3e audio A7/A7 Mono Amplifier Review

[antcollinet]

Read that this amp could withstand loads of up 16 to 2 ohms.

At 2 ohm how many watts could it deliver constantly wth a distortion < 1% THD. Did any body measure that.
Reason for this question if my NADC370 will fail beyond reparation i considering to replace it with the A7 as one of the alternatives. However i'm still impressed by the thight low reproduction of the NAD at 2 ohm 305 watt not to taking in account it Dynamic output power in these condition at 2ohm we are taking about 846 watt. Will the A7 sound the same or better than the NADC370.?

NAD C370 integrated amplifier Measurements part 2

This can be seen in figs.7 and 8, which show FFT-derived spectra of the NAD's output while it reproduced a 50Hz tone at 1W and 10W, respectively, into 8 ohms. At the lower power level, an entire series of odd harmonics can be seen that effectively disappear at the higher level. Yes, even at 1W...

www.stereophile.com

The PSU is rated < 500W - so you are definitely not going to get 250W both channels driven on a continuous basis - no matter what the load.

And I very much doubt you will get close to this. But I'm not aware of any measurements.

 

[Crook]

I would first check if they are properly put:

View attachment 444964

(pic from this thread) :

9 Channel 3E Audio Amp(s) project

My new amp modules just arrived! I will soon (after a 2 week trip) start building these into my home theater system - an Onkyo RZ50 in 5.2.4 configuration. This build is actually 2 separate but identically looking amps: - a chassis containing (3) mono amp modules powered by Mornsun LOF750-20B48...

www.audiosciencereview.com

...and then if properly rated, genuine, temp adequate, etc. Anyone can have such misses of course, tighter QC as promised should be in place after that.

All the above of course is not my job as a consumer or it shouldn't be. My job is to enjoy my gear as carelessly as it should be without worrying about anything.
So...

That is a poor show. Let's hope QC has improved for the current amps or "bang".

 

[Snarfie]

The PSU is rated < 500W - so you are definitely not going to get 250W both channels driven on a continuous basis - no matter what the load.

And I very much doubt you will get close to this. But I'm not aware of any measurements.

Thanx didn't took inacount the PSU. Basicly i don't think only pure power define the quality of an amp. For me >95% i will never use this amount of watt. Thinks like imaging, transparancy, an precise effortless sounding amp (imo this is where the NAD shines) will there be a difference between the two Amp's.

 

[antcollinet]

Thanx didn't took inacount the PSU. Basicly i don't think only pure power define the quality of an amp. For me >95% i will never use this amount of watt. Thinks like imaging, transparancy, an precise effortless sounding amp (imo this is where the NAD shines) will there be a difference between the two Amp's.

For me, looking for continuous power from an amp is pointless. You want it to deliver peak power for transients without clipping. These are going to be at least 10dB over your average (continuous) power. So if your amp can do 250W (as this one can - just about), your average (continuous) level is only going to be about 25W. Which is still going to be 12 to 15dB above your speakers sensitivity rating.

 

[Old_School_Brad]

For me, looking for continuous power from an amp is pointless. You want it to deliver peak power for transients without clipping. These are going to be at least 10dB over your average (continuous) power. So if your amp can do 250W (as this one can - just about), your average (continuous) level is only going to be about 25W. Which is still going to be 12 to 15dB above your speakers sensitivity rating.

Then there are those of us who enjoy electronic music with sustained, high-level bass content between 25 and 60 Hz, often lasting for minutes at a time. In those cases, we need amplification that can deliver continuous power -not just short bursts of 10–20 milliseconds.

Different tools for different jobs.

 

[Guddu]

Then there are those of us who enjoy electronic music with sustained, high-level bass content between 25 and 60 Hz, often lasting for minutes at a time. In those cases, we need amplification that can deliver continuous power -not just short bursts of 10–20 milliseconds.

Different tools for different jobs.

+1 +trance

 

[Kevinfc]

Absolutely astonishing performance for the price, even for five times that a decade or so ago.

 

[antcollinet]

Then there are those of us who enjoy electronic music with sustained, high-level bass content between 25 and 60 Hz, often lasting for minutes at a time. In those cases, we need amplification that can deliver continuous power -not just short bursts of 10–20 milliseconds.

Different tools for different jobs.

