Has Accuphase fixed their balanced input issue on new E-3000/4000 integrated?

[theron_day]

ASR testing indicated the E-280 Accuphase had issues with their balanced input and was not recommended. Anyone know if Accusphase corrected on their new E series releases?

 

[smygolf]

I have not read the review, what i know is that Accuphase historicly have inverted phase on balanced in/outputs.
But i do not know if it can effect the review also i do not know if the still invert the phase, my guess is Yes.

 

[kyuu]

The issue on the reviewed unit was not with inverted phase. The balanced inputs introduced a lot of noise. If you're interested in an Accuphase then the best thing to do is just use the unbalanced input and not have to worry about it.

 

[Bland_username42069]

If you look at the catalogue for E 3000 then S/N ratio is still worse for balanced than unbalanced for whatever reason.

 

[BeeKay]

If you look at the catalogue for E 3000 then S/N ratio is still worse for balanced than unbalanced for whatever reason.

True - but why that?

 

[Joachim Herbert]

From what I remember this is a typical difference between balanced and unbalanced inputs.

For example see these specs from Topping:

Topping A50 III Headphone Amp Review

This is a review and detailed measurements of the Topping A50III balanced headphone amplifier. It was sent to me by the company and costs US$199. The A50 III is solidly built and is about as thin as you want it to be. User interface is simple: short press of the power button cycles through...

www.audiosciencereview.com

So this is not "issues" but expected behaviour. Balanced connctions are less prone to external noise, however.

 

[BeeKay]

From what I remember this is a typical difference between balanced and unbalanced inputs.

For example see these specs from Topping:

Topping A50 III Headphone Amp Review

This is a review and detailed measurements of the Topping A50III balanced headphone amplifier. It was sent to me by the company and costs US$199. The A50 III is solidly built and is about as thin as you want it to be. User interface is simple: short press of the power button cycles through...

www.audiosciencereview.com

Their E-5000 shows 111dB for SE and Balanced, though

 

[Joachim Herbert]

Their E-5000 shows 111dB for SE and Balanced, though

SE is a fail in that case (pun intended).

 

[AnalogSteph]

Quite the contrary, the balanced input must be a tour de force of engineering. 111 dB(A) at 220 mV input equates to an EIN of -124 dBV(A). You're not doing that without a 3-opamp balanced receiver circuit using decidedly low-noise parts (say, OPA1612s) and sub-kOhm resistor values. If you want the gory details, read Douglas Self's Small Signal Audio Design.

Fun fact, a basic 1-opamp balanced receiver circuit of 40 kOhm input impedance could never achieve better than about 88.8 dB unweighted (~91 dB(A)) relative to 142 mV input, even when using an ideal noiseless opamp. So the E-3000 must already be sporting an above-average circuit topology.

And this is why (balanced) pro levels are higher than (unbalanced) consumer levels by anywhere from 6 to 18 dB. The most common balanced output circuit also sports 6 dB of gain. Why then hi-fi makers would include unity gain balanced inputs (instead of -6 dB at least) is a mystery to me, I can only attribute it to cluelessness from decades ago that has been dragged along all this time. Checkbox engineering at its finest.