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This is a quasi-anechoic spinorama measurement + internal amp measurements of the Genius SP-HF3000A (discontinued) powered PC/multimedia loudspeaker.
It is quite an old product and there's not a lot of data available about it online anymore - here's one link with some very basic information. 10 or so years ago it was one of the cheapest 5" two-way active loudspeaker pairs one could buy where I live (I believe price was ~50-60€/pair).
Loudspeaker measurements
A few notes on measurement methodology:
Here's the full spinorama for the powered (right) loudspeaker:
Preference rating as calculated by VituixCAD is:
Perhaps it was designed to be listened without any toe-in? Hard to say, but the overall objective performance is not good.
Driver nearfield components:
We can see a couple things here:
Horizontal directivity (normalized to on-axis response):
Impedance
Here's the impedance for both units in the pair:
As we can see, there are several visible resonances in the responses.
Distortion
76 dB SPL
86 dB SPL
Bass distortion became pretty audible around 80dB SPL and I was scared to go over 86 dB SPL.
Amplifier measurements
I disassembled the powered loudspeaker and did a few basic measurements of the built-in amplifier directly with an 8,2 Ohm power resistor.
The amplifier is based on 2 pairs of bridged TDA2030A class A/B chip amps mounted to a relatively small aluminium heatsink.
There is even a schematic of the amplifier circuit available on-line, so I drew the circuit in VituixCAD to simulate the amplifier. After measurement I compared the simulated response with the measured ones (in both cases with tone controls set to neutral / mid-point):
As we can see there is an aggressive low-cut (probably to protect the woofer) and we can also see a ~4dB high-shelf. This can be somewhat mitigated by reducing the Treble tone control by ~10-20% to be within ~1dB of the LF, but a perfectly flat frequency response cannot be achieved, e.g.:
Or:
Here's what the tone controls do at their extremes (responses normalized to mid-position response):
Amplifier response at 5W into 8,2 Ohm load:
Let's now look at HD vs input level into 8,2 Ohm power resistor with amp volume set to max:
With both channels 1% THD is reached with ~750mV input which results in 14,3V output - so power into 8,2 Ohm at 1% THD is around 28W. So perhaps the 40W per channel rating at 10% might be possible (though I think heat dissipation from the small heatsink would be very problematic at those levels).
Distortion spectrum at 5W into 8,2 Ohms:
Conclusion
Looking at the data, objectively this is not a very impressive pair of speakers. However, considering the low price (and lack of alternatives at the time) these were IMO not too bad as PC/multimedia speakers. We even used them for TV sound for a while, before buying a nicer pair - they were definitely much better for this than the built-in TV speaker. Going forward I plan to use them as a DIY project to learn more about loudspeaker design.
In case @MZKM, @pierre, @Maiky76 (or others) might be interested to do their magic, CTA-2034-A exports from VCAD are attached as well.
[EDIT 2021-11-28] In-room measurements and some listening impressions with corrective EQs added to post #9.
It is quite an old product and there's not a lot of data available about it online anymore - here's one link with some very basic information. 10 or so years ago it was one of the cheapest 5" two-way active loudspeaker pairs one could buy where I live (I believe price was ~50-60€/pair).
Loudspeaker measurements
A few notes on measurement methodology:
- The loudspeaker has been measured at ~120cm distance from any reflective surfaces, with the microphone at 1m distance from the speaker, so the first reflection was around 4,6ms after the main impulse.
- I typically try to measure at 50cm to maximize the gate length, but with this loudspeaker there was a change in on-axis response when I moved a bit further away (perhaps due to large distance [14,5cm] between woofer and tweeter), which is why I settled for 1m. The shorter gate further reduces mid-frequency resolution, sadly.
- I typically try to measure at 50cm to maximize the gate length, but with this loudspeaker there was a change in on-axis response when I moved a bit further away (perhaps due to large distance [14,5cm] between woofer and tweeter), which is why I settled for 1m. The shorter gate further reduces mid-frequency resolution, sadly.
