There's a guy on this forum from one town over who seems like a good guy and he's obviously quite skilled with tube amps, but I'd feel kinda odd trying to connect with him in person. Terrible that the internet has reduced our ability to interact naturally. I would really like to reach out to him, but I won't because it's automatically "creepy". He'd probably be fine with it, except everyone around him would be saying "what?!! never meet up with people on the internet!"
Anyway, I think this problem is finally on the way to getting sorted. George was leading me in the right direction months ago and I am just figuring it out now.
So many times I have expressed how frustrating this has been for me. I can only imagine what it must have been like for George and the rest of you to watch this train wreck.
If/when I get the new power transformer installed, and it fries again after a few days, I promise to end this thread with a very satisfying video of my amplifier being shot dozens of times with my 338 Federal.
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Sounds like step one in an exercise of "pass the buck."
All of us have moments, and often extended periods of frustration. Sometimes it has to do with not fully understanding something well enough to get it right the first time. Continued attempts usually lead to better understanding. I can't recall how many times I rebuilt the engine in several cars, especially my first car, only to blow it up again. Eventually I learned how to build a George proof engine....only to find out that something else is now the weakest link.
After working my way up the food chain at Motorola from assembly line tech to product development engineer, Motorola offered to send me to an engineering college for a degree at their expense. The only realistic choice for an engineering degree while working full time was night classes in computer engineering at a college near my house. I managed to get a 4 year degree in 3 years while working. THAT was a frustrating experience, which taught me that I did NOT want to become a software engineer. It also resulted in the death of a certain computer by firing squad....only because I couldn't get dynamite!
To this day writing code pushes me to the point of wanting to break stuff, but now I know when to walk away and try again another day. I still have two nice music synthesizers, hardware done and working but waiting for me to finish the software. Bit by bit........
I know it's frustrating for you, but it is an educational experience for all involved. Compared to some efforts, this one is relatively minor.....the SSE is really Simple, there isn't too much that can go wrong, and I played the odds. NOBODY including me expected the power transformer to be bad, since despite the abuse I have given them Hammonds just don't die.....except now TWO have died almost simultaneously, and BOTH caused C3 to smoke. 40 years of training and manufacturing experience tells me that Hammond must have changed something (or someone) in their manufacturing process.
The biggest overall effort has to be in this thread:
6L6GC AB2 Amp
A bunch of people scattered all over the world guided the design and build of an amp. The actual amp was built in Australia while much of the design ideas came from me during a time when I didn't have the ability to actually try much if it. I guessed, and chrish in Australia built. It took nearly a year, Chris got his amp and I got a new PC board design.
I'll have to check out that thread some time, George. Sounds like a good one.
I called Mouser. After explaining my situation, the woman on the phone started with "well, the thing is, Mouser only offers a 90-day replacement on defective parts." I said Hammond offers a 1 year warranty and they told me I have to go through Mouser.
So she gave me an email address and told me to send all my info (order number, etc.).
Now the waiting game begins. Hard to believe they would play this game for the cost of a transformer.
If this doesn't work out, I won't be giving Hammond or Mouser any more of my money.
I called Mouser. After explaining my situation, the woman on the phone started with "well, the thing is, Mouser only offers a 90-day replacement on defective parts." I said Hammond offers a 1 year warranty and they told me I have to go through Mouser.
So she gave me an email address and told me to send all my info (order number, etc.).
Now the waiting game begins. Hard to believe they would play this game for the cost of a transformer.
If this doesn't work out, I won't be giving Hammond or Mouser any more of my money.
George, I am a bit puzzled about something. You list the Allied 6K7VG power transformer on your SSE page, along with the 274BX and the XPWR035.
You also state "The high voltage secondary should be 700 to 750 VCT (350-0-350) to (375-0-375) it should be rated for at least 175 mA DC output."
However, the 6K7VG is only rated for 150mA on the HV winding:
What really confuses me is that I have always been under the impression that the 6K7VG (made by Hammond, for Allied) is just a re-badged 274BX. Odd that the 274BX is rated at 201mA and the Allied part only 150mA.
Also odd that you have photos of running the Allied part with your SSE - does this mean 150mA is enough?:
...or did the spec of the Allied 6K7VG change at some point? Is it not just a re-badged 274BX?
You also state "The high voltage secondary should be 700 to 750 VCT (350-0-350) to (375-0-375) it should be rated for at least 175 mA DC output."
However, the 6K7VG is only rated for 150mA on the HV winding:
What really confuses me is that I have always been under the impression that the 6K7VG (made by Hammond, for Allied) is just a re-badged 274BX. Odd that the 274BX is rated at 201mA and the Allied part only 150mA.
Also odd that you have photos of running the Allied part with your SSE - does this mean 150mA is enough?:
...or did the spec of the Allied 6K7VG change at some point? Is it not just a re-badged 274BX?
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I made this statement in post #236
I started using the Allied 6K7VG in big guitar amps with 2 X 6L6GC's, KT88's or EL34's, (sound familiar) and the Allied 6K56VG in little guitar amps with 2 X 6V6GT's back in the 70's, and off and on ever since. I routinely beat them well beyond their specs without issue.
The Hammond 274BX that I have is dated 1999, while the 6K7VG's that I have are all dated 2004. They are NOT the same. The Allied transformer is actually BIGGER than the Hammond. It has about 1/4 inch more laminations and is therefore 1/4 inch wider and a bit heavier. Granted these are old transformers and the designs have probably changed since then.
The Allied transformer is rated to operate at 50 Hz and 60 Hz, while the Hammond 274BX is rated for 60 Hz use only. A transformer can usually be run harder at 60 Hz than at 50 Hz, so that may account for the current rating differences. Are these really the same transformer now? I don't know since I don't have any new ones to check. The spec sheet still shows the 6K7VG being 1/4 inch larger than the 274BX, but the Allied spec sheet is dated 2001.
