On Fri, 2 Nov 2018 04:47:06 -0700 (PDT), "
wrote:

A few things:

a) To the extent possible, avoid Chinese equipment. Yes, the prices are attractive as compared to US or Euro equipment of similar ilk, but the build-quality (and the tube quality) is pretty wretched. That is not to suggest that you might not get a 'good' one, but the operative word is "might".

b) There are any number of sources of very high quality present-production US-made-and-sourced tube equipment for those who do not wish to purchase used and do their own restorations. Some links follow:

http://www.tubes4hifi.com/bob.htm

https://www.dynakitparts.com/shop/st-35-kit-120-vac/

There are others, but I am linking you to Dyna-based products as they have been around since the 50s in one form or another and are very well supported in the after-market.

c) Understand that tubes are quite different in how they behave when "seeing" speakers. Those used to solid-state equipment understand that as speaker impedance drops, wattage into those speakers increases. So an amp that puts 60 watts into an 8-ohm speaker may put 100 - 120 watts into a 4-ohm speaker. Solid-state devices also tend to clip badly. Tube amps, or at least those with output transformers (very nearly all of them) provide the same wattage irrespective of impedance - within limits. And tube amps tend to clip softly.

In my office at this very minute, I am running an OEM Dynaco ST35 into AR Athena speakers. The room is 11 x 15, and it does quite well. That is a clean 17 wpc/rms provided by a pair of 6BQ5 tubes in PP. Output wattage is a function of tube type, transformer design, and internal configuration.

A bit on tube design: the 12AX/AU/AVX types are twin-triodes - that is two triode tubes in one envelope. A 7199 is a pentode/triode. 6SN7 is an octal dual-triode and so forth. Those Chinese tubes you are looking at are eyewash - a way to make a cheaper amplifier tube - as well as lock you into *that* tube from *that* source. Avoid them like the plague they are. Yes, that is an actual tube type actually produced for the US military - but the Military had a need for a compact special-purpose tube. You do not.

Look for a reliable tube amp from a local (US) source such that if you need help/advice/service, it would be available. Bob Latino at VTA is every bit of that. And Dynakit Parts is another.

Peter Wieck
Melrose Park, PA
Greetings Peter,
I took your suggestion and looked at the links provided. I spoke
with my son about what I wanted to do and he mentioned that he sees
tube equipment fairly regularly at thrift stores and estate sales and
the like. So he is gonna look for some used equipment that can be
rebuilt.
Looking at YouTube I found several videos about fixing old amps,
how replacing certain caps is really important in old equipment. How
you don't even power them up before changing out all suspect caps. But
since it's all pretty open inside and point to point it looks like
something I will have no problems with.
Since it seems like most of the small amps will be low wattage
devices sensitive speakers will be needed. I think I need speakers
rated at 90 dB or better. I have no idea what used speakers to buy if
I come across any, but maybe a little research will turn up some specs
on some of the older speakers. New speakers are probably what I'll end
up with.
Tubes are a whole 'nuther thing. It looks like there is a lot to
learn about tubes. How specific types work, which can be substituted
for which, etc. Which are best in new production because NOS tubes may
not be any good. And are often more expensive anyway.
Any more advice and suggestions are welcome.
Thanks,
Eric