Electronic experience :

Here we share some of our electronic experiments.
Many factors can influence a measurement and each result can be questioned.
Do not hesitate to send us a message if you see an error!

1. 1. Wich technologies to have the best rejection for balanced output signal ?

Four methods are possible to balance a signal :
Transformer, all in box integrated circuit like SSM2142/DRV134/That 1646, twin OPA design with 1% resistor without trim, and twin OPA design with 1% and trim.
Our experiment is to measure of how much each technologie can suppress common-mode signals at its output.  
For these measurment we choose a level of +20dBu. Symmetry is measured with a millivoltmeter at the junction of two closely matched resistors.

Here under our results :

> Transformer design = 71mV.
> All in box integrated circuit = 15.86mV.
> Twin OPA design with 1% resistor without trim = 3,2mV.
> Twin OPA design with 1% resistor and trim pot = 0.09mV.

Although the transformer has the worst measurement, it does not mean that it is a bad solution to balance an audio signal.
First of all the quality of the transformer is very important, the more the length of the turns is equal and the better the rejection will be.
Also, the transformer being passive, it does not degrade the signal compared to active electronic components.
Of course, if you need color sound with harmonic distortion in low frequency, the transfomers will be a good way.
So we can say that each has its advantages and disadvantages.

In case you are looking for clean and transparent sound, here under our notations :

ONLY IF YOU’RE LOOKING FOR TRANSPARENT SOUND
	Common-mode suppression	Harmonic Distortion	Noise	Cost
OPA design with trim	****	****	***	**
OPA design without trim	**	***	**	***
Transformer	*	*	****	*
All in box IC	***	**	*	****

In case you are looking for colored sound, here under our notations :

ONLY IF YOU’RE LOOKING FOR COLORED SOUND
	Common-mode suppression	Harmonic Distortion	Noise	Cost
OPA design with trim	****	*	***	**
OPA design without trim	**	*	**	***
Transformer	*	****	****	*
All in box IC	***	*	*	****

 

We find the same results about CMMR (common mode rejection at the input).
Regarding GC Audio Products :

Inherit cartridge input unbalancing stage :

> Transformer design : RE-4K, RE-73, Gyraf, Tube Heat
> All in box integrated circuit = RE-11
> Twin OPA design with 1% resistor without trim = None
> Twin OPA / discrete components design with 1% resistor and trim pot = Langley, RE-98

Inherit cartridge Output balancing stage :

> Transformer design : RE-98, Gyraf, Tube Heat
> All in box integrated circuit : RE-11
> Twin OPA design with 1% resistor without trim : RE-15, RE-VR
> Twin OPA design with 1% resistor and trim pot : Langley, 4-K

• Noise, phase and distortion videos tests (French with English subtitles):