Alpair's aren't woofers

[Scottmoose]

Originally Posted by Bob Brines

What kind of cabinet do you have them in? What are they tuned at? Sounds to me like the drivers are unloaded at the drum fundamental.

Seconded.

One of the objects of the pensil boxes is to provide linear deflection behaviour a la a TL via the extensive damping, so theoretically they shouldn't unload to the extent many vented boxes do. However, this heavily depends on how much the stuffing density has been adjusted, and the Pensil 10.2 does depart from the alignment used in the other boxes -it's a little underdamped in the LF as I compromised the cabinet height to keep it uniform with the others.

[chris661]

Originally Posted by Scottmoose

Edit -to an extent Chris, but the MA units don't utilise this to the extent most other wideband drivers do -even the cone edges are still producing considerable resonant energy in the top octave.

Fair enough, I'd heard Mark mention micro-resonances, but didn't know the extent to which the cone decouples.

Cheers

[markaudio]

Originally Posted by southernoise

I was playing Dadawa's Sister Drum on my Pensil 10.2 thro a myref chip amp/Pass B1 buffer. At some parts when the massive drums came in the Alpairs were moving like its going to pop out of the frame. All these at moderate volumes.

Hi Southernoise,
The drivers are un-loading which isn't good. Somewhere in your system there's a mis-match. Could be lack of stuffing in the boxes, or the Chip Amp's clipping under higher load,or a combination of factors.

The latest drivers have over-load protection fitted in the form of an arrestor. Look for the "A" on the label.

Cheers
Mark.

[larryldspkr]

Since your the only one I know listening to "bent" cones, you'd be the best person to answer your own question! Don't you think?

Larry

[markaudio]

Originally Posted by chris661

I'd wait for Mark on the definitive answer, but here's what I'd expect:

- the frequency response of the upper midrange and treble will suddenly take on "interesting" aspects: IIRC these drivers depend on some decoupling between the centre and edges of the cone when producing HF. A big disturbance in the cone material (such as from folding) will throw the decoupling way off. I'd expect some peaks and dips to appear where new resonances form and previous ones don't form so well.
- the cone will be fundamentally damaged and so more damage will occur more easily: bending metal the first time is the most difficult - try it with a spoon!

Chris

Hi Chris, Guys
In order to physically de-form (bend-break) the outer edges of the cone, its got to have travelled in excess of 9-mm on the draw stroke. This is an extreme load situation for ANY driver the size similar to the Alpair 10. Distortion levels will be extreme such that issues of resonance distribution between LF and HF across the cone surface substrate become secondary.

For more insight, take a look at Matsumoto san's LF load comparison between Alpair 10 a 13cm woofer: LEANAUDIO

Matsumoto's san's earlier work inspired me to design the "Arrestor" now fitted to all new drivers (except Alp12P). We're both Mech Eng.'s and much enjoy conversing with each other.

I've destruction tested lots of drivers and rescued a fair number of them by using fingers and thumb to gently smooth out creases. They might not look pretty but is quite amasing that they still perform close to the standard drivers.

Hope this helps

Thanks
Mark.

[markaudio]

Hi Guys,
The Alpair's are light load drivers. I've never made any secret of this feature, and there's no "free lunch" when it comes to designing drivers. Full Range drivers will likely always have to sacrifice a certain amount of power handling.

I come from the "Colin Chapman" school of engineering. Its maxim is loose mass, do more with less. Anyone who enjoys Formula 1, Lotus cars et.al will understand my purist Full-Range design philosophy.

All the same, I am sensitive to end-users experiences and for some, getting the system design balance right between output and range requires some effort. Hence the introduction of the "Arrestor" to help save drivers from some accidents. Moreover, I'm now working on a new driver and frame system that gives end-users more power-train choices and better help those who over-load cones- see:

Alpair 8

Please have your say on this new thread as now is the time to influence its design.

Thanks
Mark.

[Scottmoose]

Colin Chapman. His repeated mantra was 'simplify, then add lightness.' He probably didn't come up with the phrase, but he adopted it with a vengence to the extent that to this day he's still regarded as the high-priest of efficient F1 engineering and one of the three greatest F1 designers of all time (the others being Patrick Head & Adrien Newey).

For the sake of interest, his full name was Anthony Colin Bruce Chapman -his initials make up the Lotus badge to this day.

[southernoise]

Thanks all for your response.

The track in question is here for reference.Dadawa "Sister Drum" - YouTube

If I can recall correctly, I have stuffed the cabs according to the plans and added a little more.

The Alpair 10.2 are well behaved in most of the music that I play and I listen to almost everything. Tried Mickey Harts's Planet Drum and it was also very well in control. Guess I'll have to avoid Dadawa's music on this system.

Cheers,

Edwin

[Rullknufs]

Originally Posted by southernoise

Thanks all for your response.

The track in question is here for reference.Dadawa "Sister Drum" - YouTube

If I can recall correctly, I have stuffed the cabs according to the plans and added a little more.

The Alpair 10.2 are well behaved in most of the music that I play and I listen to almost everything. Tried Mickey Harts's Planet Drum and it was also very well in control. Guess I'll have to avoid Dadawa's music on this system.

Cheers,

Edwin

Even I have problems with that particular track on my speakers, and yet I have two very good 6.5" drivers per speaker...

[Scottmoose]

I'm not surprised. Depending on average SPLs and listening distance, but this is the sort of track that all but mandates multiple quality woofers. A 5in widebander can't shift sufficient air to handle the LF dynamic range present here.