geoff wrote:
> On Tue, 05 Jan 2010 21:27:32 -0700, Gustin Johnson
> <[email protected]> wrote:
> <snip>
>   
>> -----BEGIN PGP SIGNED MESSAGE-----
>> Hash: SHA1
>>
>> geoff wrote:
>>     
>>> On Tue, 29 Dec 2009 18:49:16 +0000, geoff <[email protected]> wrote:
>>>
>>>       
>>>> Hi there,
>>>>
>>>> I seem to have a jitter issue with external MIDI timing.
>>>>         
>>> Still stuck at ~30mS jitter.
>>>
>>> Booted with "hpet=force", and the kernel (and thus ALSA) found an
>>> HPET, but the timing stayed the same.
>>>
>>> At Ralf's suggestion, I ran up Win XP Home SP2, installed the latest
>>> MidiSport drivers, installed MIDI-OX and ran a loopback test.
>>>
>>> This relies on the accuracy of the MIDI-OX timestamping, but I seemed
>>> to be getting a consistent 5mS round trip from the USB interface.
>>>
>>> Which seems to indicate there's a software level incompatibility with
>>> USB MIDI (or at least, MidiSport USB MIDI) and 3.0b3.
>>>
>>> I'm looking for suggestions to ameliorate this situation.
>>>
>>>       
>> something like
>> http://www.philrees.co.uk/products/thruunit.htm#v4
>> or
>> http://www.philrees.co.uk/products/thruunit.htm#v8
>>
>> I have never needed or used these sorts of things, but it may be useful
>> for you.
>>     
>
> Thanks for the suggestion.
>
> I had a configuration similar to that in the early 90s. To prevent the
> "drummer" sounding increasingly drunk as more (high controller
> density) parts were added to the piece, I replaced it with a Unitor 8,
> an eight port MIDI interface of the period.  
>
> It doesn't take much stacking on a single MIDI cable to bring that
> inebriation about, imho. Plus, you need a switch box for patch
> editing, which is a pita.  
>
> <snip>
>   

Any way, if you should decide to buy such a MIDI thru box, keep in mind, 
that it's easy to build one yourself, if you should be able to solder.

>>> And can anyone describe their measured low-jitter external MIDI setup
>>> with at least 4 ports, please? (where low is < 10mS)
>>>
>>>       
>> I have a total of 3 midi devices (a keyboard, BCF2000, and a synth).
>> I use the 2 ports on my Hammerfall.  I also have a midisport 2x2 that I
>> have not used for years.  If I get some time over the next couple of
>> days I will run that midi test.
>>     
>
> Thanks for considering this.

Cheers,
Ralf
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