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My setup comrpises a white Macbook circa mid 2009 with 2Mb RAM, an external Firewire drive hosting iTunes ALC files, and Audivarna, Decibel or Pure Music depending on my mood.
These feed a Cambridge Audio Dacmagic via a Wireword USB cable into an Audiophilleo 2 USB->SPDIF converter.
If I select "Integer Mode" in Audivarna, or similar in the other two programs, I get clicks on the output. I understand this is an artefact of the specific chip used to drive the USB bus on my Macbook - a bit old and portly and not up to the latest chipsets. The click is some kind of 'keepalive' type signal/check that either the chip itself, or OsX, sends down the USB bus when Integer mode is selected.
Apparently, the solution is, apart from buying a newer Mac, to insert a powered USB2 hub in between the Macbook and the Audiophilleo.
My question: before I invest in one, will that be better, worse, or the same in terms of sound quality?
Integer mode may be an advantage. However, I found that using a Wireworld USB cable, and an AQVOX low-noise USB power supply, improved sound quality, presumably by reducing jitter. I therefore assume that inserting a USB hub into the chain will increase jitter once again, and may degrade sound overall despite any uplift given by the use of Integer mode. I suppose I could invest in another Wireworld USB cable to go from the Mac to the hub, and retain the existing one to go from the hub to the Audiophilleo, but that's yet more expens and may still not bring me back into parity with what I have today.
Any advice gratefully received!
Follow Ups:
In my opinion, yes. That's what I am doing using Decibel on my mac. I like the Decibel equivalent of integer mode with the hub more than not using it and bypassing the hub. Worth a try for me. YMMV.
It may be worth cutting the power line on a cheap usb cable and connecting 5V to it for the dac end.
You can then rule out any computer power supply issue.
Hm, why should switchning to integer mode which is just reconfigures the coreaudio chain introduce clicks in power supply?
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
Does the playback buffer size differ between the integer and float modes? Does the number of chunks (frames, periods) differ in integer and float modes?
These are the questions I would be asking if the integer mode produces clicks (i.e. buffer underruns, the playing device running out of data, xruns called in linux alsa). Unfortunately the closed-source platform does not cater to those wanting to see under the hood.
Everyone talks about the integer mode - where can we read a comprehensive and credible detailed description, not just guesses and maybes?
Another link for you:
The Well Tempered Computer
===
Another link for you:
http://www.amr-audio.co.uk/large_image/MAC%20OSX%20audio%20p
====
Thanks for the link. The document puts a bit more light on the integer-mode "bypass" of the mixer. The rest contains the usual commercial software nonsense about CPU being in the synchronous timing-critical path of data to the DAC, but that does not surprise me anymore, actually more of a rule in this market.
Still we do not know if that buffer size differs (or is actually configurable) in mixer and the bypass modes.
Rob from Channel D provided this:
Mercman, thanks for the link. Although it does not reveal much, just the general stuff, no real details, I would point out the omission of stream mixer in the integer mode. It is possible the buffer size differs for the two modes, since the mixer will define its own most likely fixed buffer size, whereas the integer mode can use a different buffer size. Is it possible to raise the DMA buffer size in OSX/applications for the integer mode? Is there a counter of audio buffer underruns in OSX?
It all goes down to detailed information about the audio chain. Perhaps OSX provides the information but I have not seen anyone here mentioning it. That is why I use linux where all detailed information is readily available to anyone.
We Apple users don't like to know what's under the hood :)
Bah...
I have 3 MacBooks in my household and I certainly enjoy doing stuff to them hardware-wise. A month ago took the 2009 MacBook Pro apart to install a new SSD drive. What a hassle compared to the newer UniBody machines!
First which OSX are you using? If 10.7 (Lion) it does not support Integer Mode. Secondly, and I might be wrong on this, isn't 4MB the minimum recommended memory for using current versions of Pure Music?
I should have said - this is on 10.6 Snow Leopard and I think "as much memory as possible" is recommended :) but certainly 2Gb is supported and works fine. Ideally I would stick another SIMM in there and take it up to 4Gb or beyond, but this model of Macbook only supports up to 2Gb and is at its' maximum already.
Not sure that is material to this question, though.
If it's a white (black too I guess) MacBook from 2009, it should support 4GB and possibly 6GB (I have an older MacBook Pro which readily went up to 6GB). Check here:
http://forums.macnn.com/69/mac-notebooks/358184/a-guide-to-macbook-ram-upgrades/Nonetheless, I feel it is obscene to require 4GB to run a music player!
BTW: Isn't "integer mode" just advertizing speak for "bit perfect"? Or basically letting the program do whatever processing in the internal 64-bit format it hypes up and then converts the data to integer format for delivery out bypassing the OS? I can't imagine this should be straining on hardware (CPU/mem/USB) at all...
