Hi, the standard to define how "big" a transformer is, is VA rating.
About the physical size, there is not much on the picture to compare it with, but have a feeling that it is not that large or heavy weight?
The voltage ratings are typical for a 200W/8Ohm amp, with the possibility to drive the front end with a higher regulated voltage.
About the physical size, there is not much on the picture to compare it with, but have a feeling that it is not that large or heavy weight?
The voltage ratings are typical for a 200W/8Ohm amp, with the possibility to drive the front end with a higher regulated voltage.
What they said.
Might make a fun high end preamp transformer. Enough windings for discrete stages, HEAD amp, relay controls etc.
Might make a fun high end preamp transformer. Enough windings for discrete stages, HEAD amp, relay controls etc.
You have to go by weight when you can’t determine what the wire gauge is to determine VA. You could also load test it, and find out how much load makes it drop say 10%. You would need to do this on the main high current winding.
And my guess is that the 45-0-45 is the high current winding - because it’s on top in the schematic, and drawn larger. You could confirm this by comparing resistances - compare the 0-60 volt tap with the 30-0-30 tap. Same voltage, equal or nearly equal turns. One with the lower R is high current, the other probably significantly less. The ratio of resistances could give a guide to how much you can pull safely off the lower current winding.
And my guess is that the 45-0-45 is the high current winding - because it’s on top in the schematic, and drawn larger. You could confirm this by comparing resistances - compare the 0-60 volt tap with the 30-0-30 tap. Same voltage, equal or nearly equal turns. One with the lower R is high current, the other probably significantly less. The ratio of resistances could give a guide to how much you can pull safely off the lower current winding.
Hi all thank you for the replies! I do really like the idea of a preamp.
Wg_ski I will test it as you described today and post findings.
How would I load test it?
It is from a McCormack dna-1 which, according to the article I just read in stereophile, came with a 900va transformer. I'll look for some pictures to see if I can try to confirm that.
Again thanks for your time
Wg_ski I will test it as you described today and post findings.
How would I load test it?
It is from a McCormack dna-1 which, according to the article I just read in stereophile, came with a 900va transformer. I'll look for some pictures to see if I can try to confirm that.
Again thanks for your time
Load test it by putting a load on it. Record the output voltage at several current levels. But if you’ve received information saying is 900 VA then you can skip this. I’d still figure out which is the high current winding, and you can just do that with an ohm meter.
If it's a 900VA transformer with the primaries in parallel, then if you connect them in series, you would have a 450VA 22.5V-0-22.5V (rather than 45-0-45), which would rectify into +/-29-ish volt rails, and just right for a Pass DIY amp.
Then the 45-0-45 is high current and can take most of the 900VA. The 60-0-60 (or 18-0-18 taps) can be used for a preamp or front end with elevated (perhaps regulated) voltages.
On the main winding, you could either use the whole thing to make +/-63V, or run off the 30V taps to make +/-42. It might have been for an 8 ohm/4 ohm switch, the ratio is about right. VA rating would be around 600 if running off the lower taps. Of course you can put the primaries in series and cut everything in half, if those voltages better suit your use (if you live in a 120 volt country). Running the flux density that low would also make it really really quiet - there wouldn’t be one hint of mechanical noise.
Greetings from europe.
I had TV supply transformer with higher power rating than this one.
Cheers.
P.S. and I have a 1kW toroid autotransformer with "handcrafted" secondary windings to melt wires. It could do 2kW easily. About a foot in diameter. I don't think it's big.
I had TV supply transformer with higher power rating than this one.
Cheers.
P.S. and I have a 1kW toroid autotransformer with "handcrafted" secondary windings to melt wires. It could do 2kW easily. About a foot in diameter. I don't think it's big.