James output transformers

[MrCurwen]

I'm moving bravely onwards with my DC Darling project. Now that I have the voltages in a better shape (270V across the 1626, 180V across 6SL7), I'm looking into replacing the output transformers. Currently I have two Hammond 125DSEs working at around 27mA per channel. They're not so bad if you keep well below half of the max current rating.

I'm looking into James transformers. The looks certainly catched my eyes, and I've read much good on them on the forums.

Due to budget restrictions my choices seem to be the following:

JS-6112HS 70mA 2.5K / 3.5K 10W 29Hz~50KHz-2dB
JS-6113HS 60mA 3.5K / 5 K 10W 27Hz~60KHz-2dB
JS-6115HS 50mA 5K / 7 K 10W 25Hz~50KHz-2dB

I'm guessing the bandwidths are measured at max current; I will be running my Darling at 25 - 35 mA per channel, so well below saturation that bass response should be much better than the numbers indicate.

Which one would you recommend? Mainly which primary impedance would be best?

Any general comments on James transformers? Any experiences with SE James applications?

[h00hbt]

Try Hashimoto transformers

/H

[Allen Wright]

I used James transformers with great success for years, and always found them to sound great.

A Malaysian Chinese friend was in their Taiwan factory and said he saw identical transformers coming down the assembly line, some getting James logos, the others getting Tamura logos. As they are way cheaper than Tamura's, way to go I say.

Regards, Allen

[SY]

Ditto Allen's comment. I have had nothing but good experience with their transformers and with them as a company.

[AmadeusMozart]

Originally Posted by MrCurwen

Due to budget restrictions my choices seem to be the following:

JS-6112HS 70mA 2.5K / 3.5K 10W 29Hz~50KHz-2dB
JS-6113HS 60mA 3.5K / 5 K 10W 27Hz~60KHz-2dB
JS-6115HS 50mA 5K / 7 K 10W 25Hz~50KHz-2dB

I was pondering the same question.

In the end I ordered directly from Taiwan and bought the JS-6123HS. ( Don't forget to take the shipping costs in consideration. ) This one has 2.5K @ 90mA, 3.5K @ 80mA and 5K @ 70mA.

I know it is overkill (20Watt SE) for the 6L6GC SE (about 7 watts) but it offers the flexibility of changing/upgrading the design. Only mistake I made was ordering a choke which is not really big enough but I came up with a workaround.

AM

[knightsound]

If the OP is in Finland, has he considered Lundahl in Sweden? A significant proportion of the cost of heavy OPT's is carriage. If one assumed James and Lundahl are of similar quality, the Lundahl would be better value landed in Finland.

As regards AW's comment, also mentioned in a previous thread, regarding rebadged James/Tamura OPT's, three interpretations come to mind:

1. James are legitimately producing OPT's for Tamura to the same specification as James OPT's.
   
2. James are legitimately producing OPT's for Tamura to a different, higher Tamura specification.
   
3. James are re-badging James spec OPT's as Tamura, illegitimately.
   

Anyone who has spent time doing business in China will have had the chance to wander around a Chinese factory marveling at the number of products being labeled and packaged with the "Stars and Stripes" and "Made in America". In my first-hand experience, it has been a case of the Chinese factory copying an American product, sometimes poorly, sometimes well, but rarely better than the original. These products are then sold within China via parallel distribution channels, or exported and "mixed in" to the grey and legitimate distribution sales in the US and Europe.

Fortunately, with OPT's there's any easy way to assess what is what - measurement. I have never read or heard of a James transformer that shows the wide-range, flat frequency response of a typical Tamura OPT. Neither have I come across reports of a Tamura OPT measuring like a James OPT. Not even close. So, unless (1) or (3) are cropping up in China, is outcome (2) what was seen at the factory? It's a few years since I lived there. Perhaps some others might like to comment?

[TerryO]

There'a always ONetics right here in the USA. They are usually considered at least equal to Hashimoto and James in quality.

Best Regards,
TerryO

[chrish]

I thought that I read somewhere that James used to make the Tango, not Tamura, transformers. That is what this guy on eBay is saying, though I do realise not to trust everything said on that site! James Transformers JS-6123HS pair! Tube amplifier Tango - eBay (item 270594635118 end time Aug-15-10 06:31:26 PDT)

[pchw]

I don't think James factory is in China ..... Taiwan is not China.

[Ty_Bower]

Originally Posted by MrCurwen

Mainly which primary impedance would be best?

Good question. You've indicated an idle point at 270V, 27mA. Have you drawn the load lines on the plate curves?


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