Edits: 04/18/12
"BTW: Isn't "integer mode" just advertizing speak for "bit perfect"?"
No. It's just a more direct method of processing the file.
I feel that Lion, even though it doesn't support Integer, sounds better than Snow Leopard with Integer. Also, Pure Music and Audirvana Plus will be coming out with a "Direct Mode" for Lion in future releases.
"Nonetheless, I feel it is obscene to require 4GB to run a music player!"
Not if you are loading a gapless hi res title into memory for playback.
Quote:
------
"BTW: Isn't "integer mode" just advertizing speak for "bit perfect"?"
No. It's just a more direct method of processing the file.
I feel that Lion, even though it doesn't support Integer, sounds better than Snow Leopard with Integer. Also, Pure Music and Audirvana Plus will be coming out with a "Direct Mode" for Lion in future releases."
-----
That's the 2nd point in my message, this "integer mode" looks like just internal processing in 64-bit as their ad suggests and then sends the data to the DAC in integer format. If you don't turn on internal processing (no DSP stuff, no volume control, no EQ), then it's just "bit perfect" by definition... No big deal IMO. Nothing here looks difficult for a dual core > 2GHz processor.
As for needing 4GB. Yes, I agree that it's cheap and no big deal to get that much RAM but the point is there should NEVER be a need to dedicate anywhere near 4GB even for 24/192 music gapless for any reasonable programmer! Sadly, audiophilia lacks reason.
Back to this topic though, yeah, I think the clicking is most likely hardware/software issue - nothing to do with the RAM amount. Try an external hub, they're cheap and you can always use it for another purpose if it doesn't fix the problem. Even if you get it to work, you may be underwhelmed by the improvement.
"As for needing 4GB. Yes, I agree that it's cheap and no big deal to get that much RAM but the point is there should NEVER be a need to dedicate anywhere near 4GB even for 24/192 music gapless for any reasonable programmer! Sadly, audiophilia lacks reason."
"Never" is a strong word. I have an album (Linn St. Matthew Passion) that has many gapless tracks and would require more than 4 GB to fit entirely in RAM. There would be a potential benefit in preloading the entire play list as this would avoid any electrical pollution caused by reloading RAM while music was playing. Indeed, if the sound card or USB controllers supported 64 bit addressing and 64 bit word counts one could avoid all CPU processing during music playback (except for occasional processing to support a user interface with its "stop" button).
If one is forced to work within the constraints of an existing operating system with its memory layout and process structure there can be many benefits from having lots of real memory. This is true, for example, with Windows 7. The most obvious benefit comes from the ability to disable the page file and resulting overheads. It is possible to strip down a general purpose operating system so that it requires less memory and doesn't page, but this is not something that can be done lightly and this is difficult to do intelligently with a proprietary operating system that is not open source. I got a substantial improvement in sound quality in addition to better system stability and performance on my Windows 7 Professional system after upgrading memory from 4 GB to 12 GB. (This machine is used as an audio workstation, it's not used to playback music so stripping down the operating system was not much of an option.)
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
iTunes for OSX is bit perfect if used in the proper manner for hi res plyaback. It should be good enough right?
"iTunes for OSX is bit perfect if used in the proper manner for hi res plyaback. It should be good enough right?"Assuming CoreAudio's conversion from integer to internal floating-point and back again doesn't corrupt the stream, then yes.
I have personally never tried to play something like a DTS stream to confirm (at least for 16-bits output through the TosLink for example) to prove this. Has anyone else tried?
Edits: 04/19/12
Guys,
Look audio and computers requires tons of memory. Especially if you have lossless files. These require several buffers and are huge when doing high res.
What 4G is what like $90 or less... what's the beef?
At least 4G should be required for the best playback.
Also try the other USB port you maybe using the wrong one. They are not created equal.
Thanks
Gordon
J. Gordon Rankin
Thanks Gordon and others
I have referred to Mactracker and my Macbook is definitely capped at 2Gb.
Currently I only listen to 16/44 material, so the question of high res material is moot.
When I come to replace this Macbook with another Mac, it'll have plenty more RAM in it and I'm well aware Apple's prices are beyond the pale compared with, say, Kingston. So whatever goes in situ will probably have 8Gb for not much, but right now I don't need it until the Macbook expires.
I've also checked the USB bus and made sure I was using a dedicated controller, not the one that another internal peripheral hangs off of (can't remember what and am not in front of the Macbook to check). Both controllers use the same chipset IIRC.
I've referred to the Audivarna documentation / bulletin board and the clicking in Integer mode is a known issue with the solution as described. Just trying to avoid the expense of an external hub and want to work out if it's even noticable as an improvement. Changing to the Wireworld USB cable was a subtle but noticable improvement, as was moving from Pure Music to Audirvana. So I'm hoping there is more to come, but would be unsurprised if I actually went backwards in the process.
Tks
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