The M-16 you mention is a reasonable example of a device which might help, in that it actually IS a processor itself. It takes each individual track (up to it's own channel limit) and can add EQ, dyn, fx before sub mixing also internally. In this case, the M-16 is taking some of the load off the host computer. It won't offer any help whatsoever to the OP running software instruments as these are completely generated on the host Mac's processor. As far as I'm aware, there is no external device available which allows the offloading of the generation of software instruments to an external device.

So the OP could add an external mixer to his set-up for adding rudimentary processing, a device such as the M-16 would work. Of course, you're then limited to snapshot automation only which for many modern styles of music is rather limiting for many people. The M-16 fits very neatly into my category of 'other devices' such as ProTools MIX/HD where the job of processing is removed from the Macs's CPU.

The UA25 on the other hand is merely an audio interface. It does no processing or mixing of any kind. In common with other audio interfaces, it is only a front end for getting an audio signal into and out of your Mac via USB. Yes, your M-16 do this too, only your M-16 also has the ability to process. My ONYX mixer does that too (though only on input), before routing the audio for further processing by the host Mac. It doesn't matter whether I use GarageBand or Logic, the processing is still done on the Mac. Now, I could go and buy some of the MOTU interfaces which are also capable of some 'off host' processing- just like your M-16.

I mentioned previously of my iMac which is showing the same problems as the OP. What you're suggesting is that if I take my ONYX mixer or interface if you prefer and plug it in to my problem iMac, all my problems would disappear. They won't. They can't. Because the interface is not offloading any processor cycles from the host.

Going back to your comment about how many audio/software instrument tracks I can run on my system: as I said, my iMac which I use for admin at the moment barely runs one software instrument without glitching. My colleague uses his same spec machine all the time and regularly runs full band mixes with additional software instruments without any issues. His machine does not have an issue.

My credentials: I run a legacy ProTools MIX3 system linked into Logic (incidentally running on a Core 2 Mac Mini) via MOTU 2408 and an ADAT bridge, a MacPro running Logic ( with my ONYX for I/O), 4 Intel Core2 duo Mac Minis with Logic Express and two iMacs of the spec mentioned before running GarageBand.

My final word on this is to say that the OP's issue is the same as with my iMac. Spending money on audio I/O will not solve the problem. Just as with mine, the Mac probably coupled warrant a clean install, though it might be worth trying a reinstall just of GB first. Sorry for the long response, but just trying to clear up this difference between an interface and an off host processor. I hope the OP gets his system working again without wasting money. Happy music making all.

2GB RAM is barely enough to run the OS, max out your RAM.

Best practice is to record to external hard drive, that will also free up system drive for virtual memory.

Emm -

OSX 10.5 needs 256 mb memory and what virtual memory ??

you must be a Windows guy :-)

I run iMac with 2 gig memory in our studio and I run about 15 virtual instrument tracks with no problem.

OSX will ALWAYS use part of the system drive for virtual memory.

As virtual instruments and effects are added, more virtual memory is required.
OSX will ALWAYS have top priority, and may delay other processes, while it handles virtual memory.(pops and clicks for audio apps).

Observe the activity monitor(utilities folder) system memory, disk activity, when adding plugs.

Currently my Blackbook's virtual memory is 43GB, with only a browser and the finder open + the background processes.

Depending on your processor and disk speed you may never encounter a problem with your current load.

The OP has a Macbook, that come standard with 5400rpm hard drives it could be the bottleneck

Also for the original poster, be aware that when you open a new track in GB, you are actually opening a channel strip with effect applied.

To improve performance disable the effects.

Yes, but in this case the "bottleneck" is the integrated soundcard that is not for musicmaking an multitracking.
What you need is a good firewire or audio interface that is meant for musicmaking...
Such as Edirol FA-66 (firewire), Edirol UA-25 (usb) , Edirol UA-101 (USB) if You need more inputs, M-Audio Fast track Pro (USB), or M-Audio Solo (firewire), EMU Tracker (usb), Lexicon Omega or Lexicon Alpha (usb) ect.

They all use Core Audio drivers with zero or low latency that is essential for recording and multitracking (integrated soundcard doen not have Core Audio, it is not made for musicmaking !)

Audio interface is not JUST A SOUNDCARD (such as Creative soundblaster or similar).
USB or firewire audio interface is the essential HEART of music-making or homerecording.

Right now Your Mac has to handle all the audio rendering ect, audio interface takes this away from Mac and does ti itself. (sorry, I try to explain, but my english is not so good). Basically it takes the sound from your Mac via firewire or usb, and sends the audio to Your Mac via sub or firewire. All the processing and rendering takes place inside the interface and the playback of result comes also from the interface, not from the Mac.

I show You an example.
I use 2.66 GHz Core 2 Duo iMac (vers 9.1) with 2GB of memory and run Logic Studio 9 with Edirol UA-101 USB audio interface.
I open and play one song I'm working with and take a screenshot for You.

This song has 4 stereo audio tracks recorded @ 48Khz/24bit, 2 Virtual Instrument tracks running@ 48KHz (Native Instrument Kontakt 4 with Scarbee Jay Bass loaded and Independence Free), 12 "real instruments" or EXS sampler instruments a lot of effects running (14 effects are open) and a mastering effect strip with 6 effects). I take a screenshot somewhere, where most of the instruments play....

Take a look:


I have CPU running on 30% max !!!

This is why you need audio interface, not integrated soundcard, not soundcard or soundblaster.
You can't make multitracking without audio interface


Tommy