Are you saying there are no peaks or transients at all in such music. No drum strikes that rise above the RMS level of those sustained minute long crescendos? Crest factor 1? That just sounds like pink noise - or a square wave. Even a mere three dB means average will be half of peak.

 

[Snarfie]

Are you saying there are no peaks or transients at all in such music. No drum strikes that rise above the RMS level of those sustained minute long crescendos? Crest factor 1? That just sounds like pink noise - or a square wave. Even a mere three dB means average will be half of peak.

Interesting measurment live how much continus power is needed in some circumstances. Around minuten 4. Curious how the A7 will sound in these circumstances.

 

[antcollinet]

Interesting measurment live how much continus power is need is some circumstances. Around minuten 4.

I don't think that tells us anything about the ratio of peak to average for that section of the music. Except that it clearly wasn't 1:1

But yes - fascinating that they were running at such a high power level. I wonder what SPL they had. And the speaker efficiency.

 

[Snarfie]

I don't think that tells us anything about the ratio of peak to average for that section of the music.

Minut 7:40 they go into what they heard an saw around 500 watt regular with peaks of 750 watt.

 

[Audionaut]

Will the A7 sound the same or better than the NADC370.?

This depends primarily on the efficiency and impedance curve of your speakers.
Up to medium volumes, they will probably sound completely the same.

 

[Sokel]

I don't think that tells us anything about the ratio of peak to average for that section of the music. Except that it clearly wasn't 1:1

But yes - fascinating that they were running at such a high power level. I wonder what SPL they had. And the speaker efficiency.

I mean... you can tell:

foobar's DR meter value is only 8.
All this album is a torture, it has full 20kHz at points.

(Not as the mild white noise that is popular these days though)

 

[antcollinet]

I mean... you can tell:

View attachment 445126

foobar's DR meter value is only 8.
All this album is a torture, it has full 20kHz at points.

(Not as the mild white noise that is popular these days though)

Is that -12dB Average power? For the whole song? or specifically the part in the video at 500W?

If average, then there is still a crest of 12dB since peaks are hitting 0dB

 

[Sokel]

Is that -12dB Average power? For the whole song? or specifically the part in the video at 500W?

If average, then there is still a crest of 12dB since peaks are hitting 0dB

That's the measured RMS using Audacity's tool for the whole selected area (the whole song essentially)

That's what REW analysis shows for peaks:

We're talking no jokes here, this is a constant additive energy all the way up.
(it sounds like it, too)

 

[transformer-coupled]

This is a review and detailed measurements of the A7 / "A7 Mono" stereo power amplifier with balanced inputs. It was sent to me by the company. I have no idea what it costs in US. Audiophonics lists it for 379,00 €tax incl.
View attachment 444144
While the A7 may look like its competitors, it has a heft to it that I don't recall others not having. It really feels like it is filled with lead or something! A nice volume control in the middle adjusts the gain but it can also be bypassed using a switch in the back. Pushing the volume control quickly switches between XLR balanced and RCA. Two thoughtful clipping indicators are provided, making me wish it would be a standard feature on any amplifier. A minor nit: LED colors indicating which input is active is red and clipping in green. I think based on convention, the latter should be red.

Back panel shows nice set of features:
View attachment 444145
Trigger input is provided as is the aforementioned combo TRS/XLR balanced inputs. Low and high gain switch is provided but I focused on low gain as that is fully compatible with current audio products outputting 2/4 volts. Yes, there is that monster GaN power supply! It can of course be purchased with other options. The input connector says max is 48 volt but per designer, the mono configuration, which is just using the left channel, can go up to 52 volts. He said I could test in stereo just the same and that is what I did. I found no issues.

FYI, I was impressed with the secure way the power supply input accepts the plug. There is a lot of current and power involved here so good to see a tight fit.

One nice feature, beside trigger, is auto-shut off in case of no input signal. I left it on by accident and was pleasantly surprised when I came back and it had gone to sleep.

3e audio A7 Amplifier Measurements
Let's start with low gain, volume control set to (volume bypass didn't make a difference), and XLR as inputs:

View attachment 444146
Very nice. Well above average in performance with distortion below threshold of hearing:
View attachment 444147
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RCA input as usual loses a bit, but not much, scoring 100 dB with again, inaudible distortion:
View attachment 444149

SNR is the limit here, which is quite good actually:
View attachment 444150
At full power, it provides transparency for practically all music produced!

