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Want to convert TV audio to headphone or speaker. What impedance transformer ratio is reasonable ? Answered

Present speaker is 14 ohm. I tried a 1000 ohm to 16 ohm, it cut output to speaker by 75%. Thinking I need 1:1 transformer and probably impedance is not critical as long as it is 50 ohms or less. I will be switching between earphones or speaker. No fidelity requirements.

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NachoMahma (author)2009-04-08

. Unless you have a gross impedance mis-match, a matching transformer is not required. What is the impedance of the speaker installed in the TV? Impedance of the speaker you want to use? As long as the replacement speaker has an greater or equal impedance, you should be OK.

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willsonx (author)NachoMahma2009-04-08

NachoMahma, thks, Problem is theTV chassis (and speaker) is connected to 120V line. The Headphones must be isolated.

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NachoMahma (author)willsonx2009-04-09

. Ah. Most amps for speakers are designed for 4-16 ohm impedance. Headphones can be 1K ohm or greater. So your 16:1K xformer should work with headphones but (as you've noticed) be weak with a speaker. . For optimum performance, the impedances need to be matched, but an 8x8 (or 16x16) xformer should put you in the ballpark for most speaker applications.

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