Quote:
Originally Posted by Heatercathodeshort
Just a though but has anyone had a go at winding a high quality 100v line to 8/15ohms external transformer? I would guess it is a lot easier than rewinding the original and preserves originality.
When I read your first post I wondered if the loudspeaker you originally tested the amp with had a 100v line transformer inside the cabinet. I have encountered this a few times and it can catch you out.
I have a number of Quad 2 amps, tuners and preamps that were pulled off the tip about 30 years ago. They all appear to be low impedance versions and when tried all those years ago worked very well.
One was in an orange box filled with dry muck, sweet papers, fag ends and one can only guess. it's dirty coat had preserved it's original finish. It appeared to have been installed under a stage floor and must have been a fire hazard to say the least. I hope you manage to sort out your transformer problem.
John.
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Cheers John, to get back on topic....
The speakers I used were run of the mill 8 ohm Arcam bookshelfs. Not a transformer in sight!
I too also wondered if anyone would produce an external 'hifi quality' transformer, but why would anyone do that on a distributed system? The market would be vanishingly small I reckon.
The main thrust of my original point is that I couldn't understand how sound came out
. I've fixed and restored many of these over the years, and this is the first time I've been 'caught' (for want of a better word). This was in pretty rough condition, although not as bad as the one you descibe!
No measurements taken, but the sound wasn't too bad, and on internal inspection the OPTX was apparently wired for an 8 ohm speaker. The only difference was that the flying lead was hidden away (it's not a feature of a 'normal' TX and difficult to see anyway), and the negative speaker terminal was wired to the transformer, not to ground as is normal. It was wired according to the diag in post #1, with S&T shorted, Q&R shorted and S&R o/c. I don't have the transformers with me now, so I'm unable to measure the resistances.
This is not a problem for me anymore, but there must be hidden windings that are not shown on Quads drawings, it would be interesting to find out!