EXS 24 Logic Sampler Users Group

http://www.apple.com/powermac/

"ewald_kegel <ekegel@...>" wrote: 
>
> <http://www.apple.com/powermac/>http://www.apple.com/powermac/


Hmm -- the new displays look nice don't they. I like the wide screen format --
1680 by 1050 for the 1299 US 20" monitor. Can you buy this form factor from the
various display manufacturers? I have never seen them on Sony/Samsung/Viewsonic
etc sites. 

I can't find any new info on MacRumours or ThinkSecret about whether they have
done anything about the lack of memory bandwidth (although noise issues have
been seen to). 

If this is so it would appear that the revised G4 with the bandwidth to allow
the PC 2700 DDR to earn its keep is still not available. It looks like the L3
cache is all that is happening to speed memory access -- not really an adequate
solution for DAWs where you are running lots of plugs simultaneously. 

Regards,
M

--- Murray McDowall <murraymc@...> wrote: 
> I can't find any new info on MacRumours or ThinkSecret about whether they
> have done anything about the lack of memory bandwidth 
There isnt a lack of bandwidth as such - as the cpu is one side of the
controller the GFX, Disk and PCI subsytems can all access the memory at full
bandwidth, so it isnt *that* much of an issue for most peoples purposes. This
is still the case in the new machines though.

> (although noise issues have been seen to). 
They have? This is something there is no mention of in the specs. I would
assume it is no quieter until I hear otherwise from someone thats actually
received one.

> If this is so it would appear that the revised G4 with the bandwidth to
> allow the PC 2700 DDR to earn its keep is still not available. It looks 
> like the L3 cache is all that is happening to speed memory access -- not 
> really an adequate solution for DAWs where you are running lots of 
> plugs simultaneously. 
Mmm. I'd disagree. As I mentioned, most memory bandwidth is used either
GFX>mem or disk>mem.  IIRC the CPU->Mem bandwidth in the MDD machines is
approximately 150MB/s. To put that in context, a 24bit 96K stereo audio
stream uses approx 0.56MB/s of bandwidth. Being pessimistic and assuming that
50% of the cpu->mem bandwidth is used up by GFX and IO device access, I dont
think the lack of *extra* bandwidth is a serious constraint for most DAW
users.

If you personally find this to be an issue, I'd be interested to know what
your average track setup is (track count, resolution, plugin use, live input
use and hardware config) I think you're most likely to find you're
constrained by lack of spare CPU cycles not bandwidth to memory! If you want
to work out your bus usage, try having a play with GaugePro from :
  http://www.macgeneral.de/DownloadsHTML/GaugePro.html

Best Wishes,

Dave Peverley

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Be aware that there was a major article in the latest edition of MacAddict
suggesting that Apple may switch to IBM for their processors. The new chips
that are available from IBM offer a wealth of technology and efficiency
enhancements, the least of which is full use of the DDR RAM by its DOUBLE
SPEED 450MHz front-side bus (the current speed is singe-speed 133MHz). In
other words, you may want to wait a bit before springing for your new Mac,
if you can afford to wait some more. The new chip operates at PPC 1.8GHz
with massive boost in other areas besides MHz, eliminating the bus
bottleneck. Apple has no comment about the adoption of that chip and has not
indicated whether they would adopt the chip and drop Motorola, but hey have
offered enthusiasm for what the chip is capable of. Other chip capabilities
include up to 4 terabytes of RAM (WHOAA) and 64-bit processing! Imagine how
depressing and stupid it would be for Apple to pass this chip up!! For
details, check MacAddict: Feb 2003, Page 12.

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Pev  wrote: 
>
> > (although noise issues have been seen to). 
> They have? This is something there is no mention of in the specs. I would
> assume it is no quieter until I hear otherwise from someone thats actually
> received one.



Probably wise but there was specific mention of it from Apple -- a user of the
current "leaf blower/wind tunnel" models was saying "What about us" on the
forums.

>
> > If this is so it would appear that the revised G4 with the bandwidth to
> > allow the PC 2700 DDR to earn its keep is still not available. It looks 
> > like the L3 cache is all that is happening to speed memory access -- not 
> > really an adequate solution for DAWs where you are running lots of 
> > plugs simultaneously. 




>
> Mmm. I'd disagree. As I mentioned, most memory bandwidth is used either
> GFX>mem or disk>mem.  IIRC the CPU->Mem bandwidth in the MDD machines is
> approximately 150MB/s. To put that in context, a 24bit 96K stereo audio
> stream uses approx 0.56MB/s of bandwidth. Being pessimistic and assuming that
> 50% of the cpu->mem bandwidth is used up by GFX and IO device access, I dont
> think the lack of *extra* bandwidth is a serious constraint for most DAW
> users.


A lot of plugins are going to use some memory space for their processing of the
audio stream. Reverb particularly uses a lot of memory space and a lot or
memory I/O. So if you have on one channel a soft synth/sampler playing
streaming audio files from HD,  a compressor and some other processing like
modulation and a reverb you could easily have a lot of traffic to and from
memory.

You seem to be approaching this from first principles which is a good policy in
my view. However, if you look at what is happening with x86 hardware, most
forthcoming chipsets (Intel/VIA/SIS)  are doubling bandwidth to memory (dual
channel DDR) and are shooting for 6.4 Gb/sec (two channels of DDR 400) and even
with these designs there is some commentry and analysis which is saying that
when the P4 gets up to 3GHz RDRAM is really the best solution to keep processor
performance scaling with clockspeed. 

Fast CPUs spend a lot of time spinning their wheels waiting for the next
instruction or a data read/write to finish. To state the obvious -- the faster
these tasks are dealt with the more performance you get out of your system. The
G4 revision which offers comparable CPU to RAM bandwidth to other desktop
processors has apparently been held up. If it were not -- it would be in these
machines and Apple would be trumpetting the vastly improved memory bandwidth. I
think we should wait and read some informed commentry on these issues on the
Mac hardware sites -- what CPU revision etc. 

Regards,
M