Alternate Tube Types - DYNACO PAS-4 Owner's Manual

Alternate Tube Types

It is true that vacuum tubes made by different manufactures can actually sound different. The amount and
type of sonic differences can be subtle or fairly obvious to a discerning listener. Also, tube reliability and
longevity often varies according to manufacturer.
Vacuum tube manufacturers are still introducing new versions of older tube designs. These new designs
are commonly labeled with partly or wholly new part numbers. Furthermore, different vacuum tube
manufacturers often use different part numbers for their own versions of "equivalent" tubes. Distributors
sometimes substitute tubes from different manufacturers and/or substitute tubes with alternate part
numbers without informing their customers first.
Some audiophiles feel strongly about which manufacturer and/or particular version of vacuum tube to use
for specific applications. The tubes installed on your new PAS-4 have been selected to provide the best
sound and long life.
As of this writing, vacuum tubes are still produced by manufacturers in Germany (Siemens), Russia
(Sovtek), Czechoslovakia (Telsa), China (Sino), Yugoslavia (EI), and in England. Your dealer can
recommend U.S. tube distributors, if needed.
Alternate tube part numbers which can be used on the PAS-4:
Designator Common Part Numbers Alternate Part Numbers
V1, V4 12AX7 ECC83
V2, V3, V5, V6 6DJ8 ECC88, 6922, 7308
If tube replacement becomes necessary, Dynaco can supply you with new
vacuum tubes and/or a list of specifically recommended tubes for the PAS-4.
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Note: Because it is possible for oxidation to build up on vacuum tube pins, it is a good idea to remove
and clean them with a small (brass bristle) wire brush once a year. At this time it is also recommended
to clean the tube pins with contact cleaner. Contact cleaner leaves a thin coating on the pins which helps
prevent oxidation. The contact cleaner can either be sprayed directly onto the tube pins (don't get any on
the glass part of the tube) or can be sprayed on a clean cloth which is then used to wipe the tube pins.
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