Recently, I noticed that two of my Mac Pluses' speakers sound as if they're blown out during the bong boot sound.
You know you have a bad speaker if the sound at boot is annoying rather than pleasant. The speaker is mounted to the Mac Plus analog board via a rivet eyelets. Best way to remove is to use a drill. After a couple seconds, it will pop right off as seen in below picture. This is by far the best method for dismounting the speaker as it won't damage the board or the speaker.
After visually inspecting my speaker, oddly enough there are no visual anomalies. The speaker shows no signs of wear or tear. Comparing it to a known good speaker, I see or feel no difference.
I did so additional testing on the speaker. First I connected it directly to a frequency generator and the speaker sounded distorted between 380Hz and 460Hz, as heard in this video. Speaker sounds fine outside those frequencies.
I also checked the volume. While inside the above mentioned Hz range, the speaker was fine when the volume was below 70%. Issue only occurrs at higher volume.
I ordered a used replacement speaker pulled from a Macintosh IIsi. Note that although it's the same 0.25W 63Ω speaker, the padding on the front is a bit different, but that was no real problem other than not being exact replacement. Testing the replacement speaker, it showed no distortion at full volume.
Replacement speaker was mounted on using screws. It's not ideal as it doesn't have an original look. It's worth it however to hear that satisfying bong on boot.
I am curious what exactly caused the old speaker to go bad at above mentioned frequencies. As mentioned, the original speaker appears to be in pristine condition. The diaphragm (paper cone) is properly mounted on both the inner and outer edges. The voice coil also shown no signs of wear.
You know you have a bad speaker if the sound at boot is annoying rather than pleasant. The speaker is mounted to the Mac Plus analog board via a rivet eyelets. Best way to remove is to use a drill. After a couple seconds, it will pop right off as seen in below picture. This is by far the best method for dismounting the speaker as it won't damage the board or the speaker.
After visually inspecting my speaker, oddly enough there are no visual anomalies. The speaker shows no signs of wear or tear. Comparing it to a known good speaker, I see or feel no difference.
I did so additional testing on the speaker. First I connected it directly to a frequency generator and the speaker sounded distorted between 380Hz and 460Hz, as heard in this video. Speaker sounds fine outside those frequencies.
I also checked the volume. While inside the above mentioned Hz range, the speaker was fine when the volume was below 70%. Issue only occurrs at higher volume.
I ordered a used replacement speaker pulled from a Macintosh IIsi. Note that although it's the same 0.25W 63Ω speaker, the padding on the front is a bit different, but that was no real problem other than not being exact replacement. Testing the replacement speaker, it showed no distortion at full volume.
Replacement speaker was mounted on using screws. It's not ideal as it doesn't have an original look. It's worth it however to hear that satisfying bong on boot.
I am curious what exactly caused the old speaker to go bad at above mentioned frequencies. As mentioned, the original speaker appears to be in pristine condition. The diaphragm (paper cone) is properly mounted on both the inner and outer edges. The voice coil also shown no signs of wear.
Last edited:
