Tweeter with saturated screechy sound

[Virus]

Hello, I am posting a new topic because of what I found out so far.

I'm new to the forum and am also new to repairing audio DIY style, so let me cut to the chase.

I've acquired a pair of ATL Celebration speakers (quite unknown but sound terrific), and they seem to be suffering a problem.

ATL CELEBRATION

• Virus
• Oct 15, 2022
• german

ATL CELEBRATION.
Audax tweeter and a Vifa bass.

The tweeter on one of them has a screechy sound, especially when it hits specific freqs. I have a ton of pics:


This problematic sound occurs only when volume passes a certain threshold. I'm running an Onkyo A 8450 and it works great (except the selector which is loose).

I've measured the Ohm's on the tweeter, and it's 2.1 to 2.2 which I think might be low, but I'm not a pro. Can someone clarify?

Also, the yellow foam, do I get a replacement? I feel like it might be making problems. What does the foam do?

I've been moving the vc around the magnet, and I think I've managed to get the sound for a second, but it then disappeared. I could move it for days and never find it sounding perfect like it ought to.

What should I do? It's a real quality vintage Audax with a hefty magnet inside a real quality vintage speaker, I really don't feel like getting rid of it.

Ive replaced the tweeter, moving it from the left to the right box, and nothing helped fix it.

Please, if you have any ideas or explanations, I'd appreciate it a lot.

 

[Binkman]

Good day;
What does the other tweet measure Ω's ? (any numbers on the magnet?)

 

[Virus]

Good day;
What does the other tweet measure Ω's ? (any numbers on the magnet?)

Haven't measured the other one, there's only 1207, which is probs just the model number.

 

[gadget73]

maybe its just the pic but it almost looks like there are rub marks on the inside of the coil former on about half of the diameter. If its misaligned and touching the magnet it will do odd things.

 

[Virus]

maybe its just the pic but it almost looks like there are rub marks on the inside of the coil former on about half of the diameter. If its misaligned and touching the magnet it will do odd things.

That makes sense, but how do I fix it? I feel like no matter how I move the vc it touches the magnet.

 

[daybreak2350]

Compliments on providing good close-up pics and info. Your speakers appear to be German manufacturer ATL Elektro Akustik Vertriebsgesellschaft mbH, model Celebration, introduced in 1993. See https://www.kupindo.com/Zvucnici/64167713_ATL-Celebration-High-End-Podne-Z-Kutije.

idk all about tweeters but I have repaired a "burned out" vintage AR3 woofer/driver by fixing the voice coil and rebuilding the spider etc. There are one or two experts here on AK who do repair tweeters and yours may need to be "rebuilt" to fix the problem. Couple of things:

• The Celebration speakers are rated 4 ohms which is "nominal" rather than exact. The low ohms (2.1 or 2.2) reading is not unusual or bad in itself. Your good tweeter should measure around the same. Specs say "tweeter: 25 mm fabric dome / load capacity (nominal/music b.): 100 /140 watts".
• The good news is that you get a reading at all, indicating the voice coil is not shorted (i.e., the coil wire or a lead is not burned/melted resulting in an open circuit as a result of applying too high current/wattage too long).
• It's not clear from your pics but it appears you have disassembled/messed with it at some point. The voice coil with dome must be free-floating around the permanent magnet post throughout its entire travel (excursion). The coil must not touch or scrape on anything (not the post on its i.d. or magnet frame on the o.d.). On a typical loudspeaker the cone surround is positioned and glued to the basket rim such that the voice coil is perfectly concentric with the post so it has 360-degree clearance. Anyone who has "refoamed" a speaker must observe this. In the case of a tweeter the cone is the dome.
• I see Madisound sells Audax tweeters but 4ohm TWO25A2 is out of stock. My advice: call them 608-831-3433 and explain your situation. As I see it there are two options: 1) replace it with a high quality equivalent like Vifa or 2) either find someone qualified or diy to rebuild your defective tweeter. Madisound has long-standing good reputation for quality and helpful service.
• If you rebuild it yourself please post the rebuild process with your excellent pics. I'd like to know how!

