[LAU] PCIe audio gear [was: Too many xruns]

[Ralf Mardorf]

On Sat, 2012-09-08 at 14:59 -0700, Len Ovens wrote:
> On Sat, September 8, 2012 11:59 am, Fernando Lopez-Lezcano wrote:
> > On 09/07/2012 01:31 PM, Kevin Cosgrove wrote:
> >>
> >> On 7 September 2012 at 6:14, "Len Ovens"<len at ovenwerks.net>  wrote:
> >>
> >>>
> >>> On Thu, September 6, 2012 9:58 pm, Kevin Cosgrove wrote:
> >>>> On 6 September 2012 at 21:52, "Len Ovens"<len at ovenwerks.net>  wrote:
> >>>>
> >>>>>
> >>>>> On Thu, September 6, 2012 8:57 pm, Ralf Mardorf wrote:
> >>>>>> On Thu, 2012-09-06 at 20:35 -0700, Len Ovens wrote:
> >>>>>>> I just had to look... and sure enough they do exist:
> >>>>>>> http://ca.startech.com/Cards-Adapters/Slot-Extension/PCI-Express-to-PCI-Adapter-Card~PEX1PCI1
> >>>>
> >>>> Also, http://www.newegg.com/Product/Product.aspx?Item=N82E16815158165
> >>>> which has some customer reviews.
> >>>
> >>> The review looks bad for audio cards. I guess there is an
> >>> onboard regulator that does not allow enough current :P So
> >>> the onboard reg would have to be bypassed and an external one
> >>> added.
> >>
> >> I wonder if there's enough current to run the PCI card portion of
> >> the Delta 1010 setup?  The data converters are in a break-out box
> >> in an audio rack.  There isn't a whole lot on the PCI card, no
> >> fans, and I don't even think any heat sinks.  That might indicate
> >> low power.
> >
> > There should be no problem with power. We are running tons of Delta66's
> > and I used to have a few 1010's as well. Easy cards to work with (so I'm
> > surprised at the problems you are having). The 1010's had problems with
> > some capacitors in the break-out box (in the power supply doubler or
> > quadrupler circuit) - replacing them fixed the issue.
> 
> On any normal MB PCI slot there should be no problem as the regulator has
> to be sized to cover all the PCI slots as well as other MB stuff. In this
> case with a PCIe slot to PCI card adapter the reg may be sized for exactly
> whatever the PCI card current spec is (dumb as lots of cards, not just
> audio, assume there are some empty slots they can use the excess current
> capability from). What this really says (to me), is that the PCI standard
> does not provide enough current for all uses... or that these adapters do
> not provide current to spec... Or that some PCI cards really should have
> had an external power plug because they really draw more current than the
> MB is "supposed to" supply.
> 
> All of that is not a help really, to someone who is having problems. The
> RME solution of having a digital PCI/PCIe card powered by the MB and and
> external box with pre amps and converters on it (powered externally), is
> probably the correct solution in this case. The PCI bus is not designed to
> supply power for much more than digital activities. It is like expecting
> to get good quality pre amp stuff and phantom from USB power... your mic
> probably sounds better with 48v than 24v.
> 
> All this from the proud owner of a D66  :P  6 in and 4 out has proved (so
> far) to be more than I need. But then I have never had a drum kit to
> mic... or the more than 4 mics needed either. I have in the past used two
> mics to record vocals and guitar, but the comb filtering drove me nuts,
> one mic sounds better. So far I have not had the privilege of recording
> more than one person at a time. However, I now know what to buy when I get
> there... if PCIe is still around.

If there isn't enough current for an IO card, the cause might be a
undersized power supply unit. Whatever the specifications for maximal
current for PCI slots are, if the PSU is to weak, it can't provide the
needed current. Sum up the power consumption of the CPU, all HDDs, DVD
drives, cards, USB gear etc. and compare it with the maximum current the
PSU can provide.

Regards,
Ralf