- The reflections were removed by temporal gating at ~4,6ms in REW to get some (low) resolution of quasi-anechoic measurement down to about 500Hz range (resolution is much better above ~2kHz).
- LF response (<500Hz) is spliced from nearfield measurements (baffle step corrected) and therefore not absolutely accurate. Take the absolute shape of the response there with a few grains of salt.
- The loudspeaker front baffle was vertically aligned with the centre of speaker stand/turntable rotation
- Loudspeaker stand has been covered with a blanket to reduce potential reflections and care was taken to angle the microphone boom to minimize boom reflections
- Microphone was pointed at tweeter axis
- REW, Cross-Spectrum labs calibrated Dayton EMM-6 microphone and RME Babyface interface was used to measure, and VituixCAD to generate the spin (exported with 1/24 octave resolution)
- Measured without loudspeaker grille
Here's the full spinorama for the powered (right) loudspeaker:
Preference rating as calculated by VituixCAD is:
- Speaker alone: 2.2
- Speaker with sub: 5.2
Perhaps it was designed to be listened without any toe-in? Hard to say, but the overall objective performance is not good.
Driver nearfield components:
We can see a couple things here:
- Very prominent resonances in the port NF measurement - using the VituixCAD 'Box volume' calculator indicates these are probably undamped box height resonances
[EDIT 2021-11-28] Effect of damping material on box resonances has been explored in post #10. - There is no real crossover - woofer is running full range and breaks up. If you open the speaker you see that just the tweeter is "high-passed" with a simple electrolytic cap
Horizontal directivity (normalized to on-axis response):
Impedance
Here's the impedance for both units in the pair:
As we can see, there are several visible resonances in the responses.
Distortion
76 dB SPL
86 dB SPL
Bass distortion became pretty audible around 80dB SPL and I was scared to go over 86 dB SPL.
Amplifier measurements
I disassembled the powered loudspeaker and did a few basic measurements of the built-in amplifier directly with an 8,2 Ohm power resistor.
The amplifier is based on 2 pairs of bridged TDA2030A class A/B chip amps mounted to a relatively small aluminium heatsink.
There is even a schematic of the amplifier circuit available on-line, so I drew the circuit in VituixCAD to simulate the amplifier. After measurement I compared the simulated response with the measured ones (in both cases with tone controls set to neutral / mid-point):
As we can see there is an aggressive low-cut (probably to protect the woofer) and we can also see a ~4dB high-shelf. This can be somewhat mitigated by reducing the Treble tone control by ~10-20% to be within ~1dB of the LF, but a perfectly flat frequency response cannot be achieved, e.g.:
Or:
Here's what the tone controls do at their extremes (responses normalized to mid-position response):
Amplifier response at 5W into 8,2 Ohm load:
Let's now look at HD vs input level into 8,2 Ohm power resistor with amp volume set to max:
With both channels 1% THD is reached with ~750mV input which results in 14,3V output - so power into 8,2 Ohm at 1% THD is around 28W. So perhaps the 40W per channel rating at 10% might be possible (though I think heat dissipation from the small heatsink would be very problematic at those levels).
Distortion spectrum at 5W into 8,2 Ohms:
Conclusion
Looking at the data, objectively this is not a very impressive pair of speakers. However, considering the low price (and lack of alternatives at the time) these were IMO not too bad as PC/multimedia speakers. We even used them for TV sound for a while, before buying a nicer pair - they were definitely much better for this than the built-in TV speaker.
Going forward I plan to use them as a DIY project to learn more about loudspeaker design. In case @MZKM, @pierre, @Maiky76 (or others) might be interested to do their magic, CTA-2034-A exports from VCAD are attached as well.
[EDIT 2021-11-28] In-room measurements and some listening impressions with corrective EQs added to post #9.
Last edited:
