Xref: utzoo rec.audio:6259 sci.electronics:2915
Path: utzoo!mnetor!uunet!lll-winken!lll-tis!ames!amdahl!rtech!mtxinu!unisoft!bks
From: bks@unisoft.UUCP (Brian K. Shiratsuki)
Newsgroups: rec.audio,sci.electronics
Subject: Re: TV to receiver: a different angle
Message-ID: <940@unisoft.UUCP>
Date: 6 May 88 02:06:01 GMT
References: <1590@osiris.UUCP>
Reply-To: bks@unisoft.UUCP (Brian K. Shiratsuki)
Lines: 30
Keywords: TV stereo receiver connect isolate attenuate hack

In article <1590@osiris.UUCP> phil@osiris.UUCP (Philip Kos) writes:
>I just picked up a stereo TV yesterday (I didn't intend to buy a stereo
>model but that's another story) which has RCA (phono) jacks on the back
>for hooking up a pair of external speakers.  The manual warns you right
>out to connect these jacks *only* to 8 ohm speakers, so I don't figure
>that hooking them up directly to the AUX inputs on my receiver would be a
>good way to go.  :-)...
>[discussion of using L-pad and matching xformer to connect to aux in on
  preamp]
>...(Assume 5W power output per channel into 8 ohms
>nominal.)...

since the television has rca jacks on the back which are relatively
accessible, it would seem reasonable that neither side is connected
directly to the ac line, ala common ``hot chassis'' televisions.  so
isolation probably isn't an issue.  five watts into eight ohms comes to
2 sqrt(10), around 6 volts.  this seems like a reasonable signal to
feed directly into your preamp.  since the aux input probably precedes
the volume control, you can use that for your attenuation.

if you're worried about properly loading the amplifiers in your tv,
then you could connect 5W, 8 ohm resistors in parallel with the preamp's
inputs.

before you actually do this, you might measure the dc across the tv
outputs, to see if there's a significant amount of offset.  if there is,
then you should at least take the care to turn on the tv before turning
on the amplifier, or capacitor rather than direct couple.
-- 

				brian