Please let us know how you make out.
Good luck and Have Fun!

 

[Virus]

Compliments on providing good close-up pics and info. Your speakers appear to be German manufacturer ATL Elektro Akustik Vertriebsgesellschaft mbH, model Celebration, introduced in 1993. See https://www.kupindo.com/Zvucnici/64167713_ATL-Celebration-High-End-Podne-Z-Kutije.

idk all about tweeters but I have repaired a "burned out" vintage AR3 woofer/driver by fixing the voice coil and rebuilding the spider etc. There are one or two experts here on AK who do repair tweeters and yours may need to be "rebuilt" to fix the problem. Couple of things:

• The Celebration speakers are rated 4 ohms which is "nominal" rather than exact. The low ohms (2.1 or 2.2) reading is not unusual or bad in itself. Your good tweeter should measure around the same. Specs say "tweeter: 25 mm fabric dome / load capacity (nominal/music b.): 100 /140 watts".
• The good news is that you get a reading at all, indicating the voice coil is not shorted (i.e., the coil wire or a lead is not burned/melted resulting in an open circuit as a result of applying too high current/wattage too long).
• It's not clear from your pics but it appears you have disassembled/messed with it at some point. The voice coil with dome must be free-floating around the permanent magnet post throughout its entire travel (excursion). The coil must not touch or scrape on anything (not the post on its i.d. or magnet frame on the o.d.). On a typical loudspeaker the cone surround is positioned and glued to the basket rim such that the voice coil is perfectly concentric with the post so it has 360-degree clearance. Anyone who has "refoamed" a speaker must observe this. In the case of a tweeter the cone is the dome.
• I see Madisound sells Audax tweeters but 4ohm TWO25A2 is out of stock. My advice: call them 608-831-3433 and explain your situation. As I see it there are two options: 1) replace it with a high quality equivalent like Vifa or 2) either find someone qualified or diy to rebuild your defective tweeter. Madisound has long-standing good reputation for quality and helpful service.
• If you rebuild it yourself please post the rebuild process with your excellent pics. I'd like to know how!

Please let us know how you make out.
Good luck and Have Fun!

Thanks for all the info!

I'll try to see if I can f around with the vc and get it well aligned, if that doesn't go well, we'll check all the other steps.

 

[gadget73]

might be out of round. If it is, only thing I can think of would be to very gently squeeze it on the long side to see if you can fix it.

 

[Binkman]

Just to add: Audax is Polydax mfr. France and rated High quality.

 

[elnaldo]

That makes sense, but how do I fix it? I feel like no matter how I move the vc it touches the magnet.

Hello. I've pointed that on your other thread. Please take a pict from horizontal plane, I'm almost sure the dome is askew to one side, making the VC to rub, and that can be fixed applying some weight and some heat to reform the dome.

To restore the shape of the VC, (if needed) you need some "former" of the right diameter. Any cylinder with layers of masking tape to fine adjust the diameter could work. Inserting it inside the VC and twisting to reform the shape.

The foam is a dampening material to kill resonances under the dome. Just install again the material you removed. The manufacturer for sure knows how to make a tweeter.

 

[Virus]

Hello. I've pointed that on your other thread. Please take a pict from horizontal plane, I'm almost sure the dome is askew to one side, making the VC to rub, and that can be fixed applying some weight and some heat to reform the dome.

To restore the shape of the VC, (if needed) you need some "former" of the right diameter. Any cylinder with layers of masking tape to fine adjust the diameter could work. Inserting it inside the VC and twisting to reform the shape.

The foam is a dampening material to kill resonances under the dome. Just install again the material you removed. The manufacturer for sure knows how to make a tweeter.

From the side like this?