Edcor Universal Power Transformer for Tubelab SE

[rknize]

I am having Edcor build a power transformer for the Tubelab SE. They don't currently have one with the correct HT winding that also has a CT 6.3V winding and a 5V @3A winding (I want the option to use a 5U4*).

I am adding a pair of taps to the HT winding that will allow me to run either around 300V or 400V B+ so that the amp will take full advantage of 45s or 300Bs. Since the input stage uses a CCS, it seems like being able to switch back and forth when switching tubes should work fine with an amp like this. Obviously, making this an actual switch falls under the same category of "oops" as putting a switch on the heater supply, but that is always an option.

Here are the specs:

330-260-0-260-330 @ 175mA
6.3V CT @ 3A
5V @ 3A

They quoted me $57.98 (plus the setup fee for me), which seems fairly reasonable. Is anyone else interested in a design like this? Obviously, you still have to compromise on the OPT impedance, but I don't mind losing a little power with 300Bs seeing 5k.

I'm done with Hammond.

Russ

[kenpeter]

The only trouble with Edcor customs is knowing which ones
they allready got designed? Without calling to ask I mean...

I'm certain that many here appreciate the heads up, that
this especially useful custom design is now on the books.

[chrish]

I don't have the link on this computer, but if you go to the forums on the Edcor site there is a link to a PDF or .doc file that lists all of the power transformers that they have designs for.

Chris

[rknize]

Yes, I have the PDF and they had some that could be made to work, but I couldn't find anything with the right HT, CT heaters, and 5V @ 3A. After talking to them, they said they didn't have anything quite like it. Adding the taps is a bonus to make up for the $40 setup fee.

Russ

[rknize]

OK, so over in my SSE thread Even Harmonics and George pointed-out that I probably need 4A on the 6.3V winding to run 300Bs. I could go 5A to cover mega-crazy 300Bs, but I don't think that is in the cards for me.

Any other suggestions?

[rknize]

I talked to Edcor today and ordered the transformer. Here are the final numbers. I haven't received the invoice yet, but it should be the same. I'll update if it changed.

XPWR132 - $61.89
330-260-0-260-330 @ 175mA
6.3 V CT @ 4A
5V @ 3A

They are busy, so it will take about 3 weeks.

Russ

[rknize]

I got the sales order today. Should take 3-4 weeks. Note the new part number is:

XPWR131

It is wrong in the post above! If you order one I would double-check the specs with them because they gave me the other part number over the phone yesterday.

FYI, bumping the 6.3 to 4A only added $4 to the cost. To go to 6A to try to cover 2A3s and some of the $beaucoup 300Bs would have required a larger bobbin and a bigger core, so the cost would have gone up more significantly. She said it would be "doable" on a single transformer, though.

I figured that the majority of folks that would want to build a "more universal" Tubelab SE using one of these would probably be looking at more of the reasonably-priced 300Bs.

[SpreadSpectrum]

Just last week I got XPWR099 assigned to me. I wondered where they were going to go with the numbers from there.

[Wavebourn]

Today I've discovered a weak point of an Edcor transformer...

[rknize]

I just got the notification that the transformer has shipped. I'll post test results once it gets here.

Good timing too, as a friend of mine has loaned be a pair of Chinese 300BS tubes (the crazy globe ones with mesh screens) to try. He's got WEs now.... Prolly gonna pick up a pair of the "cheap" Shuguang 300B-98s before they go up in price more.

Russ