Yaesu SP-10 Modifications

When I purchased the Yaesu FT-991A, I purchased it with the matching SP-10 external speaker. I made the assumption that the external speaker would improve the audio experience of the radio in several ways. First, having the speaker facing the operator rather than facing upwards would improve the experience. In addition, I assumed the actual speaker inside the cabinet would be better than the one inside the radio. This was not the case.

The Speaker in the SP-10

The speaker inside the external case appeared to be identical or nearly identical to the speaker inside the FT-991A. After connecting it to the radio and listening to a few stations, I wasn’t entirely satisfied with the audio quality. It certainly was an improvement to have the speaker facing me, as opposed to the speaker inside the radio which faces upwards.

I set out to replace the speaker inside the external speaker case and to add some baffle/insulation to the inside of the case. I purchased the Dayton Audio ND65-8 2-1/2″ Aluminum Cone Full-Range Neo Driver 8 Ohm speaker from Amazon.

ND65-8 2-1/2” Replacement Speaker

The speaker didn’t exactly fit the same way the original one did, but turning it a bit, I was able to secure it without glue or any modification to the enclosure or other hardware – I can easily swap the old speaker back in if I needed to. The challenge with finding an exact fit was the mounting ring around the speaker.

In addition to replacing the speaker, I also clipped the capacitor which was connected in parallel across the speaker input to the case. I’m not sure what the intent was for this capacitor, perhaps to filter out low frequency PL tones.

Phonema PHITS Acoustic Modification Kit Y10A

In addition to replacing the speaker, I also added the Phonema PHITS Acoustic Modification Kit Y10A. The pieces need some careful alignment and replacing the cover back over the foam pieces needs some extra force. I was careful to place some of the screws in a specific order to prevent bending the case when reassembling.

The improvement was dramatic. The increase in frequency response and clarity was well worth the effort.

It should be noted that due to difference in efficiency of the new speaker I put in place, I do have to increase the volume a bit for the same loudness as the old speaker.

Final Thoughts

It really is a shame that Yaesu didn’t build this external speaker with a better speaker inside the box. For the retail price of this external speaker, it should have been better in terms of audio quality. If you’re considering purchasing this external speaker, I highly recommend the modifications described in this post.

I’m glad I have the external speaker, I don’t think I would enjoy using the FT-991A as much without it. My only complaint is the cost of the speaker for the quality of the sound before the modification.

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