phil@osiris.UUCP (Philip Kos) (05/27/88)
Well, I finally got around to checking out my TV's "external speaker" jacks (remember my TV? no? oh well..) and they certainly are NOT isolated. My DMM even loaded them down enough that the built-in speaker for the left channel switched in and out as I connected and disconnected the DMM probe. :-) For those of you who are interested and/or concerned, the TV is a Montgomery Ward model 12868. (Free karma points to anyone who can tell me what it *really* is, but that's not important now...) I suggested before that if the jacks turned out to be hot, it might be a cute trick to use audio impedance-matching transformers (hooked up "backwards") and L-pads to connect them to my receiver. The responses that I got mainly said "I doubt the jacks are hot, but check to make sure" and didn't contain any commentary on my hookup method. So now I really need to know - does anyone want to volunteer? Will my idea work? Is there a better way that won't cost more than the TV? And what about Naomi? For those who missed the original posting, the TV in question has two output jacks on the back that (according to the manual, at least) want an 8 ohm impedance connected to them. The 8 is probably just a minimum load, but I've had bad experiences before with connecting low-impedance output stages to high-impedance input stages so I don't want to bet on what the sound quality would be like if I just used 1:1 isolation transformers. My idea is to use audio impedance-matching transformers and L-pads to isolate the two ends of the chain and attenuate the signal a little. I know that I can probably get by without the L-pads but the incremental cost is so low that I feel I don't have any excuse not to put them in. So, anyone who wants to help me out is more than welcome. I would also appreciate explanations as to why my idea will/won't work - I might as well learn something from this... Phil Kos Information Systems ...!uunet!pyrdc!osiris!phil The Johns Hopkins Hospital Baltimore, MD