An Unexpected (and delightful) Journey - Thiel CS 3.6 speakers

[RickS]

Rick…are you aware of Coherent Source Services?

After Thiel folded CSS was opened by an ex Thiel tech/employee who was involved in the production of many of their classic speakers. He inherited the large inventory of spare parts.
They can service or send you original parts/drivers for virtually any classic Thiel speakers.

So if you’re in a pinch, might be worth contacting them. Even if you’re looking for some information:

Coherent Source Service - Specializing in the restoration and repair of THIEL Loudspeakers and other high performance audio components.

Specializing in the restoration and repair of THIEL Loudspeakers and other high performance audio components.

www.coherentsourceservice.com

Yes, thanks Matt! Had already consulted with him and he uses the soft dome replacements I ordered.

 

[pkane]

Yes, thanks Matt! Had already consulted with him and he uses the soft dome replacements I ordered.

I replaced the metal dome tweeters on mine with soft dome many years ago (ScanSpeak D2604, IIRC). Worked just fine.

 

[MattHooper]

Yes, thanks Matt! Had already consulted with him and he uses the soft dome replacements I ordered.

Ah right… I should have first reread your original posts as I see you mentioned them there. And of course, I mentioned them earlier and the thread as well.

I’m gettin’ old I guess….

 

[RickS]

Well, the new voice coils arrived and as I had read the soft dome is slightly taller than metal one. It is enough to contact the phase plug on faceplate. As the faceplate is diecast aluminum, once removed would be difficult to put back together. When I made the initial fit of the new voice coil, I noticed the old one had foam insert. The foam insert appeared to be in contact with one of the wires. So, decided to remove the foam insert. I reassembled the tweeter and mounted it back in the speaker and the distortion is gone! Will need to measure to be sure the foam was not a key performance part, but for now have repacked the new voicecoils and will likely keep them as spares.

 

[MattHooper]

Well, the new voice coils arrived and as I had read the soft dome is slightly taller than metal one. It is enough to contact the phase plug on faceplate. As the faceplate is diecast aluminum, once removed would be difficult to put back. When I made the initial fit of the new voice coil, I noticed the old one had foam insert. The foam insert appeared to be in contact with one of the wires. So, decided to remove the foam insert. I reassembled the tweeter and mounted it back in the speaker and the distortion is gone! Will need to measure to be sure the foam was not a key performance part, but for now have repacked the new voicecoils and will likely keep them as spares.

Great. I hope you will report back with some impressions of listening to the newly repaired Thiels.

 

[RickS]

And the saga takes a new turn...

As the suspect gasket was lying around and not something that would store well. As a unique part, felt I should not just toss it though. So decided to more carefully re-install it and avoid the voice coil wires. Put it back into service and the distortion returned. Had used some B-7000 glue to get the gasket to seat properly and was hesitant to rip out the work I had done. Originally, I had heard the distortion when playing some piano music. As I tested the tweeter again, I noticed it was noisy at the start of the track. Tbh, it sounded like hiss, so I switched out the tweeter for a different one I had from a DIY build. The "noise' went away! Now I was really perplexed.

I started searching online for another culprit and came up empty. I re-inspected my work and noticed the ferrofluid still seemed ok until I looked at the magnet assembly. I could see the gap was not clean. I checked closer and it had ferrofluid caked inside. Broke out some brushes, cotton swabs and some paper strips and gave the magnet gap a thorough cleaning with isopropyl alcohol. Once I tested, the hiss-like noise went away, and the tweeter sounds much better. It is getting a bit of a workout to ensure the noise does not return, but the hiss-like low-level distortion was a real surprise to me so thought I would share.