Seriously considering tube preamp…opinions?

Danvignau 2-28-2020
Tubes add serious harmonics to terrible recordings to make them sound better. They also add harmonics to good recordings to make them sound worse.

Tvad 2-28-2020
While a bit of an exaggeration, this is true, although tube amplification often sounds better at clipping output level (as @atmasphere has explained).

It’s a primary reason I have suggested Pass Labs Class A solid state amplification (and gently joined by @almarg).

In addition, Ralph has explained in many threads that while tube amps usually have greater **total** harmonic distortion (THD) than solid state amps, they usually have lower amounts of the components of the distortion to which our hearing mechanisms are most sensitive, and which are most objectionable from a subjective standpoint. Namely certain higher order odd numbered components, such as the 7th harmonic. Also, solid state amps typically (but not always) require greater amounts of feedback in the design than tube amps. Depending on the specific design that can often contribute to transient intermodulation distortion (TIM), which can be particularly objectionable and which is not normally specified or measured. And as far as I am aware a standard for how to measure TIM does not exist.

I almost always agree with the insights Ralph provides here, and that certainly applies in this case. At the same time, though, it seems evident that both kinds of amplification may or may not provide fine results depending on the specific amplifier and on how it synergizes with the particular speaker. So my philosophy when it comes to audio is to focus on the specifics of the particular equipment that is involved, rather than on generalities which usually hinge on matters of degree. And the main reason I leaned toward suggesting solid state amplification earlier in this thread is that in the majority of cases small two-way speakers are designed with the expectation that they will be driven with solid state amplification. Which as a result of its near zero output impedance (accomplished with the help of feedback in most cases) maintains essentially constant output voltage into varying impedances. And hence delivers more power into lower impedances than into higher impedances, as long as the amp is operated within its capabilities. I also suggested that among tube amps those having low output impedances (for a tube amp) are likely to be most suitable.

Based on the first of Ralph’s posts dated 2-26-2020 in this thread, though, it sounds like the Salk WOW1 (and other Salk speakers), like the Daedalus speakers I use, tend to be more versatile with respect to the choice of solid state vs. tubes than many others.

Best regards,
-- Al

I haven't ever listened to Zu speakers, and I couldn't find published impedance curves or other measurements for the Omen models. But based on the specs and on what I've read about them over the years I'd expect them to be very versatile with respect to choice of amplification, while at the same time being revealing of the intrinsic sonic character of the particular amp.

Also, some of the Omen models have 12 ohm nominal impedances, while others are rated at 8 ohms. And while solid state amps will typically have maximum power capabilities that are close to 1/3 less into 12 ohms than into 8 ohms, given the high efficiency of those speakers that won't usually matter. I suppose, also, that from a sonic standpoint there may be some cases where a 12 ohm load might be less than optimal for the 8 ohm tap of some tube amps.

Best regards,
-- Al
 

I had a good chat with Jim Salk, who said that at a recent RMAF show he played his Salk 9.5 towers (8 ohm, 87 db) with no problem from a 30 wpc tube in a 30x30 room. I'm likely going to change my order (I'm going to think about it a bit) to the Salk SS 6M speakers.

http://www.salksound.com/model.php?model=SS%206M 

They're 90db and 8 ohms. They're a lot more $$ than the WOW1's but the amplification needed for decent headroom will be much less; I won't find myself pushed into stratospheric prices for adequate amp power. I'll still get a 30 day trial to see how I like them. (Others on forums are comparing them to Joseph Audio, so I'm optimistic.) As folks here advised, I am *starting with the speakers* but this time, I'm also paying attention to sensitivity.