3e audio A7/A7 Mono Amplifier Review

[Ruediger]

I completely agree with you! The only limiting factor is the available capacity of the local nuclear power plant. We can't be selfish – other people need electricity too

You can have solar surplus from me for free. Can power some houses on the side. Sadly it doesn't work that way.

But look at the amps that these units potentially replace. All those "old" class AB amps f.e. - I see only more efficiency and less heat. And if one choses the A5se or 2 x A7 mono only makes a small difference in idle power consumption.

 

[Argentum 05]

You can have solar surplus from me for free.

Oh, thank you! I'll definitely take you up on your offer the next time I want to listen to jazz, blues, or Tchaikovsky's "Swan Lake." I think solar energy would be perfect for that!
But for punk rock and trash, you need all the fury of neutrons bursting from uranium-235, desperate to escape the reactor core, but held back, with the last of their strength, by graphite rods!

But look at the amps that these units potentially replace. All those "old" class AB amps f.e. - I see only more efficiency and less heat. And if one choses the A5se or 2 x A7 mono only makes a small difference in idle power consumption.

I completely agree with you. Class D amplifiers, and in particular the 3e A7 and A5, are much more energy efficient than AB amplifiers.
I'm very happy with my A7 monos – they don't get hot at all.
I think this is indirect evidence of the superior design of these amplifiers.

 

[xrqp]

100 watts of continuous power poses no problem whatsoever for the A7

I am interested in this. At least a couple people have said it. Did you test it yourself, or is there a source for this? Are you referring only to the mono unit? Thanks.

Edit: I just saw the Youtube video for Fosi V3 mono tested for continuous 100W. That is good. Is there anything else? I emailed to e3 and asked them, as Groovy suggested.

 

[Groovy]

Ask the manufacturer. https://www.3e-audio.com/contact-us/

 

[Roland68]

I am interested in this. At least a couple people have said it. Did you test it yourself, or is there a source for this? Are you referring only to the mono unit? Thanks.

Edit: I just saw the Youtube video for Fosi V3 mono tested for continuous 100W. That is good. Is there anything else? I emailed to e3 and asked them, as Groovy suggested.

Aside from the fact that these figures are based on specifications from various manufacturers, there are plenty of users out there who do not go easy on this amplifier—running it for hours on end at high volumes with inefficient speakers.

I once ran it for over an hour into a dummy load at more than 2 x 100 watts; the temperature settled at around 42 degrees, which poses absolutely no problem—even under continuous operation.
We also own a set of very large, old, and inefficient DIY speakers featuring passive subwoofers (equipped with zero-ohm air-core inductors and 1100V MKP capacitors—meaning no compromises were made). Many Class A and Class AB Hi-Fi amplifiers have failed when paired with these speakers. The A7, however, rocked these units in a way that only a handful of amplifiers have managed to do before. Its continuous power output is roughly on par with that of the Yamaha A-S1X00/2X00 series amplifiers.

The power output of the TPA325x chips is limited by their physical size, as this factor dictates their maximum heat dissipation capacity. Consequently, adding extra cooling or larger heatsinks yields negligible benefits.
Furthermore, a certain amount of heat is actually desirable in any amplifier—provided, of course, that it maintains a stable operating temperature (due to the influence of temperature on the operating point and overall thermal stability). For this reason, uncontrolled maximum convection and the use of unintended or uncalibrated fan-based cooling solutions are absolute nonsense.

The hysteria surrounding heat issues here on this forum never ceases to amuse me. There is absolutely no evidence to suggest any thermal problems with 3E Audio amplifiers; yet, people continue to fabricate non-existent issues out of thin air.

 

[F1Fan72]

Hi all, Subjective question I know but how do these compare to the V3 mono’s?

 

[antcollinet]

Hi all, Subjective question I know but how do these compare to the V3 mono’s?

Sound wise? Will be pretty much identical.

 

[F1Fan72]

Sound wise? Will be pretty much identical.

Thanks, thought so.

 

[SnakeLord]

Hi all, Subjective question I know but how do these compare to the V3 mono’s?

