Tubes vs Solid State

Ralph, how critical is the 4 Ohm factor if impedance drops to 4 Ohms from 70 Hz to 200 Hz; and does get above 6 Ohms from 60 Hz to 500 Hz? I drive my speakers with an ARC tube amp, 130 wpc??? Should I invest in the "Zero" device? FWIW, I've tried using the 4 Ohm output taps on the amp and the sound quality goes down the drain.

Bifwynne, I would certainly give the ZEROs a try and see how that works out.

If you are using the 8 ohm tap, at the 70-200Hz region the power tubes are loaded at half of what is expected for them. IOW, the output transformer live up to its name- it *transforms* impedance, so if it were to normally load the power tubes at say, 3000 ohms if there were an 8 ohm load on the 8 ohm tap, it would be only 1500 ohms if 4 ohms is on that same tap. The power tubes will thus have higher distortion and lower power as a result.

Now with a lot of output transformers, the 4 ohm tap is not nearly as efficient as the higher impedance taps are. So its no surprise that things go downhill using the 4 ohm tap.

If the speaker can be bi-wired, you could use the ZERO on just the low impedance part of the speaker and run direct on the rest of it.

Bifwynne,

Got a pair of Zeros that I need to get around to selling. slap @gmail onto my username and shoot me an e-mail if interested.

What kind of amp you will use should be always seen with the connected
amplifier. You will find a lot of high powered Tube amps which are able to drive
insensitive loads, but they will never get the magic you can get with high
sensitive speakers (in a way this can be said for Transistor amps, too).
Unfortunately it is not so easy to find such speakers because the quality &
design of the X-over is mandatory (Some owners think that - for example -
95dB Wilson speakers are perfect with 18/30W Tube amps, it is a mistake, but
what you don't know you won't hear...). Atma-Sphere will have a good selection
of Speakers which work with their Amps. I would recommend to ask Ralph for a
Recommendation (because his amps are sounding right).
Some say, the magic is in the first Watt .... well, it is not that wrong. I listened to
tube amps matched with high sensitive speakers, they showed a Performance I
never heard with Transistor amps.
Btw. the Ref 600 have no "Tube" Sound, they are pretty straight, but for those
B&W speakers for home theatre the Levinson will do.

Syntax,
Your Wilson example is a good one. Higher load impedance seems more important and beneficial than just looking at a speaker`s sensitivity. It certainly seems the higher the speaker`s ohm-load, the better tube amps(in particular) will sound. Atmasphere`s explanation makes much sense. The sound does become more alive, dynamic and natural.
Regards,