[ardour-users] 48 channels on ardour

Nikla Ratinen nikla.ratinen at gmail.com
Thu Jul 19 02:02:40 PDT 2007


You should have no problems at all with that hardware.

For a reference, here's what I'm powering my "mobile" hobbyist 16I/O 
studio with:

Ardour 2.0.3 on UbuntuStudio (low latency kernel, not realtime), booted off
from a usb drive - the usb drive is nothing amazing, just a regular el 
cheapo Lacie.
Also, I currently use this same usb drive for system and audio... The 
machine is a 1.7 Ghz
centrino laptop w 2GB mem and connected via pcmcia to Echo Layla 24 + 
ADA 8000
for 16 inputs and 16 outputs.

The 4 song project I'm currently mixing has ~30 tracks total per song, 
heavy bussing and a bunch of
ladspa/vst plugins, track automation etc - still the system works semi 
ok; occasional crashes though,
mostly when touching vst plugins during playback or when the zoom level 
is high.
Out of the 30 tracks, first 16 were taken simultaneously (drums + bass 
base session) and the
rest are overdubs. During recording sessions the system worked 
flawlessly and with very light
load, but there wasn't any plugins/bussing/automation in use at that point.

I also have another older 900 MHz Pentium III laptop to which I've 
installed UbuntuStudio + Ardour.
This one is booting from its internal drive, I think its 5400 rpm 
although it might be even slower. Anyway,
I intend to use this one for recording a couple of live gigs later in 
fall. I've tested it can take at least 45
minutes of continuous recording with full 16 inputs without xruns.

-- Nikla

John Emmas wrote:
> I'd be interested to know what hardware you guys are running to get
> 24 & 48 channels.  To be honest, my copy of Ardour often struggles to
> play just 4 channels simultaneously.
> "Struggles" is probably an exaggeration but I do get occasional glitches
> such as a short 'hole' in the sound or an occasional 'skip'.  I've never
> timed how often these happen but I doubt that I could replay 10 whole
> minutes of audio without encountering at least 1 glitch.
> My hardware is pretty old but not unrespectable.  I have a 1.2GHz Athlon
> with 512MB of RAM, but my disks are just standard EIDE types (though
> reasonably fast).  I'm running OpenSuse 10.2 with Jacklab and an RME
> HDSP9632 sound card.  Enough to run 4 x simultaneous channels without
> encountering problems, I'd have thought.  Maybe I need to tweak something??
> Just out of interest, what is considered a 'minimum spec' for say, a 24
> channel system?
> John
> ----- Original Message ----- 
> From: "John Rigg" <au at sound-man.co.uk>
> To: "Kevin Cosgrove" <kevinc at doink.com>
> Cc: <ardour-users at lists.ardour.org>
> Sent: 17 July 2007 23:04
> Subject: Re: [ardour-users] 48 channels on ardour
>> On Tue, Jul 17, 2007 at 02:17:44PM -0700, Kevin Cosgrove wrote:
>>> On 17 July 2007 at 20:04, John Rigg <au at sound-man.co.uk> wrote:
>>>> Yep. You'd have to decide if you really need to use 96kHz rather
>>>> than 48kHz. With something like a Delta 1010, most of the potential
>>>> increase in quality at 96kHz is wiped out by the increased clock
>>>> jitter, so it isn't really worth using more than 48kHz with that
>>>> particular hardware.
>>> Very interesting.  Is there much additional jitter from trying to
>>> sync multiple units, or is the internal jitter of one unit enough to
>>> degrade the quality?  How are you determining the quality differences
>>> between 48kHz and 96kHz?  Are you looking at the noise floor?  Or,
>>> maybe you've run a test like "effective bits"?  See
>>> http://www2.tek.com/cmswpt/tidetails.lotr?ct=TI&cs=Application+Note&ci=4405&lc=EN&from=rss
>> I haven't done extensive comparisons between 48kHz and 96kHz,
>> but I didn't hear enough of a difference between them to justify
>> doubling the disk bandwidth and space.
>> The Delta 1010 does have a jittery clock implementation. That's what
>> happens when the clock is on the PCI card and the converters are at
>> the other end of a 3m cable, with HF losses and crosstalk with all
>> the other signals in the cable contributing to jitter. I got a
>> noticeable improvement in audio quality just by replacing the 3m
>> host cables with 1m ones.
>> Regarding jitter when syncing, the 1010s sound better when using internal
>> clock than when synced via either BNC or S/PDIF. If I don't need more
>> than eight channels (eg. when overdubbing) I run jackd with only one
>> Delta 1010, set to internal clock. This situation can't be completely
>> remedied by using a high quality external clock, because jitter occurs
>> in the cable and the Delta 1010 hasn't got very good jitter attenuation
>> on its S/PDIF or wordclock inputs. It can be minimised by syncing with
>> very short, well-shielded cables with low capacitance.
>>>> Yes. At least one user on these lists is using it for 64 channels.
>>>> I'm currently using three Delta 1010s for 24 tracks. It's reliable
>>>> and I don't get xruns (I use large period size and monitor from the
>>>> 1010s' hardware outputs for `zero latency' monitoring though). Having
>>>> said that,
>>> Are you sync'ing your three via the BNC sync connectors or through
>>> the S/PDIFs?
>> When using all three 1010s I clock them from an Audiophile 2496 card
>> (also ice1712) in the same box, via a home-made 3-way S/PDIF splitter.
>> That way all three 1010s receive their clock signals at the same time.
>> As a bonus the 2496 also bumps the 1010s off the IRQ that is shared by the
>> graphics and network adaptors onto individual IRQs of their own. I'm not
>> using the 2496 for I/O in this configuration.
>> This is getting a little OT, but feel free to email me off list if you
>> have more 1010-specific questions.
>> John
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