MacBook Pro not as good as MacBook?

[wgscott]

In general, you can do more (harm or good) from the command line, but many of the GUI things are just as good, and occasionally have more features exposed. The advantage of the command line, ultimately, is that nothing is hidden from you, and unix has been around for 35 years, so there is a lot of functionality that isn't specific to OS X that can be used in ways the people who created OS X never anticipated.

 

Having said all that, I don't know of any way to "force the errant USB port to behave" but there may well be a way. What I found when I was poking around was that the USB port capabilities seem to get assigned dynamically on the fly.

 

The only "errant" behavior I can think of (apart from hardware malfunction) is that the OS is assuming a plug-in can be treated as USB1 instead of USB2 (it appears to make this decision when stuff is plugged in). So if it looks like the DAC is being assigned a USB1 connection, there might be an over-ride.

 

I've found the Apple bulletin board very helpful. I'm just a slightly ambitious l-user, but there are some very knowledgeable folks that hang out there.

 

[wgscott]

Yes, the mini Toslink is the same as the analogue out. When you plug in an optical cable, it detects this.

 

I use this instead of USB, with the naive assumption that an optical signal is better than an electrical signal. When I tried USB, I couldn't hear any differences. I'm not sure, but I think the reason some people prefer the USB is it allows the DAC to use higher sampling rates; my optical out on my mini for example only allows 44.1, 48, and 96 kHz. This is fine for me, so I haven't worried, but if you want or need something else, this is apparently the main limitation.

 

[Part-Time Audiophile]

Throwing yet another guess on top of the pile here, I'd second Nicholas' suggestion that the problem is jitter. Unfortunately, choosing another USB interface is only going to get you so far (ie, nowhere). I'm sure you've already tuned the system by turning off Spotlight and deselecting your HDDs from search indexing and that you've fiddled with renicing iTunes and CoreAudio (if not, hit the search on this site for both). What those tend to do for me isn't so much filling in or rounding out a sound, but simply eliminating (or minimizing) the dropouts that a distracted CPU will generate. Honestly, Apple is just as bad as M$ at writing an OS that is capable of providing rock-solid performance to any given process or thread -- there's just way too much background crap happening on a "personal" computer.

 

With a QB-9, you're going to be limited in your ability to isolate the computer from the DAC. I suppose something like a toslink to USB converter (if such a thing is made) would give you the isolation you need and still provide a USB interface the Ayre needs.

 

Alternatively, I'd reinstall OSX and follow the recommendations made by those on this forum to tweak the OS as much as possible prior to playback.

 

Best of luck!

 

[barrows]

The Ayre QB-9 already isolates the computer from the DAC. The USB receiver portion of the QB-9 is isolated from the D/A and analog stages by the use of optocoplers. The optocoplers should provide complete galvanic isolation of the D/A and analog sections from the computer.

As the Async interface in the QB-9 provides about the lowest jitter possible for any interface, I also doubt the problem is jitter related.

As Jim stated at first, the QB-9 is not a source of the problem, as it sounds very good with his MB. The problem is within the MBP.

 

[Nicholas.Bedworth]

I thought that also, based upon my years of using optical fiber for scientific and technical applications, where it definitely is superior to wire for many applications.

 

However, in the audio world, TOSLINK will not sound as well as IEEE 1394, AES or S/PDIF can, despite the essentially infinite bandwidth of a glass optical fiber cable. Presumably this deficit is caused by the performance of the transmitters and receivers used. Older plastic TOSLINK (sort of glorified monofilament fishing line) sounds much worse.

 

People "prefer" USB primarily because, for the electronics designers, it's easier to implement, and (usually) doesn't involve writing drivers for Mac, for PC, for Linux, etc. So that's why USB is being hyped to the heavens by the manufacturers and their commercial interests.

 

Is there anything inherently special about USB that makes it particularly beneficial for audio purposes? In practice, USB obviously has plenty of drawbacks, as any implementation of a given bus has. There's no free lunch, and for electronics designers who "can't do software", they're really quite limited by the possible interfaces to use.

 

USB is certainly "universally" available on PCs and many other devices, but of course as you have found out, some USBs are created more equally than others.

 

[Jim Smith]

Thanks all!

 

I may have located the source of the difference. If so, it's not complicated. Computer gurus need not apply.

 

Even though I checked everything multiple times, in one instance, the way I did it may have been in error. At least, I hope so.

 

As luck would have it, now I have to go out for most of the evening, and can't confirm it until I return.

 

Guess I'm hoping we wasted some cyberspace, and unfortunately, some of your time, but that the MBP is good to go. We'll see.

 

Although the 1 dB offset in level at 1kHz "digital zero" is still strange...

