Need some help with Thiel CS3.5 crossovers

I've noticed some issues with my 3.5's recently so I decided to pull the woofers and take a look at the caps. Low and behold I have a couple blown caps. I intend to recap them myself. However there are some components I don't recognize. Next to each group of caps there is a silver cylindrical component that I'm not familiar with. The only labeling I see appears to say H15000 nohm 15000H. Here is a pic

If any of you folks could identify that for me I'd really appreciate it.

Also, is there any reason to suspect or replace the coils or resistors while I've got the crossovers out of the cabinets? Any recommendations for caps? Obviously this is my first time doing this and I appreciate any help you guys can offer.

Thanks a ton!
thanks for the reply Einric. I'm going to pull a couple and see if I can come to any kind of consensus on capacitance. Of course they're 25 years old, so that may be a chore. Any chance these are fixed value inductors? That would seem to be odd in a crossover (from the little I've seen) but a 15000nh inductor would be about that size? There is one that appears to have been damaged when the cap next to it burst and its construction appears to be a coild of foil type substance. Past that I'm still guessing. I've sent an email to Thiel to see if they would identify them for me.

Thanks again!
Basically, the large value non-polar electrolytics are being bypassed by 1uf metallized polypropylene ("MKP" type, 400VDC, though 250VDC replacements would work just fine) and 15pf polystyrene (replacement value not critical, just make them all the same if you replace them). The original MKPs are made by Solen, but the Dayton brand from Parts Express would also work as replacements. You can get Bennic replacement non-polar electrolytics and Solen MKPs from Madisound. Personally, I would recap both crossovers with identical parts keeping all values the same. The coils should be fine as well as the resistors, but you can measure the resistors easily to check.

I have a set of CS3.5s in daily use, fantastic speakers with the right amp. A crappy amp just won't do, believe me, night and day with a good amp. I've got a good stock of spare parts for them I've accumulated over time. If you don't mind, take a look at the pics I've posted of an extra crossover I have and let me know if your values are the same.

I do know that Thiel used Dynaudio D28AF and D28/2 for the tweeters and two model numbers for the Scanspeak mid-woofer (mine are 13M8521, but I bought a pair from someone once and they were 13M3808, physically very similar, maybe even identical). I'm curious to know if there were any variations to the crossover. I can't say for sure what tweeter was used with this crossover (probably D28/2), but the mid woofer was definitely 13M8521. S/N is 4331 on this crossover.


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Dread my midrange drivers are 13M8521 and are original. One of them is on the way back to Thiel to be rebuilt. My tweeters are D28/2 and are replacements provided by thiel about 5 years ago. My crossovers appear identical to yours from the components right down to the construction.

On a side note, what the heck did Thiel use to glue the conductors in place? It took everything I had to get those things out and I pretty much destroyed them in the process.
Dread - the black adhesive used to glue down the caps and resistors does look like E6000. I'm wondering what the clear adhesive used to glue down the coils and the hook up wire is. It looks almost like hot glue, but is much stronger. May be a thick epoxy of some kind.

I believe you are correct, it is clear hot melt glue and tie wraps.
Guys I really appreciate all the help! I'm learning a lot as I go and I hope I'm not boring you old hands. Since the only option on getting my midrange repaired appears to be sending it to Thiel (at $300 for the rebuild) and I'm not made of money (please no jokes about cavier tastes on a vienna sausages budget :) ), I'm trying to come up with the most affordable way to get my crossovers back in action. Both crossovers have the same cap blown (see attached photo), which is a 1uF 5% polypropylene. What would be the downside or sides to replacing just the 2 blown caps? I can't find a source for the Versa-Tronics caps anywhere (though they do appear to still be in business) Would replacing all the 1uF caps be a better idea? The reason I ask is that the 100uF caps (4 per crossover) appear to be pretty pricey.

Second questions, what does the exact some cap being blown on both crossover tell me? I found that very interesting.

Side note, I the only source I've found for the 15pF polystyrene caps is at

Thanks Again!


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Paid Member
2011-02-26 2:12 am
Bozeman, MT
I would purchase some 100uf Non-Polar Electrolytics from Madisound or Parts-Express and some 1uF Solen Poly Caps.
Any more than that and you are going to really be changing the crossover alot for something that is probably well tuned.
The Non-Polar next to the popped Poly cap is a 66uF, you will have to parallel 2 33uF NPE's to get that value.

Those Polystyrene caps are probably still just fine.
I'm just really surprised that the Solen Poly Cap popped and the electrolytic didn't.
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Tube_Dude - I'm confused about those caps. The gentleman at Thiel told me they were 15pF I even wrote it down. And from looking up the capacitor codes from Wikipedia for small value caps 15000H would translate to 15pF + 0 extra digits with H tolerance. So that would seem to support what the Thiel rep told me. Am I being dense?


Paid Member
2011-02-26 2:12 am
Bozeman, MT
It is very possible that You are correct Chunk.
I'm not terribly good with small value identification.
If Thiel told you they are 15pf then I would stick with that.

To be honest you may even be able to leave them out.

But....Like I said the polystyrene capacitors are sealed and if they are not leaking I would say they are just fine.
Some modern polystyrene capacitors have 100k+ hour service life at rated voltage.
I seriously doubt that you have exceeded the rated voltage of those caps in a crossover or you have exceeded their service life.
The midrange does occasionally come up on ebay and you can also post a wanted to buy on audiogon, both have worked for me. Keep in mind the midrange is problematic and 2 of the 3 I purchased have been in less than stellar condition, one actually totally seized and sold as "perfect"... Anyway, the rebuild kits are no longer being made and a "new" condition midrange (as would be from Thiel) would be extremely valuable. $300 is way too much, these speakers are selling for between $500-$800 a pair, and that is the entire speaker. I was quoted a price of $250 for the mid from them years ago, price is not going down.

Just recap the crossovers with new electrolytics and films (1ufs) and make a call as to whether to reuse the polystyrene, based on some searches, it appears these are actually very robust and probably could survive anything coming at them from the amp.

The 100 uf caps at madisound are only $2.40.
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