Intro
Sometimes we can read questions why more expensive "high-end" components are not tested at ASR. The reasons are obvious - there must be a piece available to be tested. Let me make a small try - a result of my short test dated January 2019, when I was asked by the Halo A21 owner to check his amplifier.
Parasound HALO A21
It was a nicely built power amplifier produced between the years 2002 - 2020.
Basic parameters per the manufacturer
The amplifier is well built, as one can see from the following photos:
The case is heavy, with appropriate heat sinks and good craftsmanship. Not seen that often nowadays.
2. Some measurements
I have had no intention, and no idea, 5 years ago, to write a review of this amplifier. But, it is probably worth sharing.
2.1. THD distortion at 100W/1kHz/4ohm
THD = 0.0098%. Please note very low content of mains related spuriae from the linear power supply. It is my deep persuasion that it may result from operator's experience and knowledge how to setup the measuring circuit properly.
2.2. THD distortion at 328W/1kHz/4ohm
2.3. CCIF IMD 13+14kHz at 21Vrms 4ohm load
The result is very good, taking into account very high signal level - tested at more than 100W/4ohm.
2.4. THD vs. frequency
Measured at 10W/4ohm. There is a progressive rise of distortion with frequency, indicating to decreasing feedback factor with frequency. The result is not perfect, however not to be audible.
3. Conclusion
Parasound Halo A21 was a well built, rugged stereo power amplifier, reasonably priced in a class of high-end amplifiers. The parameters are respectable, with exception of distortion rise with frequency. I appreciated very low content of mains frequency related spectrum lines.
Note: more specs in the attached pdf
Sometimes we can read questions why more expensive "high-end" components are not tested at ASR. The reasons are obvious - there must be a piece available to be tested. Let me make a small try - a result of my short test dated January 2019, when I was asked by the Halo A21 owner to check his amplifier.
Parasound HALO A21
It was a nicely built power amplifier produced between the years 2002 - 2020.
Basic parameters per the manufacturer
- Power output: 250 watts per channel into 8Ω (stereo), 750 watts into 8Ω (mono)
- Frequency response: 5Hz to 100kHz
- Total harmonic distortion: 0.2%
- Damping factor: 1100
- Input sensitivity: 1V
- Signal to noise ratio: 112dB
- Speaker load impedance: 4Ω to 16Ω
- Dimensions: 445 x 194 x 485mm
- Weight: 27.3kg
The amplifier is well built, as one can see from the following photos:
The case is heavy, with appropriate heat sinks and good craftsmanship. Not seen that often nowadays.
2. Some measurements
I have had no intention, and no idea, 5 years ago, to write a review of this amplifier. But, it is probably worth sharing.
2.1. THD distortion at 100W/1kHz/4ohm
THD = 0.0098%. Please note very low content of mains related spuriae from the linear power supply. It is my deep persuasion that it may result from operator's experience and knowledge how to setup the measuring circuit properly.
2.2. THD distortion at 328W/1kHz/4ohm
2.3. CCIF IMD 13+14kHz at 21Vrms 4ohm load
The result is very good, taking into account very high signal level - tested at more than 100W/4ohm.
2.4. THD vs. frequency
Measured at 10W/4ohm. There is a progressive rise of distortion with frequency, indicating to decreasing feedback factor with frequency. The result is not perfect, however not to be audible.
3. Conclusion
Parasound Halo A21 was a well built, rugged stereo power amplifier, reasonably priced in a class of high-end amplifiers. The parameters are respectable, with exception of distortion rise with frequency. I appreciated very low content of mains frequency related spectrum lines.
Note: more specs in the attached pdf
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