3e audio A7/A7 Mono Amplifier Review

[Bleib]

At least for those using these as integrated amplifiers with just one input (2 inputs if you count XLR and RCA as that). I rather think of the A7 as a power amp with bypassable volume control and expect the inputs, EQ, room correction and bass management to be handled by a pre-amp. But each to their own.

Of course we can add things with other units. But it's also true that we used to get tons more features for the price in the past. Then came the purist era which also very conveniently helped to maximize profits

 

[harkpabst]

Of course we can add things with other units. But it's also true that we used to get tons more features for the price in the past. Then came the purist era which also very conveniently helped to maximize profits

Yes, but that's not exactly a new thing. I don't know about the US, but at least in Europe this purist area started in the 1980s, mostly driven by the British cottage industry.

 

[Roland68]

At least for those using these as integrated amplifiers with just one input (2 inputs if you count XLR and RCA as that). I rather think of the A7 as a power amp with bypassable volume control and expect the inputs, EQ, room correction and bass management to be handled by a pre-amp. But each to their own.

Of course we can add things with other units. But it's also true that we used to get tons more features for the price in the past. Then came the purist era which also very conveniently helped to maximize profits

But we don't want to go back to the Stone Age either.
These kinds of things belong on the digital side, even for analog devices. Such functionality makes little sense in analog and is both problematic and lossy.
The final step should be the conversion to analog, which is why such amplifiers don't need much more than one or two inputs and volume control.

At some point, you have to break with old habits, otherwise development stagnates.

 

[Urtica]

No, it didn't really have a considerable power reserve, just a considerable amount of volume pot travel left. If you tried to make use of this, the amp would distort heavily, so you cannot call that a reserve.

What you experience is just a much higher input sensitivity (lower input voltage for maximum power input) due to higher gain. If you can reach your desired target SPL with just a small turn of the knob, you simply have less granular volume control, not higher power. It's not the amp "coming to life" earlier, it's your perception playing tricks on you.

The speaker doesn't care about amplifier gain or the characteristic curve of the potentiometer. It will always need the same power for the same SPL at the same frequency.


One very plausible (and likely) reason would be a lower damping factor (higher output impedance) of the AU-D7. This would result in a little less bass control and potentially somewhat different tonality (although the impedance of the Linton is pretty flat except for the min and max values up to ~300 Hz).

Thank you for your explanation.
I have one more point. If we compare the Sansui AU‑D7, which delivers 80 W RMS, with the 3E A7se, which delivers 130 W RMS at 8 Ω, it might seem that the louder amplifier would be noticeably louder. However, using a simple formula that relates amplifier power to sound level:

ΔLSPL=10log⁡(P2/P1)
we get:

ΔLSPL=10log⁡(130/80)≈2.1 dB
This is a very small increase — it represents the maximum possible difference if both amplifiers were pushed to their limits. My own experience confirms this: both amplifiers sound very similar in loudness, showing that they are well matched to the Wharfedale Linton 85th in a 20 m² room.

Now I’ll focus on shaping the sound character of the 3E A7se. For this, I’ll use the Wiim Pro Plus and its parametric EQ.

 

[harkpabst]

ΔLSPL=10log⁡(P2/P1)
we get:

ΔLSPL=10log⁡(130/80)≈2.1 dB
This is a very small increase — it represents the maximum possible difference if both amplifiers were pushed to their limits. My own experience confirms this: both amplifiers sound very similar in loudness, showing that they are well matched to the Wharfedale Linton 85th in a 20 m² room.

Yes, that's absolutely correct.

These kinds of things belong on the digital side, even for analog devices. Such functionality makes little sense in analog and is both problematic and lossy.
The final step should be the conversion to analog, which is why such amplifiers don't need much more than one or two inputs and volume control.

Or even no volume control as far as I'm concerned. I fully agree.

 

[peng]

Hi,
However, certain things surprised me. Subjectively, I perceived the bass in the Sansui as slightly stronger than in the 3e A7se. This may be due to the fact that it is a bit softer and less tightly focused than in the 3e. Moreover, I achieved 80–90 dB on the Sansui with the volume knob at around 10–11 o’clock, and the amplifier still had a considerable power reserve.

You can't go by the volume setting. The Sansui likely has much higher gain than the 3e amp. It's scaling of the volume dial is also likely to be very different in the old days. My Marantz preamp (much older than your Sansui) is like that, volume at 9 to 9:30 O'clock is enough. Again, volume position does not correlate well with the rated output of an integrated amplifier. A better way to tell how much reserve you have it to keep cranking it up until you hear sign of clipping, and measure the SPL you are getting, then you can do some calculations.

