Bad SP3 Documentation

[Randy Farmer]

I just received a new pair of SP3 speakers and began their installation
last night. I built a new custom cable to feed the speakers from the
outputs of my stereo amplifier using the pinout data supplied in the SP3
manual. I also verified that the pinout shown pictorially (in two places
in the manual) matched the schematic. Upon installation, nothing worked
correctly -- I could only get right channel audio out of one of the
speakers. I spent a while troubleshooting last night and resumed this
evening. To make a somewhat long story short, I discovered that although
the SP3 pictorials and schematic showed that the input connector
expected right channel audio on the tip and left channel audio on the
ring, the speaker was actually wired for left channel on the tip and
right channel on the ring. Strangely enough, this is exactly the pinout
shown for the speaker and headphone jacks in the K3 and K3S manuals. The
connection from the left speaker output jack to the right speaker input
carries right channel audio from the ring on the tip of the interconnect
cable. I opened up one of the speakers and verified that it was wired to
match the K3 standard. Once I reversed the left and right input sources
the stereo pair started behaving as they should. If you're only using
one SP3 in a mono configuration it will work just fine; it's only when
you try to connect a pair in stereo that the documentation error becomes
troublesome. I'd be real curious to know how the SP3 docs got to be so
wrong. This problem should be corrected ASAP.

73...
Randy, W8FN
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[Bob Wilson, N6TV]

I agree.  Figure 2 in the SP3 manual has it backwards.  The Elecraft K3 and
SP3 both follow the standard convention for a TRS or "stereo" connector:

Tip = Left
Ring = Right (an alliteration that's easy to remember)


Furthermore, when using TRS-to-RCA patch cables:

White = Left
Red = Right (another alliteration that's easy to remember)


However, I have several cheap TRS to RCA patch cables that reversed the
colors (that's whey they were cheap).  Always use a continuity checker to
verify that Ring connects to Red, Tip to White, Shield to Shield, an no
shorts.

Figure 4 looks correct though, because it's talking about the cable on the
OUTPUT connector for second SP3, which must be placed on the RIGHT, and it
says a MONO cable can be used, so tip = RIGHT makes sense in that context
only.

I agree that the labeling of R and S (Ring and Sleeve) appears reversed in
the schematic.  It's the TIP (VFO A, left channel) that goes to the
speaker, not the RING.

Of course everything gets mixed up if CONFIG:L-MIX-R isn't set to A  b.

73,
Bob, N6TV

On Tue, Jun 26, 2018 at 7:45 PM, Randy Farmer <[hidden email]> wrote:

> I just received a new pair of SP3 speakers and began their installation
> last night. I built a new custom cable to feed the speakers from the
> outputs of my stereo amplifier using the pinout data supplied in the SP3
> manual. I also verified that the pinout shown pictorially (in two places in
> the manual) matched the schematic. Upon installation, nothing worked
> correctly -- I could only get right channel audio out of one of the
> speakers. I spent a while troubleshooting last night and resumed this
> evening. To make a somewhat long story short, I discovered that although
> the SP3 pictorials and schematic showed that the input connector expected
> right channel audio on the tip and left channel audio on the ring, the
> speaker was actually wired for left channel on the tip and right channel on
> the ring. Strangely enough, this is exactly the pinout shown for the
> speaker and headphone jacks in the K3 and K3S manuals. The connection from
> the left speaker output jack to the right speaker input carries right
> channel audio from the ring on the tip of the interconnect cable. I opened
> up one of the speakers and verified that it was wired to match the K3
> standard. Once I reversed the left and right input sources the stereo pair
> started behaving as they should. If you're only using one SP3 in a mono
> configuration it will work just fine; it's only when you try to connect a
> pair in stereo that the documentation error becomes troublesome. I'd be
> real curious to know how the SP3 docs got to be so wrong. This problem
> should be corrected ASAP.
>
> 73...
> Randy, W8FN
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>

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