ATI AT522NC Stereo Amplifier Review

[Head_Unit]

This quirk has led to angry phone calls from my wife while I was abroad on client matters, because the TV would turn on but no sound would come on.

You don't have the internal TV speakers enabled? Or it's not possible? My default is the TV runs internal speakers, NOT the stereo, because of fear of just such phone calls. The horror! The horror!

 

[RichB]

You don't have the internal TV speakers enabled? Or it's not possible? My default is the TV runs internal speakers, NOT the stereo, because of fear of just such phone calls. The horror! The horror!

And to all those out there with two cars, you have no right to get upset when your, still-under warranty, car won't start. Just use the other car for cripes sake

I suspect there are many, like me, that have a unwritten contract with the less AV obsessed members of the family to provide a system that is as easy to use as a TV. I am not sure I achieved that, especially with the many wonders of HDMI, but I try.

Concerning ATI, they have corrected issues with amps that required manual intervention after power loss (AT6000/AT4000) and amps that power off (AT5xxx) while receiving a signal. Those concerned and still experiences these issues can contact ATI for a correction.

- Rich

 

[jhaider]

You don't have the internal TV speakers enabled? Or it's not possible? My default is the TV runs internal speakers, NOT the stereo, because of fear of just such phone calls. The horror! The horror!

No, the internal TV speakers are not enabled. I love my family, so why subject them to that?

As @RichB notes immediately above, ATI has resolved this issue. It is now moot for me anyway. Since me moved and the audio electronics are all now remotely located I no longer use the AT4007, because I can now use the DSP-amps with loud fans my speakers were designed to use rather than using separate processing and amplification.

Anyone interested in owning that fine amp should see this post though. One thing to note is @amirm measured 121dB SNR at full power, consistent with ATI's published spec (>120dB dBA at rated power). That indicates ATI's specifications are accurate-to-conservative. ATI rates AT4007 as 5dB quieter (>125dB dBA SNR at rated power), which is ~5dB better than the @amirm's results for nCore NC400,~2dB better than @amirm's results for Purifi, and ~12dB better than Benchmark AHB2. (The last one surprised me; I did not realize Benchmark's high SINAD was a result of low distortion, despite an SNR that is not class leading.)

 

[ConeyIsland]

Just ordered the AT6000, somewhat based off of this thread/reviews. Also want to thank y’all for talking me out of Marantz, I’ve landed with a X3700 for a pre, while driving rear speakers.

I’m kind of at a loss on what speakers to use this with. I really want bookshelves, as my office is a little small for big towers. I’ve been eyeing the Focal Sopra N1’s, any other thirsty amazing bookshelves other there?

 

[peng]

Just ordered the AT6000, somewhat based off of this thread/reviews. Also want to thank y’all for talking me out of Marantz, I’ve landed with a X3700 for a pre, while driving rear speakers.

I’m kind of at a loss on what speakers to use this with. I really want bookshelves, as my office is a little small for big towers. I’ve been eyeing the Focal Sopra N1’s, any other thirsty amazing bookshelves other there?

Philharmonic Audio

 

[Head_Unit]

I really want bookshelves, as my office is a little small for big towers.

Pictures! You're going to put them on shelves? On desktop? How far away? We like our Focal 936, Sopra should be very good, but I do favor 3-ways for best midrange clarity. Also many bookshelves are ported too high to cover all the lowest frequencies. Are you going to add a sub? Or Nah? The Focal CC900 sounds quite nice and amazingly is also ported down at 40 Hz, you could run a couple of those on their side (or Sopra equivalent). But if you are super nearfield then some kind of studio monitor designed for that might be better.

 

[ConeyIsland]

Pictures! You're going to put them on shelves? On desktop? How far away? We like our Focal 936, Sopra should be very good, but I do favor 3-ways for best midrange clarity. Also many bookshelves are ported too high to cover all the lowest frequencies. Are you going to add a sub? Or Nah? The Focal CC900 sounds quite nice and amazingly is also ported down at 40 Hz, you could run a couple of those on their side (or Sopra equivalent). But if you are super nearfield then some kind of studio monitor designed for that might be better.

I just got a call back from the dealer, the AT6000 is backordered without ETA I’m told.

 

[Head_Unit]

I suspect there are many, like me, that have a unwritten contract with the less AV obsessed members of the family to provide a system that is as easy to use as a TV.

Hence why I have 5 or 6 TCL Roku TVs Wired my buddy's setup similary-TV+DirecTV comes out of the TV. In theory he can listen to that through the stereo via ARC but I don't think he ever does.

 

[Head_Unit]

I just got a call back from the dealer, the AT6000 is backordered without ETA I’m told.

Sucks...then my question becomes why don't you consider powered monitors? That might fit your application.

 

[ConeyIsland]

Sucks...then my question becomes why don't you consider powered monitors? That might fit your application.

I’ve considered it, the SM9’s were on my short list. I just wish they weren’t discontinued. In general monitors don’t look as good either as regular speakers. The Focal Kanta’s are a beautiful speaker, I fell in love. I also run the Focal BE tweets in my truck on AB amps, and absolutely love the sound.

Are there measurements for the AT4000/6000 on here? I searched but couldn’t find anything.

 

[jhaider]

Are there measurements for the AT4000/6000 on here? I searched but couldn’t find anything.

