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Circuitbenders Forum => Circuitbending discussion => VJ stuff => Topic started by: the_zombiest on August 21, 2006, 03:49:04 PM

Title: line out?
Post by: the_zombiest on August 21, 2006, 03:49:04 PM

is it possible to have a line-out with wobble vision?  I have a old shitty cheap stereo that takes rca plugs so to use wobble vision through my stereo means that I can only 'see' the sound and not hear it...

Title: Re: line out?
Post by: Circuitbenders on August 21, 2006, 04:34:27 PM

err....

I'm sure that question made sense in your head.................... ::)

Title: Re: line out?
Post by: the_zombiest on August 21, 2006, 04:45:10 PM

I think it still makes sense in my head too... maybe not so much in orange text, but do you see where i'm coming from?

Ok i'll try explain better.  I have a tendency to be shit at explanations as I like tangents and frequently feel the need to step a little too far away from my point... Like so.

I got a small tv.  I fitted the 8 phono sockets. 4 for yoke in and 4 for board out.
My shitty old stereo that i got for free has 2 phono sockets. 1 for the left speaker and 1 for the right speaker.  In order for any soundwaves to be shown on the TV, both the left and right outputs need to be used leaving no room for my shitty old speakers thus rendering my stereo silent...  I know the whole point of the tv-oscilloscope is to see the sound... but i wanna hear it too. 

I guess an easy way of solving this is to just use the sprung terminals and speaker wire... but that means I have to spend more money that I don't have because I bought phono sockets for this project. Or should i splice together a couple of leads so it can go: stereo > WV > speakers...or can i just plug my speakers into the two remaining yoke in phono sockets?....  Or should I just give up on explaining and make some cheese sandwiches? 

Title: Re: line out?
Post by: Circuitbenders on August 21, 2006, 05:07:12 PM

Well, the first thing to do is to get a decent amp with two sets of speaker outputs and theres your problem solved. ;)

Alternatively you could always just wire up another set of phono speaker outputs in line on the back of your 'shitty old stereo' but you might want to measure the impedance across the yoke in terminals and read up on speaker / amp impedance's if you can find something on the net. TV yokes seem to have completely random impedance values but will probably be way below 8ohms, which is why if your amp has speaker protection built in it will cut out the sound at high volumes to prevent the amp overheating when running a wobblevision from the speaker terminals.

Running an amp to a wobblevision to some speakers might be safe and then again it might not. For some reason i find it virtually impossible to explain speaker and amp impedances to myself let alone to anyone else. Theres some vaguely useful stuff here:
http://wolfstone.halloweenhost.com/Audio/spkimp_SpeakerImpedanceMatching.html
http://www.epanorama.net/documents/audio/speaker_impedance.html
http://www.mmproductions.co.uk/faqspe3.html

off that last one:
'If you run two 8 ohm speakers off one amp channel, the combined resistance reduces to 4 ohms. Add a third, and it reduces to 2.6 ohms. A fourth, and it goes to 2 ohms. So, you must be careful when running several speakers that the amplifier will run power into 2 ohms. If it wont, you may damage the amplifier.'

make of that what you will  :-\

Title: Re: line out?
Post by: the_zombiest on August 21, 2006, 05:20:34 PM

well, adding an extra output to the stereo seems like the easiest option... i should try thinking outside of the box more often.  Thanks again sir.

Title: Re: line out?
Post by: the_zombiest on August 21, 2006, 06:32:57 PM

it seems to work ok with the new line-outs.  i get some interference from the WV dependant on what combos I have between yoke-in and board-out and sometimes an odd 'melty' kinda smell, but that aside I'm happy with the result... although I can't get the mad-wicked increasing circles effect.  Guessing that it's the type of tv i'm using or that i haven't found the right combo yet :)

Title: Re: line out?
Post by: the_zombiest on August 21, 2006, 06:42:53 PM

Quote from: the_zombiest on August 21, 2006, 06:32:57 PM

it seems to work ok with the new line-outs.  i get some interference from the WV dependant on what combos I have between yoke-in and board-out and sometimes an odd 'melty' kinda smell, but that aside I'm happy with the result... although I can't get the mad-wicked increasing circles effect.  Guessing that it's the type of tv i'm using or that i haven't found the right combo yet :)

 :P = the closest emoticon to the window licker.

I realise now for the increasing circles that you need all 4 yoke-in sockets filled by speaker noise!

it looks so purty

Title: Re: line out?
Post by: andy_wheels on August 21, 2006, 08:11:34 PM

I've also recently delved into the wonderful world of wobblevision. it took ages for me to find a black and white telly to do it on!

i've placed the box of joy near the remote speakers which are in another room from the amp. i've stipped a tiny bit of the speaker cable and tapped into the signal for the wobble trigger. couple of croc clips on a jack lead, and it's wibbly joy. just another option which could be used if you want to tap into a single stereo speaker system...

i'm at a cestron 'wave vessel' stage. hmmm, i 'm getting an urge to see the four yoke circle setup....

god, this is addictive. hope i don't kill myself poking around. i had a sparking moment last time i went in there. from the board. erm, er..