslink cable not USB

Set the output settings in the Audio Midi set up to 16 bit and 44k if you are playing CDs or MP3s encoded to this level.  Note: when connecting the toslink to the DACMagic the default setting is 24 bit and 48k.

Nic

Haven't looked in this forum in a while. You're quite right that the optical toslink out is the best. Mac's running from their internal batteries are jitter-free with the DacMagic, but when connected to the power supply, there is measurable jitter. Cambridge actually had a letter-to-the-editor of Stereophile on the topic, after making their measurements.

http://www.stereophile.com/digitalprocessors/cambridge_audio_azur_dacmagic_da_converter/index3.html#

so let me get this straight, your mac Mini in the upstairs TV room has a Toslink optical cable into the DACMagic, then phono cable to the Beoport, then phono cables to the PC Input on the Beovision 6

by the way, are you using any software on your Mac like  BM-Link  or Linkplayer or MyBeoPort  

The MyBeoPort application is interesting because it does not need a B&O Audio Master in a Masterlink system to work

Introducing MyBeoPort

Hi,

I'm currently using a combination of BM-Link and Linkplayer on the Mac, generally I use BM-Link 95% of the time but occasionally I will use Linkplayer to pick up the record player source which is connected to my Overture (audio master, however not N-Music compatible) downstairs.  I'm not 100% convinced about the quality of sound when it comes out of the Beoport through the line in on the mac, far to many connections in the chain.  I will eventually sort out splitting my masterlink cable so I can run once source direct to the TV to pick up the record player directly.

DACMagic massively improves the input and thus output from BeoPort, my personal opinion is to avoid the analog sound stage of the Mac if possible.

Nic

Hi Nic,

I fully agree with your views on the benefits of the DACmagic, particularly when connected via the TOSlink. It's a fantastic little box.

I output from a MacMini, running Snow Leopard and LinkPlayer 0.95 (which is very good indeed), via a TOSlink to the DACmagic, then from the DACmagic to BeoPort I use high quality co-ax with gold phono plugs to gold stereo jack. Music sounds so much clearer with bass definition much crisper and the mid-range really sharp too.

Like you I've also played with the bit-rate and freq., but here I'm not sure I agree, I know it's very personal, but I think it sounds better with 16-bits and 96khz. The trouble is when making these changes I have to go into my study then return to the sitting room to replay the same piece of music so direct comparison isn't perfect, but very interesting nonetheless.

Anybody else experimenting in this way?

Best

Rob

I did play around quite extensively with the various settings changing the bit rates etc on the audio output of the sound card.  I decided to go with the recorded format for the music I have which was 44khz 16bit, the reason for this is purely that the Mac can transmit the audio through the digital output without performing any up-sampling.  I don't think the soundboard in the mac is of a very high quality otherwise we would not be getting such an improvement in quality when outputting through the Dac Magic.  

On a technical level when you increase the output sample rate to 96k the macs / software or hardware must up-sample your 44khz recorded audio to the 96khz output range.  If the original file was not recorded at 96k samples per second then the computer must create 52k samples per second to fill the gaps.  The main problem with this is that 96 and 44 are not easily divisible, if it was 44 and 88 all the computer had to do would be duplicate.  In this case an algorithm would have to be used and I doubt the Mac would do this well.  So with a 44k-88k upgrade you are not going to improve quality as the gaps are being filled with duplicates no extra data is being added, with a 44-96k upgrade you are potentially downgrading the quality as you can not directly split 1 sample in half to create two, this leads to errors and potential glitches in the music and will probably change the shape of the music.

Have you tried changing the algorithm on the DACMagic it does make a difference (little button on the front), I also had to tweak the bass and treble settings on my devices connected to the beoport as I found I had previously compensated for the lack of texture from the Macs analog out.

Luckily I could sit in the same room whilst I played around with the different settings, it was quite a tedious process.

One mans settings will never work perfectly for someone else as every speaker will reproduce sound slightly different as will its placement in the room, size of the room, shape of the room, etc etc.  Ultimately if you like what you hear then thats what its all about, I swear it can become an obsession fiddling with the settings I changed my mind about 1 million times.