By the book 150 mA is not enough. Most people run their output tubes around 70 mA each, and the 12AT7 gets 8 to 10 mA per side. There is also about 5 ma wasted in bleeder resistors. This puts the total draw at 160 to 170 mA.
I also know that a lot of SSE's have been built with 6K7VG's and people seem happy with them. My SSE was the daily driver for my computer speakers for about 3 years right after I built it. It was on whenever my PC was on which was a lot. I had the bias set at about 80 mA per output tube with some jumpers to go to 100 mA for bass heavy music. This pushed the total current to about 225 mA, and at that point the 6K7VG got HOT, too hot to touch. Again I considered a science experiment, and let it run hot. It's still in the amp today.
Would I put a 6K7VG in an SSE today, yes, but I still have some in their boxes from 2004, so why not. I bought a bunch for guitar amps when they were around $40 each. The newest Hammond I have is from 2009. I have no experience any of their newer stuff, either Hammond or Allied branded.
I started using the Allied 6K7VG in big guitar amps with 2 X 6L6GC's, KT88's or EL34's, (sound familiar) and the Allied 6K56VG in little guitar amps with 2 X 6V6GT's back in the 70's, and off and on ever since. I routinely beat them well beyond their specs without issue.
The Hammond 274BX that I have is dated 1999, while the 6K7VG's that I have are all dated 2004. They are NOT the same. The Allied transformer is actually BIGGER than the Hammond. It has about 1/4 inch more laminations and is therefore 1/4 inch wider and a bit heavier. Granted these are old transformers and the designs have probably changed since then.
The Allied transformer is rated to operate at 50 Hz and 60 Hz, while the Hammond 274BX is rated for 60 Hz use only. A transformer can usually be run harder at 60 Hz than at 50 Hz, so that may account for the current rating differences. Are these really the same transformer now? I don't know since I don't have any new ones to check. The spec sheet still shows the 6K7VG being 1/4 inch larger than the 274BX, but the Allied spec sheet is dated 2001.
By the book 150 mA is not enough. Most people run their output tubes around 70 mA each, and the 12AT7 gets 8 to 10 mA per side. There is also about 5 ma wasted in bleeder resistors. This puts the total draw at 160 to 170 mA.
I also know that a lot of SSE's have been built with 6K7VG's and people seem happy with them. My SSE was the daily driver for my computer speakers for about 3 years right after I built it. It was on whenever my PC was on which was a lot. I had the bias set at about 80 mA per output tube with some jumpers to go to 100 mA for bass heavy music. This pushed the total current to about 225 mA, and at that point the 6K7VG got HOT, too hot to touch. Again I considered a science experiment, and let it run hot. It's still in the amp today.
Would I put a 6K7VG in an SSE today, yes, but I still have some in their boxes from 2004, so why not. I bought a bunch for guitar amps when they were around $40 each. The newest Hammond I have is from 2009. I have no experience any of their newer stuff, either Hammond or Allied branded.
I have not heard back from Mouser. It is obvious to me that this will be a game of pass the buck. I will continue to be a pain in Mouser's and Hammond's butt, but I have accepted the fact that they are probably both going to screw me, so...
I went ahead and ordered an Allied 6K7VG directly from Allied. Yes, I know I am still basically buying a Hammond, but I feel better giving Allied my money (not Mouser) and to my pleasant surprise the Allied 6K7VG is only $99 CAD plus $15 DHL shipping. This is by far the best deal on a transformer for the SSE. I wish I had looked into this more before buying the Hammond from Mouser, for $148 CAD. An added bonus - Allied provides the ability to RMA defective parts directly on their site.
Who knows, maybe Mouser will surprise me and honour the Hammond 1 year warranty. I won't mind having a spare.
I went ahead and ordered an Allied 6K7VG directly from Allied. Yes, I know I am still basically buying a Hammond, but I feel better giving Allied my money (not Mouser) and to my pleasant surprise the Allied 6K7VG is only $99 CAD plus $15 DHL shipping. This is by far the best deal on a transformer for the SSE. I wish I had looked into this more before buying the Hammond from Mouser, for $148 CAD. An added bonus - Allied provides the ability to RMA defective parts directly on their site.
Who knows, maybe Mouser will surprise me and honour the Hammond 1 year warranty. I won't mind having a spare.
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Back in my youth there were only two mail order parts catalogs, Lafayette Radio Electronics, and Allied Electronics. Lafayette carried Birnbach's transistor amplifier boards which I used for low powered guitar amps. 1 watt of germanium power for about $10, a lot of $$$ when I was making $1.05 / hr.
Lafayette died with the end of the CB radio boom and Allied got eaten up by Radio Shack in the 70's and the catalog vanished for a few years. They survived long enough to be bought by the giant that operates another RS (Radio Spares) in the UK and the catalog returned.
They have an "excess inventory" page that often contains for good stuff for budget prices. I got a bunch of 500 volt electrolytics there several years ago.
6K7VG just landed on my doorstep.
I can confirm this is definitely not just a re-badged Hammond 274BX. The plate stack is a good 1/4 inch thicker (as George said), it is heavier (obviously) and all the tap wires come out one side (whereas they are split between the two sides on the 274BX.
Oddly, the branding on the label is Hammond, not Allied. I hope to have time to get it installed and do some testing on Sunday.
I can confirm this is definitely not just a re-badged Hammond 274BX. The plate stack is a good 1/4 inch thicker (as George said), it is heavier (obviously) and all the tap wires come out one side (whereas they are split between the two sides on the 274BX.
Oddly, the branding on the label is Hammond, not Allied. I hope to have time to get it installed and do some testing on Sunday.
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