elctrocompaniet eci 80d quality and reliability

[janul]

Dear audio enthusiast,

I recently purchased electrocompaniet eci 80d liking its sound. I did chcek some reviews before and after and I have to say I do have doubts about its built quality and possible concequencies in its acuracy in sound performance. Namely if you chcek pictures from whats going on under the hood, you can see thet there are two small inductores. Both of the output cables are conected way to close to them. I am not amplifier specialist by any mean but in elementary school we studied that the inductor does produce magnetic field. The output terminal cables are suncked in this magnetic field and I would like to know what negative efects does this have on amplifier performance. I have to say that I realy do not understand what I see under the hood of some british as well as electrocompaniet (being norvegian) compared to japenees amplifiers tideness.

Thank you for any clarification and help
Jan

 

[Matias]

Looks like power supply is the right board. The main left board has the digital conversion and headphone amp circuitry on the bottom, the output transistors attached to the heatsink on the top, and of course the long speaker wires crossing the amp to the bottom right binding posts.

What I'm not sure is why there are these center inductors and looks like rectifiers in the middle. First I thought of a class D output filter, but it's class AB, so no need. So I still have no idea what they do.

But I agree that the wire routing is not optimal. Even less with untwisted, unshielded wires, which AFAIK are more exposed to EM noise.

 

[janul]

I have update to the topic. After some not very extensive accoustic treatment of the room, by my ears the amplifier does perform really well. I have also chceked layouts of some more expensive amplifiers and by my humble but honest conclusion (whatching parts placements, cabling, some percieved tideness etc) the amp is not backward in its build at all, maybee even over avarage.

 

[0ID]

The coil is part of an L + R (inductor + resistor) output filter with the purpose to stabilize - avoid high frequency oscillations.
It is fine as it is, the speaker output wire is connected to the end of coil, so it is a part of it.

 

[janul]

Thank you, apreciated

 

[solderdude]

Its probably part of a circuit similar as shown below.

Indeed it is to avoid oscillations. It ensures a 'nice load' to the amp when it is confronted with exotic (high capacitance) cables.
It is often used in amps in combination with a Zobel (Boucherot) circuit.
The corner frequency is so high up that it won't influence audio bad but does ensure RF and oscillations cannot occur due to an unexpected/incorrect load.

see:

Taming the LM3886: Stability | Neurochrome

Simulate the gain margin and phase margin to assess stability in an LM3886 chipamp. The impact of the Zobel Network on stability in audio power amplifiers is simulated in TINA-TI.

neurochrome.com

 

[0ID]

Its probably part of a circuit similar as shown below.

Indeed it is to avoid oscillations. It ensures a 'nice load' to the amp when it is confronted with exotic (high capacitance) cables.
It is often used in amps in combination with a Zobel (Boucherot) circuit.
The corner frequency is so high up that it won't influence audio bad but does ensure RF and oscillations cannot occur due to an unexpected/incorrect load.

see:

Taming the LM3886: Stability | Neurochrome

Simulate the gain margin and phase margin to assess stability in an LM3886 chipamp. The impact of the Zobel Network on stability in audio power amplifiers is simulated in TINA-TI.

neurochrome.com

It is just one resistor and one inductor.

 

[solderdude]

Just like in the schematic I posted.

It is a very common circuit and have never seen an amp with low pass filter you posted.
In the circuit you posted the resistor will get the full audio spectrum at full power on it and be effectively in parallel to the speaker.

The big resistor and inductor are in parallel (not in series) and form the 'output inductor' and 'damping resistor' in this circuit.
Sometimes you see a power resistor with the coil wound around it.

also see an explanation here:

Cables 2 - Ohm and Away

 

[0ID]

I see that you want to be right, so have your way. Although I still see in my amp one coil and one power resistor.

 

[solderdude]

As explained the coil and resistor you see are in parallel that's why you only see these 2 components.
I used this same circuit in all speaker amps I designed and built (was about 30 years ago).

Below a circuit from Elliott sound products

https://www.embedded.com/matching-and-tuning-audio-amplifier-output-stability-and-sound-performance/

 

[Klonatans]

Talking about reliability, I have ECI 80D for 4 years and never had any issues.

 

[sigbergaudio]

Electrocompaniet is generally regarded to be reliable. It's an old brand, and seeing 20-30 year old EC amplifiers on the second hand market is not uncommon here in Norway.