I recently purchased a pair of these from Meniscus. They are not on their website yet. I e-mailed my inquiry. Mark hooked me up.
Seas website blurbs:http://www.seas.no/index.php?option=com_content&view=article&id=561:prestige-titan-launch-news&catid=41:news&Itemid=194http://www.seas.no/index.php?option=com_content&view=article&id=556:h1825-06-27tac_gb&catid=45:seas-prestige-tweeters&Itemid=462
Here is the retail price and info on MAD, just for more information:https://www.madisoundspeakerstore.com/hard-dome-tweeter/seas-prestige-27tac/gb-h1825-aluminum/magnesium-dome-tweeter/
It supposedly is simply an improved 27TBFC. Copper cap where there was not one before, titanium (Titan line) voice coil former, a reshaped and carefully damped chamber, as well as being shipped/sold in matched pairs. I'll admit, the $91 price tag seems a bit high for production with a glass-reinforced plastic faceplate, but truth is you don't find titanium formers in very many drivers that cost less than $100. Normally they are aluminum, glass fiber, or Kapton. Seas uses a Corian material in their diamond line tweeters, so maybe they don't use metal faces often either. (I see Excel units are cast faces) The faceplate is really thick when it comes down to having plastic faces of any sort, along with what appears to be a metal hexagrid. The chamber cup and integrated divot remind me of those in the DX/XT line from Peerless, basically a sinusoidal curve of Pi length rotated around the Y axis. It's not quite a half-torus shape. Being that the TBFC is a bit splashy, and these have a copper cap to reduce HD, that is what tickled my fancy. More on the tweeter choice will come when I start posting info about the design path.
My first run-ins on the trusty ol' S&L WT2 left me perplexed, as this is the spec sheet info:
I see the spec sheet as 900 Hz and 13 ohms, not 830 Hz as listed. And these are what I got:
The second one has a higher magnitude, but otherwise looks to be normal. Obviously, I would not call these a matched pair were it my judging. Mark said he noticed that as well, as he had measured them before he shipped them out and wondered if I would also raise an eyebrow. So- he shipped me another pair, with one that matched #2 above rather well, and another that appeared to be a bit 'off the mark'. I'm a bit disappointed in Seas for having these sold as a matched pair, and that there was this much discrepancy in a $180 pair of tweeters. I would think that this much shift would be unheard of at this price point.
He also said they will be QCing drivers for better matching tweeters, etc, and including the DATS T/S runs on a nice sticker that you can slap on the driver magnet. The sample stickers I got look pretty cool. I don't know if this will be an offered service, or if this is something that they will be doing per order as they come for free. You'll have to contact Mark about that. Either way, I as pleased I was able to get a matched pair through their diligence. He let me keep and tear into the other pair that weren't as accurate as I saw fit.
Here are the measured data of the second set:
Number 2 and 3 overlay with only about a half-ohm magnitude difference at resonance, and the T/S are really similar as well. I imagine these will be really close over all.
Being the recent practice I and others have had at adjusting the tweeters' specs, I used Bill's method of a putty knife prying up around the surface to loosen and remove the cap. This worked really well for these 2 tweeters, and I didn't have to saw a gap first as the knife fit between without adjustment.
First subject, #1, had about a 1" cotton ball wedged between the inner side of the divot and the vented pole piece in the magnet. That was all it had behind the magnet. There is also a felt ring atop the pole, which is generally a good addition in terms of FR. As in my normal tweeter adjustment MO, I gently inserted this into the pole-hole, and added about a 1.5" square of Ultratouch 1" thick. Then I glued the cap back on with E6000 and awaited cure for remeasurement. This was the result:
The Q parameters were a bit higher, as was the Fs, but this is a lot closer to spec than it was. I would even call this within tolerance compared to the 'approved' pair.
Tweeter #4 appeared like it would be additionally perplexing. The tangential sway above resonance from the typical roller-coaster impedance was a head-scratcher. I did the same mod to this unit as I did to #1, and resulted in this:
This had a shape that was more like the others. That 'sway from 1k to 1.8k was still there, albeit at a different magnitude. Well, I didn't think that tearing back into the rear and stuffing would change anything for the better, as it should look like the other 3 if that were the inherent cause. OK, time to remove the faceplate and see what I can observe...
The surround is glued to the rear of the faceplate, so be careful if you remove the faceplate. Another note about the faceplate is that the polarity markers are really hard to find, and are on the structural cross-members. They are not on the terminals or the terminal supports, so I marked mine with a red Sharpie. They were also hard to see in the photo below, so they are enhanced for detail.
More in the next post...