No, but I could guess that they are likely a China set of trannies. That is not a bad thing, they are just not as reliable or consistent as many USA-made units. Unfortunately, Classic Tone has gone out of business and they don't look like CT branded units. The ones you have will be as good as any amp made in china ( which is most of them... ).
I believe that transformers are a bit of an inflated selling point for an amp. They are all made just as they were 60+ years ago. And you cannot convince me that the metallurgy of today is worse than it was 60 years ago... That being said, what makes a good transformer to you, me, or anyone else? A working one is what. I have played with Mercury, Classic tone Heyboyer, and cheap China units and you know what the difference was between them? They each sounded slightly different, but they all worked and none was appreciably better than the other. Every manufacturer today says they have a " custom made " O.T. It's a crock of bull crap. They do in fact have a custom Tranny set, one that was built to their spec and has their name slapped on it. You know what else has a spec and you can put your name on? A China set of Trannies that don't come branded and are made for the amp du jour you are building. I bought a Classic Tone O.T. to replace the China unit I was prototyping my amp around and there was no difference in sound or quality. In fact, the China unit was made a little more balanced on the two primaries ( the resistance between each primary lead to the Center Tap was more equal ) than the CT unit was. The China unit has a plastic bobbin and the CT was waxed paper. Absolutely no difference between them sound or performance wise.
Transformers are expensive and should last for the life of the amp. So there generally isn't any reason to go out and buy 5 different O.T.'s to try and get a better tone from your amp with. So the manufacturers shroud the market in mystery, buzzwords, and other selling points to make theirs be the first and the only one you purchase. Amp makers need a way to sell their amp and what better way than to make you believe their transformer set is special and you can't get another like it. The whole thing about the O.T. being the heart of the amp and all. A custom transformer set is simply made to the vendor's spec and has perhaps a higher level of consistency between each set. All this means is that the transformer was made to suit that amp and is made to a tighter tolerance than perhaps other off-the-shelf units.
An O.T. has a primary impedance and there is a range or tolerance it can be made within to suit a particular tube type or design goal. An output tube has an ideal range of primary impedance that it wants to see from the O.T. Where the O.T.'s primary resistance sets in that range can have a pretty large effect on the sound of the amp. This is why the sound of the amp changes a little when you use the wrong impedance setting on the amp for the speaker cab you have. The secondary of the O.T. ( which includes your speaker load ) is reflected through the transformer onto the tubes. This reflection is based on a ratio/conversion and changes how the tubes operate/sound. Often the only major difference between one output transformer and another is the primary impedance. A difference of a few ohm's can change things quite a bit. What sounds better is in the ear of the beholder.
Does a Mercury Magnetics transformer set sound better than a China-made set? It better, the MM set probably costs 3X as much! The construction of the unit does have a small ( read that as perhaps only just audible ) impact on the overall sound. The single largest impact on the sound will be the primary impedance though. If you have a set made with considerably more iron content than another, you may also notice a change all else being the same. Like most things, a transformer is the sum of all parts and there are not too many parts in a transformer to change. So if two different transformers from two different companies are made to relatively the same spec, they should sound very close to the same if not identical. When you start changing every aspect of how a transformer is made vs. another for the same amp design, there will be more evident changes in sound, but whether it actually sounds better is up to you.
I think O.T swapping is a slippery slope. You can spend a lot of money to only get a small change and you may or may not like it. You can spend Mercury Magnetics money and it may be better than the original, but you will have spent half the price or the amp to get that little bit better, or perhaps not? I always suggest going with what your budget allows. Like most things, you tend to get what you pay for. I'm not saying MM is better, they have the largest marketing budget and their units cost more as a result, but if deciding between a Classic Tone, a Heyboer, an Edcor, or a Mercury Magnetics, go with the one that best meets the design needs of the amp at hand first and then go with the highest dollar your budget will allow second.
You hear all those stories about Ken Fischer, Dumble, and others alike that reject 30% of the components they receive because they don't sound right yadda yadda, well that is likely them slightly embellishing it a little and also very likely them trying to get the sound they want from the amp and having to change half the stuff out to finally find the part that made the difference they needed. I wouldn't find it hard to believe that an O.T. could be the culprit for what makes an amp sound this or that enough to go searching for a solution. On the other hand though, if the shop was 100* the day you fell in love with the sound of the amp you made that day and the next day the shop was 60* and you weren't happy with the sound of the next amp you built, it could simply be the temperature of the shop and nothing else. So many variables come into play.
