"Decibel" for Mac

[jantheman]

I find that this depends on the age of your Mac. If you have a model which features an Intel Core2Duo and an NVidia chipset, everything sounds pretty much of a muchness via MacOS - There's also a USB bug that means any USB DAC sounds a bit poor because every 16384'th sample is zero.

A nice shiny new Mac with an i3/i5/i7 processor will blow the old ones out of the water as they seem to have ironed out the issues. I've recently tried a swanky new top of the range MacBook Pro and it sounds STUNNING running Audirvana in Integer mode.

Well my mac mini 2010 has a core 2 duo but so does my pc. Maybe it is the os but you would be using the same os on any other mac as well so it all seems a little confusing. I dont use the usb...I prefer toslink. Anyways I gave up worrying about this ages ago...never found a proper explaination...its just one of those imponderables.....

[Slippershod]

...its just one of those imponderables.....

probably, and maybe lovejoy was joking (i.e. the 'every 1648th is a zero...' bit) but somehow I suspect not...

any further info LJ would be much appreciated...

[Slippershod]

sorry to bump this - but can anyone else elaborate on the 'issue' Lovejoy mentioned a couple of posts above (macs with core2duo processors and usb soundcards)?

I don't think he was joshing - but can't google anything

[purite audio]

Macs aRe bit perfect, their USB output is usually limited to 24/96 unless you go for an Async USB dac like the M2Tech 'Young', the only bug in I tunes is that if you have a playlist with files of mixed sampling rate ( 44.1 96 176 etc ) Itunes will upsample or downsample everything to 24/96, unless you close ITunes change the sample rate in Audio Midi and then re open ITunes playback software such as Amarra and PM get around this bug.
Keith.

[Slippershod]

thanks for that Keith - I know you're well up in this stuff ( to put it mildly) so guess I should leave it there, but, just to be sure, you have read post 8 above by lovejoy (rich)?

[purite audio]

USB Bug! Never heard of that, or that a new i7 core will sound better? I am afraid I don't have a brand new MBp to hand to test that theory, I use Amarra and their 'cache' feature which loads everything into RAM, the only thing I have heard better is the new Weiss MAN server.
KR Keith.

[Werner Berghofer]

Never heard of that, or that a new i7 core will sound better?

Me too: I have never heard of this alleged USB bug, and I can assure you that there’s absolutely no difference in USB playback quality between my Mac mini (Intel Core 2 Duo) and my 17" Macbook Pro (Intel Core i7).

[Slippershod]

thanks again, Keith, and Werner ... hmmm, I wonder if Rich was having a bit of a larf - didn't sound like it.

c'mon Lovejoy, can you help us out ...?

[lovejoy]

Sorry for the delay. I've not been around all weekend.

I've had 3 Macs, all from the same vintage - Core2Duo/NVidia chipset machines dating from 2007. I first ran into the USB bug when I bought an M2Tech HiFace when, for the first few versions of drivers, I'd get nothing but pops and clicks every second - it sounded a bit like playing a scratched CD. Thankfully Keith at Purite and the guys at M2Tech were onto it and provided a fix. I was one of a very small number of people reporting this problem so the issue seems to be with a certain issue of Mac. If it's any help to anyone I have issue 3.1 of Macbook Pro - I'd have to check on the Mac Mini and the iMac but they all had the same problem (and the same hardware).

The problem re-emerged when I started using Audirvana, but only in Integer mode (and I know that my Audiolab 8200 supports Integer mode as it plays without issue on the brand new i7 Macbook Pro). So it would seem that the problem is only audible with integer mode (which I believe is what the HiFace is doing too) but I also believe that there is a knock-on effect with digital audio output in general with this particular vintage of Mac.

I wouldn't panic too much as I seem to have just been VERY unlucky with my choice of Macs and if you're not hearing any difference between i7 and Core2Duo then you're not affected but the differences (via optical or USB) between the i7 and my Core2Duo units are blazingly obvious.

For a bit of a sanity check I built a 'Hackintosh' using an old PC I had going spare - Once again, it's pretty much the same hardware (processor and chipset) that my older Macs are based on.. Guess what? Exactly the same problems! Clicking in integer mode and generally tonally flat and lifeless sound from iTunes or Audirvana in normal mode. So I removed 'HackOS' and installed Ubuntu and now it's sounding stunning!

There is mention of this particular bug over on the Audirvana thread on Computer Audiophile, but I'll stress again that I am one of a VERY small number of people who has experienced it (so it may even be in a certain batch of chipsets and not a problem throughout the range).

Sorry to be a bit of a scaremongerer.

[Slippershod]

hi Rich - apologies, I've sent you a PM, not realising you'd posted the above, for which many thanks.

not sure I'm absolutely clear however: if yer Mac's affected, will you clearly hear (i.e. pops and distortion) the problem (in 'integer' mode at least), or is it more of a tonal (flat) thing as you seem to be saying towards the end ... ?

one weird thing I've found with my emu tracker pre, is that it tends, once it's been on a while, to develop an 'undersea echo' type effect with all sound (system / recording etc), and needs a turn-off and reboot to correct... wonder if it's connected to the issue you've raised?