power transformer rating and tube current - SimpleSE

[tubelab.com]

The Allied 6K7VG is rated at 150 mA, but it is also rated for 50 Hz operation. It can deliver 175 mA when used on 60 Hz. The Allied 6K7VG is a Hammond 274BX with an Allied (made in Canada) label on it. There are two differences, the Allied has all of the leads comming out of one side (one less hole to drill) and it costs less ($44).

I have put these in guitar amps for several years, and in a few SimpleSE's including one that I routinely use with EH KT88's biased at 100 mA each. As with most Hammond transformers, they get warm.

The B+ is 430 to 440 volts with a tube rectifier, and 450 to 460 volts using SS depending on line voltage and bias current.

[chrish]

Hello namatjera,

The bad news is that you are probably going to have to order some stuff from overseas, but the good news is that the Aussie dollar is strong at the moment (or the US dollar is weak).

This is what I ordered:

Antique Electrical Supplies http://www.tubesandmore.com/
Hammond 374BX power transformer
Hammond 193H choke
Hammond 12"*10"*2" chassis and matching cover plate
coupling caps - your choice, I used Hovland .22uF 600v
JJ ECC81
JJ E34L*2
JJ GZ34

Edcor http://www.edcorusa.com/home.html
XSE15-8-5K output transformers

Digikey http://www.digikey.com/
All of the stuff in the parts list except the 3W metal film/oxide resistors

Motor run capacitor http://cgi.ebay.com/80-mfd-500-VAC-C...QQcmdZViewItem

Mounting clamp for motor run capacitor from RS http://www.rsaustralia.com/cgi-bin/b...cape&Nr=avl:au


Since building, I have had a failure of the solid state diodes and one JJ rectifier. Don't use a standby switch as this caused the problem. I have used Sovtek GZ34, Svetlana 5U4G and some other soviet surplus with success since. Have tried JJKT88, Winged C EL34 and ex Soviet 6L6 tubes, JJ E34L are cheap and sound the best. Have tried NOS Mullard, RSD and JJ ECC81. Could not really tell any difference between NOS Mullard and JJ and maybe just a little difference between JJ and RSD (cheap German brand).

Output transformers are the little Edcors. I run an active crossover and split the <80Hz to a solid state amp and separate woofers. If you want moderate price and good performance I would try the new GXSE15-8-5K (8 Ohm), or the GSXE15-6-5K (6 Ohm) transformers from Edcor. I have a pair of these on order to try at some time in the future.

You might want to ask Edcor for a quote to make you a power transformer. Posted above, someone got this transformer from Edcor part number XPWR033 760VCT @ 200mA, 6.3V (No CT) @ 5A, 5V @ 3A.
For $20 they will design for you, so you could ask for a 240 volt version of this. You could then combine shipping with the output transformers and save some.

I ordered all of the small components from Digikey. RS is more expensive, but shipping is only $11 AUD. Might still be worth Digikey. Problem will be sourcing the IXUS constant current device. Not sure of the price on these, but it might be worth buying a couple extra in case you fry one.

Overall I have been very happy with the service and product from Antique Electrical supplies and Edcor.

Gooid luck with the build!

Chris

[don9146]

Originally posted by w5jag
Charlie,

I use my Simple SE as the amp in our home theater setup, so it runs VERY long hours on weekends and over holidays when everyone is at home. Even after 15-16 hours, the transformer and choke are cool to the touch with the 6L6/EL34/6CA7 type tubes and a 5Y3/5R4 rectifier. When I use KT88/6550 and higher voltage rectifiers, the transformer tends to get warmer than I like after 7 or 8 hours, but I'm not sure how much of this is actual heat generated in the transformer, or pickup of radiant heat from the output tubes. When I fry this transformer, if I can't find a suitable hamfest replacement for a buck or two, I will use the One Electron power transformer from AES.


