Philharmonic 15" Pedestal Speaker Output Transformer

[Jeremy S]

Hey everyone! Long time lurker, first time poster here. Currently restoring a Philharmonic with the 15 Magnavox pedestal speaker. Unfortunately, the output transformer in my speaker is shorted. 

I am looking for find a suitable replacement transformer. Before I scour the internet for an option, I was curious if anyone else had recently replaced one of these and what part that you used? Open to recommendations!

Jeremy

[Thomas Day]

I would check out Hammond transformer company. They make several models that would work with t.he tubes used in the amplifier. Another option would be Heyboer transformer in Grand Haven Mi. They made a new power transformer for my Allwave 23. Not cheap, but worth it to restore the radio. .

[Jeremy S]

Thanks Tom! I have been looking at the Hammond 1608A-1650A Series. One issue I see is that my VC is 38 ohms, the Hammond options are only rated for up to 16.

Per my RCA manual, with a PP 6L6 class A, cathode bias, I need an impedance of around 5000 ohms. However, I have never sized an output transformer for a parallel push-pull circuit. With this being a parallel PP circuit, how does that affect the load resistance? I know from past experience that impedance has some wiggle room as long as you are in the ballpark, at least on most consumer grade radios. Per the manual, undistorted output is 40W.

I sent a message to Heyboer to see fi they can rebuild my transformer, or can sell me a custom replacement. I also reached out to Hammond for their recommendations.

[Thomas Day]

For me, since I didn’t have the original speaker, the transformer I used allows 8 or 16 ohm speakers. I plan on using a regular 3 way hi fi speaker. You could do the same, and save the original speaker til you can find a good transformer, and just use the built in resistor pack and field coil. Check the actual dc resistance of the voice coil. 16 ohms may work ok.