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#390263 - 07/03/14 08:04 AM
Re: Faulty Technics EX35 speaker
[Re: Dave L.]
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Senior Member
Registered: 01/16/02
Posts: 2330
Loc: North Yorkshire UK
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Ideally, the replacement speaker should be 4 Ohm Impedance, however, it shouldn't be a problem substituting a single 8 Ohm speaker for a 4 Ohm original. Speaker Impedance varies considerably over the frequency range and the quoted impedence is a nominal value over the frequency range. Replacing the original with an 8 Ohm speaker, you will probably experience a slight drop in sound output, for a given volume setting on the EX35, and possibly a different sound quality compared to the original speaker.
Substituting the other way around i.e. 4 Ohm for original 8 Ohm, is NOT recommended and could result in damage to the amplifier - particularly at high sound levels - since a lower impedance speaker will draw more current from the amplifier output circuit. If you wish, you could use two 8 Ohm speakers in Parallel to provide a 4 Ohm load. When connecting two speakers together, you need to make sure that they are connected correctly i.e. in Phase, otherwise you will experience partial sound cancellation between the two speakers. Speakers usually have some kind of identifying marks on the connectors - either a '+' and '-' sign or a Red dot on one of the terminals. Like marked terminals should be connected together. If the speakers do not have identifying marks, then connecting them together incorrectly will NOT do any damage to the speakers or the amplifier.
If there are no markings on one or both speakers, You can achieve the correct 'phasing' by one of the following methods :
1. Trial and error - connect the speakers in parallel and just listen to the combined sound output. Reverse the connections on one speaker and listen again - the loudest result being the correct phasing....
If you find it difficult to determine if the phasing is correct using the above method, then use method 2.
2. Before fitting the speakers in the EX35, fit a couple of wires to one of the speaker's connections and then briefly connect a 1.5 Volt battery across the wire ends. Carefully observe the movement of the speaker cone as the battery is connected - it will move either out or in as the battery is connected. Note which connection is made to the Positive terminal of the battery and in which direction the speaker cone moves. Repeat the process on the second speaker, reversing the battery connection as necessary, to achive identical directional movement of the cone, to that of the first speaker. Again, note the terminal which is connected to the Positive terminal of the battery. Connect the two speakers together ensuring that the connections which were connected to the test battery's Positive terminal, are wired together. The two speaker combination can then be wired to the EX35's amplifier output - polarity is not important.
Note : When connecting the test battery, only do so briefly - just long enough to observe the direction of cone movement - to avoid over heating the speaker's voice coil.
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