WTB Martin logan Sequel ll high voltage transformer

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Hi Guys

Do know where to buy the HV transformer from sequel ll ?

And the seller that able to ship item to Singapore.

Or can i recoil back the transformer and any forumers here able to
Advice the transformers specification.

Your kind advice n info is greatly appreciated.


I assume the TO is asking for the HV-Transformer of the Bias supply not the audio-transformers.
After my knowledge the secondary of the Bias-Trafo delivers 450V.
If You can´t find a dedicated 230V prim, 450V sec trafo you might use 3 identical standard small-wattage power transformers with single primary and single secondary windings (say for exampe 10VA EI-types with 12V secondaries (lowvoltage winding) or any value You prefer).
The first trafo shall be connected as usual to Your Power line of 230V.
The two remaining trafos shall be connected with their secondaries (lowvoltage) conneceted in parallel to the first trafo´s secondary (lowvoltage).
Their primary windings shall be connected in series and used as output.
In theory this should give 460V of output.
Due to the transformer´s regulation and losses the output willbe somewhere around 460V.
If the trafos are not chosen equal, but just two of them, You may fudge with output voltages or could use a 115V power line.
These small power trafos are easy to source, cheap and reliable and offer a certain flexibility for generating the right output voltage.

In case You did mean the audio transformers my first idea would be look for original replacement parts.
The above mentioned Plitron are excellent parts, but they won´t offer any advantage under the Sequel´s special conditions.
Under different circumstances their quite high price could be justified by higher performance.
With the Sequel though their advantages can´t be used to any good.
Been there done that.
A cheaper alternative would be a pair of 230V/6V toroids (20VA-80VA).
That results in a U of 1:68 to 1:70. depending on the losses of the trafo .. same as the original.
These suffice also as the Sequel is a hybrid ESL with a highish xover frequency where the high inductance of the plitron transformers is simply not needed (those are fullrange capable audio-trafos, which makes them more difficult to wind and costier).
Even though these toroids are of much better quality than the original trafos and typically result in quite different sets of measurements, the heavy equing of the Sequel panel will also equalize the end results.
The considerable sonic advantages would only shine through if the complete speaker is build up new around the panel, prefferrably in an active fashion and a different bass solution.
If You can´t find appropriate toroids then You may use a Quad or Hex of parallel/seriel connected 10VA EI-cores with single prim/single sec of 230V/6V again.
Those are closer to the simple lowquality audio trannies ML (and most other ESL companies also) used to use.
Due to heir increased stray inductance the upper bandwidth limit would be around 12-15kHz (the original didn´t electrically reach much higher than 12kHz either).
A side benefit of those cheap trafos is, that the electrical phase shift remains much lower than with toroids, thereby easening the amplifier´s life alot.
But again ... in this special surroundings transformer quality rather doesn´t matter.
Go for the easiest and cheapest to source.

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