4 ohm speakers.
- Thread starter ford93
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Depends on the boombox. Most conventional amplifier modules operated in SE configuration are stable down to 3.2 ohms or so. Some such as the M9994 uses 2.5 ohms speakers but seem to suffer from blown amp modules more frequently than other boomboxes. Amps that operate in bridged mode, however, normally are recommended to be used with 8 ohm loads. You will find this to be true such as with the M70, Aiwa 950/955/880. The M90, however, uses 6-ohm speakers with a BTL amp. For the M90, I would not suggest to go with 4-ohm woofers. If you do, then I recommend adding a 2-ohm power resistor in series to maintain the original impedance. Not ideal since resistors have straight resistance and not frequency varied impedance. Also because resistors will reduce current consumption but without any real benefit since the excess current is converted to heat rather than put to use. A BTL amp operated with 4ohm load can be likened to a SE amp operated with a 2-ohm load.
MasterBlaster84
Boomus Fidelis
Geeez couldn't Super just say "no"? 
Norm you are an encyclopedia of technical knowledge and it's damn good to read your posts.
Norm you are an encyclopedia of technical knowledge and it's damn good to read your posts.
BTL configured amps can technically produce 4 times more power than SE amplifiers. Let us just say that with 2 amplifiers per channel, each connected to one end of the speaker connections, the voltage potential across the load is double. As you might can guess, the additional voltage imparted by the BTL config means it slices easily through loads which is why the recommended output load impedance is almost always double what the same amp module operated in SE config would be. Play it safe and keep the minimum load the same as the original speakers or more. In an effort to maximize the perceived power output of the relatively small amps of boomboxes, most manufacturers will use the minimum impedance speakers the amp can tolerate. Inserting 8 ohm speakers into a system that is capable of handling 4-ohm loads would result in 1/2 the power ouput than as which would otherwise be observed with an 8-ohm load. As you might guess, for marketing reasons, that would not make any sense.
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