SDA 1C wiring oddity
crcolby
Posts: 18
After nearly a year's delay I am now set to modify a pair of SDA 1C's. First, I wanted to write on the enclosure beside each driver the color coding for the wires that should feed it. Somebody has already been inside these enclosures, so I will note but cannot trust what I will find.
The 1989 wiring diagrams M9101038 by Rick Schimpf do not say whether Mr. Schimpf was viewing from the front -- X-raying to the rear terminals -- or the other way round. I'm assuming the view is from the front and hoping that some coding on the driver terminals will corroborate this.
All four 6511s (the "stereo" drivers) are shown with the black (+) lead connected on the right terminal of the driver, again, as viewed from the presumed front. That keeps the four speakers in phase.
As for the 6510s -- the dimensional drivers -- the left channel's drivers also have the (+) leads (blue in their case) connected to the right. I guess that keeps the left speaker's 6510s in phase with the 6511s. In contrast, the right channel's blue (+) leads connect to the left sides of the drivers. So either the right-channel 6510s get installed upside down, or the right channel plays out of phase with all four 6511s and the left 6510s.
I might have expected all the 6510s to be out of phase with the 6511s, but it's odd to me that Polk would break symmetry this way. Does anybody have any ideas?
The 1989 wiring diagrams M9101038 by Rick Schimpf do not say whether Mr. Schimpf was viewing from the front -- X-raying to the rear terminals -- or the other way round. I'm assuming the view is from the front and hoping that some coding on the driver terminals will corroborate this.
All four 6511s (the "stereo" drivers) are shown with the black (+) lead connected on the right terminal of the driver, again, as viewed from the presumed front. That keeps the four speakers in phase.
As for the 6510s -- the dimensional drivers -- the left channel's drivers also have the (+) leads (blue in their case) connected to the right. I guess that keeps the left speaker's 6510s in phase with the 6511s. In contrast, the right channel's blue (+) leads connect to the left sides of the drivers. So either the right-channel 6510s get installed upside down, or the right channel plays out of phase with all four 6511s and the left 6510s.
I might have expected all the 6510s to be out of phase with the 6511s, but it's odd to me that Polk would break symmetry this way. Does anybody have any ideas?
Comments
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All you need to know is the positive leads (either black or blue) go to the positive terminal marked with a red dot on the driver basket.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
Thanks, F1nut. Emboldened, I put my screwdriver to work. With these two photographs of the right crossover, can someone say whether my SDA 1C's can accommodate dual monoblocks through an isolation transformer. Some of the drivers are stamped with the date, December 28, 1989. The right speaker's SN is 11811. Left is 11873.
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ALL 1Cs can accept the isolation transformer. There are some units--identified by serial number on a notice from Polk--that need some extremely minor modification if the OEM connector set is desired (and can be sourced. Some parts are out-of-production.)
If the speakers already have pin-blade SDA interconnect sockets, you're all set to use the OEM transformer. Looks to me like that's what you've got, based on the white (ground) wire from the speaker cable post to the SDA connector. If you're using a big "dreadnought" transformer, you'll be installing other sockets anyway. Most folks seem to be using the Speakon-style connectors.
