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Supplemental
Information
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The tables on the left use
the 5 test frequencies of the ORION Test CD. The measured voltages are
examples and ideally should not deviate by more than 0.2 dB from the
nominal values.
The nominal values in dB of the top table were measured on my new ORION-3.3 pcb and compare closely to the values of the original pcb that I have had in use for a long time. I measured the response using ARTA and an E-MU Tracker Pre. The calibration for 0 dB was done with the Tracker Pre output loaded by the 10.2 kohm input impedance of the circuit. Use the Response Spot Check spreadsheet to record your measurements and to calculate the deviation from nominal in dB. If you have a signal source other than the Test CD, then you can use the tables for 8 spot frequencies.
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Revision 1/19/06 of the ORION Construction Kit
Documentation describes an obsolete mounting scheme for the midrange driver, by
screwing it directly to the midrange and tweeter baffle A. Instead, the midrange
driver should be held by the magnet. See https://www.linkwitzlab.com/orion-rev1.htm
. While it is not absolutely necessary to use this different mounting scheme to
obtain good sound, it should be noted that all development work for ORION-3.3
was done with a magnet mounted midrange. I cannot say what is lost without
magnet mounting, since I never reverted back to panel mounting in the evolution
of these loudspeakers. A midrange driver mounting kit is available from Wood Artistry.
The SEAS L26RO4Y D1004-04 woofer has a larger magnet structure and greater excursion capability than the Peerless XLS 830452. To take advantage of this requires a higher power amplifier than the AT6012 such as the AT1806. Also, the bottom woofer's magnet would protrude past the grill cloth unless it is mounted with a wooden spacer Q of at least 5/8 inch (16 mm) thickness. The outline of part Q is a 12 x 11.5 inch rectangle with a centric through-hole of 240mm diameter. The 11.5 inch width must have 2 x 3/4 inch cut-outs at the two bottom corners to clear parts J.
20 July 2015 - R66 in the U12B stage should be 110k if the SEAS L26RO4Y woofers are used. It should be 68.1k if the original Peerless XLS 830452 woofers are used. The circuit diagram above and the material list show the incorrect value.
5 October 2011 - Added graph to read woofer drive difference between v3.4 and v3.3
3 October 2011 - Added Orion-3.4 information to circuit schematic, material list and G.
5 September 2011 - Added gold plated RCA to material list
18 August 2011 - Material list completed
11 August 2011 - First posting of Supplemental Information
The new material list is under construction. Finish target: 19 August 2011.
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