Opinions of the Jamo Reference R 909?

[David Gatti]

Any dipole experts have an opinion on this design? They certainly look impressive. Anybody heard it?
According to Linkwitz, the mid to tweeter crossover is 9kHz!

http://www.jamospeakers.com/Default....roductID=17625
http://www.linkwitzlab.com/design_of_loudspeakers.htm

[dkxdn]

The crossover is 250 and 2000hz - look at the specifications site. But in the text it says:

"The result is a cone that can deliver output up to 9kHz without sonic break-up, a recipe for an amazingly transparent reproduction of vocals.
Beyond those frequencies it’s the turn of the Scanspeak tweeter to take over."

A little confusing but I think that JAMO only wants to say that the midrange driver is free from peaks and thats not typically for Seas magnesium drivers ...

Im looking forward to listen to this new commerciel dipole design !

Specifications:

system 3-way dipole
Woofer (inch/mm) 2 x 15 / 2 x 380
Midrange (inch/mm) 5½ / 150
Tweeter (inch/mm) 1 / 25
Sensitivity (dB - 2,8V / 1m) 89
Impedance (Ohm) 4
Weight (kg/lb) 63,1 / 139.1
Dimensions (HxWxD/mm/in) 1276 x 488 x 541 / 50.2 x 19.2 x 21.3
Frequency Range 25 - 30.000
Crossover Frequency 250 and 2.000
powerShortTerm Min 800

[Mutley666]

So, how easy would it be for us DIY enthusiasts to replicate these speakers?

I would assume being a commecial speak they have a passive crossover network, and therefore only passive equalization? Could a couple of high efficency, high excursion 15" woofers be passively equalized to run open baffle?

[cph2000]

It sure looks like two of the new 15" SLS peerless woofers, in this configuration there would be a sensitivity of 97-100db !
To match the sensitivity of the midrange and to get rid of the dipole cancelation, you could connect a very large coil in series with the woofers, creating a first order low pass with a very low xover frequency. This would create a linear responce up to the baffel cancelation frequency, above this frequency we get a first order roll off.

[Salas]

Hmmm do you think that a point source low sens tweeter can through well at over 3 metres to follow the impact of 2x15''? At the price point it will surely find home in big living rooms. Waiting for first impressions.

[cph2000]

I'm not sure that I follow what you are saying. If the xover is at 250Hz, you are looking at using 12dB of the woofers sensitivity to reach at least 75 Hz !