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December 08, 2019, 07:03:04 PM

Author Topic: 4 ohm speakers from 8 ohm taps  (Read 509 times)

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Offline Jamier

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4 ohm speakers from 8 ohm taps
« on: May 19, 2018, 09:39:22 AM »
After researching the safety of running 4 ohm speakers from 8 ohm taps, I tried this with a Stereomour II for several hours yesterday. After 4 or 5 hours the PT seemed very, very warm.I realize that the amp must double the current under these conditions and so increased heat is to be expected, but is this safe enough to do?  I really liked this pairing, but I'm not interested in melting down my beloved SII.The impedance curve for this speaker dips to 4 ohms at 45Hz, 200 Hz and remains slightly below 4 ohms beyond 4KHz.

Jamie
James Robbins

Offline Paul Birkeland

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Re: 4 ohm speakers from 8 ohm taps
« Reply #1 on: May 19, 2018, 11:22:48 AM »
After researching the safety of running 4 ohm speakers from 8 ohm taps
The amp won't know the difference.
After 4 or 5 hours the PT seemed very, very warm.
Yes, that's normal.
I realize that the amp must double the current under these conditions and so increased heat is to be expected
The quiescent (average) current does not change.

No harm will come from doing this, but have you tried wiring the OT to 4 ohms?
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Jamier

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Re: 4 ohm speakers from 8 ohm taps
« Reply #2 on: May 19, 2018, 11:55:09 AM »
PB,

       Thanks for your response. I did wire the OTs for 4 ohms on a different SII that I also used with these speakers. The SII that is wired 8 ohm is one that I put film caps in the PS and getting to the OTs is a bit of an ordeal.

Jamie
James Robbins