I recently got the power and output iron from an old Scott Amp or receiver. The power transformer (TR15), appears to have been used with ~30W/channel units with 7591A output tubes. The output transformers are TRA-8-5-2, and I haven't been able to find any info about them on the web so far. If they really belong with the TR-15 power transformer, I would suspect them of being 30-35W capability, but I'm not sure. They certainly look hefty enough. Can anyone out there offer any clues?
I saw that page, too, but the output transformer numbers I have don't match what's listed there, though the power transformer number does agree. I had one of the output transformers on the bench, and it checks out at 6k plate-plate primary impedance, with primary inductance almost too high to measure under large signal excitation (~300H). Sure looks like a 7591A transformer to me...
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If it works with 7591s, it works with 6L6s.
Scott "iron" lacks UL taps. How about AB2 triode wired 6L6GCs?
Hard to say at this point - I may do something fiendish with sweep tubes. I'm getting in quite a windfall of classic iron. How did the Scott output transformers compare to similar Fisher units? So far, I have output transformers for Fisher 500B, 500C, 400, and now these Scott things.
I don't know about specifics, sorry. Neither Fisher nor Scott used junk and their stuff was priced accordingly.
Well, the way my "Kingfisher" amp sounds indicates that the old Fisher iron was good stuff, and that amp used transformers from a 500B. The 500C transformers are supposed to be even better. I'll have to think a bit to come up with an appropriate use.
Our EL84 Class A triode El Cheapo variant uses a Scott LK48 as a donor, and it is a stunningly little amp. Nice iron.
dave
dave
The only EL84-ish iron i have around at the moment came from organs, along with a pair of Sony SE transformers from (I think) a R-R tape deck. I haven't measured the characteristics of those transformers yet. As far as 6L6-type iron is concerned, all the organ transformers I've gotten in so far have inferior characteristics as compared to the Scott and Fisher iron (at least as far as primary inductance is concerned). This is to be expected, as the Scott and Fisher units have lam stacks that are about 3X thicker than the organ transformers. Having said that. I'll be trying to use a pair of 6K Wurlitzer transformers in a new creation. More information (and a new thread) when it gets going.
Possible home for a pair of the Fisher 500C transformers - P-P amp using 300B or 6S4S in A2 mode. Since the price of even 4 Chinese 300Bs is a bit heart-stopping, I may go with the 6S4S instead.
The Sony SE ones are TamRadio and really quite good. The 600 ohm secondary can be used to feed a sub amp.
dave
dave
It was VSAC 2003 (IIRC) when the Oregon Triode Society, after testing a number of output transformers, decided on a group build using Fisher 500C outputs in a 300B PP design. I have used them in that application as well, sound wonderful. I currently have a pair in a triode wired PP 6CA7 amp that uses a 12AT7 diff driver. Again, sound very, very nice. I also have a good supply of Scott transformers. As was mentioned, none of it is junk.
By the way, the Fisher 500B iron is also nice and it is physically a bit smaller than the C.
I didn't get the power iron, but I have enough odd bits floating around that may make the grade. A custom SMPS is also a possibility, making for a very compact package indeed.
My Sony SE XFMRs have the similar color coding (same primary colors, yellow for 600 ohm output tap), have flying leads. The number stamped on top is 1-427-041-05. They are definitely 5k, and with a large signal primary inductance of ~29H.
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I did some searching around, and mine look exactly like those in the thread here called "TamRadio/Sony SE OPT's". Nice to know they're famous. I may treat them to something more authoritative that a pair of 6AQ5s, though.
I just receied a pair of fancy-pants Fisher 500C output transformers today, and intend to reserved them for the triode p-p application I mentioned earlier in this thread. An idle question - what would it take to significantly better their performance with currently produced transformers? James? Hashimoto? Lundahl? Do tell...
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