And after all, this is a model from the early 1980s. How old-school its construction is can be seen in this video:

Seems like a good integrated amp, but again, based on the specs and posted measurements, the amp should be transparent enough that in a blind listening (that's what I have been trying to do with my A7 and my other amps, just for fun though) it will sound extremely similar to modern amps such as the 3e A7se or other well designed class AB amps. Science, measurements are far more reliable than sighted listening impressions.

 

[peng]

Thank you for your explanation.
I have one more point. If we compare the Sansui AU‑D7, which delivers 80 W RMS, with the 3E A7se, which delivers 130 W RMS at 8 Ω, it might seem that the louder amplifier would be noticeably louder. However, using a simple formula that relates amplifier power to sound level:

ΔLSPL=10log⁡(P2/P1)
we get:

ΔLSPL=10log⁡(130/80)≈2.1 dB
This is a very small increase — it represents the maximum possible difference if both amplifiers were pushed to their limits. My own experience confirms this: both amplifiers sound very similar in loudness, showing that they are well matched to the Wharfedale Linton 85th in a 20 m² room.

Now I’ll focus on shaping the sound character of the 3E A7se. For this, I’ll use the Wiim Pro Plus and its parametric EQ.

Very little difference indeed for real world use, but the main advantage of the A7 SE is that it is rated for 4 ohms (it says 6 hm, but with dip to 3.5 ohm so..). So while for your use case both are adequate, the A7 SE is still going to be a little more comfortable with the 4 ohm rated Wharfedale Linton.

 

[peng]

Updates? I'm about to either buy these or maybe a hypex for BMR monitors I have on order

No issues so far, happy with what I got, two 48 V 5 A gaN bricks are doing a good job. As I mentioned, started my AB comparison sessions but will have to wait for the next weekend to do a more proper one, i.e. level match with REW/Umik-1, and with selected DSD, HR PCM tracks etc.

So far has only done it in Mono, heard no difference whatsoever.

 

[Roland68]

Or even no volume control as far as I'm concerned. I fully agree.

That would severely limit the device's use as a desktop amp, and also for many hi-fi systems. It would make such a device significantly more expensive and perhaps even unsustainable for the manufacturer.

What would be the difference if you turned the volume control all the way up? And what would be the advantage?

There would be no difference in sound, and the disadvantage would be the loss of the ability to limit the maximum volume, for example, when using it with a DAC, or to adjust it for an AVR or other devices.

 

[Mort]

This was the A7 mono test? We assume the A7 stereo is similar?

What's the A7 se? I didn't see it on us Amazon.

 

[Roland68]

This was the A7 mono test? We assume the A7 stereo is similar?

What's the A7 se? I didn't see it on us Amazon.

This is a test for the A7 and A7 Mono. They are completely identical devices, except that one channel of the A7 Mono is not populated with components.

The A7 has one TPA3255 per channel and is therefore capable of handling 2 ohms.
The A7se uses only one TPA3255 for both channels, which is why it can only be used with impedances of 4 ohms and above. The difference in power output is negligible.

 

[Mort]

The A7 has one TPA3255 per channel and is therefore capable of handling 2 ohms.
The A7se uses only one TPA3255 for both channels, which is why it can only be used with impedances of 4 ohms and above. The difference in power output is negligible.

Got it. Thank you so much.

So if I want to use these with Philharmonic Audio BMR monitors, which dip to 3.5 ohms a bit, I should stick with the A7.

The A7 stereo will have half the output of the mono right?

 

[harkpabst]

I meant to agree with all your other points, I did not want to talk you into agreeing to my comment, of course.

That would severely limit the device's use as a desktop amp, and also for many hi-fi systems. It would make such a device significantly more expensive and perhaps even unsustainable for the manufacturer.

Certainly less usable as a pure desktop amp. 90 % of all desktop amp users appear to assume that 90 % of all amp users are desktop amp users. I disagree to at least 90 % of those.

I cannot follow your reasoning why omitting the volume control could make an amp more expensive, though.

What would be the difference if you turned the volume control all the way up? And what would be the advantage?

There would be no difference in sound, and the disadvantage would be the loss of the ability to limit the maximum volume, for example, when using it with a DAC, or to adjust it for an AVR or other devices.

As simple as what isn't there cannot break.

@3eaudio have just announced their upcoming range of multi-channel amps (including 2 as a multiple of 1 channel) with integrated PSU. No volume control. I like that.

Mulit-channel Amp,Which one you would like to own?

Hi Amigoes We are preparing to build a multi-channel amp. Wanna know which model is more popular for users? If you are interested, please help us get your vote. Leverage A5(TPA3251),A7(TPA3255) PFFB design with built-in GaN Power supply Pure-Amplifier without volume control, configurable...

www.audiosciencereview.com

 

[somebodyelse]

So if I want to use these with Philharmonic Audio BMR monitors, which dip to 3.5 ohms a bit, I should stick with the A7.