The A7 uses post filter feedback (PFFB) so it is essentially load (speaker) independent:
View attachment 444151

Crosstalk while much better than average, is a bit worse than 3e audio A5:
View attachment 444152

As is typical here, above 1 kHz, distortion does climb:
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View attachment 444154

This is one powerful little amplifier, easily besting its nicely mentioned specs:
View attachment 444155
View attachment 444156

View attachment 444157

Edit: forgot to include the power vs frequency sweep:

View attachment 444184
Power is more or less sustained across the full audible band:
View attachment 444158
View attachment 444159

Its distortion goes from 0.05% to huge amount as it clips so I could not test it at 1% THD at higher frequency. So I searched for power point at just 0.05% which disadvantages this amp a bit.

My reactive loadbox still doesn't like these bridged amplifiers so I could only test the left channel (although per above, stereo and mono performance were the same):
View attachment 444160

View attachment 444161

You have to keep reminding yourself that this much power is coming out of this little box, no bigger than the old CD cases!

Finally, the amplifier is rock solid on power up:
View attachment 444162

Oh, too much on my mind so I forgot to run the power up/down glitch test.

Conclusions
If my memory serves me right, 3e audio was the first company to bring us high performance TI TPA3255 class D amplifiers with PFFB. While they have more competition now, it is clear they intend to stay on top of this game, squeezing every bit of performance out of this architecture, while providing nice feature set. We are talking high performance, high power amplifiers that are tiny yet deliver what people need in most cases.

I am happy to recommend 3e audio A7 / A7 Mono stereo audio amplifiers.

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As always, questions, comments, recommendations, etc. are welcome.

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Great review as always, just perfection got even better...

 

[transformer-coupled]

thank you so much @amirm

...but having got the great 3e diy modules and the 3e A5 stereo power amp with nice bypassable volume control, the perfection will be only achieved if @3eaudio make the auto-power-off deactivatable just the same as needed volume bypass for using our high end preamp, we need deactivatable auto-off feature BECAUSE WE LOVE TO LISTEN MUSIC OR MOVIES AT LATE NIGHT AND AT THAT SO LOW LEVEL, AUTO-OFF THINKS THERE IS NO AUDIO SOURCE AND IT DISCONNECT, AND ITS SO DISAPPOINTING but otherwise the 5A 3e Audio audiophile power amp is almost perfect and thank you again for it.

 

[wwenze]

Notice these discussions of "peak" always end up with encountering, clashing and crashing at a particular issue?

Nobody can quantify what "peak" means

So you want to design the amp for 20dB crest factor? 10dB? 6dB? 0dB? Which value is the safest? This is why different products do it differently.

Some people demand unlimited current into 1ohm. Others demand unlimited peak. No right or wrong.

I should also remind that, for their ability to save on power supply (capacitor and transformer) size by using a high switching frequency, class-D amplifiers tend to have less temporary power storage (the abovementioned capacitor and transformer), which is kind of the design goal. I know I'm conflating amp with PSU, but kind of relevant

 

[Old_School_Brad]

Are you saying there are no peaks or transients at all in such music. No drum strikes that rise above the RMS level of those sustained minute long crescendos? Crest factor 1? That just sounds like pink noise - or a square wave. Even a mere three dB means average will be half of peak.

Of course, that’s not what I’m saying. The point isn’t about running an amplifier at 100% all the time -it’s about demanding sustained, significant continuous power over extended periods. Those are two very different things. The demands I have for an amplifier is that it will indefinitely be able to sustain low frequency bass at high SPL without breaking a sweat.

Just as an example, I have three tracks in my playlist that I want to play at high SPL. That kind of playback demands real continuous power -not just short 10–20 ms bursts.

Spoiler: Exhibit A (3-4 minutes of continuous bass)

Spoiler: Exhibit B

Spoiler: Exhibit C

 

[Old_School_Brad]

Is that -12dB Average power? For the whole song? or specifically the part in the video at 500W?

If average, then there is still a crest of 12dB since peaks are hitting 0dB

This is an older in-room measurement I saved from when I played this track on my setup. I don't doubt the power figures in that video.