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Dynaco A-25 Philips variant

Pio1980

Pio1980

AK Member
Been looking for A-25s for a couple decades as I've somehow never encountered Dyna speakers. Found scroungy pair of A-25s with Philips style stepped front white dome tweeter, 5 position switch, and Alnico plug magnet woofer with grey blanket box liners, all looks stock and unmolested bedded into the black tar goo. One woofer spider has sagged and due to the tight clearance in the gap, I inverted the woofer to reverse the sagging. Sounds as good as rep and quite appealing overall in spite of horrid storage and handling.
 
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Well, Crap!

The woofers have gone noisy during run-in. If the spiders have come loose they may be repairable, if the VCs rattling then probably not.
 
I hope you can repair them. I love mine. Any chance the noise is due to part of the surround coming unglued and flapping a bit? That could be an easy repair. If you get the noise to happen by gently depressing the cone by hand (without playing music) then you might get a better idea what is going on.
 
Well, benched them with a signal generator on a small utility amp. One is doing great now with LF sweep, the other has a warped spider pulling the VC off-center. Not sure what comes next but may try wetting the spider with denatured alcohol to see if it softens it enuff to force recentering.
 
Pix of the variant's drivers

Here goes, look familiar to anyone?
The mirror image is the backside of the tweet. Note that the driver wiring is heavier guage than the common versions.
Drivers were originally sealed with tar to baffle with four trim screws each seating them into the tar. The grey goo is duct seal compound I used to reseal them on to the baffle.
 

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The tweeter is a Belgian-made Phillips from the 70's.
They were VERY popular back then, and went into a LOT of different speakers (Avid 102 for instance).
The alnico-magnet woofer looks like a CTS/Eminence?
The manufacture number for CTS is 137.
The manufacture number for Eminence is 67.

Steve
 
Nothing visible in the pictures looks like a dyna A 25 -- neither driver, the particle board front baffle (though the aperiodic vent is not visible, and that would make them look more familiar. Why do you think they are A 25s?
 
Because they are configured so with the plastic vent grille below the woofer, have the (1) Dynaco baffle cover nameplate, and 2 other A-Kers reported having this version in past postings. Trust me, I've cross-checked many pix and these are original OEM A-25s tho' the only ones like this I've seen.
 
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It's a Peerless woofer.I have a pair of these myself,but with the later greyish grill,they're called Scan-Dyna.In this picture below there's a Seas woofer however,so both are possible...who said the A-25 history was simple?
Scan-DynaA-25variant1974.jpg

With a Peerless woofer and Philips tweeter:
dsc0067yf9.jpg
 
Weird -- I don't speak Danish either, so I don't know if those pictures are showing A 25 variants or homebrew improvements. But the Skan Dyna was a driver manufacturer as well as a speaker builder(?) before David Hafler came upon them and got them to produce speakers for him. So its odd they would use other manufacturer's drivers. And that woofer (in both the picture by the OP and the danish website) has doping on the outer edge of the woofer, something I have never seen in the many A 25s I've seen or in their literature, or in the picture from Skan Dyna literature posted. Nor have I seen tweeters glued in with black stuff, and grills held on by glue, even though there appear to be the staples or holes made by staples that once held on the velcro. And then there is the logo glued onto the terminal plate (though partially scratched off) -- maybe these were a distributor variant? Beats me.
 
Nat, The Peerless woofer's cone is heavier and denser than the one normally seen. It seems to be an excellent mid-woofer. I can't account for the stinginess with the mounting screws. I seem to get better midrange fill-in with the switch up one step from center "NORMAL" position.
I would like very much to find another of this Peerless woofer.
Rolf, Thnx for contributing.
 
I poked around a bit and found a danish(?) thread about A25 variants with bunch of Seas kit literature, posted, if memory serves, by Rolfe. The variants I saw weren't visibly aperiodic, if that matters. But their frequency response curves were notably more flat than that attached to the Peerless driver A25. So maybe Seas changed to their own drivers later to improve the design. But that's a WAG.
 
That curve on the SCAN-DYNA sheet is with the Scanspeak/SEAS style woofer, not the Peerless. The one in the photo is ident to mine and the Philips/Peerless variant like mine.
 
Yeah -- just wondering if it suggested a lower efficiency for the Philips tweeter, or less power handling. Same woofer, noticeably different high end curve.
 
I have not heard both versions, just this one, so I cannot say what the subjective differences or what a consumer RTA might demonstrate. Does the standard version have a choke in the x-over?
This sketch and pic for the Philips/Peerless variant is from the Danish forum;
 

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Standard xover

A-25/35 SEAS/ScanSpeak xover, no choke, different value HF coupling cap.
 

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Very interesting -- the lack of a coil would allow more high frequency output from the woofer, and the resistor values are also lower. That probably explains the more balanced frequency curve. (I realize I didn't even look at capacitor values, which would also affect things).
 
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