Admittedly, this is technically NOT aDIY question, but who better to ask than DIYers??? I just bought a set of RF-83s and hooked them up to a Yamaha M-2 amp. It fried out a channel in about a minute (or less) at less than indicated rated wattage. I have fairly abused this amp for around 25 years and never hurt anything but speakers. I think their advertised impedence is WAY below 8 ohms. I know, its "nominal" but my old DCMs were "nominal" 8 ohms as well and I never had a problem with my amp. I read on another thread that an ohmeter will indicate about 75% of actual impedence. My DCMs read 4.8 ohms (x 1.33=6.384 ohms) and the RF-83 read 3.4 ohms (X 1.33=4.5 ohms). Any thoughts about these RF-83s being falsely advertised as 8 ohm speakers? Finding outputs for the M-2 seems nearly impossible as well. Toshiba hasn't answered my queries. 1979ish transistors don't come cheap, and I can't find a modern equivalent. Thanks in advance for your help.
Almost certainly a modern transistor could be added to the circuit but not necessary without modification. The good old TO-3 metal button style package is long gone and has been replaced the TOP-3 or something like that. I think some of the foundries in South America still make TO-3 package transistors but getting one that drops in to the circuit without modifications could be more work that the amp is worth. Anyhow posting of an DIY power amp forum is the go for this request.
Regards
John Q
Regards
John Q
Again I am just starting out in the area of speaker design but the DC resistance of a speaker driver will not be the same as the nominal impedence. It could be indicitiave of the nominal impedence but even if the speaker is rated at 8 ohms it would vary from 6 ohms to 9 or 10 ohms in reality.
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