Questions about RCA 5751tubes

Me, if I ordered and paid for a Sylvania 5751 triple Mica tubes, I should get a Sylvania 5751 triple Mica tubes, period!

I do not need someone telling me that the RCA is better sounding than the Sylvania etc. etc. The bottom line is, you should get what you paid for. What if the Sylvania sounds better to you than the GE or the RCA? Only you can tell in your system.

Oh, the label(1 and 2) is the Gm measurements of the tube where (first one indicates triode 1 and the second triode 2 for the 5751 which is dual triodes) which, in most instances, many confuse as an indication of the tubes being the numbers to match so that the tube pair can be called "match pairs".

"1.5," "1.6," "1.7," and "1.9" do not appear to me to be representative of filament draw. The 5751 is listed in my older GE tube manual as drawing 0.175 amps at 12.6 volts. If the 1.5 were amps, it would mean nearly 19 watts filament dissipation, which is obviously wrong for a low power dual triode. I don't know what those numbers would represent.

That tube manual lists gm (transconductance, also referred to as mutual conductance) for the 5751 as 1200, without specifying whether that is average, minimum, etc. My Hickok 800A tube tester lists 1250, specifying that as being for an "average tube," NOT an "average new tube," which it indicates will "be higher." So 1300/1350 would seem to be reasonably good numbers, while 1640/1740 sounds excellent, although the difference between the two sets of numbers leads me to question how well matched they are. The numbers before and after the slash, btw, I would assume are for each of the two triode sections within the tube.

HTH,
-- Al

Mechans:
I love the humility.. And I think we are all jackass's
for being so nuts about musical reproduction. So much
more in life to do and we get all crazy about audio..

You should get what you order no matter what ..No excuses,,,Unless the person selling has a problem and contacts you with an explantion,it ain't the right way to sell......If you order a new Ford and the Salesman drops off a new Chevrolet at your doorstep..You may or may not be too happy.....

I really cannot speak for the group and cast braod aspertions about the general nature of humility. Tom92602 is clearly not a silly audiophile but a very correct and presumambly serious fellow. He is not a Humble Jackass I aplogize.
I missed one Huge point I really made an idiot of myself.
I thought our OP had asked for RCA and got JRC. I see now he asked for Sylvania and got RCA. this is truly no sarcasm intended at all criminal. That kind of behavior earns dealers a questionable charater tating in this case there is no question he is totally wrong by subbing which ever tube he deems fit too. I mean this perhaps that should be punishable with sanctions and a ban from Agon. Our poster should recieve a pair of excellent triple mica Blackplate 1950 vintage Sylvania 5751s. If he is not allowed to exchange them I will offer a pair of my own to barrow long enough to get an idea of what they are like.
OP please contact me through the AGON mail system.
I am not a dealer but have many tubes and may sell some in the future.
That is the only disclosure of potential conflict of interest I can think of. I do not have Sylvania 3 mica BP 5751s for sale only for him alone to borrow. I have JHs, Gold Brand, (? 3 mica) and Sylvania consumer regular. Many have rubbed or warn print but there is a way to identify them that readily distinguishes them from the JRC RCA which have almost Identical plates and getter rings.