The ebay listing could be full of errors (or lies) for sure.
The ebay photos indicate completely different transformers than yours:
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Thank you!
Based on Transcendar's currently available products, that puts your OPTs somewhere between their 15 watt (2.2kg) and 20 watt (2.9kg) units.
I'm starting to feel like I am getting to the bottom of things now. Usually that means I am due for something to shift the paradigm and show me that I will never understand.
I am still puzzled how the Hammond 1628SEA can blast out the bass with only 16 Henries.
The ebay listing could be full of errors (or lies) for sure.
The ebay photos indicate completely different transformers than yours:
yes, if that is the one, then that is indeed different...i saw that one too...would be nice to know the specs, the specs you posted is definitely for the ones i have..
i suspect that those are EI75, a 1 inch core stacked to 35mm, i have those bobbins too...
this is pp opt i made using the EI75 core with brackets and end bells..
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I guess I will find out... in several more weeks.
I wish I could measure them and share the results here.
According to the data on Hammond's web site the 1628SEA is 48 Hy and 11 pounds.
Tube Output (25 - 75 Watts) Single Ended - HI-FI (1627-1642 Series) - Hammond Mfg.
this is a real big OPT, 1 3/4 center leg stacked to 3 to 4 inches from my reckoning, tbh, i have yet to make an OPT this big, the biggest i have done was 1 1/2 inch center leg stacked 2 inches, that was an 800 ohm OPT for a 6C33.....
core saturation is a function of power handling and naturally the bigger the core area, the more power it can handle..
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All this talk about SE is making me want to try it with my existing PP setup. I've already done it, and I can see that these transformers will take an imbalance of 100mA and not come all that close to saturation. I got bored once, and pulled half the tubes in an amp that was wired in a way that would work (usually I wire left as a pair and right as a pair regarding heaters. Each pair in series from 12V, but I have one amp that I wired cross-channel, so you can pull half the tubes and effectively turn it into an SE amp). It sounded good enough, but I didn't run any power testing on it. I would expect a pair of 250VA coils to work as a 5W SE transformer though.
Tony: Do you also wind toroids?
Tony: Do you also wind toroids?
Agreed. 5W or 100W of clean power? hmm... The only practical reason is 1/2 the electric power...
Then there is the other way of doing SE with a typical toroidal dual pri dual sec transformer. Connect it SE, and then inject voltage into the unused secondary to counteract the magnetic flux of the primary... I still haven't tried this, but I read about it and other than the wasted electricity, it should work fine. In my case, if the primary idle is 300V, 100mA, then I can put 1.67A through one of the 18V secondaries to null it (and waste 30W of power). Now that I've written that out, I realize, I could also use it like PP, but one half of the primary is connected with a CCS instead of an amplifying device... Same wasted power, just moved from secondary to primary, right?
Then there is the other way of doing SE with a typical toroidal dual pri dual sec transformer. Connect it SE, and then inject voltage into the unused secondary to counteract the magnetic flux of the primary... I still haven't tried this, but I read about it and other than the wasted electricity, it should work fine. In my case, if the primary idle is 300V, 100mA, then I can put 1.67A through one of the 18V secondaries to null it (and waste 30W of power). Now that I've written that out, I realize, I could also use it like PP, but one half of the primary is connected with a CCS instead of an amplifying device... Same wasted power, just moved from secondary to primary, right?
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They have conflicting information on their site, it seems.
I have a habit of going straight to the data sheets to find specs because typically that is where the most complete and accurate information is found (for any product, in my experience).
https://www.hammfg.com/files/parts/pdf/1628SEA.pdf
Check it out. Says 16.2 Hy. I do believe the 48 Hy listed on the website is actually correct. Thanks for pointing that out.
New Output Transformer Tube Amplifier Audio Single-Ended Z11 Oxygen-Free Copper | eBay
You can make an offer and get the price down a bit from there.
I read somewhere (can't find it now) that someone ordered these and got UL tapped versions.
Please note that these are just a roll of the dice. I do plan to try them out but I already know I will be buying something better (I'll get back to you via PM regarding that).
I may build another SET in the future and these Chinese ones may be sufficient for that project. Heck, they might even be good enough for my main system. Who knows?
I made some quickie measurements this morning that are sure to add to the confusion.....
I have one of those $20 Chinese "everything" testers, so I stuck the primary wires of several OPT's, and three chokes into the socket and pressed the "rest" button. The readings are probably useless as they stand, but some relative assessments can be made.
Triad C-7X choke. Rated 10 H 270 ohm. …….measured 12.87 H 239 ohm (confirmed with ohmmeter)
Mystery HP choke 12.02 H 242 ohm. It's similar to the C-7X.
Hammond 156C choke rated for 150 H at 3700 ohms tests as a 3420 ohm resistor
Toroidy OPT's repeatedly tests as a DMOS fet even though I'm only inserting two wires.
Transcendar "300B" OPT tests at 29.87 H and 273 ohms
Hammond 1628 SEA measures 28.61H and 167.7 ohms
Edcor CXSE 25 measures 19.44 H and 82.3 ohms
Old well used Edcor XSE15 5K ohm measures 13.75 H and 125.4 ohms.
I uploaded the wrong picture, which is now fixed, but they are now out of order. First picture is the Transcendar, then the big Edcor, then the small Edcor, then the tiny Hammond 156C, then the big Hammond 1628SEA
Note the bright metallic blue "pimp my ride" paint on the big Edcor. The early ones really did come painted like this. I guess it generated more hate mail than likes, so they changed to the current "bland blue".
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Thanks Cogitech,
Well they may well be just the ticket for your main system....after all they have features such as this.
"Designed with the latest bile fever concept"
"output cow is not afraid of cumbersome"
And of course the disclaimer.
"Please allow minor deviation due to manual measurement."
Gotta love the translation tools.
They certainly meet my original criteria so I hope they are good sounding units. Looking forward to hearing about them when they arrive, and I will have to pay you a visit when you get the amp done. I think I will hold off for now, still trying to decide which tubes for my first SET build.
Cheers
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Indeed those readings seem to be useless. The XSE15-5k is rated as 3 Hy and the CXSE25-5k is rated as 50 Hy, for example.
I was considering buying one of those testers and now I am thinking no.
Even the Edcor "bland blue" almost inspires hate mail. Rather than doing that, I'm just not buying them. Their $90-$110 USD shipping charge doesn't help, either (for us Canucks).
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Thanks Cogitech,
Well they may well be just the ticket for your main system....after all they have features such as this.
"Designed with the latest bile fever concept"
"output cow is not afraid of cumbersome"
And of course the disclaimer.
"Please allow minor deviation due to manual measurement."
Gotta love the translation tools.
They certainly meet my original criteria so I hope they are good sounding units. Looking forward to hearing about them when they arrive, and I will have to pay you a visit when you get the amp done. I think I will hold off for now, still trying to decide which tubes for my first SET build.
Cheers
Oh yes, you'll see all sorts of references to cows and bile if you look up transformers on ebay. Eventually you just come to expect it.
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