I have an ATI AT525NC (NCore) amp that will be deployed in the spring at another location and I need to test it before then.
My office and main system use AHB2 amplifiers.
I have edited this post since I changed the test configuration.
This provides an opportunity to perform some Single Blind Tests comparing the two.
Here is the configuration for the test.
During the test, the MiniDSP channels were switched and no differences were found. This was done to make sure the MiniDSP was not affecting the test.
I have not yet done the single-blind-test (SBT) part so, for now, it is me listening and quick switching.
The AHB2 and AT522NC do sound different. These are most easily recognizable playing close-mic'ed female vocals, and percussive instruments, and recordings with good stereo imaging.
In all cases where they differed, I find the AHB2 to the cleaner sounding amp. The sound stage is more defined. The ATI sounds does not produce the sibilants as naturally and seemingly dulls the leading edge of drum hits and guitar strings. As a result the AHB2 sounds more lifelike and louder, though it is not.
This was surprising, so more than once, the outputs were re-measured with 1kHz 0 dBFS sinewaves. At 2.83 volts and the ATI is a just a hair louder, 0.02 volts which is insignificant. It was not a gain issue.
EDIT: I did find the AT525NC voltage varied during steady 1 kHz tone from 2.75 to 2.86 volts.
Whereas, the AHB2 was always 2.85 volts.
One album exemplified the differences more than the others, but all showed the same results.
Feist's "Metals" has excellent percussive sounds, up front female vocals, and wide imaging.
The AHB2 was exemplary and the ATI just did not excel.
To be fair, I am sure that if I walked in the room, I would not know which was playing but with the A/B switch it was not difficult.
Here are some images of the setup.
This was the original level match. I later changed it -3.0 dB and -8.5 dB to make sure that both channels were using the DSP processing. This made no difference.
The setup.
I am actually surprised by these results. The expectation was the AT525NC would be indistiquishable.
- Rich
My office and main system use AHB2 amplifiers.
I have edited this post since I changed the test configuration.
This provides an opportunity to perform some Single Blind Tests comparing the two.
Here is the configuration for the test.
- The MiniDSP SHD is used as the source for both amplifiers. Its DSP permits level matching between .1 dB. In actuality, matching was 0.06 dB.
- The MIniDSP outputs 1 and 3 are the left channel and 2 and 4 are the right channels.
- Both amps were level matched to approximately 2.83 Volts measure with a Fluke 87V sinewave voltmeter.
- Music selections are streamed by Roon to a Raspberry PI3 running DietPi and Roon endpoint to the MiniDSP USB DAC.
- This passive A/B switch was used to switch instantaneously between sources: Amazon.com: Nobsound Stereo 2(1)-IN-1(2)-OUT Amplifier/Speaker Banana Female Audio Splitter/Switcher Passive Selector: Electronics
- Roon -> RPI3 (DietPi Endpoint) -> MiniDSP USB Input
- MiniDSP out 1 & 2 -> ATI525NC -> Nob switch Input A
- MiniDSP out 3 & 4 -> AHB2 -> Nob switch Input B
- Nob switch out -> Revel M123Be speakers
During the test, the MiniDSP channels were switched and no differences were found. This was done to make sure the MiniDSP was not affecting the test.
I have not yet done the single-blind-test (SBT) part so, for now, it is me listening and quick switching.
The AHB2 and AT522NC do sound different. These are most easily recognizable playing close-mic'ed female vocals, and percussive instruments, and recordings with good stereo imaging.
In all cases where they differed, I find the AHB2 to the cleaner sounding amp. The sound stage is more defined. The ATI sounds does not produce the sibilants as naturally and seemingly dulls the leading edge of drum hits and guitar strings. As a result the AHB2 sounds more lifelike and louder, though it is not.
This was surprising, so more than once, the outputs were re-measured with 1kHz 0 dBFS sinewaves. At 2.83 volts and the ATI is a just a hair louder, 0.02 volts which is insignificant. It was not a gain issue.
EDIT: I did find the AT525NC voltage varied during steady 1 kHz tone from 2.75 to 2.86 volts.
Whereas, the AHB2 was always 2.85 volts.
One album exemplified the differences more than the others, but all showed the same results.
Feist's "Metals" has excellent percussive sounds, up front female vocals, and wide imaging.
The AHB2 was exemplary and the ATI just did not excel.
To be fair, I am sure that if I walked in the room, I would not know which was playing but with the A/B switch it was not difficult.
Here are some images of the setup.
This was the original level match. I later changed it -3.0 dB and -8.5 dB to make sure that both channels were using the DSP processing. This made no difference.
The setup.
I am actually surprised by these results. The expectation was the AT525NC would be indistiquishable.
- Rich
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