Thiel CS2 upgrade

[VP Electricity]

So I bought my old roommate's Thiel CS2s from him, becoming the second owner. When I moved in, he was running them, and I've heard them long before I ever bought them.

The grilles were always unremovable as long as I'd been around.

Well, I pulled them out of storage to put into the customer lounge at the shop. Tom pulled the grilles off. They had been double-stick taped on.

The tweeter opening is pretty carefully routed into the MDF grille frame. Hard to tell how BOTH tweeter domes got pushed in.

No idea how long they'd been like that, either. Can't tell if it was a pissed future-ex-girlfriend or roommate ten years ago, or before my friend got them (Supposedly NIB from local dealer, but dealers have done worse).

Pulled the tweeters, Dyn D-28 AF, no longer made, doesn't have replaceable VCs. Thiel has a few on hand of what replaced the D-28 AF for $135 each, but states that Morel has a direct replacement. Madisound said the best replacement was the MDT32, since it has the 110mm faceplate.

So put them in, mounting them with double-stick tape since the hole centers don't align (will drill out the cabinets if I keep them).

There is definitely a slight improvement in the treble. Not as much as I'd hoped - this room is really bright, I was hoping the new tweeters would help out more with that than they did.

But here's the difference I did not expect:

These speakers have always imaged low for me. I've had to slouch down to get the image where I'd like it. I have a long torso - I'm 6'4" sitting down and 6'0" standing up, I've been told - so I've ascribed this effect to that.

But now that I've put these tweeters in, I get a slightly higher image.

I'm wondering if the old bashed-in tweeters had a 4-5k peak and these have a lower output in that range?

Any suggestions? (Which don't involve me taking it apart and putting the old D28s in for comparison?)

[Chad]

When it tweet has more "zing" on the tippy top they will image a bit higher, it's a psycho-acoustic thing. That's why "Imaging tweets" do what they so. Notice that they are crosses incredibly high just to add some air.

[VP Electricity]

I always interpreted that imaging tweeters were backing into that effect, since the only psychoacoustic effect I know of for higher localization is a dip in response in the 4-6k range (depending on the shape of the outer ear, varies somewhat from listener to listener). So I figured that more output up top was creating a mild "dip" in that range. In my experimenting, a much narrower dip with a parametric EQ works much better (for me, around 4500).

So, Chad, are you saying that these are two seperate effects? Or are we talking about the same effect and different means of creating it?

[Chad]

I'd say the latter. One is a boost the other is a cut with some makeup gain

[VP Electricity]

When I do the high-Q cut at 4500, I don't do any makeup gain. Maybe I should try that.

Morel screw centers did not map over Dyn screw centers. Double stick tape thickness keeps grille from completely inserting into grille fittings. Bah.

[Chad]

what about driver sensitivity?

Tweeters ain't resistors, that crossover was designed for a specific driver, not for the driver that fits in the hole.

[VP Electricity]

Yeah, I'm clear on that, thanks. ~

D28AF was listed at 91dB, MDT32S listed at 90dB.

DCR is 0.1 ohm different. Fs is very close. Morel doesn't list many of the other T/S paras, but with Thiel cosigning it, I figured, what the heck. The response plots show the Morel extending higher into the top end than the Dyn, and the Dyn having a lower-Q Z-peak than the Morel.

But I still think the biggest difference is due to those crushed dome diaphragms

[Chad]

Whew, I forgot the emoticon, glad you picked up on the joke, I was texting and typing at the same time. Damn work.

[Jpeezy]

image height problems could've been caused by those old ass tweeters having some response differences, left to right, I too have a pair of these speakers and refuse to get rid of them( had them 20+ years and they were used when i got them), when they worked correctly, they were so smooth in response that they would seem as though they disappeared, very hard to tell that there were speakers where they were. you may want to check the woofers too, hard to tell without pushing on cone but the adhesive has failed on both surrounds and dust caps. i contacted thiel by email,never got a response. so any tips on driver replacement would be welcomed greatly. never had problems with imagining until the drivers started to fail , then yes it was obvious something was amuck.