Why Change?
I’m an Elecraft “fan boy” but the speakers have always fallen short of what I believed Elecraft should have produced. The stock speakers are narrow in range and are not of the best for CW operators. The 4-ohm speaker, while within spec for the amplifiers in the K3, is too much load on the internal amplifier of the K3. This situation leads to the amp cutting out if running at moderate to high levels for a prolonged period.
The Path:
The K3 supports stereo. I have limited desk space, so a second enclosure (adding a 2nd SP3) does not work for my situation. My solution was to create a powered, stereo version that used a more suitable driver supporting the full voice range, with a nice resonance around 750Hz for CW.
I purchased a class-D stereo amp: https://www.amazon.com/dp/B09KGXTX2C?ref=ppx_yo2ov_dt_b_fed_asin_title
and a pair of 2.5 inch drivers: https://www.amazon.com/dp/B07H2TBKM6?ref=ppx_yo2ov_dt_b_fed_asin_title
RFI suppression was added to the incoming wiring, passing the leads through an FT-82-43 three times. A 1000uf 35V cap was added to the 12V supply, at the amplifier board. Each channel input was padded to reduce the levels to keep the volume in range. The pads consist of a 2K-ohms resistor in series with 100 ohms to ground. (Your results may vary.)
The driver support structure was printed from PLA material. This modification is such that the speaker can be returned to a stock configuration in the future if desired. The file for the support frame is available on GitHub.
The Result:
The result is amazing with lots of dynamic range and the ability to truly support the stereo mode when operating split with a sub-receiver, or in diversity receive mode. The spatial imagery is better than I had anticipated. The SP3 now provides a real, wide sounding experience, even though the drivers are in close proximity to one another.
The K3 transceiver’s internal audio amps are unburdened, so no more thermal shutdowns. CW now has a sweet note that allows operating for hours without fatigue.
Hope this information finds you well, and is helpful! More photos and information are available at: https://github.com/ldocull/Stereo-Elecraft-SP3/tree/main
73 de WR9R