Thanks.@prof
I didn't totally follow all that, but that's due to my level of ignorance.
Don't feel bad. A lot of designers don't get it either!
Good question. Cartridges are very different in how they respond to loading. My Denon 103 is a 14 ohm cartridge (as I recall) and likes 100 -200ohms load. More load drops signal level, dont ever go that far, and makes the sound rather dead. No load is rather bright.Roger, you might want to do some reading at the links I posted in my prior post. Most of this post (except perhaps the comments about subjective listening) is incorrect. As I pointed out earlier, the load is not for the cartridge's benefit- its about the preamp.
On the other hand the Lyra cartridges are so low in impedance that they dont respond to loading so we, in the SF audio society did some tests and found the Lyra best unloaded.
There is not any relation to speakers and amps that I would care to make. A cartridge is a source, the load is a resistor. Not much else going on.
The 6SN7 was made for black and white TV and was never, to my knowledge, used in the audio chain.There's plenty of old school audio electronics that used the 6SN7. As you know, its geometry is similar to that of the 6CG7/12BH7 and 12AU7 (the latter being the same as the 12BH7 but with the entire structure sawed in half). If you need examples, Google:
https://www.google.com/search?client=ubuntu&channel=fs&biw=1440&bih=729&tbm=isch&...
Now if the 6SN7 is not really a good audio tube, why does VAC use it on the entire line of amps as input tubes? He could have used a 6SL7 or 6CG7 or variant.Its because it *is* a good audio tube. That is why so many manufacturers used it on the old days, prior to octal based tubes being replaced by miniature tubes. Its considerably less microphonic than 6DJ8s, although almost any signal tube has to be hand picked for low microphonics.
Folks, you can't just pull a tube out of a box and expect that it going to do the job. It really should be tested, but testing for microphonics means listening to the tube to see if its acceptable.
I don't agree with George's comments about microphonics equating to euphonic character! As anyone who has played with tubes knows, microphonics is *not* musical or euphonic. If you hear that quality in a microphonic tube, its doing that **in spite** of the microphonics!