Thiel Owners

@8th-note Glad to read that your CS6s are working again. We are fortunate to have Rob/CSS! Thiel Audio went into bankruptcy about one month after I bought my 2.4s. Rob opened not long after and I asked him about replacement drivers. He said none are available for that model but that he can rebuild them. When I did my upgrade, I found his name on two of my drivers (one was dated well after the speakers were built, so he must have serviced that one).

Re: CS6 Woofer Rebuild & Replacement

I thought I would document my experience of removing and replacing my CS6 woofer in case there might be any useful tips for other Thiel owners.

When I figured out that I had blown my woofer I called Rob and basically asked, "What now?" Rob was very patient and helpful but I also learned a few tricks myself. Here are the steps I went through.

1. Lay the speaker on the floor on its back. Do not try to remove the woofer with the speaker standing up. Rob suggested it would be easier to do the operation if you can put the speaker on some sort of stand but I had to make due with the floor because I had no way to lift a 170 lb. cabinet onto a table, nor did I have a table that would support it. When you lay the speaker on its back it is really helpful to put a pillow under the upper cabinet so that the upper part of the cabinet is slightly off the floor. That's so that you can get your fingers under it to stand it back up again. I learned this the hard way the first time I laid the speaker down to hook up the spades to the terminals.

2. Have a thick cotton towel handy to lay on the face of the speaker over the mid/tweeter so that when you remove the woofer you have a place to set it without scratching the baffle.

3. The 9/64 allen wrench required to remove the screws is an odd size so you will need a complete set of SAE allen wrenches that include that size.

4. There are screws for the trim plate and then seperate screws that hold the woofer to the baffle. In the case of the woofer they are the same size. However I strongly recommend placing the trim plate screws along with their washers in a separate baggie with a label. The reason for this will become evident below. Remove the screws for the trim plate and be careful to remove and keep track of the tiny thin black washers. They like to fall into the cabinet and bury themselves in the insulation. If you lose some of these washers it is extremely difficult to find replacements. There are also tiny black rubber O rings which can also get lost. Those are easier to replace but still rare. Of course I would never be so stupid as to lose any parts like this but I'm pointing this out just in case.

5. Take a photo or two to document where the rubber o-rings go. Once you remove the trim plate and account for all the hardware you can remove the screws holding the woofer to the baffle. According to Rob I should have been able to get my old fat fingers to grip the edge of the rubber surround where it meets the basket and lift the woofer out of the cabinet. Forget it. Ain't happenin'. I was afraid I would damage the rubber surround so I called Rob back and asked if I could pop it out by removing the passive radiator and reaching around to get under it. Rob complimented me on my speaker repair ingenuity and agreed that would work.

6. To remove the passive radiator you need to remove the trim ring and then remove the radiator. The screws for the trim ring and the passive radiator are different lengths. IMPORTANT: Keep the screws separate and label them along with their respective washers (both metal and rubber). Steve put them all in the same bag. Steve used the wrong screws to reinstall the passive radiator. Steve broke the passive radiator. Don't be like Steve.

7. Even when I had access to the bottom of the woofer I could not lift it up out of the baffle. It was stuck. Fortunately there is a brace that goes under the woofer with a inch or so clearance. I used a plastic scraper to apply some leverage between the brace and the woofer magnet and popped it loose. Then I figured I could lift it out as Rob had recommended. No effin' way. That sucker is heavy and it didn't want to budge. I was able to push up the bottom of the speaker from inside with one hand and get my fingers between the basked and the baffle with the other. Then I could get both hands under the baffle, lift the speaker up and out, turn it over, and set it on the towel face down. There is enough wire to be able to do this.

8. I am an absolute novice when it comes to soldering so I watched a couple of Youtube videos and got myself a 25 watt Weller soldering iron at Lowes. Rob had noted that they use silver solder which has a higher melting point so when I went to desolder the wires from the speaker terminals it took a little time before the solder melted but when it did the wires came off readily. The wires from the crossover were crimped around short wires that were attached to the speaker terminals in a simple arrangement.

9. I followed Rob's directions about packing the driver because if it breaks in shipping it could be very expensive to fix. The repair was $600 on a sound driver - I would hate to know what it would cost to fix a broken one.

10. CSS had the driver fixed in several days and sent it back. Rob sent some silver solder to reconnect the wires to the speaker terminals. I cut off the ends and stripped the wires, crimped them around the woofer wires at a 90 degree angle, and soldered them in place. With a low wattage soldering iron you have to be patient but eventually you heat up the wires enough to melt the solder and make a good connection. At least I took a photo and noted which crossover wire goes to which driver terminal. C'mon, I'm not that stupid.

11. Replacing the woofer back in the baffle was pretty simple. There are metal inserts in the baffle material for the screws but I suspect you have to be really careful to not overtighten them. Hopefully you noted where the washers and rubber o-rings go so you can put them back properly.

12. When I replaced the passive radiator I used the long screws to fasten the trim ring. I heard what I thought was a couple of cracking noises so I stopped and took it back out. The screws bottomed out and stressed the soft wood of the radiator and cracked it. The unit was still intact but there were cracks. I gathered up a bunch of clamps and carefully applied wood glue to the interior of the cracks with a toothpick and clamped it all the way around. I'm comfortable that it's as good as new, but damn, I was pissed at myself for making such a dumb mistake. My mood changed considerably when I fired them up and they sounded wonderful. I think they sound better than they did before but that's probably my imagination.

The moral of the story is that we are very fortunate to have support for decades-old highly custom designed speakers for which the manufacturer is out of business. I'll add my voice to the chorus of shoutouts for Rob - he was an absolute pleasure to deal with and I wish him a long, happy, and profitable career in giving extended life to these amazing speakers.

@8th-note, Great job reporting!
Geesh, $600 for a driver rebuild !?
....And with so much work on your part.

@tomthiel, sorry I was off the forum for a week and didn't see your response about 2.7 development until recently.

I'm unclear why the 2.7 needed a HIGHER frequency woofer XO point than the 2.4's 1000Hz. The 3.7's 4.5" midrange should be able to much better handle lower frequencies than the 2.4's 2.5" midrange. Indeed, the 3.7 XO is at 300Hz, so the mid can go at least that low. So why not lower the XO point of the 2.7 woofer to say 500Hz for better power handling and even less beaming? That would stress the 2.7/3.7 midrange less than in the 3.7, and stress the 2.7/2.4 woofer less than in the 2.4, so a win/win with a lower XO point, but you state it is higher, and with 14X more capacitance, it would seem a LOT higher. Hmmm.  Please expound.

To that point, why wouldn't the 2.7 use 4x100uF film caps or even smaller to get to 416uF, rather than one massive 400uF? It would seem the slight increases in space and price 4 or more film caps would create would more than offset the potential sonic deficit of one giant electrolytic directly between the amp and wonderfully pure coax driver.

Indeed, that's the weakest link of the 2.4 for me, the excursions required of a 2.5" cone (effectively less when including the hole in the middle for a tweeter dome) to move enough air at lower frequencies at higher volumes, to below say 250Hz (2 octaves below XO point, so only -12dB; if playing 100dB, mid asked to put out 250Hz percussives at 88dB (round 'electrical' numbers, not taking acoustic roll-off contributions to the end-result 6dB/octave slopes.)).  Ask Rob how many 2.4 coaxes I've gone through, and not due to lack of clean watts and amps!