#11170 LOW 1.75-ha: XO-1.75 sound output quality regression over XO-1.5

[Zarro Boogs per Child]

#11170: XO-1.75 sound output quality regression over XO-1.5
----------------------+-----------------------------------------------------
 Reporter:  Quozl     |                 Owner:  wad          
     Type:  defect    |                Status:  new          
 Priority:  low       |             Milestone:  1.75-hardware
Component:  hardware  |               Version:  1.75-B1      
 Keywords:            |           Next_action:  diagnose     
 Verified:  0         |   Deployment_affected:               
Blockedby:            |              Blocking:               
----------------------+-----------------------------------------------------
 Reported by Tabitha Roder, Tom Parker and Kevin Gordon on XO-1.75 B1,

  * "sound to be scratchy",
  * "turn on tune sounds different",
  * "something less pleasing, but I can't describe it",
  * "boot chime is a little tinny".

 I've tested audio in OpenFirmware.  I agree there are more high frequency
 components to the audio.  They are audible via the speakers, and via
 headphones.  The headphone audio level is much lower than on XO-1.5.

 A repeating test can be made as follows:

 {{{
 ok sound d# 6000 ms sound-end many
 }}}

 This works on XO-1, XO-1.5, and XO-1.75.

 The following Python script was used to generate regular chimes from a
 batch of laptops:

 {{{
 #!/usr/bin/python
 import sys
 import telnetlib

 del sys.argv[0]

 tn = {}
 for xo in sys.argv:
     print xo
     tn[xo] = telnetlib.Telnet(xo, 23)
     tn[xo].write('\r')
     tn[xo].read_until('ok ', 1)
     tn[xo].write(': qz sound d# 5000 ms sound-end ;\r')
     tn[xo].read_until('ok ', 1)
     print xo, 'ready'

 while True:
     for xo in sys.argv:
         tn[xo].write('qz\r')
         tn[xo].read_until('ok ', 8)
 }}}

 Each laptop was started with:
 {{{
 essid qz
 telnetd
 }}}

 The chimes were recorded with a Zoom H4n, at a distance of roughly two
 feet from the row of laptops.  From left, the laptops were XO-1.75 B1,
 XO-1.75 B1, XO-1.5, XO-1.  Three cycles, therefore 12 chimes, were
 recorded.

-- 
Ticket URL: <http://dev.laptop.org/ticket/11170>
One Laptop Per Child <http://laptop.org/>
OLPC bug tracking system