Here, no. These things are effing heavy, so I can't imagine anyone wants to ship one to Amir. I also can't imagine Amir would relish wrestling with one on his test bench.

Dr. David Rich evaluates measurements of an AT6002 and takes a deep dive into the design here:

ATI AT6002 Multi-Channel Power Amplifier Review - HomeTheaterHifi.com

ATI, Multichannel, Power Amplifiers

hometheaterhifi.com

 

[pma]

Interesting the reviewer does not understand the origin of PSU intermodulation artifacts in the spectrum due to poor PSR.

 

[RichB]

Interesting the reviewer does not understand the origin of PSU intermodulation artifacts in the spectrum due to poor PSR.

Since you make this claim, please enlighten us.

- Rich

 

[RichB]

Here, no. These things are effing heavy, so I can't imagine anyone wants to ship one to Amir. I also can't imagine Amir would relish wrestling with one on his test bench.

Dr. David Rich evaluates measurements of an AT6002 and takes a deep dive into the design here:

ATI AT6002 Multi-Channel Power Amplifier Review - HomeTheaterHifi.com

ATI, Multichannel, Power Amplifiers

hometheaterhifi.com

And then some, I had two AT6002s and a AT6006. They were quiet at the speaker and very good amps.
If I had to describe them, I would call them smooth.

I did not like the heat, weight, and occasional transformer hum and do not regret the switch over the AHB2s.
They are nice amplifiers but, I have left big-iron behind.

- Rich

 

[DonH56]

Since you make this claim, please enlighten us.

- Rich

Guessing @pma noticed the review shows low-level power-supply spurs around 120 Hz, and that they couple into the output is shown in the distortion plots, but there is this comment in the middle of the review: "The origin of the small spurs, which are spaced at 120Hz (the full wave rectifier fundamental frequency), is not clear." I don't know what Dr. Rich was thinking when he wrote that since he clearly knows they are related to power noise, perhaps he meant the cause of the sidebands' high level in the distortion plots was not obvious relative to the low level at the actual power harmonics. Guessing he didn't want to speculate about the internal coupling cause; usually power supply noise sneaking into the bias or signal path (low PSRR).

SWAG - Don

 

[ConeyIsland]

The power output between the ABH2 and the 6002 is drastically different. I do appreciate the cleanness of the amp though. Would I be better waiting for the 6000 to come back in stock, or should I look at the Parasound A51?

 

[RichB]

The power output between the ABH2 and the 6002 is drastically different. I do appreciate the cleanness of the amp though. Would I be better waiting for the 6000 to come back in stock, or should I look at the Parasound A51?

Yes, the AT6002 has 3 dB more output in stereo mode and the AHB2.
The AHB2 has more power in bridged mode, though less headroom driven into clipping.

I bi-amped the Salon2s with the AT6002s and do so with the AHB2s. They don't clip when I play movies at levels that we consider loud and with music.
I can clip with AT6002s and AHB2s (stereo) playing music when trying to do so, but I do not need to so, so I don't.
Two friends also have AHB2s driving Salon2s that bridge them, they cost more but the has clear benefits:

- Better measurements
- Lower heat
- Light weight
- No transformer hum
- Absolutely silent, thought the AT6000 are up there.

- Rich

 

[ConeyIsland]

Yes, the AT6002 has 3 dB more output in stereo mode and the AHB2.
The AHB2 has more power in bridged mode, though less headroom driven into clipping.

I bi-amped the Salon2s with the AT6002s and do so with the AHB2s. They don't clip when I play movies at levels that we consider loud and with music.
I can clip with AT6002s and AHB2s (stereo) playing music when trying to do so, but I do not need to so, so I don't.
Two friends also have AHB2s driving Salon2s that bridge them, they cost more but the has clear benefits:

- Better measurements
- Lower heat
- Light weight
- No transformer hum
- Absolutely silent, thought the AT6000 are up there.

- Rich

Thanks Rich, very good information there. Just curious, how does Parasound compare to these?

 

[RichB]

Thanks Rich, very good information there. Just curious, how does Parasound compare to these?

Now, you are asking how they sound.

I find the AHB2 has more apparent detail than any amp I have had including the Parasound.
The Parasound are nice but had a mild buzz in my speakers.

The AT6000 was quiet, I tended to turn them up louder than the Parasound though, perhaps due to less distortion.
I don't turn feel the need to turn up the AHB2s as loud, so that's different even though they have the most distortion.

I am of the opinion that the driving real loads, some amps may incur more distortion and linearity issues not readily found in reactive load, single tone testing.

- Rich

 

[ConeyIsland]

Now, you are asking how they sound.

I find the AHB2 has more apparent detail than any amp I have had including the Parasound.
The Parasound are nice but had a mild buzz in my speakers.

The AT6000 was quiet, I tended to turn them up louder than the Parasound though, perhaps due to less distortion.
I don't turn feel the need to turn up the AHB2s as loud, so that's different even though they have the most distortion.

I am of the opinion that the driving real loads, some amps may incur more distortion and linearity issues not readily found in reactive load, single tone testing.

- Rich

For the AT4000/6000 Is there something where shielding could be applied to the PSU to stop the noise, or is it the PSU itself?

I’ve wondered if 3D printing a case for the 1ET400A in ESD filament would net any positive results.