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Step up transformer?

bryans12v

bryans12v

Marantz / Altec Junkie
Subscriber
Today I picked up a really nice pair of Quad II amps in a lot of other goodies. They're very clean under the layer of dust. They are euro voltage models but luckily they came with all the cords for power and preamp connection.

They also were in a bin with this transformer which I the folks thought was a step up transformer. Looks like it has 120V secondary but wouldnt I need 120V on the primary side? Possible it's just wired up backwards to work? Please pardon my ignorance but I've never really needed one of these devices and dont know anything about them. I would assume a step up could also function as a step down but would love a second opinion.

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Look at how it is wired. Tells you what connections need to be made to get specified output from specified input.

Can't transformers be used either way, up or down if that is all they are?

Ohmmeter reading will tell what the voltage ratio is.
 
Well it looks like it is wired up backwards with the transformer primary feeding the load.

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One thing that seemed off was if it were being used as a bucking transformer it would use this plug for the HV input.
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Think I'm going to give it a test with a variac and confirm its output.
 
Seems to check out.

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I tried to do some research last night on using bucks to boost and it seems that most say it's not an ideal solution. Again, I know very little about these. None of what I could find in my search was specifically related to powering audio amps.

Do you guys think this thing will be suitable? If not, I dont mind spending a couple bucks on a proper solution. I looked online for a few and cant find anything other than cheaply built step up transformers.
 
I'd post a new thread and just ask if a step down transformer can be used as a step up transformer and show what you have. That thing has to be a lot nicer than some crap wound oversees in the last year. There are a number of transformers on the market that can do either up or down in voltage. I think you are fine. Someone knows transformers enough to let you know how that unit will work for the intended purpose and if there would be a change in the max current. But I think that stuff came as a group as they were used as a group.
 
it might be slightly less efficient when run backwards but transformers are just ratio devices. Yours is running 1:2 instead of 2:1. See what the loaded output voltage is, adjust the voltage selector on the Quad amps if necessary. I'm inclined to think you'll be fine though.

I'm using a small industrial control transformer for the HV supply on something. It was meant to do 208 or 480 to 120v, I have it backwards and wired for 208 output and fed into a bridge rectifier. Works quite well.
 
It needs to be used "backwards" for your application, and it will work for that purpose. Slightly less efficient than the conventional way, but it is vastly over-rated for your application ,so a handful of Watts wasted is not significant.
 
It'll be loafing with a 1KVA rating. You can't buy a better one for $300... a smaller one will have more voltage drop under load.
 
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