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UAD1 + logic 7 + digi HD - PCI bandwidth??


New Member
hi, hoping for some technical wisdom here from any universal audio software engineers that may be lurking in this forum... ;)

am configuring a new system, beginning to work on it. details:

G5 dual 2,0Ghz / 1,5GB RAM / OSX 10,3,4 / logic 7 / digidesign HD2 hardware (core+accel card) / DAE+DTDM driver / UAD1 v 3,6,0

generally speaking, things are working OK. however.. when attempting to work on a fairly heavy mix, I am having what I suspect is PCI bandwidth issues. in sections of the track where there are quite a few UAD plug ins active, I am hearing little stops and glitches in the audio -only on tracks with UAD plugs inserted. I am reading about 60% usage on the UAD meter, and have set the CPU limit as low as it will go (75%) in the configuration settings thing. btw, when I turn off the UAD with the switch in the UAD meter, the problem goes away immediately...

my DAE usage is minimal - I run almost everything on native tracks, and just use the ESB buses to benefit from some TDM plug ins. also, in this particular mix I am running 5 mono audio tracks on DAE as well.. so I can't imagine that I am making massive demands on the PCI bus via the HD hardware. I'd like to be able limit the PCI bandwidth used by the HD cards in order to better share with the UAD, but apparently there is no way to do this. and also (apparently) there is only _one_ permissible order in which HD cards must be installed, leaving me no choice as to where to put the UAD1. so I am fresh outta options..

I have no problem with getting less UAD plug in performance if the PCI bus can't deal with it (there is already plenty of power on this system) - but I just want the few 1176s and LA2As that I do use to work properly and not hiccup intermittently..

any advice anyone can give on how to achieve this would be most welcome. and yes, I have already figured that for now my workaround is to just 'be my own PCI bus limiter', ie, instanciate less UADs... :(




Universal Audio
UA Official
Hi Antonio,
Sounds like you are in fact running to the bandwidth problems associated with the G5 :-( One thing you can try is altering your MIN_GNT setting in the UAD-1 Meter's Configuration menu (File>Configuration) to 128 (it probably is at 64). Or if it is at 128, try going to 64. This is basically changing the \"priority\" of the UAD-1 in relation to the other cards on the PCI bus and might give that little extra performance that you are looking for. Also running a higher buffer size (512, 1024) will help with general performance as well.


New Member
thanks james.. will try the MIN_GNT setting thing and see how that goes.

as for i/o buffer size - I have no way of adjusting this on my setup - there is no user adjustable buffer setting when using digi HD hardware, or at least not to my knowledge.. can't find any buffer settings in the audio hardware/drivers pane in logic 7, only for core audio which I am not using.

anyway I hope you have some luck improving the UAD PCI performance on G5s, even if it is apple's fault that the G5s PCI is less than stellar shall we say..
...I really prefer your 1176 to the bombfactory TDM one, pls don't make me have to use that one too often! ;)

btw, I work for an audio consultancy here in paris, we sell and maintain gear for a lot of élite music producers, artists, composers and studios here in france. I already love demoing the UAD to clients, but it would be great to not have to warn them to expect somewhat less than ideal performance on the G5! am stating the obvious, clearly UA would like the same, so I hope it can be improved.


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