OT replacement confusion

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OT replacement confusion

Postby sitka_spruce on Sat Mar 19, 2016 11:51 pm

I have this Marshall 9100 (420-430V on the plates) that is due for a OT (El96 lamination) replacement surgery. I'm a bit confused when it comes to the values and features of these. It seems a bit low e.g. going with a 45W tranny if a pair of outputs can produce in excess of 60W clean. Then how can I see to that the chosen tranny would provide me with the right amount of headroom? Would that be the wattage rating or the lamination or somehow both?

Channel A is KT77s, which I hear prefer a similar impedence loading as the KT66, which should be in the region of 6-7k. Then most seem to be clones of Radiospares and Drakes at 8k or so, which may sound cleaner but cuts back on output and frequency range (the latter could actually be a positive for me). And I wouldn't mind to have this OT of lower headroom

Channel B is KT88s, which I would assume would prefer something closer to 4-5k. Here I want more headroom, but it would seem a bit counterintuitive should I go with a 65W rater Music Man OT which have lower lamination than the stock Dagnall tranny of 60W. Been looking into Hiwatt and Ampeg trannies (or clones thereof) for this purpose. Those Ampeg ones feature as much iron as some 100W Marshall trannies, the Hiwatt ones about as much as a 50W Marshall one, yet are said to be headroomier than those... :S

Any insight would be appreciated.
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