Nuvista Tubes - General

This is old stuff gd.

Right. I'm pretty sure there was a recent thread though here on the forum quoting Nelson Pass as to his thoughts on amplifier evolution. If I'm not mistaken it is somewhat at an impasse. To that end a fellow (Roger) from HCAT chimed in with a new (purportedly) design that many folks here poo-pooed for various reasons. The posts got rather argumentative and the thread was subsequently deleted.

I'm not all that interested in class D. If anything I'd go class A, tubes or a hybrid. Anything "new" in that realm?

@viridian

No apology necessary. I’m very appreciative of your input (and clarifications). And I get what you’re stating (and agree) about purchasing based on sound quality, long term reliability and serviceability. That writes and sounds much easier than it is. Not always so easy to make a choice, given the hundreds if not thousands of available choices. Also, it's rather impractical to attempt to listen/audition all options.

Back to nuvistor for a moment, I received a message from Musical Fidelity in response to my inquiry as to where/how the improvement is between the M6si and their nuvista lineup. I don’t know what they mean by "psu", so perhaps you could translate that acronym. Thanks.

The following is from MF:
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The Nu-Vista 600 has the benefit of the Nu-Vista valve preamp stage. The preamp is directly coupled to the input stage so you have shorter signal paths, we have an improved psu over the M6si.
You hear the beauty, warmth and transparency of the valve stage and the transients and power of the transistor power amps.

The Nu-Vista 600 has 4 transistors per channel and outputs 200 wpc, the N800 has 10 transistors per channel and outputs 300w.
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No, directed at all tubes, unless direct output coupled.

I don't believe anyone has made a tube amp/preamp that is direct coupled (no caps or transformers in the signal path) from input to output, like you can with solid state.

The KSS OTL was direct coupled from input to output. You can do it, you just have to jump through some hoops.

I don't think direct coupling is a good idea for either solid state or tubes, because the timing constant of the amplifier goes lower than its power supply. At that point, its possible to modulate the supply, which in turn introduces IM distortion.

We limit the bandwidth of our amps to 1 or 2 Hz for this reason, but we do employ direct coupled inputs and outputs.