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Answers for Questions relating to VINTAGE AUDIO EQUIPMENT
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Hi-Fi Stereo - Loudspeakers
Amplifiers / Receiver - Ohm rating / Impedance of speakers.
Question:©What is speaker impedance?
Answer: Speakers come most often in impedance values of 4, 8 or 16 Ohms. This value determines how much electrical load a speaker puts onto an ampifers output channel. Ideally one would match the speakers to the amplifer's impedance rating. While in most cases where one connects one speaker per output channel to a (solid state) amplifer, considering speaker impedance can be neglected, because speakers usually are already matched to what an amplifer can handle, considering of the impedance of speakers becomes particularly important when 2 or more speakers are connected to the same amplifer output channel to be used at the same time. And: Tube amplifers require to set the impedance load at the amplifer (at rear panel) according to the speakers to be used.
Question:©When is considering speaker impedance important?
Partucularly when connecting 2 or more speakers to the same output channel. And: Vacum Tube amplifers require to set the impedance loading at the amplifer according to the speakers to be used.
Modern multi channel surround sound receivers / amplifer usually have several speakers, but each speaker connects to it's own separe output channel. For this selectign the speaker sof rimpedanc eis sualy not important.
Vintage Hi-Fi Stereo Amplifiers often have terminals to hook up 2 (or more) pairs of speaker. As such equipment has only 2 output channels, if wishign to hook up more than one pair of spekaers and use both pairs at the same time, speaker selection for impedance becomes important.
Question:©What impedance speakers to use?
When operating two or more speaker pairs on the same amplifer channel at the same time selecting the right impedance speakers is partucualrly important.
Why? Most vintage Hi-Fi stereo amplifiers that have connections to hook up more than one speaker pair if using more than 1 pair at the same time switch the connected pairs of speakers in parallel. That reduces the load impdance or resistance of the speakers in half. For example: Two 16 Ohm speaker pairs at the same time reduces the load to 8 Ohms. Two pairs of 8 Ohm sopeakers to 4 Ohms. Two pairs of 4Ohm speakers would be 2 ohms. Most ampifers are designed to drive a 4 Ohm minimum load. If the load impedance would be 2 Ohms - Do NOT do it! This will over load the amplifer and almost all modern ampifiers will get damaged by this requiring expensive electronics repairs starting at $100+.
Speaker Impedance Selection Considerations:
A) If planning to use 2 (or more) pairs of speakers on the same amplifer channel at the same time: Get 8 Ohm (or 16 Ohm) speakers so that the amplifer can handle it. Most amplifers that allow to connect more than 2 pairs of speakers allow only to use 2 pairs together at the same time. Consult the owenrs manual for your equipment for complex arrangments.
B) If wanting to get the most volume out of the amplifer and connecting only one pair of speakers to a steo amplifer (one speaker per channel): Get 4 Ohm speakers..
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