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Diogenes

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  • Birthday 06/04/1982

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  1. Your best bet is to just watch out for a used SEAS 25 TV-EW on eBay and go with that. Matching parameters with new drivers will be difficult and require replacing both since the other original woofer will have suffered loss of flux over the years anyways. (So, better to get another that's aged similarly.) You'd also run into fitment issues with newer drivers as the recess goes right up against the sides of the baffle in these.
  2. Yours are stock production A-25s. It's just that they're from the couple of months in 1970 when SEAS was having severe production issues leading to supply shortages to those using their drivers and Scan-Dyna (the builder of the speakers for Dynaco) had strained relations with them due to their founding Scan-Speak with a couple of head hunted SEAS engineers and a bit of industrial espionage in driver design. (It was big news in the region at the time even receiving mention in some Danish newspapers.) Since Scan-Dyna couldn't get SEAS drivers and Scan-Speak hadn't geared up yet for driver production, they had to fall back on the Philips tweeter in lieu of the SEAS H087 and Peerless L100WG in place of the SEAS 25 TV-EW woofer. The crossover had to be tweaked with the addition of the inductor as the woofer didn't roll-off naturally the same as the SEAS and needed help to blend with the tweeter. As for the tweeters not working, that's probably due to bad caps. That's a very common issue with these. Since you have them apart, it wouldn't hurt to take a multimeter and check the tweeters and resistors just in case something else has gone bad.
  3. Yeah, you're definitely seeing issues from softening spiders, hardening surrounds and, the most significant impact, loss of flux strength in the alnico. Just to help, here's a more complete set of factory parameters for the 8ohm version of the 25 TV-EW: The round frame SEAS drivers were introduced at the same time as the 25 F-EW. They're actually the F-EW's basket, but were used on the 25 TV-EWs that continued to be produced only on an OEM basis for Dynaco and others. That's if they're marked as SEAS. The Scan-Speak clones always had the round frames.
  4. It's understandable, folks tend to figure any unusual A-25 must be an early one. For the record, this is what an early A-25 from the initial run looks like: For your Hatras, I've not yet found any literature for them, but I'd venture probably ~1975 from what I can tell.
  5. The brand is "Hatra". There should've been a label across the aperiodic vent that said it, but those often fall off over time. It was a European brand, as you can tell, and built by the Danish crew behind the Dynacos. Though, by the time of these, I couldn't tell you what they were calling themselves. Scan-Dyna, Scan-Speak, Scan-Sonic, Dantax...all the same people, different companies yet not and confusing ownership that's for sure. Most likely happened after Hafler bought into ownership of Scan-Speak, but before his people there started also building Ortofon speakers. Anyways, Scan-Speak drivers with the Scan-Speak "Vario-Vent", as you guessed. Not common speakers, but basically newer versions of the Scan-Dyna A-30 MkII. Here's an example of another set of Hatras like yours where one of the labels is still intact (they weren't properly marked on the back either):
  6. Factors to consider: these are old drivers. Rubber surrounds are not immortal, they stiffen with age (plasticizers leach out and the flexible long chain polymers break into shorter molecules that results in a hardened material). This can drive Fs up as compliance goes down. In contrast, spiders get very soft with age, which can drive Qms way up. These two factors interact with one another, so it's hard to say which way things will end up. Most importantly, these have alnico magnets. Alnico V, the kind used in these drivers, loses ~3-5% of its flux strength per decade just sitting on the shelf and more if it's being exposed to temperature swings, shocks or a magnetic field such as is formed by music being played through a voice coil. Too much power, a clipping amplifier or even just touching the input lead on an amp and causing a ground hum can cause significant demagnetization of the drivers. When the Dynacos were new, Dynaco, Scan-Dyna and SEAS were seeing high rates of woofer returns due to loss of flux, upwards of 30% typically, from the speakers being used. It was a major impetus to SEAS to develop the ceramic magnet 25 F-EW, long before the civil war in Zaire led to the cobalt crisis that forced other manufacturers to change over, as ceramic doesn't have the demagnetization issues. You're most likely measuring the after effects of significant loss of flux strength in the motors, softened spiders and hardened rubber surrounds. This makes it hard to get old Dynacos to match in mismatched pairs, actually, if they haven't been exposed to the same environment and use all their lives. Your only options are to completely tear the drivers apart, have the motor remagnetized and recone them (not recommended as you can't get the right parts anymore), or buy a few more drivers and test them until you find a set that match 'close enough'.
  7. 68lbs on those A-350s per the specs (the immediate predecessor, the Model 350, was 87lbs but only about 200 of those were made), so it seems you'll be dealing more with awkward bulky weight than sheer mass. Be surprising if you can find many others who have had them, those A-350s are rare speakers from the time ESS owned the brand. Very unusual with their pseudo-omnidirectional design courtesy the piezo tweeter firing into a reflecting cone.
  8. There were two A-30XL, early production with a SEAS tweeter and late with the Polydax HD100D25. These are the specs I have for the early unit, which should be the same as the later: Power handling is a pretty meaningless number. Back in the days when reviewers actually did measurements rather than give subjective drivel, speakers were tested with transient bursts in excess of 2kW before compression caused distortion. Just make sure you have amp enough and don't call on them to play unreasonably loudly (small speakers aren't made to play loudly in a large space). Clipping kills speakers, not too much power unless you're playing sine waves or expecting too much excursion from the driver.
  9. Early 303As were indeed glued on and possibly nailed as well. I had a set that needed their woofers repaired that had silver threads through the grille cloth (to help date them) where the grill was absolutely impossible to remove. I tried prying to the point of hearing cracking wood and had to give up at that point lest I destroy everything up front in the effort. Ended up giving them to another fellow and he had to resort to using a circular saw to cut open the back as he couldn't remove the grilles either. Shame the only method that worked was so destructive. The woofers were interesting being an early example of a slit cone to control resonances with tape to seal against leakage. It was the old tape falling off and flapping against the cone that had caused the woofers to rattle and need repair.
  10. Dynaco did make a handful of three-ways, but you're probably right about them being earlier production A30XLs before switching to the Polydax/Audax tweeter. Look like what you have?
  11. The A-25XL used the 1" SEAS H086, which was a marked improvement (smoother response, lower distortion, greater extension, ferrite magnet over alnico so no longer susceptible to loss of flux from overpowering) over the 1.5" SEAS H087 used in the A-25.
  12. Diogenes

    Scandyna A-30X

    Too many years too late, but this page has some specs for this particular series of Scan-Dynas: Hifigoteborg - Scan-Dyna Speakers
  13. Here are some specs for yours, ~'75 as well. The wire tail in lieu of banana jacks was pretty typical of European built speakers for the European market at the time.
  14. Those are the Scan-Dyna A100 from 1975/6.
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