New member. Hist + Ribbon bounce?

[Sac]

Hi all. Just discovered this forum yet I have had a pair of centaurs for the last 10 years. Previously I had a pair of IMF transmission line ts80IIs. I fatigued of the top end on the IMfs and was looking for something more "airy" up high.

I'd heard some ribbons in a 2nd hand shop and was impressed, ended up buying the centaurs off eBay simply because they were ribbons, unseen and unlistened to. Was initally shocked when I hooked them up, turned up the amp and could barely hear any top end while I was standing, learnt quickly that the top end is very directional and was more than satisfied when I got my ears down to the right level.

What did grind on me was the lack of bottom end, in comparison to the IMfs where the cabinet was probably three to four times the size they were very shy. I added a mk v125 sub which improved things, but still aren't that satisfied with the bottom end. The bottom end of the IMF and the apogee ribbons would be great.

Ribbon bounce: when I drive them hard the ribbons visually bounce/resonate maybe at 10-20Hz with an amplitude of a cm or so. What is the physics here. Is the resonance from the sound produced by the woofers or is it due to the current going through the ribbons themselves that puts them into resonance.

I don't regard the volume produced as excessive, but have no idea how much power the speakers are getting at this stage(using a 200wpc rotel). Despite the visual effects the sound is fine, am I overdriving them, does it stretch the ribbons? Imagine it would be hard to burn out the ribbons?

Thanks for any comments.

[Vansloneker]

Hi and welcome to the club.

What do you mean with Hist?

Apogee indeed made a choice of woofer on the Centaurs not understood by many. Like you, I've added a sub woofer.

When I push my Centaurs, the ribbons will bow like a sail in the wind. For me this is the signal to back off a little. But you write that yours oscillate. The behaviour of ribbons has been discussed often in this forum. Recently, here is a topic about it.

[Sac]

Thanks for the reply and the link, but unfortunately not much there other than a few "in the breeze" opinions about what causes the bowing or oscillating and whether its normal, sign of deterioration, harmful etc.

[Graz]

Hello Sac

I am familiar with both speakers, and two more dissimilar approaches to presenting music you are unlikely to find!!

The IMF has a nice, forceful, slightly slow but large scale serve of just about anything you can play on it. For rock, large classical and even house music these things can really play well enjoyably, a good serve of what the larger IMF's could do. They can also play quite loud. I considered getting some of the larger REF's myself 20 or so years ago actually. Downside is the MID-Hf, not anywhere near as believable as the Centaur, music yes - live, no. The efficiency was good, making for a holiday for the driving amp!

The Centaurs are really a more personal use speaker, certainly capable of lovely sound they tend to bend your music tastes a little towards the smaller size female fronted jazz ensembles (imho). The 26" ribbon has a very believable grasp of the midband when in good order, and whilst some can criticise the lack of low end slam (particularly when compared to transmission line speakers) the Centaurs cone/ribbon blend was ahead of the opposition when released. They are designed to play at moderate volumes, and really are absent below 45 hz when listening at normal volumes. The bass cones on this design (like the C-Minor) were chosen because of their upper blending to the ribbon rather than low end extension. That said - partnering with a good hard hitting current amp like a real Krell seems to pull in more bass extension - again - not comparable to IMF TDL/s for depth.

Ribbon movement. The 26" ribbon should not be limp, or misshapen. The lateral appearance of the ribbon should be flat, not curved. Movement would be expected in use, but this would be no more than +-5mm at the extremes. If the ribbons have signs of burning on the front, lateral curl, vertical sag or flap around during normal use they probably will have been overdriven.

Amplifier requirements are similar to the planar Apogee's imho - use of an amp with low damping or lack of current will yield disappointing results, use of a good amp disproportionate to their modern second hand value will show you what they can really do.

Subs. Some have gotten enjoyable results - but I believe it would be near impossible to integrate two levels of cone to anywhere near the level of the full planar Apogee's, even the smaller ones. Difficult...


Ultimately, I think these two speakers would appeal to two entirely different sets of ears