What's likely to happen when an 845 tube fails?

I like the DeHavillands a whole lot, and think they're built pretty well, but some other amplifiers can present real issues when faced with this sort of thing.

Two specific incidents I saw with the Opera Audio/Consonance Cyber 845/211 (same amp that uses a different bias resistor to run either tube) when I handled them came from excessive current draw by the output tube.

The owner of the 211 amp was going through components in the power supply over time. The amp had previously been repaired; when it failed again, it came to us. We discovered the 211 was drawing more current than it should, made the repair, and advised him to buy a new set of 211 output tubes.

The 845, which were a more or less new pair of amplifiers, were the more hairy. Same sort of issue, but the tube was less sound than that just described. It completely barbequed the power transformer. Supposedly, the amount of smoke was incredible. The owner was truly lucky to be able to power things down as quickly as he did. Otherwise, his home might well have burned up as well.

Bob, I think you've been considering the DeHavilland 845s for over a year, correct? Pull the trigger on those amps already!

As you heard, the true TL (though most don't know, Bud insisted TL was MOST critical for the mids, not the low end) Fried C sats do not need any more than an SET to drive them. And, for me, driving a loudspeaker means a minimum 95 dB at the listening chair without breaking a sweat.

The wonderful, surprising, and (to most people) impossible to believe thing about the series crossover Bud espoused is that you almost gain the ability to divorce yourself from the choice of amplifier. By that I mean, by varying the ZETA value, yet still keeping them first order in the truest sense of the word, you can make them sound as forward as a pair of Lumenwhites or as rich and luxurious as any Vandersteen. Or, looking at it from the amplifier perspective, as lively as Naim or as relaxed and liquid as a CJ. All of this, for the very miserly sum of a couple of caps and a coil. So, that's always a consideration in lieu of amplifiers if you seek to alter the sound down the road - after the DeHavilland 845s, of course.

PLEASE let us know what you think of the Dueland caps in those beauties when the time comes.

Rfogel8, "there's no substitute for good amplification, especially with speakers as revealing as the C's."

You know, Bob, you're absolutely right.

As time continues to pass, I find it crushing that technologies Bud Fried evangelized like true TL midrange loading, where the music simply flies out of the speakers in a way that makes so many others sound like they're running in peanut butter, and the incredibly wide degree of tuning ZETA provides continue to disappear into the ether.

213cobra, "most 300B amps have had too little discipline in the deep bass region to be usable on truly full-range speakers."

Although someone here recently disagreed vehemently with me on this point, I agree with Phil's comment.

Also, I might have heard the same 845 amp Phil uses at a Zu get together two months ago here on the East Coast, though I'm not sure.

Bob, I've been around the DeHavilland 845 monos you're considering, both at the local dealer who had it on display, and at the customer (our own Sbank) who wound up purchasing it. They're quite a competent, and I believe, well-engineered pair of amplifiers.

That said, I'm going to guess the amplifier is going to be used in powering your Fried C3/L-C4 satellites. Is that right or wrong? If it is those speakers, as we've discussed many times, you don't need very much at all to drive them, and low end isn't a concern in this instance. After yesterday, where I was at an old tube amplifier builder friend's workshop, and we drove an old pair of Dynaco A25 with a 2 wpc 45 SET amp, I'm more convinced about the Fried's requirements than I was before that. No matter what you go with, the Frieds will be more than fine.