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What's in the Box 
Refurbished SP3 Speaker
One cable to connect it to either a K3S or K3

The SP3 can be used with any receiver capable of driving a 4-ohm load. The speaker is passive (non-amplified), ensuring no susceptibility to RFI in the present of a transmitted signal. The SP3’s custom-built, wide-range driver has excellent sensitivity and deep bass response.

The A/B switch on the front panel of the SP3 can be used to select one of two mono sources. Further, when used in conjunction with a second SP3 this switch can be used to select one of two stereo sources. The Elecraft K3 and K3S transceivers take full advantage of this feature, since both provide rich binaural audio effects (AFX), as well as user-adjustable left/right balance between main and subreceiver audio.

Rear-panel input jacks accept either mono or stereo cables, simplifying station wiring. An output jack is provided for connection to a second SP3. When two SP3s are used, the A/B switch on the first unit controls source selection for both.

High Performance Matching Speakers were designed by audio expert Dr. Bruce Edgar.



  • Dimensions (see Figure 1)  The tilt stand height matches the Elecraft K3 and K3S transceivers, the KPA500 Amplifier and the P3 Panadapter.  Allow an additional 2" (5 cm) space behind unit for rear panel connectors.

  • Weight:  4 lb, 12 oz ( 2.2 kg)
  • Speaker Size:  3” x 5” (77 x 127 mm)
  • Speaker Impedance:  4 ohms
  • Magnet Type:  Neodymium
  • Power Handling Capability:  15 W
  • Frequency Response:  100-20,000 Hz
  • Sensitivity:  90 dB SPL




Q: Do I need to add an amplifier to the SP3?

A: No.  While there is no amplifier inside the SP3, the amplifier of the K3/K3S works quite well for most ham shack applications.  The SP3, at 90dB efficient, will produce quite sufficient sound levels.  If more sound pressure level is needed, consider adding a 2nd SP3 to use the 2nd amplifier inside the K3/K3S.

Q: May I purchase one SP3 now and add a second one on at a later time?

A: Yes.  The SP3 has the connections to allow you to add a 2nd one at any time.  The SP3 ships with the wiring needed to expand a 2nd SP3 without disassembling the shack.  Simply plug the 2nd SP3 into the back of the 1st SP3 and set the K3/K3S menu to 2 speakers.

Q: Can I connect a 2nd radio to the SP3?

A: Yes.  The SP3 has a front panel switch to allow the operator to easily switch between 2 transceivers.  Even if they have a single channel or dual channels of audio, this can be supported.  The A/B switch on the front of the speaker allows rapid switching when needed.

Q: What is unique about the way the SP3 sounds?  Isn't it like all other communications-grade speakers?

A: The SP3 is unique because it was designed to produce low-distortion audio for long periods of time.  Unlike most communications speakers, the presentation of the audio will appear to come from behind the grille and will sound very natural.  This is most important For operators who will be using their radios for hours at a time.

Further, for those who operate higher fidelity transmitting systems, the SP3 is designed to present an accurate image of the transmitted audio for analysis and reporting.

Q: Why doesn't the SP3 have any controls for filtering?

A: The controls for filtering and response shaping are actually in the K3/K3S radios.  There are 2 Parametric Equalizers in the K3/K3S, separate for CW and Phone modes.  You can add these features to the Audio Effects (AFX button), and you have a powerful set of tools to shape the audio the way you want.  For this reason, there was no reason to add more controls to the speaker itself.

Q: Can the SP3 be used with other radios?

A: Yes.  The SP3 is compatible with any other radio that has a speaker output.

Q:  Will the SP3 work with the KX3 and KX2?

A:  No.  The KX2 and KX3 have headphone output but not full speaker outputs.  You can, however, add a small amplifier to power the SP3 with them that way.