I believe that transformers are a bit of an inflated selling point for an amp. They are all made just as they were 60+ years ago. And you cannot convince me that the metallurgy of today is worse than it was 60 years ago... That being said, what makes a good transformer to you, me, or anyone else? A working one is what. I have played with Mercury, Classic tone Heyboyer, and cheap China units and you know what the difference was between them? They each sounded slightly different, but they all worked and none was appreciably better than the other. Every manufacturer today says they have a " custom made " O.T. It's a crock of bull crap. They do in fact have a custom Tranny set, one that was built to their spec and has their name slapped on it. You know what else has a spec and you can put your name on? A China set of Trannies that don't come branded and are made for the amp du jour you are building. I bought a Classic Tone O.T. to replace the China unit I was prototyping my amp around and there was no difference in sound or quality. In fact, the China unit was made a little more balanced on the two primaries ( the resistance between each primary lead to the Center Tap was more equal ) than the CT unit was. The China unit has a plastic bobbin and the CT was waxed paper. Absolutely no difference between them sound or performance wise.
Transformers are expensive and should last for the life of the amp. So there generally isn't any reason to go out and buy 5 different O.T.'s to try and get a better tone from your amp with. So the manufacturers shroud the market in mystery, buzzwords, and other selling points to make theirs be the first and the only one you purchase. Amp makers need a way to sell their amp and what better way than to make you believe their transformer set is special and you can't get another like it. The whole thing about the O.T. being the heart of the amp and all. A custom transformer set is simply made to the vendor's spec and has perhaps a higher level of consistency between each set. All this means is that the transformer was made to suit that amp and is made to a tighter tolerance than perhaps other off-the-shelf units.
An O.T. has a primary impedance and there is a range or tolerance it can be made within to suit a particular tube type or design goal. An output tube has an ideal range of primary impedance that it wants to see from the O.T. Where the O.T.'s primary resistance sets in that range can have a pretty large effect on the sound of the amp. This is why the sound of the amp changes a little when you use the wrong impedance setting on the amp for the speaker cab you have. The secondary of the O.T. ( which includes your speaker load ) is reflected through the transformer onto the tubes. This reflection is based on a ratio/conversion and changes how the tubes operate/sound. Often the only major difference between one output transformer and another is the primary impedance. A difference of a few ohm's can change things quite a bit. What sounds better is in the ear of the beholder.
Does a Mercury Magnetics transformer set sound better than a China-made set? It better, the MM set probably costs 3X as much! The construction of the unit does have a small ( read that as perhaps only just audible ) impact on the overall sound. The single largest impact on the sound will be the primary impedance though. If you have a set made with considerably more iron content than another, you may also notice a change all else being the same. Like most things, a transformer is the sum of all parts and there are not too many parts in a transformer to change. So if two different transformers from two different companies are made to relatively the same spec, they should sound very close to the same if not identical. When you start changing every aspect of how a transformer is made vs. another for the same amp design, there will be more evident changes in sound, but whether it actually sounds better is up to you.
I think O.T swapping is a slippery slope. You can spend a lot of money to only get a small change and you may or may not like it. You can spend Mercury Magnetics money and it may be better than the original, but you will have spent half the price or the amp to get that little bit better, or perhaps not? I always suggest going with what your budget allows. Like most things, you tend to get what you pay for. I'm not saying MM is better, they have the largest marketing budget and their units cost more as a result, but if deciding between a Classic Tone, a Heyboer, an Edcor, or a Mercury Magnetics, go with the one that best meets the design needs of the amp at hand first and then go with the highest dollar your budget will allow second.
You hear all those stories about Ken Fischer, Dumble, and others alike that reject 30% of the components they receive because they don't sound right yadda yadda, well that is likely them slightly embellishing it a little and also very likely them trying to get the sound they want from the amp and having to change half the stuff out to finally find the part that made the difference they needed. I wouldn't find it hard to believe that an O.T. could be the culprit for what makes an amp sound this or that enough to go searching for a solution. On the other hand though, if the shop was 100* the day you fell in love with the sound of the amp you made that day and the next day the shop was 60* and you weren't happy with the sound of the next amp you built, it could simply be the temperature of the shop and nothing else. So many variables come into play.
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