Best Currently Available Express OT in 2022?

[gfarina55]

Hello,

What is the best Express OT (for a "traditional" build) currently available in Oct. 2022?

Pacific w/the 7.5K primary: https://pacificaudiomagnetics.com/colle ... ype=Output

or

Mercury w/the 6.6K primary: https://www.mercurymagnetics.com/wp-con ... -KF-OT.pdf

I read the "Rate the Express Output Transformers" thread above but a lot of the OT's discussed are no longer available.

Thanks!

[ViperDoc]

Or Heyboer with a 6K6 primary:

https://shop.amppartsdirect.com/collect ... 77b1&_ss=r

A 7K5 primary is incorrect.

[Roe]

Or the RJ pacific with 6k6 Z

[wpaulvogel]

Hammond 1650G? I think it’s made as a clone to the Stancor A-3801. It looks like it anyway with the ratings and the stacking of the laminations is similar to the A-3801 also.

[pdf64]

I’ve killed a 1650G in a JTM45 build. Shorted turns in the primary. It was worked hard, cranked, for several hundred hours, but nonetheless, an unexpected failure still disappointing. It’s not like a valve short took it out.

[gfarina55]

I did not realize those Amp Parts Direct transformers were Heyboer. The price is right and people on this forum seem to like them in Expresses, so that's probably the answer.

Roe, is the "RJ Pacific" available somewhere?

[martin manning]

Another Heyboer source: https://www.mojotone.com/Mojotone-TW35- ... ransformer

Contact rj on the Pacific. https://ampgarage.com/forum/viewtopic.p ... 37#p438037

[ViperDoc]

I did not realize those Amp Parts Direct transformers were Heyboer. The price is right and people on this forum seem to like them in Expresses, so that's probably the answer.

Roe, is the "RJ Pacific" available somewhere?

The “-H” designates Heyboer, “-M” designates Mercury Magnetics. I can only report on the APD Heyboer, I used it in a P2P Express build I just did. It sounds awesome. If anything, it’s quite Voxy with loads of sparkle and is quite compressed when turned up.

[Gainzilla]

Holy cr@p! 10A on the filaments?! I had no idea...

[RJ Guitars]

Holy cr@p! 10A on the filaments?! I had no idea...

One of my personal favorite pieces of Wreck History...

Somewhere in the archives, my own speculation about this has been published previously. It was based on a discussion with Patrick from Mercury Magnetics (A great guy no longer with us ) Patrick shared stories of working with Ken Fischer and told me of a time when Ken brought in one of his favorite old PT's, taken from a TV set. He wanted to have MM make clones of this tranny for his amplifier biz... It's impossible to know the model or the real story but my speculation was that a PT from a TV set would certainly need to support a bunch of tube heaters. Could this be the origin of the Wreck PT?

It might be kinda cool but otherwise worthless info to study some of those old TV set transformers and see if there was anything close to the Wreck specifications. I've got some old Stancor PT's that are close to the right specs for a Wreck build except for that 10 amp heater tap. It's a bit late to think of salvaging PT's from old TV's for most of us but I think it's safe to say that you could get by with a lot less power capacity on the heater tap.

[rooster]

A lot less, yep. And I say this because from my experience it's the filament winding that actually causes vibrational buzzing in a PT, and heat. And a 7-10A tap? It takes BIG WIRE inside those bell covers to do that. I mean seriously, have you ever seen a 35W amp with a bigger PT? It's way overkill for the 5 tubes involved. A Fender Quad Reverb/Twin Reverb uses a 5.5A heater tap for example.

My first two Heyboers (purchased from Moose), had a buzz caused by the filament windings. Phil at Heyboer is a good man to deal with, he said it sounded like they didn't pot it very well and to send them back for replacement. Which I did. The new ones were fine, but of course all of this caused me a lot a thought about the filament supply in any PT. I have always thought - after this experience - that when MM tells you that a poorly built PT can cause noise at the speaker, they were in fact referring to the filament wind and not much else.

[Gainzilla]

One of my personal favorite pieces of Wreck History...

... t's impossible to know the model or the real story but my speculation was that a PT from a TV set would certainly need to support a bunch of tube heaters. Could this be the origin of the Wreck PT?

Wow, that IS cool. I love all the little backstory details. I was thinking maybe the high current gives a more robust tone, kind of how hifi guys like high current amplifiers.

[Reeltarded]

Those two ideas sound like belief in magic, but what is real is people use the similar thing that others are successful with then they start attributing reason.

Power transformers that do the same electrical thing have no outcome on 'tone'.

Hi-Fi guys like high current capacity because they like to crank low distortion small amps and there probably aren't a long list of brands and types that are used by the top 10 snobs. lol.. I laugh, but I'm not kidding. The last thing a curve geek wants is sagging dynamic phase shift.

They still don't know that tube amps aren't the best choice for program playback. What would we talk about?

ADCOM 555: When it's critical that all the frequencies arrive consistently at the same time from zero to your sweet-spot.

[thomasks]

I have the MM OT in my clone, and it sounds awesome to me! I agree that the PT probably doesn't have any effect on tone. But you have to have the HP to crank it.

[Mark]

Marstran also sell Trainwreck style transformers.

http://marstran.com/JTM45-100-JMP100%20 ... RMERS.html