Tascam us-144mkII

[Ralf]

On Fri, 2011-04-08 at 08:16 -0500, Scott Lavender wrote:
> 
> 
> On Thu, Apr 7, 2011 at 9:42 PM, Scott Bohon <scott.bohon at gmail.com>
> wrote:
>         Hello!
>         
>         Thank you all for help on -rt kernel.
>         
>         Now I need to get my USB Audio-MIDI Interface working - Tascam
>         us-144mkII. I think that I need to disable ehci-hcd (USB 2.0).
>         How do I
>         do this? Can it be done per port? Doesn't this slow down my
>         interface,
>         and thus cause more latency? Is there hope for USB 2.0
>         support?
>         
>         Should I look for a different interface? Any suggestions for
>         an
>         affordable solution with USB 2.0 or PCI?
>         
>         
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> 
> Hi Scott,
> 
> I do not have any practical experience with USB, therefore I cannot
> provide any answers for your technical questions.  I can, however,
> offer some generalized knowledge. 
> 
> I do not believe that USB1 provides enough throughput for acceptable
> latencies.  I believe that USB2 *can* provide decent latencies, but it
> seems to be rather hit or miss per interface, computer, and OS.  I
> understand that USB3 is designed to provide more throughput than
> firewire does currently, although we don't know how strictly this
> standard will be implemented.
> 
> Ultimately, some people have had very good success achieving
> acceptable latencies with a USB interface, others have not.
> 
> 
> For a suggestion, I would recommend a PCI card personally.  I concede
> that it is invasive, requiring you to open your computer, but I feel
> there is a variety of stable, inexpensive PCI audio interfaces that
> have a history of working well including the M-Audio Delta series.
> 
> I believe you can get an M-Audio Delta 44 for around $130 (used for
> $93) that will provide four inputs and four outputs with a convenient
> break out box.  I forget how long the cable is between the card and
> the box, something like three feet or four feet.
> 
> Although you can probably find a firewire interface for slightly more
> money that would avoid having to open your computer.  Others might
> offer firewire suggestions for comparably priced interfaces that are
> working with Ubuntu.
> 
> Cheers,
> ScottL

'Cards meeting the USB 1.1 specification have sufficient data transfer
capacity to support high quality sound operation if their circuit design
permits. However, USB 1.1 data throughput allows for concurrent use of a
limited number of channels and/or limited sampling frequency and/or
limited bit depth. For example 2 channels in and 2 channels out at 48
kHz/16 bit, or 2 channels out and no input at 96 kHz/24-bit. For a
higher number of channels and/or digital signal parameters, USB 2.0 or
higher is needed.'

Assumed USB audio devices should be ok, I imagine issues regarding to
shared IRQs, printer, mouse, keyboard, webcam, removable media.

I've got two Envy24 PCI cards. I auctioned one of those Terratec EWX
24/96 cards at Ebay for around 30 EUR (42 USD). Perhaps Envy24 PCI cards
are the cheapest usable cards. Avoid to get a Terratec EWX 24/96,
because it doesn't sound good, but try another Envy24 card, if you don't
like the Tascam us-144mkII.

OTOH, this Tascam might have a better sound quality than any Envy24
elcheapo PCI card and it supports USB 2.0 and USB 1.1:

http://www.thomann.de/gb/tascam_us144mk2.htm

Pardon, I didn't read the whole thread. Why do you need to use USB 1?

Cheers,

Ralf