I removed one 3156 woofer and found this mid size transformer next to 1280 network inside cabinet.
Anybody has any idea what it is for?
(Uppppppps...I forgot how to add picture...)
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I removed one 3156 woofer and found this mid size transformer next to 1280 network inside cabinet.
Anybody has any idea what it is for?
(Uppppppps...I forgot how to add picture...)
These are the pictures of the transformer. I heard that one of the woofer was connected as for a fullrange. I am not sure if this is for that purpose.
I'd assume it's a 15067 autotransformer used to maintain an 8 ohm load from the paralleled 3156's.
See here: http://altecpro.com/pdfs/vintage/Spe...r%20System.pdf
Sorry, i didn't see the pics before i posted.
Where is the transformer wired in?
Looks like a 70 volt line transformer.
I am not sure it was ever connected to anything because the cut of the cable is very clean.
The model looks like NS-105
MACHING TRANS
And it marked as
1-2 8ohms
1-3 120W 70V
1-4 100W 70V
I remember that former user of this speaker used one of the LF woofer as a fullrange unit.
My guess is that the transformer is probably from the the original, or subsequent installation where multiple speaker systems were fed from a 70 or 120 volt distribution line.
While i don't have a clue about that particular brand or model, those transformers usually tend to fall short of what we'd call "hifi". Altec's Peerless transformer division made some of the best in the business, and i think it's still a preferred practice to avoid their use in hifi applications if at all possible.
If you don't have a use for them or value them in any other way, they can be a source of quality magnet wire for various DIY hifi projects from wiring tasks to winding your own inductors.:D
... maybe not the moldy thread anyone wanted to see dug up from the dead, but the board seems stable so we're trying to get some pics up for posterity. :-)Quote:
Originally Posted by mah
So these Altec / Peerless 15067 Autoformers came out of a moldy oldy (A6 presumed) 8256 with the nominal 2x 3156 installed.
There are 2, paralleled for each cab.
Input (tip) was to yellow (terminal 3, 1/2 impedance), from a hacked-in plastic plate 1/4" jack.
This was likely paralleled with an old-timey (locking?, curved blade) round electrical receptacle (also seemingly hacked in).
I should have taken specific note. I presumed it was just to run to the HF section.
The A6 sheet shows a setup using a single Autoformer.
The 3156's were paralleled themselves.
- Why would someone parallel 2 15067's in a single cab using that tap / what do you end up with?
Of course I suppose I could just hook the 3156 back up to them and see...
- The wiring is neatly-enough and consistently done between both cabs and bound. The 15067's were as deep as anyone could conceivably put them into the corners (what installer or sound guy would bother? - maybe some?) ... so I'm wondering if it looks like a factory setup to anyone.
No real need to solve the mystery, just curious conversation fodder.
The impedance matching autoformer on the woofer began in about 1938 with the Lansing Iconic. It reduced the native 12 ohm woofer load to, if memory serves, six ohms.