Win W5JAG

I'm considering making a tube amp to power a 5.1 home theater (and SACDs) as well. How do you have your setup configured? i.e. Is the amp powering the fronts only? Running through a pre-amp?
I would like to get "tube power" to all 5 channels and have the .1 with its own separate amp, but I am not sure about the best way to accomplish this. The true 5.1 tube amps I have seen for sale are ridiculously expensive .

Thanks for the input,
Don

[chrish]

Don,

You can do it a number of ways. First off, you will be using the tube amp as a power amp only. That reduces some of the complexity as you do not have to worry about volume controls on the amp.

You will need to do the 5.1 decoding either with a surround sound pre amp , such as this http://www.rotel.com/NA/Products/Pro...ils.htm?id=463

Or you can use a surround sound receiver that has pre-outs (outputs from the pre amp section before the on-board power amps). I had a browse through the Denon amps, and it looks like they start to have pre-out from this model up http://www.usa.denon.com/ProductDetails/3510.asp#

If you want all external amps and are starting from scratch, a surround sound pre-amp might be the best final solution. If you are happy to have tube amps for the front left and right and/or don't want external amps for all speakers, a receiver with pre-outs might be better. Also, if you go the receiver route, you might already have one at home that allows you to do this. Also allows you to start slowly with the building of the amps while having a complete working system from the start with the on-board amps.

Cheers,

Chris

[Ty_Bower]

Originally posted by Zap
Just another option to consider, Edcor makes a Power Transformer...

The part number is XPWR033. Full specs, 760VCT @ 200mA, 6.3V (No CT) @ 5A, 5V @ 3A.

What happened to the Edcor XPWR transformers with the 5 volt windings? I can't find any on their website.

[Zap]

I'm not sure if they were ever listed on their website, but I found out about them by calling. If they have produced a design (for you or someone else) in the past they will wind it for you without the $20 custom winding charge. Otherwise for an additional $20, they will make a design to your specifications.

They can look up what is in their catalog and find things close to what you're looking for too. Their service was really great!

[Ty_Bower]

I gave them a call, and talked for a short while. There isn't a "catalog", but they do have a database of different units they can produce. I'm assuming these were all custom jobs at one time or another. I didn't spend a lot of time asking them to search out everything that might be close, but I did jot down a couple notes. Maybe if someone sees something here that might be useful, it'll help them if they go to call. Be sure to ask and check carefully, since I can't swear I didn't accidentally write down some incorrect numbers. All of these come with a 120 volt, 60 Hz primary.

XPWR007, 275-0-275 @ 200mA, 6.3V @ 6A, 5.0V @ 3A
XPWR017, 275-0-275 @ 250mA, 6.3V @ 5A, 5.0V @ 3A
XPWR008, 300-0-300 @ 200mA, 6.3V @ 4A, 5.0V @ 3A ($57.33)
XPWR041, 340-0-340 @ 120mA, 6.3V @ 4A, 5.0V @ 3A ($51.01)
XPWR???, 370-0-370 @ 200mA
XPWR033, 380-0-380 @ 200mA, 6.3V @ 5A, 5.0V @ 3A ($59.48)

[nigelwright7557]

Originally posted by Zap
Just another option to consider, Edcor makes a Power Transformer that I just ordered a week ago that is 760V @ 200mA. George said it should work just fine, and it probably provides a bit more headroom. The additional plus is that it costs only about $60, so its rated higher than the Hammond, and cheaper to boot. If you're ordering OPTs from Edcor, you'll probably save some cash on shipping too.

The part number is XPWR033. Full specs, 760VCT @ 200mA, 6.3V (No CT) @ 5A, 5V @ 3A.

A cheap way to get an HT transformer is to use one transformer to get your 6V3 then step it back upto high volts using another transformer in reverse.

For my pre amp I used a mains to 12VAC (for heater on ECC83) then a 18VAC to mains to step it back up to 180VAC. It works a treat but using cheap off the shelf transformers.

You mentioned smoothing, to get rid of hum I used a PI filter with two caps and a resistor and this works very well.

One other problem occurred with the 1N5408 HV rectifier was switching noise this was coming through on my tweeters. I killed that with a small cap across the HT.