"Quivering" Duetta Tweeters

[Spirit84]

It has been a very long time since I have posted.
I had stepped away from the hobby for quite awhile - but the Audio "bug" has hit again and I am (gulp) back!
I would love for any of you technical experts - of which I am am not one of - to explain to me why the tweeters in my DSigs quiver. This happens mostly when the volume is up high.
My first reaction is that the amps are clipping but I thought that I am running with sufficient power.
I am running 4 Mono amps (Odyssey Audio) - in otherwords, one amp per channel.
Here are the specs for the amps:

1 x 200+ Watts RMS @ 8 Ohms (each)
High Class A /AB
Additional 60,000µF memory bank for 180,000µF total (each)
>120 amps current delivery
Additional 400 VA Plitron transformer for 800VA total (each)
Nichicon Muse capacitors, Vishay/Dale resistors, extra WIMA metal film capacitors
Power consumption when idle ±35Watts

Any help or advice would be very apprecaited.

[Zardoz]

Just want to clarify how you have your amps connected. You said 4 amps, but also said one per channel. Are you running surround sound with 4 Duetta's, or are you running one amp to the bass panel, and one amp to the mid/tweeter on each of two Duetta's?

[JarreYuri]

I guess that he means that he uses 1 amp for every x-over part.
1 for left mid/treble.
1 for right mid/treble.
1 for left bass.
1 for right bass.
1/ "channel".

[narkotic]

From my experience, I have seen this happen on a set of Divas that I had new MR/TW ribbons installed in, the cause was that there was a short between the trace return foils. Check this at both ends of the ribbon to ensure that there is adequate spacing between the traces to keep them separated.

[BobM]

Yeah, the same thing happens on my Duetta sig's. At first I thought it was only in the right channel speaker, but it is also happening in the left one, just that the light in the room tends to illuminate the right one more so it is easily seeable as a reflection on the aluminum. I hear no noticeable sound degredation from this. It occurs regardless of the amp used.

It's almost like there is a breeze in the room moving them, rather than a "quiver". Like someone is blowing on the ribbon. It is more pronounced as the volume is turned up.

My best guess is that this ribbon is stretched pretty long and only anchored at top and bottom. The magnets are doing their job and as the current is turned up there may be a bit of fluctuation going on in the magnetic field in the middle of the ribbon where the tension may not be as high as at the ends. Remember, the ribbon is pleated, and maybe the pleats have stretched a bit with years of use and the tension is not what it is on a new ribbon.

[Spirit84]

I guess that he means that he uses 1 amp for every x-over part.
1 for left mid/treble.
1 for right mid/treble.
1 for left bass.
1 for right bass.
1/ "channel".

Yes Jarre - this is exactly how my system is connected to the power amps.
Sorry - I should have been clearer.

[Spirit84]

Yeah, the same thing happens on my Duetta sig's. At first I thought it was only in the right channel speaker, but it is also happening in the left one, just that the light in the room tends to illuminate the right one more so it is easily seeable as a reflection on the aluminum. I hear no noticeable sound degredation from this. It occurs regardless of the amp used.

It's almost like there is a breeze in the room moving them, rather than a "quiver". Like someone is blowing on the ribbon. It is more pronounced as the volume is turned up.

My best guess is that this ribbon is stretched pretty long and only anchored at top and bottom. The magnets are doing their job and as the current is turned up there may be a bit of fluctuation going on in the magnetic field in the middle of the ribbon where the tension may not be as high as at the ends. Remember, the ribbon is pleated, and maybe the pleats have stretched a bit with years of use and the tension is not what it is on a new ribbon.

Thanks for taking the time BobM. This makes sense.
Funny thing though - I played the same song on the system over 2 evenings. The first night it really quivered (breeze, vibration, shaking, whatever!) and then the second night it was rock steady. I am going to try and replicate this again over the next 2 evenings and confirm that I am not crazy.

[Vansloneker]

If I play my Centaurs very loud the MRTWs will go bow like a sail in the wind. That to me is a signal to decrease the volume a bit. In my opinion they are over driven when it happens. The mix of the music also has to do with it. Often I can go to +20 or +25 or even +30, while on a particular track +15 is the limit. I only push the volume if I can clearly watch both MRTWs.

[apogee_admin]

It can be due to the front to back pressure differential caused by the bass panel, not the mid/tweeter itself.

Try this, if you are running bi-wire disconnect the mid/tweeter and play the same piece at the same volume, you might find it moves the same way with no signal going to it.

Having said that, you can get some flapping at higher volumes, are the tweeters original?

Jon

[Spirit84]

It can be due to the front to back pressure differential caused by the bass panel, not the mid/tweeter itself.

Try this, if you are running bi-wire disconnect the mid/tweeter and play the same piece at the same volume, you might find it moves the same way with no signal going to it.

Having said that, you can get some flapping at higher volumes, are the tweeters original?

Jon

I will try the experiment later tonight when I get home from work.
Yes - the entire speaker is original; nothing has been modified/upgraded.
Jon: In you opinion, is this a clippin issue. I think I have sufficient power but I am not an expert.

[Rabtah Bte Senen]

Hi, I am also having problem with my Duetta Signature Tweeters. There are too much slack and they bang
against the cover all the time. How can I tighten the tweete? I am worried now as there is a bent at the center of the tweeters on both sides. Please help. Thanks Rabtah.