2kVA toroidal transformer, where to buy?

[emuman100]

I'm looking for one for the AV800 amplifier. The manual says it needs 2x 65V secondaries for stereo operation. I'm guessing a 130V center tapped will do the same thing as two 56V secondaries. Anyone build a stereo AV800 or know of a supplier to find such a transaformer?

Thanks.

[andy_c]

In the latest AudioXpress issue, Charles Hansen mentions Bicron, who I hadn't heard of before http://www.bicronusa.com . I'd be interested to find out what they quote you on these. They have a PDF file http://www.bcrn.com/Media/ToroidalPowerTransformers.pdf that lists the standard configurations for AA/AU/BU series on page 7, but with blanks for the voltages. They have a 2 kVA model listed. I guess this is some kind of semi-custom arrangement. If you do get a quote for these with dual 65 VRMS secondaries, could you post here with the pricing?

Thanks

[emuman100]

Thanks for the info. Would I need two 65V secondaries or a 130V secondary center tapped?

Thanks.

[andy_c]

Either two 65V secondaries or a single center tapped 130V secondary will work with a single full wave bridge rectifier. Some people prefer the double full wave bridge configuration which requires two separate secondaries. Now that I look at their catalog, it doesn't explicitly say that their single secondary design is center tapped, so maybe it's a safer bet to get a quote on the dual secondary version.

[mwh-eng]

You could build your own transformer if you don't mind doing some manual labor. I'm curious about the cost of a store bought 2KVA toroidal power transformer. You may be able to get a tape wound core sample from Mag Inc.

[emuman100]

andy_c,

Double full wave bridge configuration? You mean this?

mwh-eng,

I'm guessing $300+?

[andy_c]

Oops! Well there's one with a center tapped transformer. Yes, that's it, so scratch my earlier comment. It was incorrect.

[Eva]

I guess using a single 2KVA unit will be more expensive than using 2x 1KVA units, 3x 750VA units or 4x 500VA units, since higher power transformers tend to be produced only on request in very small quantities but low power ones are produced in large quantities and tend to be in stock

It would be a great idea to compare prices before buying, for example, 500VA transformers with two 32V secondaries may be cheap and very easy to find. You may even get a discount by buying 4 units and they will do the same job as a 2KVA unit

[mwh-eng]

I agree that using two 1KVA units may be better. I did a quick design to find the tape wound core size needed for one 2KVA. Requires 2 huge cores stacked, from one core manufacturer. Would be better, IMO, to build two 1KVA units with one core each. This spreads out the power and the dissipation. Requires more area but less height.

I will try to get a price quote on these cores. I realize you probably do not want to make your own transformers, but some folks do, and getting an estimate of the cost may be useful for comparison.

Be sure of your specifications: Will you be running high continuous power, or are you just wanting to provide high peak power? If you only require high peak power at a relatively low duty, then you can trade-off some transformer size with capacitor size. Your highest power requirement at the lowest frequency required, helps to size the transformer and capacitors.

[mwh-eng]

Submitted request for price quote for tape wound cores. Waiting for quote. Probably can get samples from manufacturer.