Updated Dynaco A25 schematic

[Pete B]

They're ceramic. No H number, I don't believe.

I'll be doing a build with these soon, and will run the impedance, Fs, and Q, at least, and post them here. With some head scratching, I could likely get Vas, as well, since I have closed boxes for them....

I'd go traditional vented tuned to 35 Hz, might put an extra thick layer of damping on the back wall.

Not sure if that is listed here but you might want to have a look:
http://www.seas.no/index.php?option=com_content&task=view&id=33&Itemid=57

 

[Zilch]

Thanks, Pete,

There seems to have been an earlier "ER" variant from the '70s, 4 Ohms, with lower power handling and response to 9 kHz.

Gonna be fun figuring out what these are and hearing them.... :thmbsp:

 

[Rolf Zetterberg]

Taken from SEAS own papers:
25F-EW 89dB
25F-EWX with a stronger(=bigger) magnet 91dB
25F-WB with the weakest magnet,but with a lighter cone(22g instead of 33g),35Hz instead of the other two's 25Hz which results in 93dB and rec crossover fr 3000Hz instead of 1500Hz.