In article , Patrick Turner
wrote:

[snip]

A known tube amp hater pointed you in the terrible direction of one of
the the worst designs ever to be seen at

http://members.aol.com/aria3/output.htm

This type of audio amp uses tubes to be directly connected to the load,
and it is called an OTL, or output transformerless amplifier. They are
notoriously unreliable. But some sound excellent while working.

I assume you are referring to Trevor above. I don't have direct experience
of the valve amps he quoted, but my (perhaps unreliable) recollection is
that they have had good reviews in magazines from reviewers that
like/prefer valve amps.

Tube amps with output transformers are able to achieve a better match
between the load and the tubes so the matching of tubes is relatively
unimportant, and the reliablity is far better, so that 5,000 hrs can be
expected from an output tube such as a 6550.

It is probably correct that the power efficiency tends to be better using
transformers. However I'd avoid using 'match' here as speakers tend to be
designed assuming the power amp is a low-impedance voltage source.

If you listen 2 hrs per day, 365 days per year, you get 6.8 yrs out of
an output tube. Whilst some solid state gear might last that long
without a service, a lot do not,

No idea what percentage of what commercial designs you call "a lot".
Perhaps you could specify?

FWIW most of the amps I use are 20+ years old, and from personal
experience, and working in the field in the past I'd say most of the SS
amps I know about survive quite well for well over 6.8 years with no
necessity for any service. Don't have any reason to assume that the designs
I knew were unusual. Hence I would not have said "a lot" as you do above.
I might have said "a few", but I don't know what percentage, designs,
etc, you have evidence on.

That said, I assume that you'd regard this as irrelevant as the OP was
asking for a valve amp recommendation, not a comparison of opinions on
reliability and long term service costs: valve versus transistor. :-)

and the cost of a fix for a high end SS amp may well be more than the
cost of re-tubing in say 6 years.

In some cases, perhaps, but perhaps a misleading generalisation. I'd say
that SS amps tend not to go wrong as often as you seem to imply, and SS
devices are cheaper than valves. Hence I have my doubts that the probable
running/reliability costs for SS would exceed valve in timescales of the
order of a decade. So I'd advise the OP to take your comments on
reliability with some caution if they think this is a relevant issue.

So far as I am concerned, both SS and Valve kit can be quite reliable
and work well over long periods, but after some years a change of valves
can become advisible as you say. Hence if the OP is willing to pay a fair
amount for a decent design, I would hope this was not much of an issue.

Agree with the comments about finding people who already use or understand
valve amps if you are interested. And on listening first if you can. That
may well be more useful than comments here as we may not really know
exactly why the OP would personally prefer one choice to another.

Slainte,

Jim

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