Are you sure about the impedance? Erin's review says 4.5R minimum. In either case I doubt you'll find much difference between the A7 and A7se as even 3.5R is pretty close to the nominal 4R that the A7se is built for. Also that's at ~1.5kHz where you're not going to need loads of power.

 

[Mort]

Are you sure about the impedance? Erin's review says 4.5R minimum. In either case I doubt you'll find much difference between the A7 and A7se as even 3.5R is pretty close to the nominal 4R that the A7se is built for. Also that's at ~1.5kHz where you're not going to need loads of power.

I could be wrong.

Here is what stereophile measured.

"The minimum impedances were 2.9 ohms between 152Hz and 190Hz and 2.5 ohms at 1220Hz. As the electrical phase angle (fig.1, dotted trace) is high in several frequency regions, the effective resistance or EPDR (footnote 1) drops below 3 ohms over most of the audioband and below 2 ohms from 69Hz to 181Hz and from 861Hz to 5.5kHz."

 

[TurtlePaul]

Are you sure about the impedance? Erin's review says 4.5R minimum. In either case I doubt you'll find much difference between the A7 and A7se as even 3.5R is pretty close to the nominal 4R that the A7se is built for. Also that's at ~1.5kHz where you're not going to need loads of power.

Erin measured the original Scanspeak woofer. Stereophile measured the new SB woofer.

"The minimum impedances were 2.9 ohms between 152Hz and 190Hz and 2.5 ohms at 1220Hz. As the electrical phase angle (fig.1, dotted trace) is high in several frequency regions, the effective resistance or EPDR (footnote 1) drops below 3 ohms over most of the audioband and below 2 ohms from 69Hz to 181Hz and from 861Hz to 5.5kHz."

The EPDR doesn't matter for these Class D amps. Only minimum impedance.

 

[somebodyelse]

I could be wrong.

Here is what stereophile measured.

"The minimum impedances were 2.9 ohms between 152Hz and 190Hz and 2.5 ohms at 1220Hz. As the electrical phase angle (fig.1, dotted trace) is high in several frequency regions, the effective resistance or EPDR (footnote 1) drops below 3 ohms over most of the audioband and below 2 ohms from 69Hz to 181Hz and from 861Hz to 5.5kHz."

Having checked the manufacturer's product page I see the bass driver has changed since Erin's review, which explains the difference. Given the lower impedance dips there may be some justification in using the A7 instead of the A7se. EPDR is about heating in a class AB amp and can be ignored for class D.

 

[KL....]

Having checked the manufacturer's product page I see the bass driver has changed since Erin's review, which explains the difference. Given the lower impedance dips there may be some justification in using the A7 instead of the A7se. EPDR is about heating in a class AB amp and can be ignored for class D.

Thank you, @somebodyelse, Yes, EPDR is about Thermal Heating of the Output Devices, usually not an issue ClassD, but still needs to be considered, why, where the case is not well/sufficiently ventilated and/or the LC cannot handle the Current/I (Heat affected) and/or PS Voltage/V rise/fluctuation (Bus Pumping, which the PS needs to absorb/control, due to LC output Filter/Load feeding/reflecting back to the PS because it is not being fully absorbed by the Load and affects ClassD efficiency) where the unwanted Voltage fluctuation creates distortion and can trigger overvoltage protection, shutting down the amplifier, particularly with low-frequency signals. Suggest, Consider/Yes, Ignore/No....

 

[TurtlePaul]

Thank you, @somebodyelse, Yes, EPDR is about Thermal Heating of the Output Devices, usually not an issue ClassD, but still needs to be considered, why, where the case is not well/sufficiently ventilated and/or the LC cannot handle the Current/I (Heat affected) and/or PS Voltage/V rise/fluctuation (Bus Pumping, which the PS needs to absorb/control, due to LC output Filter/Load feeding/reflecting back to the PS because it is not being fully absorbed by the Load and affects ClassD efficiency) where the unwanted Voltage fluctuation creates distortion and can trigger overvoltage protection, shutting down the amplifier, particularly with low-frequency signals. Suggest, Consider/Yes, Ignore/No....

From this very review we have the answer. Refuted by test. Full power (bus pumping seems to be increasing power) at high phase angles.

 

[peng]

I could be wrong.

Here is what stereophile measured.

"The minimum impedances were 2.9 ohms between 152Hz and 190Hz and 2.5 ohms at 1220Hz. As the electrical phase angle (fig.1, dotted trace) is high in several frequency regions, the effective resistance or EPDR (footnote 1) drops below 3 ohms over most of the audioband and below 2 ohms from 69Hz to 181Hz and from 861Hz to 5.5kHz."

The A7 SE is rated for 4 ohm load so it can handle thise dips. Just about any 4 ohm nominal speakers will have dips below 4 ohms. The BMR’s impedance is not the issue, but the sensitivity is a bit low for sure. Get the 10 A brick that will help.