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Matching Speaker impedance to Amplifier

SeattleHiFi

SeattleHiFi

Active Member
I have a question for those of you on the forum with more experience using tube amps than I!

I tried my Speakers the other night out of the 4ohm tap on my Line Magnetic 216 kt88 based amp. I loved the way it sounded. Particularly bass was much tighter (more definition and impact). I also liked what it did to the mid/high frequencies, nice kind of mellow out (my speakers are on the bright side.)

Supposedly my Dahlquist DQM 9 are rated 8 ohm, 95 db eff. I have the old 'stereo review' article which puts them closer to 90db eff in the midrange, and an impedance range from 5-16ohm. The lowest impedances being at 40, 120, and 10,000hz. So the effect on the sound seems to correspond with these measurements to me.

The question is, does this have the potential for harming the amplifier? i ran it for a few hours, the power tranny was very hot, a bit more than when run on the normal 8 ohm tap for the same
period.

Any thoughts or suggestions? Am i overthinking this?
 
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You are making the amp work harder. Unless you're driving the hell out of them, I doubt you'd have an issue. I've done similar things and driven speakers off of the adjacent taps with no ill effects. If it sounds better to you go for it.
 
nj pheonix said:
You are making the amp work harder. Unless you're driving the hell out of them, I doubt you'd have an issue. I've done similar things and driven speakers off of the adjacent taps with no ill effects. If it sounds better to you go for it.
Click to expand...

Agree, as long as tube current / bias is good go for it. I've had certain 8 ohm speakers that sounded better off the four ohm taps of my Dynaco 70. I remember that from a long time ago. Thing is, when you change the Z load on the secondary of the output transformer, the primary Z will change slightly to, so if your amp has an adjustable (fixed) bias, you may want to check and or adjust it. Your not going to hurt anything though, whether it's adjustable or not. Have fun and experiment.:music:
 
thank you for the Input! It really is interesting how many variables exist in a given audio system, and one or two different small decisions can have such an impact.
 
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