Why do my speakers "POP" when I turn off preamp?

Dawgcatching,

When you shutdown your preamp - it's circuitry goes through
a "shutdown transient". That is as it loses power, the
circuitry goes through a type of "death throw".

Some amps and preamps have a "muting circuit" to disconnect
the output before the transient. Yours evidently doesn't have
that circuit.

You should always power up your equipment in the direction of
signal flow - source components on first, then preamp, then
finaly power amp.

When you shutdown your system - the order is reversed - the
power amps should be shutdown first. So if you follow
the proper shutdown order - the power amps should already
be shutdown when you turn off the preamp - so the shutdown
transient won't damage the speakers.

Note - the power down transient of the preamp may not be
suppressed by the volume control - depends on the preamp
design. So you can't depend on a volume control to save
your speakers.

As Paul suggests, learn / practice proper startup / shutdown
proceedures before you damage your speakers.

Dr. Gregory Greenman
Physicist

Jea48,

The input impedance to an amp is quite high. Therefore, it
doesn't take much signal for the amp to see it.

If you install a shunt - or even if you try to short the
output - that shunt or short is still in parallel with the
amplifier input. [ Any "short" you place on the terminals
still has a finite resistance - so it's not a true short. ]

Even though most of the "signal" current from the shutdown
transient is sent through the shunt - a tiny amount still
finds its way to ground through the amps input stage.

Result - problem not solved.

The only safe solution here is to shutdown the amp.

Dr.Gregory Greenman
Physicist

Dawgcatching,

When C-J wrote your manuals, perhaps they were assuming that
your C-J tube preamp would be paired with a tube power amp,
and that your SS power amp would be paired with a SS preamp.

That way, your tube power amp would be powered down [ to
extend tube life ], when you powered down your tube preamp.

In the latter case, your SS power amp would remain on with
the SS preamp.

Mixing tube and solid state components can be problematical,
depending on the design - although the marriage of the two
technologies can have a positive effect - exploiting the
advantages of both.

For example, tube preamps will usually have a greater
amount of DC voltage on their outputs. That's OK with
tube power amps which are capacitively coupled. However,
many transistor power amps are "direct coupled" - no
coupling capacitors in the signal path - thus expecting a
very low DC component from the upstream SS preamp.

If the upstream preamp is tubed, and the power amp is a
"direct coupled" SS - there can be problems - which can
easily be remedied by installing coupling capacitors.

Moral to the story - you just have to be aware of the
various characteristics of the components you link together,
for proper "care and feeding" of your stereo components.

Dr. Gregory Greenman
Physist