 

I'll report tomorrow on my findings.

 

[mb9061]

Glad you may have found the culprit Jim, hope it works out.

 

Probably a topic for another thread (and several threads have hit on this already) - but I said I'd report back on Snow Leopard and at least on my 2009 macbook it sounds noticeably better. Clearer, crisper. It wasn't fatiguing to begin with, but this is a step better....which makes me wonder what was wrong with Core Audio before since this appears to be a rewrite on Apple's part. I have Amarra Mini for demo as well and I'm one of the few that doesn't care for it.

 

Also...I seen a few posts here questioning the implementation of USB and indicating firewire was better...I thought we were at a point here with the technology where USB was sorted out and headed in the right direction? Sorry, again this is probably for another post...

 

Marc

 

[Jim Smith]

Thanks all!

 

What a great forum this is. Helpful attitudes. Knowledgeable participants.

 

FWIW - A pet peeve of mine has been an all-too common lack of correct advice on some audio forums, not to mention a discouraging lack of courtesy. Not so here.

 

Found the problem. Not sure how I missed the culprit in this case, especially after multiple checks. If it’s possible to be too frustrated, maybe that was me.

 

The MBP was down about 1.5 dB at 32 & 64 Hz. I checked both laptops – or so I thought. Turns out that the eq was on, set for manual. The “window” menu – the equalizer below iTunes – wasn’t selected, as it was for iTunes, but nonetheless, eq was on. I can’t remember turning it on, nor do I believe Apple shipped it turned on. Anyway, with the spectral balance skewed to thinner sound due to a lack of weight on the bottom, although I’m embarrassed to have gone through this public humiliation, I guess I’m glad I could hear it.

 

One more thing - I’m in the middle of evaluating an amplifier for a manufacturer. I knew better than this, but I still did it - never evaluate two things at once. You WILL get confused.

 

Current analysis:

 

Compared to both CDPs on hand - both MacBooks sound very good. And not all that different.

 

If the Ayre C5-xe-mp CDP is the reference, then the MacBook/QB-9 is very slightly soft and the MBP/QB-9 is very slightly more squeaky clean, but at this point, it doesn’t allow the feeling of the flow of the music to move along quite as well as the CDPs or the MB. Wondering if any differences are a function of the USB interface at this point. Honestly speaking, these are relatively trivial distinctions. Hey, it’s subjective, but there you have it…

 

Both MB/QB-9 combos are real “space” champions. Great focus. Great dynamics. Details just pop out at you.

 

Bottom line, as originally intended, I’m going to start carrying the MBP/QB-9 with me to voicing projects.

 

Thanks again to everyone!

 

PS – Still don’t understand the digital-zero difference. Maybe the eq, although it looked flat at 1kHz to me, was up very slightly, just enough to kick the meter up to +1 from 0. I’ll check it again when I get a chance.

 

 

[barrows]

glad you figured it out. Although I admit I do not know why, but to my ears using Pure Music with its memory play mode provides a nice improvement to Itunes alone. Give it a try sometime (or Amarra).

I would not be surprised if the MBP/Pure Music/QB-9 combo ends up clearing besting the CD-5xeMP.

 

[davidR]

Jim that is a pesky problem and I'm glad you found it. I've experienced this myself in the past double checking triple checking and I believe when you install a new version of Itunes it has EQ enabled by default. Interesting that simply turning it on has this effect. It does make a thinner, edgier sound with it enabled.

 

[wgscott]

I think if you change something on the equalizer in iTunes, it turns it on. So it and the gain need to be unchecked manually. Once it is on, it does signal processing. I've never been fully convinced that iTunes uses the coreAudio equalizer; the one Play.app has is coreAudio, and seems to behave somewhat differently (and within the confines of my limited testing, sounds terrible).

 

[Nicholas.Bedworth]

On the Windows side of things, Windows Media Player uses the Windows DSP audio stack (entirely new starting with Vista) and the resulting sound is euphonically smooth, rich, and the soundstage seems to arc forward somewhat towards the listener.

 

It's not "accurate" but at least the adulturation is quite pleasant; it's the opposite of dry and thin. Given that the main idea here was to drive external consumer-grade home theater receivers, the approach to the voicing is reasonable enough.

 

Of course with WASAPI, JRMC etc. bypasses this DSP and gives you bit-perfect output. Just select WASAPI in JRMC and le voila, complete bypass of the Windows audio stack. What could be easier?

 

This is confirmed using Weiss' bit perfect transparency audio files.

 

[nrwatson]

Jim

Glad you figured it out not a waste of cyberspace as I learnt from it

(maybe that is a waste