unable to select buffer setting higher than 1024

donreynolds · Post by **donreynolds** » Fri Dec 03, 2010 6:46 pm

I have Digital Performer 7.21 on OS X 10.6.5 on a MacPro dueal 3 Ghz intel, with 4 GB 667 Mhz DDR2 FB-DIMM/ 500 GB HD. I am using 2 896HD interface units units on a firewire card. I record my projects at 48Khx/24 bit.

My issue: I am only able to select up to 1096 as a buffer setting.

I noticed on my G4 with DP 5 installed that the higher buffer settings were available up to 2048 and 4096

What is the reason for this? Why can't my MacPro select these?

Do I need more RAM, and if so what is the max that I can utilize?

Thanks in advance for your time.

Don

buzzsmith · Post by **buzzsmith** » Fri Dec 03, 2010 7:38 pm

Someone may correct me, but I think you can get the same result by changing the host multiplier.

If you want 2048, select 1024 with a multiplier of 2.

Buzzy

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donreynolds · Post by **donreynolds** » Fri Dec 03, 2010 8:09 pm

I tried that Buzzy. No different. I think that is more when you are using two different interfaces or something. Thanks for the suggestion though.

YouTube · Post by **James Steele** » Fri Dec 03, 2010 8:17 pm

Wish I knew the answer to that one. Good question for a MOTU person. I'd give 'em a call. I saw another thread that said their phone service is improving. Running a PCIe-based system with a 424 card and HD192 and 24I/O, all we ever get is 1024 buffer at most. Only MOTU's firewire systems can have a larger buffer.

donreynolds · Post by **donreynolds** » Fri Dec 03, 2010 9:11 pm

Yeah I know. It is funny that my G4 can select them though and the MacPRo cannot. I will try to call Monday. I sent a PM to Magic D. and a few others that may know. Maybe they will offer a suggestion if they have time.

I will post if I find out. it would really be helpful at time to bump it up to at least 2048.

donreynolds · Post by **donreynolds** » Fri Dec 03, 2010 9:12 pm

Stuff like that just bugs me...

Frodo · Post by **Frodo** » Sat Dec 04, 2010 1:01 am

As far as I can remember, MOTU's drivers always max'd out at 1024. I must also say that I've only used a PCI MOTU interface with a 2408.

Now, Built-In is interesting. On my laptop I can get a buffer of 2048 using Built-In. For reasons I don't understand, 4096 appears but is grayed out.

On my MacPro, I use an SSL PCIe interface. It's the only one, afaik, that has a two-way channel for data in and data out. The max buffer is 512, but because it's dual channel, it totals an aggregate 1024 on the buffer. However, each 512 is discreet and not shared as it is on other interfaces.

Apparently, the buffer limit is determined by the audio driver with some consideration to what the DAW host will accommodate. Another DAW has buffers as low as 32 whereas DP's bottom line is 64. DP's upper end buffer number varies from one audio driver to the next. MOTU has always registered with a max 1024 at least where PCI-based interfaces go.

Dunno what the jammy is with FW interfaces, if different.

Armageddon · Post by **Armageddon** » Sat Dec 04, 2010 4:15 am

If I'm not mistaken, I have the ability to get to 2096 with my rig (I believe it's dependent on your interface, not your software or CPU/RAM), but it causes all sorts of serious glitches, so I've always stuck with 1024, which most VIs and whatnot suggest is the optimal buffer, anyway. I'll have to experiment with it again, but I could definitely use the extra buffers.

Dwetmaster · Post by **Dwetmaster** » Sat Dec 04, 2010 7:14 am

My 896hd or mk3 maxes at 1024 as well.

David Polich · Post by **David Polich** » Sat Dec 04, 2010 8:23 am

I have an Apogee Duet and 2048 is the highest option for me.

Yes, it is a MOTU interface thing. And yes, "host multiplier" refers
to the number of audio interfaces you are using.

i7user · Post by **i7user** » Sat Dec 04, 2010 8:40 am

James Steele wrote:Only MOTU's firewire systems can have a larger buffer.

Because FW is so S_L_O_W...
Are you getting processor spikes? If not, why worry about it?

YouTube · Post by **James Steele** » Sat Dec 04, 2010 9:04 am

i7user wrote:
James Steele wrote:Only MOTU's firewire systems can have a larger buffer.
Because FW is so S_L_O_W...
Are you getting processor spikes? If not, why worry about it?

Only reason I worry about is that I learned from someone that a larger buffer can sometimes speed up offline BTD (Bounce To Disk).

I have a UAD-2 Duo card. If I run too many plugs-- in one case I was dropping LA-2A instances with abandon by duplicating a track for several tracks of layered backing vox-- it will actually slow down BTD to real time speed.

I had a project that would not bounce faster than realtime. I removed a Liquid Mix instance first since ANY instance of LM will eliminate ability to BTD faster than realtime. It was STILL slow. I removed about 10 instances of LA-2A, reducing DSP load at idle of my UAD-2 Duo from 52% to about 24%, and suddenly my offline BTD went VERY fast again.

What does this have to do with buffer size? The person I know had the same issue, but he was able to increase his buffer to 4096 and his BTD went fast again. He feels it's not a PCIe bandwidth issue, but just that the larger buffer helps the processor(s) on the UAD-2 work faster when you're using a lot of instances. I may try using the "Built In Audio" option and then unceasing the buffer to confirm this.

jloeb · Post by **jloeb** » Sat Dec 04, 2010 1:29 pm

Largest buffer option here is 2048. Apogee Ensemble thru firewire, 14 GB RAM installed, no PCI cards.

Armageddon · Post by **Armageddon** » Sat Dec 04, 2010 9:45 pm

James Steele wrote:Only reason I worry about is that I learned from someone that a larger buffer can sometimes speed up offline BTD (Bounce To Disk).

Like I said, I can select up to 2048 (thanks to jloeb for posting the correct number!), but the audio seems to break up. I can see 4096 on my list, but it's grayed out. However, the last time I attempted this, I was running Tiger, DP 5.13, a slower hard drive and a much earlier software/firmware revision for my Konnekt 24D, so I may try it again. It would be awesome to get my money's worth out of this interface ...

motuscott · Post by **motuscott** » Sun Dec 05, 2010 3:37 am

64-1024 here w/ MOTU828II and 2.4GHz Intel Core 2 Duo.

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