Connect TV audio output to old stereo amp

[Al Moodie]

Hi,

Not sure if this is the correct forum, but it is the only one I am
familiar with.

I have an old audio system, Technics SU 8022 stereo amp attached to
large quaulity technics speakers, works fine.
Have a Sony Bravia LCD TV which has an audio output socket which I use
for headphones occasionally.
Does it make sense to attempt to connect the TV's audio output to the
Technics amp to get better sound quality.

Sony TV Audio out:
500mVrms (100% modulation)
More than 1 Vrms at max volume setting
Impedance 47k ohms

Technics amp input:
Phono 2.5mV 47k ohm
Aux 150mV 27k ohm

I assume I will need some kind of voltage/impedance matching between
the two units.

Al Moodie.

 

[William Sommerwerck]

There's no reason you shouldn't connect the TV. You will definitely get
better sound. *

See if the TV has a regular pair of RCA audio-output jacks, which you should
use instead of the headphone jack. Regardless of which you use, there will
be no need for voltage or impedance matching. (I don't know where you got
your specs, but the TV does not have a 47K audio output impedance. It's
about 1/20 that.)

One possible problem... If your TV is connected to a cable system, you might
have hum problems. You'll need an isolation transformer. The MCM 33-8700 is
a good choice; I use it in my system. A double-male coupler (MCM 33-480)
might also be handy.

* Cheap speakers have gotten surprisingly good. If your Technics speakers
are really old and really mediocre, there's a chance the speakers that came
with the TV might have better over-all quality.

 

[Al Moodie]

There's no reason you shouldn't connect the TV. You will definitely get
better sound. *

See if the TV has a regular pair of RCA audio-output jacks, which you should
use instead of the headphone jack. Regardless of which you use, there will
be no need for voltage or impedance matching. (I don't know where you got
your specs, but the TV does not have a 47K audio output impedance. It's
about 1/20 that.)

Thanks for your response.

I want to use the headphone jack for output because using the jack
mutes the TVs speakers and allows me to control volume using the TV
remote (the stereo amp does not have a remote).

I assume this is just a cabling problem, headphone jack male split to
RCA audio plugs.

Al.

 

[Peter2]

Thanks for your response.

I want to use the headphone jack for output because using the jack
mutes the TVs speakers and allows me to control volume using the TV
remote (the stereo amp does not have a remote).

I assume this is just a cabling problem, headphone jack male split to
RCA audio plugs.

Al.

I'd recommend trying the RCA jacks first. Most (many) have circuitry that
detects a connection and mutes the output. The headphone jack is likely low
impedance and as such won't match the amplifer as well.

 

[William Sommerwerck]

I'd recommend trying the RCA jacks first. Most (many) have

circuitry that detects a connection and mutes the output. The
headphone jack is likely low impedance and as such won't
match the amplifer as well.

There's no need for matched impedance.

 

[[email protected]]

Hi,

Not sure if this is the correct forum, but it is the only one I am
familiar with.

I have an old audio system, Technics SU 8022 stereo amp attached to
large quaulity technics speakers, works fine.
Have a Sony Bravia LCD TV which has an audio output socket which I use
for headphones occasionally.
Does it make sense to attempt to connect the TV's audio output to the
Technics amp to get better sound quality.

Sony TV Audio out:
500mVrms (100% modulation)
More than 1 Vrms at max volume setting
Impedance 47k ohms

Technics amp input:
Phono 2.5mV 47k ohm
Aux 150mV 27k ohm

I assume I will need some kind of voltage/impedance matching between
the two units.

Al Moodie.

There are several issues.

First of all, do not use the phono input; it is designed for a
magnetic cartridge, has RIAA equilization, and will seriously
overamplify the bass frequencies.

Second, I would spend some time reading the manual for the TV, and
studying the function of the audio output RCA jacks. If they can be
configured to suit your purposes, they would be preferable to the
headphone jack.

Third, you are setting up a situation where the TV will be turned
off, but the amplifier will still be on. For a number of reasons,
this is not desirable.

PlainBill

 

[William Sommerwerck]

You are setting up a situation where the TV will be turned off,

but the amplifier will still be on. For a number of reasons, this
is not desirable.

Other than wasting electricity, what would they be? I've already pointed out
the possible ground loop, but that occurs whether or not the TV is on.

 

[Al Moodie]

First of all, do not use the phono input; it is designed for a
magnetic cartridge, has RIAA equilization, and will seriously
overamplify the bass frequencies.

I am using the AUX input.

Second, I would spend some time reading the manual for the TV, and
studying the function of the audio output RCA jacks. If they can be
configured to suit your purposes, they would be preferable to the
headphone jack.

I have used the headphone jack because it is accessible from the side
of the TV. Works just fine and the sound quality has improved. To
access the audio output jacks I will have to remove the TV from the
wall to gain access, a pain, but will do so when I have more time.

Third, you are setting up a situation where the TV will be turned
off, but the amplifier will still be on. For a number of reasons,
this is not desirable.

Other than I forget to turn it off when I go to bed, how is this
undesireable.

You have given me advice before on badcaps forum, small world, thanks
again.

Thanks to all who posted.

Al.

 

[Peter2]

Really? I've not heard of this function with an RCA socket, but I don't
deal with much domestic audio equipment.

Can you or someone post a link to how this works?


Cheers,


Gareth.

I've seen mostly mechanical type switching. I've a TV that does just this,
plug in to the RCAs and the speakers are muted.

 

[[email protected]]

I am using the AUX input.

I have used the headphone jack because it is accessible from the side
of the TV. Works just fine and the sound quality has improved. To
access the audio output jacks I will have to remove the TV from the
wall to gain access, a pain, but will do so when I have more time.

Other than I forget to turn it off when I go to bed, how is this
undesireable.

You have given me advice before on badcaps forum, small world, thanks
again.

Thanks to all who posted.

Al.

Wasting electricity is the obvious problem. Possible transients as
the set powers up and down is a second. Accelerated aging of the
components in the amp would be a third.

PlainBill