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A25 xover photos and ???

Guest vintfan

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Guest vintfan

Hello all, I'm new to this excellent forum. Quickly, I starded 4 years ago in audio addiction with mostly new and expensive gear until I discovered vintage stuff. My system now comprises of an CA-1010 Yamaha amp, CT-1010 tuner, Thorens TD-165MKII/Shure M91ED and Dynaco A25 speakers.

I'm still trying to figure out the different types of A25 models. From what I understand, there are 3 generations: First, ScanSpeak Alnico drivers with vent above the 1.5" tweeter. Second, Seas Alnico drivers retaining the 1.5" tweeter with vent below the woofer. Third, Seas drviers with new ceramic magnet woofer and 1" tweeter, vent still below the woofer, this time gaining 3dB in efficiency.

What puzzles me is the crossovers. I took out the xovers from 2 pairs with same ceramic magnet woofers but one pair has the 1.5" tweeter and the other 1".

Crossover no.1 has 6 resistors when I thought 5 was the max, the 5 px switch and a 5µf cap. Notice how the white wire seems to have been cut from the last resistor and inserted between the 5th and last. This all seems stock xcept for the white wire.

Xover no.2 has 3 resistors, what seems to be a small inductor, a 3 px switch and an 8µf cap. All stock this time. Would this be the A25XL xover?

I have the recommended Seas 27TFFC H881 tweeters installed with the ceramic woofers. I tried both xovers and the 6 resistor 5px switch units give sweet, rich and musical characteristics to my A25 compared to the 3 resistor 3px switch units which are harsh and shouty. Caps are all original for now but I have Solen film and foil in the waiting. Other mods are DNM reson wires installed inside with xovers outside the boxes for ease of change.

If you have any more details or suggestions to help me figure out these crossovers please let me know as I am trying to squeeze all I can out of this marvelous old design.








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Hi interesting pictures,

What is interesting is that the cone in your pictures looks like the older version used with the ALNICO woofers, but you say these are all ceramic magnet which suggests that they're another version than the F-EW that I've commented about. They should have higher efficiency, but not the increased output around 2 kHz that I've mentioned.

Most have the part number printed can you tell us what that is?

Your pair with the white wire moved, have the same design as every early A-25 I've ever seen, that would be 4 total. This leads me to think that they were perhaps upgraded with the ceramic woofer, and moving the white wire helped to match the levels by increasing the output. The moded design is the same tweeter XO as was used in the A-50.

The other pair probably are true A-25XLs based on the 3 position switch and 1" tweeter:


I'd be interested to know the part number for the 1" tweeter.

Pete B.

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Guest vintfan

Thanks for your reply Pete. To answer you questions, you know how the saying goes: a picture is worth....

I've also included my personal rendition of the A25 crossover with new parts. Note how I used the brown wire from the cap to either of the inductors to replace the switch. This wire is not soldered at the inductior's end for now, until I decide which setting I like best. Then I will add up the resistor values on each side and use only tow. The sound is very good with this xover. I would not say better but more stable.














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Thanks for the pictures, I've never seen that old 1" dome.

Here's a 1990 25F-EW, which as you can see has a very different cone, they must have revised it along the way, it does now have the H250 designation:




Pete B.

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Guest vintfan

How's the sound with this H-250 from the 90's? Is it a perfect match replacement without mods to the cabinet? Solen here in Montreal says the CA25RE408 (H250) is the replacement for the older 25F-EW. I looked at the parameters of both 25F-EW from the 70's and 90's and there seems to be small diffrences.




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>How's the sound with this H-250 from the 90's? Is it a

>perfect match replacement without mods to the cabinet? Solen

>here in Montreal says the CA25RE408 (H250) is the replacement

>for the older 25F-EW. I looked at the parameters of both

>25F-EW from the 70's and 90's and there seems to be small







I've commented that this later 25F-EW does not sound, or measure, right at all:


See also post #6 in that thread.

Those data sheets are interesting, I have the SEAS data book that includes the exact data sheet for the 25F-EW that you link to, but it does not include the CA25RE4 that you reference. SEAS made these drivers in a huge number of variations, paper with, no coating, edge coating, full coating, rubber edge, foam edge, and later with poly cones. There were versions with dynamic voice coil damping.

And many were available with different magnet sizes.

There is a CA, by the way the C stood for fully coated as I understand it, the A for paper, in this data book but it is the

CA25FEY. The cone looks like the later 1990 25F-EW, it almost

seems that this F-EW is mislabeled. The CA25FEY, in this data book, has a much more output above 2k as compared to the uncoated paper versions, just as I noted through listening, and it has a foam edge

by the way. The response doesn't begin to roll off until about 4 kHz, whereas the older uncoated F-EW begins to roll off above 2 kHz.

I think that this F-EW with the coated cone is a good driver, perhaps better than the uncoated, but it would require more crossover changes to correct for the extended response.

Pete B.

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