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Matching power amp and speaker impedance

I've searched the forum for speaker impedance discussions but they are all too technical for me. I would like a simple and direct answer (try please).

I have owned a pair of Focus Audio FS-888 speakers (90db/w; the nominal impedance 4 ohm) . I have questions regarding matching the proper impedance (ohms) between the speakers and my Marantz No.9 power-amps.

I mostly listen to all sorts of classical music at moderate volume level in a 400 sq-ft listening room. I listen to music 5 hours every day.

Q#1: The Marantzs have 3 input taps -- 4, 8 and 16 ohms. Which one of the inputs shall be used with FS-888. (The main concern is tube life. Of course, the longer the better.)

Q#2: I've been using 4ohms and I got about 8 months tube life on the EL-34. Isn't that too short live?

Question #3: In regards to prolonging the tube life, does it matter of using ultra-linear (70watts) or trio-mode (35watts)?

I emailed to Focus but they haven't answered yet. Thanks in advance to answer my questions.
hivision

Showing 1 response by hivision

hivision OP
9 posts
 
Thank you Newbee. That's very helpful.

What's the sound of the 4 ohms output tap compared to 8 ohms and 16 ohms?

The amp has 4 EL-34s per channel. According to you, the amp power output is on the conservative side. In terms of efficiency, does it mean the 16sohms is the "easiest" to drive and sound more powerful than the others?

5 hours is the playing time. Total on-time may be 7 hours a day. I have tried different brands for the passed 10 years. I settled with "C-Wing". They are more stable than others in my experience.
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