Matchless lighting new build using MM P18RS

[Mick Bailey]

In replicating a transformer with the original construction and windings, then often the line voltage in the US is higher now than it was back in the day and output voltages are higher. Even classic amps suffer from over-voltage and there are regular postings here illustrating that problem. Here in the UK we have higher voltage at different times and in different regions. I measured 258v a couple of days ago. Plus, we're getting stung with the EU harmonization scheme where primaries are actually wound for 230v - even though many are marked for 240v. Fender amps come into this country wired for 230v. Put that on a supply that averages almost 250v and the B+ is way higher than it should be.

I can't recall in recent years buying a PT were the voltages weren't much higher than the nominal ratings.

Then there's the consideration of using what you already have.

[J M Fahey]

replicating a transformer with the original construction and windings, then often the line voltage in the US is higher now than it was back in the day and output voltages are higher.

That's pure superstition.
What they must duplicate (if they wan to be anally accurate) is the *secondary* ,whatever it was (current/voltage/wire/turns/layers/etc.) , but the primary must have proper turns and wire section for *current* wall voltages.

[Mick Bailey]

That's pure superstition.

I disagree. Many winders still spec 115v primaries for US guitar PTs, both replica and new build. Yet since the late 60s 120v has been widespread. European-made transformers also conveniently use 115v/230v dual primaries, which gives over-voltage for the US and UK.

Classic Tone (amongst others) states they replicate vintage PTs with 'modern' 120v primaries to ensure secondary voltages are correct. At least they're doing things properly.

[Dave H]

I think Juan meant it was the winders' pure superstition in duplicating the original 115V winding when the voltage is now 120V.

[ThermionicScott]

That's what I was getting at -- transformers that were designed for 115V at the wall, and now produce much more, and people insisting that theirs be just like the original...

Even if you get one with a 120/125V primary, it doesn't hurt anything to spec the secondary a little cooler. Hammond's AC30 reissue PT specs 275-0-275 instead of the original's 280-0-280 (to say nothing of what an original wind would produce on today's wall voltage), so at least they've considered the issue.

[J M Fahey]

Well, Hammond is clearly a Tech Company, and run by Engineers or competent Techs; others sell "Mojo" , as in: "this is an accurate clone of transformer pulled from Marshall serial number 1234567 , made in 1967, used by Slash to record AFD" or what amounts to that.

To be more precise, the "superstition" bit lies in the mind of the buyer, the seller believes in another God whatsoever, often known as the Golden Calf



also known as The Mighty Greenback:

[mort]

FWIW Mercury offers many of their PT's with a lower B+, including the P18RS. It's the P18RS-M and costs just a few bucks more. When I have a job where the customer wants Mercury I always go with the "M" variation.

[Mick Bailey]

I think Juan meant it was the winders' pure superstition in duplicating the original 115V winding when the voltage is now 120V.

My apologies, Juan - I got the wrong end of the stick with that one.

[J M Fahey]

Oh please Mick, no need to

Plus, you know, I should have been more clear in my answer, after all there is a reason people writes things such as:
English Miscommunication, Cultural Differences, Language | IOR

Oh well