[gobet@shaw.ca]

Hi, thinking of trying S5's ( 8 ohm) on 4 ohm tap of Eico HF-81, is this a no no , what are the dangers or any advantages? Thanks

[Rick58]

Hi, thinking of trying S5's (8 ohm) on 4 ohm tap of Eico HF-81, is this a no no , what are the dangers or any advantages? Thanks

I don't think it will damage anything, but you may not get the full power out of the Eico that way. I think it depends on the voltage output capabilities of the amp. You will likely have a better (higher) damping factor, due to lower source impedance, but this will probably not make a sonic difference.

The frequency response may be affected (it might roll off the treble, or even accentuate the treble ...). I don't know enough about all this stuff. Actually, I guess if the damping factor is better, and the speaker's impedance varies a lot, it could 'smooth out' the frequency response (make it sound flatter across the spectrum).

If you don't usually crank the sound to max volume, it will likely be fine (no power limitations). Will it sound better? Don't know. Interesting experiment. Let us know!

[Rick58]

Actually, many "8 ohm" speakers' impedance vs. frequency curves dip below 8 ohms (sometimes as low as 4 ohms, usually in the bass region), so the 4 ohm tap may even be 'better suited' for the speaker.

Maybe someone (Louis?) can publish an impedance curve? or comment on whether or not this speaker's impedance stays above 8 ohms over the entire 20Hz - 20kHz range ...

Some speakers made for SET amps remain >8 ohms all the way across, so the 8 ohm tap would probably be better.

[gobet@shaw.ca]

Thanks for the info, seems the advantages may or may not be worth the effort, as mentioned more spec info on this speaker would be helpful, as an aside does anyone have an opinion on the benefits of tube dampers?

[el dub]

Btw... there are products, such as Zero Impedance by Paul Speltz, which allow you to match speakers and amps of different impedance at not too large of an investment. (zeroimpedance.com)

lw

[Louis O]

Hi gobet@shaw.ca,

Thanks and you could try it. This won't hurt the amp and when I use these taps on my amps it can sound more dynamic, but that depends on the particular amp.

I would imagine overall the 8 ohm tap will sound the best.

Thanks,
Louis

I will have graphs made public soon.