[OlesonMD]

Does anyone have a good source for toroidal transformers?

One tranny is needed for replacement in a 300 watt power amp.

1kva (or higher)

[jtwrace]

http://www.antekinc.com/

http://www.plitron.com/

[poseidonsvoice]

Does anyone have a good source for toroidal transformers?

One tranny is needed for replacement in a 300 watt power amp.

1kva (or higher)

As jtwrace said.

Just be careful with larger toroidal transformers, other than larger size (which needs to be accomodated for because your chassis size is finite), you also have larger inrush currents and hence may need a larger fuse on the hot leg. If you have a soft start (a well designed one), then this shouldn't be an issue. Bigger doesn't necessarily mean better, it could be just BIGGER problems!

Anand.

[Dan Banquer]

Does anyone have a good source for toroidal transformers?

One tranny is needed for replacement in a 300 watt power amp.

1kva (or higher)

www.plitron.com

I've used them for years, good stuff.

Regards;
Dan Banquer

[OlesonMD]

Still looking for a transformer as mine has a low grade (60hz?) hum that is audible from 15 feet away in a quiet room.

OEM - Bicron P/N BX3828B4534. 1KVA rating. Manufactured for Rockford. Data and technical info no longer available from Bicron.

This transformer was used in 5 amps:

Rockford RF2000 / Hafler JF2000 Signature Series / Hafler Pro-6000
Sound Values Mosfet 32 / Sound Valves Mosfet 32B

Other than physical size, would any 1KVA tranny from any other manufacturer do the job, or are there other factors involved?

The tech I had looking at this (and who replaced all caps in the power supply) said this was beyond his ability.

I have researched Plitron, Bicron, Triad, as well as others.

[markC]

Lots of other factors involved. Input - parallel or series. Output - parallel or series, centre tap, voltage? You could make several types work, but you need to know what the original tranny's specs are. Or @ the very least what the amps rails, etc. require.

[HAL]

Is it hum or buzz that you are hearing?  Hum is 60Hz related and buzz is 120Hz related.

Toroidal transformers are sensitive to DC on the AC line.  If the transformer did not hum in other applications with the same filter caps, and the power draw is the same from the amp, then most likely it is not the transformer causing the noise.

If it is buzz, then might be DC on the AC line causing the transformer core to saturate.  That will cause buzz.

[OlesonMD]

The humming (buzzing?) was evident before we re-capped. That was the original reason for the cap replacement/upgrade.
 
My tech claims it is the tranny. But as I listen, it may be more of a buzz, and it sounds higher than 60hz. It radiates through the chassis top.

What would cause DC on an AC line? Is there a fix for this?

[HAL]

Are the replacement caps higher in value than the original units? 

[NekoAudio]

You should try disconnecting all other gear from the circuit and see if it still hums/buzzes before spending more effort on replacing components. If there's still a problem after you remove everything else from the circuit, then you know it's either your power or the device and not a noisy device sharing your electrical circuit.

If that's the case, then it's possible there is a problem with your power. As HAL implied, try it on different circuits or at a different location. Preferably somewhere that you know has good power. If there's no problem at this other location, then it may be time to call an electrician.

[OlesonMD]

The replacement caps are an exact match in values.

Different electrical circuits have been tried, in different residences, different cities..........all with the same result, humming.

[HAL]

DC on the AC line is caused by a non-linearity in the wiring.  Dirty contacts at the power meter is an example.  Had this happen at my place.  I spotted it by seeing high distortion on the AC line with a Fluke 43B Power Quality Analyzer.

Try NekoAudio's suggestion to rule out other equipment interactions causing the noise.

If this toroid has been tried in multiple places, in multiple amps and the filter caps are the same value, then it is most likely the transformer core windings are loose. 

Since the transformer you have is working, it can be measured for the specs to compare to new units.  Someone like Plitron or Maryland Toroid should be able to check your unit and supply a new one with the same specs.   

[OlesonMD]

Thanks for all of the help! I think we'll pull this tranny out and send it to Toroid of Maryland.

I've heard lot's of positive comments on them. And they build right here in the
USA.

Has anyone here ever used them?