Which high power SET


I'm looking for a high power SET to drive harbeth shl5, using Shindo masseto pre amp.

Have short listed Verdier 845, Audion black shadow and Wavac MD805m. All three should drive harbeth sufficiently. Any opinions on the above 3 amps are most welcome, especially thoughts on matching with shindo pre amp.
edoit

Showing 2 responses by larryi

I doubt that there are many here, or for that matter anywhere, who have heard your particular combination of gear with the three candidate amps. I have only heard the WAVAC and the system sounded quite good so it is a possible choice.

I own a low-powered SET amp (parallel 2a3) as well as a pushpull triode amp (45 tube) and a pushpull pentode amp (349 tube). All of these amps sound different and quite good. I don't think one should be completely committed to one particular approach as being inherently better than another. At this time, the pushpull pentode amp is in my system because it delivers the most realistic sounding midrange and punchier bass (though not as nuanced bass as the parallel 2a3). In other words, if you are looking for something better than your 30 watt pushpull amp, candidates for "better" may be another pushpull amp from a different designer or one using a different tube or design implementation. I would personally be wide open to trying different options and I would insist on hearing these options in my particular system.

I have heard 211 and 845 SET amps in various systems and they can be very good sounding. But, at least when run in extremely efficient systems, these amps don't deliver quite the same sound as a 45 or 2a3 SET (the amps I generally prefer). I suspect that every choice has certain tradeoffs and one must listen and decide which tradeoffs to make.

I think that where some power is really required, but not extremely high power, OTL amps should be in consideration. These amps are amazing when it comes to perking up the sound--they are fast, dynamic and have oodles of "presence" without being overly harsh and unpleasant. Some may not exactly fit into the category of being "refined" sounding, but, you may change your priorities once you hear them. Like any kind of topology, diffent implementations are voiced differently so you would have to hear the different choices. I happen to like some lower-powered SET amps because they can deliver a lot of the same kind of lively sound of OTLs (taking into account there MUCH lower output), but one really must have ultra efficient speakers.
As Almarg pointed out, it is not necessarily efficiency, but the impedance curve of the Harbeths that MAY make them incompatible with most SET amps. Most SET amps have a fairly high output impendance compared to other topologies. Push pull amps can also have a highish output impedance, but, typical SET amps tend to be even higher. The high output impedance of most SET amps will interact with the low impedance of the speaker in ways that will cause frequency response to be uneven. The same can be said of OTL amps which also tend to have higher output impedances. The only way to really find out if such interaction renders the speaker/amp combination unacceptable is to try the amp with the speaker (it is even possible, though less likely, that such interaction will be felicitous).

I am somewhat on the fence as to whether the 28 watts will be adequate or not. Clearly, that amount of power with the Harbeths will not allow for playback at extremely high volume in a large room. But, if you play at reasonable levels, this amount of power may be adequate. As Atmasphere pointed out, long before a SET amp has reached its rated power, it will already be straining. I have personally found that SET amps do distort somewhat gracefully--they become "thick" and slightly muddy and stop getting louder, while pushpull amps will distort more harshly (albeit at higher volume levels for the same rated power). It may well be the case that the higher powered SET amp will be pushed into obvious distortion only for brief moments and you might be willing to live with that. Hence, it is really hard to say one way or another if a particular power level is adequate, which is why some people advocate huge amounts of reserve power (I don't because I like the sound of lower powered amps of all kinds).