Focal Aria 900 series: Amp load measurement

[Pinox67]

Some weeks ago, I helped a friend to set up its home theatre. He had to choose the best loudspeakers mix of different brands, some “home made”. Not an easy task. Among listening tests and calibrations, I made also some basic measurements and comparison with mine, based one Focal Aria 900 series and Focal Dome Flax.
I share below input impedance measures of these ones. They can be useful to match with a right power amplifier.
The graphs show:

• Module (middle curve) – [ohm]: resistive load.
• Phase (upper curve) – [degree]: capacitive (if negative) or inductive (if positive) load.
• EPDR (lower curve) – [ohm]: Equivalent Peak Dissipation Resistance; it incorporates both the impedance and phase data, reflecting the "resistive load that would give rise to the same peak device dissipation as the speaker".

Focal Aria 936

Specifications:

• Type: 3 ways bass-reflex, floor standing
• Drivers: three 6.5” Flax Bass; 6.5” Flax bass midrange; 1” Al/Mg TNF inverted dome tweeter
• Freq. Response (+/- 3dB): 39Hz – 28KHz
• Sensitivity (2.83V/1m): 92dB
• Nominal Impedance: 8 ohm (min 2.8 ohm)
• Crossover frequency: 260Hz, 3100Hz

Impedance measure:

Min Impedance: 2.6 ohm @ 100-120Hz
Internal resonance: 70Hz, 97Hz, 8600Hz
Tweeter primary breakup mode: 22Khz

These loudspeakers do not appear easy to drive: in the major part of bass and mid-bass, where “energy” is needed, the impedance is below 4ohm (they should be better stated 4ohm speakers, not 8ohm). EPDR has minimum in low frequency, around 34Hz (2ohm) and 85Hz (1ohm), values where the capacitive load is high (phase reaches high values, 65deg). Other critical low values are around 440-600Hz (1.8ohm), with inductive load.
Used alone in full spectrum, a power amplifier able to drive low loads (i.e. high current) is strongly suggested.


Focal Aria 906

Specifications:

• Type: 2 ways bass-reflex, bookshelf
• Drivers: 6.5” Flax bass midrange; 1” Al/Mg TNF inverted dome tweeter
• Freq. Response (+/- 3dB): 55Hz – 28KHz
• Sensitivity (2.83V/1m): 89.5dB
• Nominal Impedance: 8 ohm (min 4.6 ohm)
• Crossover frequency: 2800Hz

Impedance measure:

Min Impedance: 4.4 ohm @ 180-230Hz
Port / Box resonance: 25 Hz / 50Hz
Internal resonance: 208Hz, 380Hz, 8600Hz
Tweeter primary breakup mode: 22KHz

These loudspeakers appear easier to drive: in the bass and mid only minor parts of impedance values are below 5ohm. In very low frequency, EPDR has minimum around 40Hz (3.2ohm) and 63Hz (3.6ohm): for the first the load is capacitive, not too high (phase is -40 deg); the second one is inductive (24 deg). Other minimums are around 125Hz and 400Hz, with 2.5ohm.
Overall, they can be driven by a less "strong" power amplifier.


Focal Aria CC 900

Specifications:

• Type: 2 ways bass-reflex, floor standing central
• Drivers: two 6.5” Flax bass midrange; 1” Al/Mg TNF inverted dome tweeter
• Freq. Response (+/- 3dB): 57Hz – 28KHz
• Sensitivity (2.83V/1m): 91dB
• Nominal Impedance: 8 ohm (min 4.3 ohm)
• Crossover frequency: 2800Hz

Impedance measure:

Min Impedance: 4.3 ohm @ 180-230Hz
Port / Box resonance: 23 Hz / 41Hz
Internal resonance: 154Hz, 190Hz, 775Hz, 8600Hz
Tweeter primary breakup mode: 22KHz

These loudspeakers appear quite close to 906 as load. In the major part of bass and mid-bass only minor parts of impedance values are below 5ohm. In very low frequency, EPDR has minimum around 32Hz and 55Hz (both at 2.9ohm), the first is capacitive (phase is -40 deg), the second inductive (30 deg). Other minimums are around 143Hz (with 2.2ohm), capacitive (-36 deg) and around 390Hz (with 2.7ohm), inductive (28 deg).
Overall, they can be driven by a power amplifier without big effort.


Focal Dome Flax

Specifications:

• Type: 2 ways compact sealed
• Drivers: 4” Flax bass midrange; 1” Al/Mg inverted dome tweeter
• Freq. Response (+/- 3dB): 80Hz – 28KHz
• Sensitivity (2.83V/1m): 88dB
• Nominal Impedance: 8 ohm (min 4 ohm)
• Crossover frequency: 2500Hz

Impedance measure:

Min Impedance: 16.5 ohm @ 230-350Hz
Box resonance: 152 Hz (sealed)
Internal resonance: 9000Hz
Tweeter primary breakup mode: 22KHz

These small loudspeakers are easy to drive, even if they are the less sensible respect to the other loudspeakers (88dB), as expected. They are stated at 8ohm, which is too conservative: the impedance does not go below 16ohm!
Also the Phase graph is very good, with oscillations lesser of 20 deg. So, EPDR is not severe: only a minimum at 180Hz with 11ohm; others two at 121Hz and 2.8KHz are of 13ohm.

 

[nemanja_t]

Thank you for sharing!

 

[Head_Unit]

Focal Dome Flax

Wait, what? Obviously a typo but I don't see a 2x4" + tweeter Aria model. ???
Thanks SO much for the measurements, we were really wondering what the port tuning of CC900 is. And SR900 if you have one around

 

[Pinox67]

Wait, what? Obviously a typo but I don't see a 2x4" + tweeter Aria model. ???
Thanks SO much for the measurements, we were really wondering what the port tuning of CC900 is. And SR900 if you have one around

I refer to This for dome flax, that can be used as surround, back or also “dolby speaker” channel, pointing to ceiling. Yes, it has 1 mid range and 1 tweeter, a cut&paste typo, corrected.
For the CC900 I’ll try to measure the port tuning.
Unfortunately I do not have an SR900 available to measure.

 

[Head_Unit]

I refer to This for dome flax...Unfortunately I do not have an SR900 available to measure.

Ah, those are cute! I'd send you SR900 but to Italy is probably rather expensive

 

[Helicopter]

I will have to keep my eyes out for some Dome speakers. I have some 16 ohm vintage receivers and the only things to pair them with so far are vintage speakers and DIY.