Ohm Walsh Micro Talls: who's actually heard 'em?

Rebbe,

After some investigation, the ARC sp16 I use is also a candidate for you at least technically, though the cost may be a tad higher.

Here are the specs:

260 ohms Single Ended main;

20K ohms minimum (amplifier input) load and 1000 pF maximum capacitance

So ARC recommends a ratio actually of about 77:1 for this pre-amp, which is well beyond the 10:1 minimum that many indicate in general.

With your Bel Canto's input impedance of 10000 ohms (half the ARC recommended value) the ratios with ARC sp16 would still be over 38:1, still almost 4 times the consensus minimum, so I think the Bel CAnto will work fine with any of the tube pre-amps identified above (Manley, ARC, Juicy) with the similar low output impedance specs.

YEs, the consensus also seems to be that the higher ratio the better for optimal interfacing between amp and pre (sounds kinky), so who knows where a 10:1 minimum comes from?

10:1 is based on reasonable power loss across the preamp output: the pream-amp circuit is a power divider. At 10:1 preamp to amp impedance only about 10% of the voltage signal is "wasted" in the preamp output stage. However, no preamp has a perfectly falt output impedance across the audible frequency range. The 10:1 should be applied to the peak output impedance of the preamp, not the manufacturer's stated nominal impedance. Impedance mismatch is a predictable source of coloration. The preamp is a voltage source that prefers to see an infinite impedance so that it is not loaded down which results in voltage sags and distortion.

The best SS amps use FETs for differential input stage for this reason.

BTW: My Walsh 5 Mk IIIs will be going back to Ohm for repairs on one driver. I spoke to John and decided to upgrade to the Walsh 5000. John says the improvement in sound will be "evolutionary," and they have double the peak power handling and go a little lower. I'll take any improvement I can get with these most fantastic loudspeakers.

Everybody,

Thanks for the advice. There's a Manley Shrimp up on A'gon right now. A little pricier than I'd like (and no remote) but output impedance is only 50K ohms, so I'm seriously considering it.

Fascinating discussion, by the way. I've learned a ton from you guys!