[Rick[_4_]]

Hi, I have an unconventional setup for my phono stage.
I am using an integerated amp w/ phono using pre-amp out to the aux on my
main pre-amp. Essentially a phono stage with variable gain.
My question is could this setup damage my main pre-amp?

Rick

[Serge Auckland[_2_]]

"Rick" wrote in message
...
Hi, I have an unconventional setup for my phono stage.
I am using an integerated amp w/ phono using pre-amp out to the aux on my
main pre-amp. Essentially a phono stage with variable gain.
My question is could this setup damage my main pre-amp?

Rick


No, that won't cause any damage, and is in fact a sensible thing to do if
you have a spare integrated amp. However, are you able to disconnect the
signal getting into the power amp section of the integrated? If so, then do
so, there's no point in driving the power section of the integrated
needlessly. You can then come out of one of the tape outputs rather than the
main pre-amp output, unless you find that having a variable gain on the
phono is useful.

S.
--
http://audiopages.googlepages.com

[Drew Eckhardt]

On May 24, 12:25*pm, "Serge Auckland"
wrote:
"Rick" wrote in message

...
I am using an integerated amp w/ phono using pre-amp out to the aux on my
main pre-amp. Essentially a phono stage with variable gain.

However, are you able to disconnect the
signal getting into the power amp section of the integrated? If so, then do
so, there's no point in driving the power section of the integrated
needlessly.

As long as it's not a tubed integrated having a signal applied there
it's not going to hurt anything, and leaving the power amp connected
is not going to make a noticeable performance difference.

If you want to do anything and the amplifier section has fused output
rails you might remove the fuses and save the 25-50+ Watts a typical
class AB amp's output devices dissipate at idle. It's greener and
will make your listening room cooler if you don't have air-
conditioning. Sometimes there are fuse holders on the back panel,
sometimes they're inside. "modern" amplifiers eschew fuses in favor
of current limiting circuitry so that may not be an option.

[[email protected]]

On May 24, 3:25*pm, "Serge Auckland"
wrote:
You can then come out of one of the tape outputs rather than the
main pre-amp output, unless you find that having a variable gain on the
phono is useful.

If this individual was not interested in variable gain there would
likely be no reason to do this _unless_ the main pre-amp does not have
a phono-stage. In that case, I agree with you that coming from a fixed
"Tape Out" makes better sense if the primary pre-amp has line-
matching capacity.

I keep a Revox A720 as my tuner/pre-amp for my main SS system. It does
have matching pots so I can level all my inputs at the pre-amp such
that switching from tuner to CD to tape to phono to cassette (yes, I
am a dinosaur and own and use all these obsolete technologees) without
a jump or drop in level. Not all pre-amps have this, nor do all
tuners, tape machines and so forth have output level controls for
their line-out. So, such flexibility may be an issue.

As to applying signal to a power-amp (tube or solid-state) without a
load it is NOT a good idea. Apart from the waste of energy, there is a
real potential for damage to the output stages depending on the
design.

Peter Wieck
Melrose Park, PA

[Rick[_4_]]

Thanks for the input Peter. I do not matching pots on my primary pre-amp, so
the variable gain comes in handy. I'll take a look inside the integrated for
a fuse to pull for the power amp.

Rick
If this individual was not interested in variable gain there would
likely be no reason to do this _unless_ the main pre-amp does not have
a phono-stage. In that case, I agree with you that coming from a fixed
"Tape Out" makes better sense if the primary pre-amp has line-
matching capacity.

I keep a Revox A720 as my tuner/pre-amp for my main SS system. It does
have matching pots so I can level all my inputs at the pre-amp such
that switching from tuner to CD to tape to phono to cassette (yes, I
am a dinosaur and own and use all these obsolete technologees) without
a jump or drop in level. Not all pre-amps have this, nor do all
tuners, tape machines and so forth have output level controls for
their line-out. So, such flexibility may be an issue.

