Leak, Quad, PYE, Dynaco, Radford - Transformer Iron Quality

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marantz123

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Hi all

Found some interesting information about the quality of the iron used in Leak, Quad, PYE, Dynaco and Radford valve-driven amplifiers. Bringing this to the forum for feedback here as I doubt that all of it is fact, hence personal experience from those in the know would be very valuable content for this forum going forward if its not documented here already.

Apparently, when the Quad2 was being manufactured in 1953, England was in still in massive debt since the war, and as a result steel was expensive, was rationed for a time after the war, with good quality steel as used in transformers being very expensive.  The cost resulted in Quad using a lower quality of steel in the power transformer which did not affect performance or audio quality, or cause any adverse issues. This steel does not age well in the long term and loses some of its magnetic properties, causing the transformer to run much hotter and possibly a reason for the wax leaking out of them. It is also mentioned that Quad did not respect the minimum physical spacing suggested between a pair of KT66's, and were focussed on building a compact chassis, which attributed to greater heat transfer from the valves into the transformers, thus increasing the temperature. Quad used the very expensive steel in their output transformers though, so longevity/quality of these components should still be very good.
Leak - apparently went a similar route but with a lower quality of iron in both output and power transformers. (Personally I find this hard to believe judging from the cult-like following and praise for the audio quality..so, concensus needed on the ageing of its iron, and which transformer and amplifier models are running hotter now).
Radford apparently used a similar quality of iron in both power and output transformers and are possibly ageing well..or not..( consensus needed here).
PYE Amplifier transformers -  PYE had military infrastructure/ radio communication manufacturing contracts during the war and had access to the best quality and quantity of steel and possibly used this in both their power and output transformers..as these transformers are still very good. (Music to Skollies ears !  :)) Most of the other English manufacturers didnt have access to the same quality of steel and those who had access were limited in quantity and paid exorbitant prices.

Dynaco -  apparently the Z565 output transformers were the best that Dynaco has made and its ageing is still very good with early production being hand-wound in America, and later production being machine-wound in Japan with a 4xxxxx part number. These were used in the ST-35 and the SCA-35. The output transformers (the A470) used in the ST70 do not age as well... no supporting information on this though.

Overall,  PYE seems to age the best, followed by Radford, along with the Dynaco Z565.

Thanks
Marantz123.

 
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