Identifying original 515B cone

[Bonzo75]

I am interested in driving the Altecs with low powered SETs and therefore have no interest in if the latter ones can take more power.

[GM]

OK, the 'best' is the original field coil 515 [how deep are your pockets], #2 original AlNiCo 515 [how deep, etc.] and at this point need to know if planning on using in a horn cab since only early 515B are best in horns with later Bs [and later recones] except 515C [ceramic] are more suited for vented cabs [lack the early 515's 'snap', though still a little 'sweeter' than 416s]. Having had early Bs, some with recones, I can attest that the difference isn't subtle, so sold the recones back when they were worthless for other than being AlNiCo.

Really, one can argue that the 515-8G, which even though ceramic is overall the closest to the original two performance wise in a horn. Once moving to the 'B' onward with Fs in the 20s we're trading efficiency for BW, which generally is going in the wrong direction for SET coupling where ideally it will be a high efficiency matching impedance one.

Jim Dickinson's excellent 515 'cheat' sheet: http://www.wmeckle.com/INTRO/LARGE/Altec.htm

That said, as you can see, short of buying from a one owner with complete docs, etc., what you can wind up with is a crap shoot without measuring T/S specs plus frequency, impedance response and if you buy to recone; other than what he sells, not sure Bill/GPA can replicate my early Bs based on some things said WRT when reconing some other models.

All that said, his 515-8G, pricey as it is now with the price hike, is quite the performer, a better 'fit' to SET tubes due to its ~38 Hz Fs and if it's a matching impedance I'd be surprised if one could 'blindly' hear any difference Vs my ancient '50s AlNiCo Bs unless it was one of those high power SETs where the ceramic can better control the driver [a bit more 'dry' sounding].

GM

[Bonzo75]

Thanks.

I have heard an 817 with 515-16g pairs in each speaker, and am EV 906 8g.

He said that the 515b and 288g would sound better, so that's my end goal.

I have now sourced myself the good looking 515b pair I posted above with the 21184-3 number, and an 21184-2 pair that came from the back of an A5 in a theater in Italy to an owner who sold them to me after using in an A,7. They also have a serial number that is 391837 and 391823. All are 16 ohms.

I hope this works. If it doesn't work in the 817 cabinet, I will try the G

[GM]

OK, 288 definitely a better 'fit' with 817. What horn you planning to use?

'391' is Altec date code

'8' can be '58, '68, '78

'23', '37' is week made

So these could be early or late...........

No clue what the '6' stands for unless made somewhere in Europe.

GM

[Bonzo75]

The horn is markus klug's wooden 1505.

This will be a long term project. Once the 817 is done I will play with the 288 swapping it out with TAD 2001 or adding a TAD tweeter, to check if it works. I am buying the Altec drivers now because they go up in price. The speaker gets built after I move from my current place to a new one which is a while away.

Ignore the 6, that was a typo. I was about to say the serial numbers are separated by 116 when my mobile when I must have typed in something wrong. Anyway based on what you said the serial number could be done over a period of time. The cones do have 21184-3 however

[Bonzo75]

What's the best way to store. If each driver is kept in an individual box, or together, does the magnet affect anything? Also, can stuff around the box affect the magnet?

[GM]

Guess it depends; I stored a pair of NOS 421-8H for years facing down in their boxes, but Ga. heat caused them to eventually sag completely out of the gap, so placed them face up and many years later they were bottomed out, so placed them out in the Summer sun till they slid back in and been storing them vertically in the Winter and regularly rotating them in Summer heat ever since to keep the surround goo from messing up the gaskets.

GM

[Bonzo75]

Interesting. So vertically over winter is the answer