As to applying signal to a power-amp (tube or solid-state) without a
load it is NOT a good idea. Apart from the waste of energy, there is a
real potential for damage to the output stages depending on the
design.

Peter Wieck
Melrose Park, PA

[Serge Auckland[_2_]]

wrote in message ...
On May 24, 3:25 pm, "Serge Auckland"
wrote:
You can then come out of one of the tape outputs rather than the
main pre-amp output, unless you find that having a variable gain on the
phono is useful.

If this individual was not interested in variable gain there would
likely be no reason to do this _unless_ the main pre-amp does not have
a phono-stage. In that case, I agree with you that coming from a fixed
"Tape Out" makes better sense if the primary pre-amp has line-
matching capacity.

I keep a Revox A720 as my tuner/pre-amp for my main SS system. It does
have matching pots so I can level all my inputs at the pre-amp such
that switching from tuner to CD to tape to phono to cassette (yes, I
am a dinosaur and own and use all these obsolete technologees) without
a jump or drop in level. Not all pre-amps have this, nor do all
tuners, tape machines and so forth have output level controls for
their line-out. So, such flexibility may be an issue.

As to applying signal to a power-amp (tube or solid-state) without a
load it is NOT a good idea. Apart from the waste of energy, there is a
real potential for damage to the output stages depending on the
design.

Peter Wieck
Melrose Park, PA


Applying a signal to an unloaded amplifier isn't a terribly good idea, but
then nor will it do any damage unless the amplifier is unstable. There
shouldn't be any waste of energy either as the power amp will swing all that
voltage, but with no load, there won't be any current and so no power. I
wouldn't do it to a tubed amp, but a decent modern SS should be fine. After
all, many integrated amps have a headphone output which is no more than a
few hundred ohm resistor in series with the headphones, thus virtually
unloading the output although it still swings the full voltage.

S.
--
http://audiopages.googlepages.com

[[email protected]]

On May 26, 6:58*pm, " wrote:

snip

As to applying signal to a power-amp (tube or solid-state) without a
load it is NOT a good idea. Apart from the waste of energy, there is a
real potential for damage to the output stages depending on the
design.

It is certainly true that tube amplifiers can be damaged by running
them without a load due to the output transformer. However,
traditional competently designed solid-state designs don't use output
transformers given their inherently low output impedance and can be
safely operated without a load. They also don't consume significant
power unloaded except for power dissipation due to bias currents.

[[email protected]]

On May 26, 11:29*pm, wrote:
On May 26, 6:58*pm, " wrote:

snip

As to applying signal to a power-amp (tube or solid-state) without a
load it is NOT a good idea. Apart from the waste of energy, there is a
real potential for damage to the output stages depending on the
design.

It is certainly true that tube amplifiers can be damaged by running
them without a load due to the output transformer. However,
traditional competently designed solid-state designs don't use output
transformers given their inherently low output impedance and can be
safely operated without a load. They also don't consume significant
power unloaded except for power dissipation due to bias currents.

For the most part, I agree with you and Serge. But as a keeper of
considerable vintage equipment and some of that from the early SS era,
there are risks with applying signal to *some* unloaded SS designs. I
have a couple of amps from that era that would allow me to fry an egg
on top were I to do that. At the same time, the amps do not seem to
take any damage when that happens - nor do I let them run all day
that way. But, as an example, sometimes one of the animals might pull
off a speaker wire - and if I am not right in the room, the amp may
run unloaded until I get to it. Or my wife might not notice when she
is listening from a distance. Again, no damage but considerable heat
with some designs. I caution people to avoid the condition if
possible. Yes, I use good connectors, but our animals can get quite
enthusiastic when at play, and they love to hide under or behind the
speaker stands while they stalk each other.

I try to err on the side of caution when I give advice - mostly I do
not know the exact equipment involved - and in this case the OP was
not forthcoming.

Peter Wieck
Melrose Park, PA