As far as i know, the latest revisions of the V3 monos have proper PFFB implementation bringing it close to the A7xx performance wise on the higher frequencies spectrum. So i wouldnt expect any gain in sound quality in general.

If you feel like you arnt happy with the sound of your current setup for whatever reasons, try to reposition the speakers/change your listening position and there is still EQ to be used according to your room response.

 

[john61ct]

I often hear people mention things like "fatigue." I don't know what they mean.

Discussion of Fatigue

From Analogholic Most people think it comes from "too bright" or harsh a sound, but he goes through a litany of other possible issues. distortion, reduced contrast, limited headroom, poor bass timing, room reflections, speaker placement, gain structure, amplifier and speaker matching, low...

www.audiosciencereview.com

 

[F1Fan72]

As far as i know, the latest revisions of the V3 monos have proper PFFB implementation bringing it close to the A7xx performance wise on the higher frequencies spectrum. So i wouldnt expect any gain in sound quality in general.

If you feel like you arnt happy with the sound of your current setup for whatever reasons, try to reposition the speakers/change your listening position and there is still EQ to be used according to your room response.

Very happy with my setup and with some Fosi fans underneath the V3, very cool after hours of playing..

 

[xrqp]

I once ran it for over an hour into a dummy load at more than 2 x 100 watts; the temperature settled at around 42 degrees,

Thanks for sharing this. So I think you are referring to the e3 A7 stereo. So the mono would be even better heatsinking. Since you tested it for an hour, that is even better than the FCC 5 minute test. This is great.

 

[TurtlePaul]

The power output of the TPA325x chips is limited by their physical size, as this factor dictates their maximum heat dissipation capacity. Consequently, adding extra cooling or larger heatsinks yields negligible benefits.

This physical size heat dissipation limit theory isn’t the reason the 3e A7 doesn’t need a bigger heatsink.

Look at the Powercube voltage results. Into 8 ohms, the amp can delver 31 volts. This is voltage clipping. Into 2 and 4 ohms it can deliver 29-31 volts at any phase angle. It can reach voltage clipping with any reasonable load.

The cooling design allows the amp to reach voltage clipping as low as 2 ohms with a 52 volt power supply. 3e has addressed current by using 2x TPA3255 in PBTL mode and has addressed cooling with the heatsink and case design. They cannot however provide a higher voltage power supply because this is a fundamental limitation of the TPA3255.

It would only be reasonable to have a bigger heatsink if the chip could do more than 52 volts power supply input.

 

[TreyHaynie]

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
View attachment 444148

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:
View attachment 444153
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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Just fired mine up and wow. I had been using an old marantz avr (sr5008). Crazy this little box gets my martin logan b1's what feels like twice as loud. AB receivers have that "warm" sound, but I'm not missing much so far with the A7. What is lacks in "warmth" it makes up for with punch and slam.

 

[Guddu]

Just fired mine up and wow. I had been using an old marantz avr (sr5008). Crazy this little box gets my martin logan b1's what feels like twice as loud. AB receivers have that "warm" sound, but I'm not missing much so far with the A7. What is lacks in "warmth" it makes up for with punch and slam.

Without going into too much details, How do you describe this "warmth" which is missing to you?
*no sarcasm.

 

[TreyHaynie]

I think the marnatz (and other A/B amps) somehow slightly roll off the top end frequencies in a way that is pleasant to my ears (but not doing so much that it sounds flat or boring). Honestly the A7 is right there as well, the more I listen to it.

 

[Ropeburn]

I think the marnatz (and other A/B amps) somehow slightly roll off the top end frequencies in a way that is pleasant to my ears (but not doing so much that it sounds flat or boring). Honestly the A7 is right there as well, the more I listen to it.

Pretty typical of a good AB amp: wide bandwidth. You can be certain there's no rolloff in hearing range.

 

[TreyHaynie]

Well you can still roll off all the way to 100k hz cant you? Hence the term "roll-off." Like a gradual decline, not a firm cut.

 

[Ropeburn]

Well you can still roll off all the way to 100k hz cant you? Hence the term "roll-off." Like a gradual decline, not a firm cut.

Typical AB response:

You cannot hear that.

 

[TreyHaynie]

It looks like the roll starts at 20k hz, so you might be able to.