Disklavier

Corrections:  The MIDI spec actually states 15 meters (= 49.2 feet) max 
cable length.  I should have said "your DKV, with its 70-foot cable".

Bob

Robert Welcyng wrote:
> Don,
> 
> The MIDI specification does call for a maximum MIDI cable length of 50 feet.
> 
> What is the reason for specifying maximum cable length? Well, if you are 
> a manufacturer of MIDI equipment, your device had better be sensitive 
> enough to operate with up to 50 feet of MIDI cable or you are not 
> meeting the spec.  A conservatively designed device will still operate 
> satisfactorily beyond the 50-foot cable limit--although it is not 
> guaranteed to.
> 
> MIDI uses current loop signalling--nominally 5 milliamperes.  Loop 
> current does decrease with the greater resistance of a longer loop. 
> Also the rise and fall times of the data pulses--nominally less than 2 
> microseconds--will increase as the cable length increases. These 
> considerations set the minimum performance required of the optoisolator 
> receive circuit of the DKV.  If MIDI were an analog system, performance 
> might gradually degrade as the signal degrades.  Being digital, however, 
> there is a sharp division between working and not working with no 
> gradual degradation in between.
> 
> If your DKV, with its 90-foot cable, is operating to your satisfaction, 
> my advice is: Save your money and don't worry about it.
> 
> 
> 
> Don Shifris wrote:
> 
>>I have tried to purchase such a device and have not been able to find one. 
>>Can you direct me to a vendor ? I have been calling it a line driver. The 
>>local guitar stores don't have anything.
>>
>>Thanks,   Don
>>
>>
>>>Good morning, everyone, and greetings from the World Piano Conference in 
>>>Slovenia.
>>>
>>>In a message dated 6/26/2003 12:21:29 AM Eastern Standard Time, Don writes:
>>>
>>>
>>>
>>>>I have not worried at all about diskettes since you told me about
>>>>vanBasco's jukebox. I drive my MX80 with an xp PC. It works great except
>>>>for one song (William Tell Overture duet). I believe that
>>>>this problem is
>>>>due to the fact that my cable is about 70 feet long.
>>>
>>>I believe that the maximum recommended lenghth of a MIDI cable is 45 feet. 
>>>You can even connect shorter MIDI cables together with barrel connectors 
>>>in order to get up to 45 feet.
>>>
>>>Beyond 45 feet, it is advisable to have the electrical signal refreshed. 
>>>There are MIDI mergers and splitters that have their own power supply that 
>>>can do this.
>>>
>>>Regards,
>>>PianoBench
>>>
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>>>Todd's family web site was completely updated 01/15/03.  It contains some 
>>>fun disklavier content and links to midi sites among many other things, 
>>>The url is:
>>><http://MuncyFamily.com>http://MuncyFamily.com
>>>
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>>
>>
>>
>>
>>
>>To Post a message to the group, send it to:   disklavier@...
>>
>>To Post a private message to Todd Muncy, the group's founder and moderator, send it to:
>>disklavier-owner@...
>>
>>To reach our group's web site go to:
>>http://Yahoogroups.com/group/disklavier
>>
>>Todd's family web site was completely updated 01/15/03.  It contains some fun disklavier content and links to midi sites among many other things, The url is:
>>http://MuncyFamily.com 
>>
>>THINKING OF LEAVING THE GROUP?
>>If you are thinking of unsubcribing because you are getting too much mail, go the the web site and change your email delivery option instead.  That will fix the problem, while maintaining your access to the group.  If you insist on leaving us completely send a blank email to:
>>disklavier-unsubscribe@... 
>>
>>Know someone who wants to join?  Have them send a blank email to:
>>disklavier-subscribe@... or give them this link:
>>http://Yahoogroups.com/group/disklavier/join 
>> 
>>
>>Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ 
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>>
>>
> 
> 
> 


-- 
Robert Welcyng
Anchorage, Alaska