Dali 800 Up-Grade
As mentioned in the HES-I article, my friend Michael has a pair of Dali 800s, making good partners for his Joplin 2A3 PP amplifier. This amp delivers some 8 watts per channel and has an unexpected firm grip on the Dalis. Having two bass drivers, presumably tuned differently, our main suspicion was that the Dali800 had an unusual even impedance profile, in particular in the bass region despite an overall 4 ohms impedance.
One of the ribbon tweeters thought time was up and we decided to install new ScanSpeak R2604/832000s in replacement of the Foster cone tweeter and Foster planar super-tweeter. MDF inserts were made for the new tweeters and time was ripe to take a closer look at this Dali 800 speaker.
Taking the Dalis onto the
test-bench proved to be slightly embarrassing,
because we had both found the Dali 800 a fine and
easy-to-listen-to speaker with properties that would
easily compete with many modern designs. We both miss the
classic Vifa M21 bass drivers (with the light-weight
paper cones and narrow suspension) in current Tymphany
driver range. This bass driver has punch and drive and
the frequency response has a smooth roll-off making
crossover work very easy for diy'ers.
The Dali 800 crossover turned out
to be quite a mess. I can't believe Dali ever
launched a speaker with a crossover like this. The choice
of drivers is excellent, the combination of an 8"
and 6" driver for bass is not a bad idea at all
(with the lower bass close to the floor producing
significant amounts of bass due to room-gain), but the
crossover must have been made at the desk and never put
on the test bench.
What was expected to be a couple of hours work on tweaking the tweeter crossover turned out to be a completely new crossover for the Dalis, so here we go.
Dali 800 measurements, as-is:
Above left: Above the impedance of
the Dali 800, as-is. Indeed an easy load! Flat in
the entire 100-20000 Hz range and with modest
phase angles in the bass region. No wonder the
Joplin doesn't complain when driving these
speakers excessively loud. 4 ohms minimum.
Above right, simulated frequency
response at 1 meter distance. Not too well in
accordance with actual measurements due to P17
and M21 being connected in parallel for creating
the response files. Having the P17 some 25 cm
lower than the M21 probably makes crossover lobing more severe than seen here.
Simulated response at 2 meters distance.
Complete crossover kit available at Jantzen Audio
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Response from another client:
Hei Troels. Takker for fine delefiltre.
Lyden ble utrolig mye bedre med ditt oppsett. Mvh.
The Foster cone and planar tweeters