Just the other day my friend brought over the schematic for his Cary Audio
300SE Monoblock amps. Much to my surprise I find that the designer of the
amplifier is using a CV378 rectifier to feed a 1200 uF electrolytic cap
bypassed by a small 0.1 uF cap, then into a 20 Ohm/7Watt resistor and onto
another 1200 uF electrolytic cap. Isn't this bad for a any tube rectifier,
to have 1200 uF on the first PSU cap? It surely goes against the textbooks.
The comment from my friend is that the past owner of theses amps complained
that his tube rectifiers did not last very long.....

"Rich Sherman" said:

Just the other day my friend brought over the schematic for his Cary Audio
300SE Monoblock amps. Much to my surprise I find that the designer of the
amplifier is using a CV378 rectifier to feed a 1200 uF electrolytic cap
bypassed by a small 0.1 uF cap, then into a 20 Ohm/7Watt resistor and onto
another 1200 uF electrolytic cap. Isn't this bad for a any tube rectifier,
to have 1200 uF on the first PSU cap? It surely goes against the textbooks.
The comment from my friend is that the past owner of theses amps complained
that his tube rectifiers did not last very long.....


Oh dear. Another one.
Convert it to a CLC power supply with 47 uF max. ath the cathode and
220 uF or so after the L, or put in some silicon diodes with current
limiting resistors.

Cary states that the supplied CV378 should last for years.
Yeah right. They probably took off the glass bulb from the socket and
put in some SS diodes underneath.

--
Sander de Waal
" SOA of a KT88? Sufficient. "

in article , Rich Sherman at
wrote on 2/14/05 3:13 PM:

Just the other day my friend brought over the schematic for his Cary Audio
300SE Monoblock amps. Much to my surprise I find that the designer of the
amplifier is using a CV378 rectifier to feed a 1200 uF electrolytic cap
bypassed by a small 0.1 uF cap, then into a 20 Ohm/7Watt resistor and onto
another 1200 uF electrolytic cap. Isn't this bad for a any tube rectifier,
to have 1200 uF on the first PSU cap? It surely goes against the textbooks.
The comment from my friend is that the past owner of theses amps complained
that his tube rectifiers did not last very long.....


Yes, that is a bad idea. The surge charging the caps beats up the rectifier.
Do not do as they have done!

The rest of the circuit is standard fare . . .

Jon