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
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
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.
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.
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
Chris
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
Russ
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?
Any other suggestions?
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
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
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.
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.
Just last week I got XPWR099 assigned to me. I wondered where they were going to go with the numbers from there.
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
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
I finally got to the warehouse to retrieve another pair of tubes for you to try. I need to go to the post office tomorrow to mail my taxes, I will send them as well.
There was another thread detailing the treatment of Wavebourns amp by Fedex
One has a rattle, but it appears just to be cement in the base. Thanks again!
The iron should get here on Wednesday, so I'll hopefully post test results by the end of the week. Looking forward to putting C4 in so I can cut the hum.
The iron should get here on Wednesday, so I'll hopefully post test results by the end of the week. Looking forward to putting C4 in so I can cut the hum.
Here it is.
Wire coloring leaves a few things to be desired, but it seems to work as expected.
Voltages came in a bit high, even under load. The top row is the Tubelab SE in "45 mode", with about 25mA per tube. Meters are reading: 660VAC winding, 520VAC winding, B+ at the filter cap. Bottom row is in "300B mode", running Shuguang 300Bs (not mine) at about 28mA per tube. First two meters got swapped: 520VAC winding, 660VAC winding, B+.
The B+ in "45 mode" is a bit higher than I was hoping, but it is within range of what a lot of folks run it at. I'm using a Hammond choke that measures about 82 ohms, so some series resistance there would help bring it down for anyone concerned (or one could use the 6H Triad choke which is 150 ohms). I'd say the B+ in "300B mode" is right where it should be.
I've run the amp for an hour or so with the 300Bs and the transformer is only slightly warm. I'll let it go for a few more hours to let is heat soak. It does have a slight mechanical buzz, which is a little sad, but it's not too bad.
I had to put a fan on it because the tiny temporary heatsink on the heater regulator is not enough. It keeps tripping the thermal protection. The heater windings are where they ought to be. A tad on the high side, but not too bad.
Wire coloring leaves a few things to be desired, but it seems to work as expected.
Voltages came in a bit high, even under load. The top row is the Tubelab SE in "45 mode", with about 25mA per tube. Meters are reading: 660VAC winding, 520VAC winding, B+ at the filter cap. Bottom row is in "300B mode", running Shuguang 300Bs (not mine) at about 28mA per tube. First two meters got swapped: 520VAC winding, 660VAC winding, B+.
The B+ in "45 mode" is a bit higher than I was hoping, but it is within range of what a lot of folks run it at. I'm using a Hammond choke that measures about 82 ohms, so some series resistance there would help bring it down for anyone concerned (or one could use the 6H Triad choke which is 150 ohms). I'd say the B+ in "300B mode" is right where it should be.
I've run the amp for an hour or so with the 300Bs and the transformer is only slightly warm. I'll let it go for a few more hours to let is heat soak. It does have a slight mechanical buzz, which is a little sad, but it's not too bad.
I had to put a fan on it because the tiny temporary heatsink on the heater regulator is not enough. It keeps tripping the thermal protection. The heater windings are where they ought to be. A tad on the high side, but not too bad.
G said:
No, I shipped it by FedEx...
Design of bells is toyish. Period.
Buying Edcor transformers you need to consider ordering of mounting hardware somewhere else.
I've never seen mesh-plate tubes in person before. They are strange and cool at the same time. Is the blue glow on the glass typical? I mean, it makes sense given there are holes in the plate, but it has a bizarre pattern.
Wavebourn said:
i would agree about the mounting flange. The bells are fairly thin sheet metal and the tabs are stamped right into it. You can bend them with your fingers. I would not expect them to survive shipment anywhere mounted by them. I meant to ask them if they offered bells for flat-mounting them.
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