REALITY S - Measurement Whitepaper
I would like to start showing the final result. Below in this measurement whitepaper you can find all other types of measurements.
Measurement WITH impedance correction:
See the curves with the 9300, High-End linear without any bumps, but with a smooth roll-off and a perfect midrange too !
Note: This is the ideal Brüel&Kjaer listening curve - this is perfect.
1. The white curve is on-axis.
2. The yellow curve is 20-degree off-axis.
DO NOT look below 500Hz because of the wave-length, see near field measurement of the loudspeaker (freq. response below 500Hz).
NOTE: There is NO smoothing of any curves.
Click picture to see measurement in full size.
REALITY S is a commercial high-End loudspeaker, which is available as full diy kit too, no woodworking or finishing is necessary. An assembling manual will be avalable on-line to let you do the assembling yourself.
When I am developing a new crossover/loudspeaker I am always optimizing the loudspeaker to between 15 and 30 degree off-axis measurements / listening, because I do like a smooth roll-off in the upper octaves. I also want the Brüel & Kjaer ideal listening curve and this speaker is following this curve. Then I can feel the depth in the music.
The REALITY S contain a simple 1. order crossover, which is full phase coherent (an advantage). First order crossovers are used by famous brands like Thiel, DynAudio, Sonus Faber and many others.
The disadvantage of 1. order is the level of power to the tweeter can't be as high as when using other high order crossovers. (The 9700 long term power handling is 225 WATT rms w/12dB per octave, or 125W rms w/6dB per octave, which is more than enough.)
Because the 1. order power handling limits the crossover frequency must be high (or normal), in this case 2.8kHz. It is not possible to crossover the units lower than that, when using 1. order crossover.
To be able to get a very good result from a 1. order it is a requirement that the cabinet is free of bumps and peaks on its surface, especially around the tweeter. If not, then it will cause peaks and drops on some frequencies.
Here are the measurement results of the cheap REALITY S loudspeaker. I am using the 9300 tweeter from Scan Speak during the first measurements. The 9700 tweeter will be compared to the 9300 tweeter too.
NOTE: The measurements were performed on units, which have been during their break-in period. This is important to note that, because the Thiele small parameters are changing to be better after break-in.
It is not possible to measure valid loudspeaker specifications before break-in and therefore a crossover must be developed to units, which have been during their break-in period.
This is the on-axis frequency response made on a distance of 2 meter (and not 1 meter).
DO NOT look below 500Hz, a near field measurement is necessary. I will show you one later in this document.
This is a very good on-axis response with a fine roll-off in the upper octaves.
The midrange has a very soft bump and therefore the frequency response is only +-3dB flat on-axis. (Note: On a distance of 2 meter.)
NOTE: There is NO smoothing of any curves.
Click picture to see measurement in full size.
This is the on-axis frequency response made on a distance of 1 meter.
DO NOT look below 500Hz because of the wave-length, a near field measurement is necessary. I will show you one later in this document.
Now the curve is more flat.
NOTE: There is NO smoothing of any curves.
Click picture to see measurement in full size.
All the next measurements are made on a distance of 1 meter and 30 degree off-axis.
The response from the units:
1. The yellow response is the Scan Speak REALITY bass unit with 1. order crossover.
2. The white curve is the Scan Speak 9300 tweeter with 1. order crossover.
3. The red curve is when the tweeter is in opposite phase to the bass: VERY GOOD QUALITY of a 1. order.
4. The gray curve: Total off-axis frequency response measurement.
This is a great and smooth 30-degree off-axis roll-off.
The midrange is very good, no peaks, but flat.
NOTE: There is NO smoothing of any curves.
Click picture to see measurement in full size.
Here is the off-axis waterfall plot.
The waterfall tells a lot of how a speaker does sound.
This is a very good plot and I know it is difficult to find a loudspeaker with a better plot.
Where is the waves in the waterfall plot?
Quiet water, the sea is dead, from the first time the sound is -40 and below !
This tells a lot about the cabinet. It is dead and without resonance's.
NOTE: There is NO smoothing of any curves.
Click picture to see measurement in full size.
Here is the near field measurement of the bass unit:
1. The yellow curve is the near field measurement of the bass unit.
2. The white curve is the near field measurement of the port.
3. The red line is the complex sum of the unit and the port.
The individual responses of the unit and port are shown and the their complex sum. Both curves must be added to find the lowest frequency of the bass unit, for example the -3dB point or the -10dB point. Imagine a line of the yellow curve from 20Hz to 55Hz. Then you can see the -3dB point is 30Hz.
You can also see the port tuning frequency is 32 Hz, because here the port and the unit is 180 degree out of phase to each other.
REALITY S don't have any impedance correction in the bass area like REALITY 3D !
NOTE: There is NO smoothing of any curves.
Click picture to see measurement in full size.
Here is the REALITY S impedance and electrical phase:
1. The red curve the impedance is WITHOUT impedance correction.
2. The yellow curve the impedance is WITH impedance correction.
3. The white curve is electrical phase WITH impedance correction.
The absolute minimum impedance is 6.9 ohm (in the bass area). Else it is very linear around 8 ohm WITH impedance correction.
I would recommend tube amplifier users to get the speakers WITH impedance correction. The electrical phase is very linear too, except in the bass area (the REALITY 3D loudspeaker is linear in the bass area).
NOTE: There is NO smoothing of any curves.
Click picture to see measurement in full size.
Oh, I did forget to show you the difference between the 9300 and the 9700.
1. The white curve is the 9300 tweeter on-axis.
2. The yellow curve is the 9700 tweeter on-axis.
2. The red curve is the 9700 tweeter 20-degree off-axis.
DO NOT look below 500Hz because of the wave-length, the already shown a near field measurement is necessary below 500Hz.
There is no big difference in the response of the two tweeters.
The well known 9700 tweeters peak on 12kHz is not found in the REALITY speakers because of the neoprene front plate !
The 9700 off-axis response is more flat around 6kHz and start to roll-off later than the 9300.
NOTE: There is NO smoothing of any curves.
Click picture to see measurement in full size.
Do-It-Yourself
Assemble the REALITY S yourself. Here is the diagram and the simulations of this easy-to-do crossover.
As you can see on the simulations, a loudspeaker must be measured to find the right values of the components, the behavior of the units must be measured.
Note: You have the half sound pressure when the sound is dampened -6db.
See in full size: Click diagram and simulations.
Note: The capacitor C1 must be changed to 4.7uF, when the Scan Speak 9700 tweeter is used.
The speaker is playing the bass too. Please try without sub-woofer, before you jugde this loudspeaker !
Best regards,
Peter
Acoustic Reality - Denmark