(EN) OPM3320D-E19, E23 Dual AUDIOFEEL DISCRETE OP-AMP Medium impedance

LOW-NOISE DISCRETE OPERATIONAL AMPLIFIERS

Eagle shape

OPM3320D-E19;  Dual , Eagle shape, Medium impedance type
(Effective height: 19mm)

OPM3320D-E23;  Dual , Eagle shape, Medium impedance type
(Effective height: 23mm)

As the first feature of this product,

The technology of eliminating the disadvantages of silicon transistor (cold, thin and dry sound) is applied to the signal amplification stage, so it is warm, gentle, clear and transparent like the sound of a tube. In addition, the effect of electromagnetic waves and external noise is small, so the sound is clear, transparent, spacious and open.

As a second feature,

The technique of increasing the driving force of the output stage is applied to the output stage to reproduce a clear sound, and there is no loss from a small signal to a large signal. By outputting the same as the input signal, the delicate signal is reproduced as it is, And the expression of emotion is wonderful. Compared to existing op amps, AUDIOFEEL-Discrete-Opamp performs well for audio. AUDIOFEEL-Discrete-Opamp gives you a taste of music in every way.

In a third aspect,

It can be used interchangeably with all existing op amps used for audio (if the final amplifier gain is less than +20dB(x10)). If you know the feedback impedance of the amplifier, you can make a better choice.

FEATURES
Small size
Slew rate improvement
Optimized for analog audio
Built-in input offset voltage adjustment function
Low Power Quiescent Current
High-Quality Audio-Grade Discrete Operational Amplifiers
Consists of high performance individual parts
High input impedance with JFET
Dip 8 Pin Compatible with the general Op Amp
Clean and Crisp, Rich and Non-Irritating and Relaxing Signal Output
Do not use it as a buffer amplifier (Gain = 1)
Do not directly drive the power load. (Headphones, earphones, etc.)

The bottom mounting board area is the same as the size of the IC socket, so there is no restriction in use.
Can be installed in places where the height of peripheral parts of socket is 19mm or less.

APPLICATIONS
Hi-End Audio Pre-Amplifiers
Active-Filter
Differential Current Mode Op-Amp Circuit for Active-Filter
Professional Audio 

 

TECHNOLOGY APPLIED
Small Signal Buffer Amplification Circuit
Absolute Current Limit, Overcurrent Limiting Circuit
Electronic Circuits for Preventing Floating 

 

ABSOLUTE MAXIMUM RATINGS
Supply Voltage(Vs) :                                  ±18V or +36V
Input Voltage :                                            ±Vs
Differential Input Voltage :                          ±0.7V
Output Current
   Internal Current Limit (1) :                       ±200mA
      Allow the average current Vs = ±5V :   ±90mA
      Allow the average current Vs = ±10V :  ±50mA
      Allow the average current Vs = ±15V :  ±30mA
Storage Temperature Range :                     -40°C to +100°C
Operating Temperature Range :                  -20°C to +70°C 

Notes:
(1): Be careful not to short-circuit between the output and other terminals (ground, + Vs, -Vs). If it is shorted, the internal output stage parts will be damaged. The reason is set for maximum sound quality.

(Caution) Do not directly drive the power load. (Headphones, earphones, etc.)
Since the OPM320 series is designed for audio signals only, do not directly drive devices that require power such as headphones or earphones.
If you forcefully drive a device that requires power, you may lose delicate performance and sound quality may be degraded.
Be sure not to exceed the conditions of "Internal Current Limit (1)" above.

 

SPECIFICATIONS
Input offset voltage :  <±0.5mV (@ VS = ±4.5 to ±18V)
Slew Rate:                 50V/uS (Vs=±10V, 9Vpp, G=x1, RL= 600 ohm)
OPEN-LOOP GAIN : 70dB (Vo = ±10V, Rload = 600 ohm)
Gain-Bandwidth Product : 6Mhz (@ G = 1, Vs = ±10V)
Output impedance  : 0.38 ohm
Output Voltage Swing (Rload = 600 ohm), Vrms (Vpp)
   Vs = ±5V :         2.6 (7.4)
   Vs = ±10V :       5.9 (17.2)
   Vs = ±15V :       9.3 (26.5)
Power Quiescent Current (2)
   Vs = ±5V :         26mA
   Vs = ±10V :       28mA
   Vs = ±15V :       30mA
Dimensions :        22(W) x 36(H) x 16(D) mm 

Notes:
(2) In the power supply circuit, it should be designed so that Quiescent Current (Power Current) can be supplied sufficiently.
It should be used in a circuit that can supply enough quiescent current (power current).

 

Please use this product under the following conditions.
It is recommended that the final amplifier gain be less than x10 (+ 20dB) in the op amp circuit.
If you use an extension connector for this product, please connect the line length as short as possible.

 

How to choose OPM3320D(or OPM3320S) and OPM2320D(or OPM2320S)
The OPM3320D (or OPM3320S) and OPM2320D (or OPM2320S) can be selected by the value of the feedback resistor in the op amp circuit
1. OPM3320D (or OPM3320S): Suitable for low impedance circuits
    Feedback resistance less than 5K ohms
2. OPM2320D (or OPM2320S): Suitable for high impedance circuits
    Feedback resistance above 5K ohms
3. If you can not find the feedback resistor value, it is recommended to operate 2 types directly. But the difference can be felt slightly. 

The feedback resistor is:
In the op amp circuit - the resistor connected between the input terminal (- or Inv) and the output terminal.

  

Idea to maintain performance of discrete op amp
Here are some ideas for keeping your discrete op amp up to peak performance.

Our discrete op amp features delicate, rich and powerful sound.
We've been working on a number of new technologies to make sure we get a very good sound.
The components used in the discrete op amp are equipped with precision, delicate, high-performance components.
Performance of this type of discrete op amp can change depending on the environment.
 
Check that the discrete op amp you are using meets the following specifications.
1. Is there any foreign matter on the surface of the discrete op amp? (There are some invisible contaminants, conductive materials, etc.)
2. Is the surface of the discrete op amp exposed to moisture?
3. Is the surface of the discrete op amp exposed to smoke or gas?
4. Is the discrete op amp used for a long time?
5. Do you feel that the sound performance is lacking?
For the above reasons, the surface of the discrete op amp may be contaminated, and as a result, the sound performance may be insufficient.

To maintain the best performance of the discrete op amp;
Periodically check the condition of the discrete op amp and clean the discrete op amp.
We recommend that you periodically clean the discrete op amp.

 A method for cleaning a discrete operational amplifier;
1. Wash with spray cleaner for electronic circuit board. (See how to use the cleaning agent)
2. Clean the eco-friendly cleaner for electronic circuit boards using a brush (such as a toothbrush). (See how to use the
cleaning agent)
3. Clean with ultrasonic cleaner for electronic circuit board. (See how to use the cleaning agent)
 
(Note) If you feel that your newly purchased discrete op amp is not performing well, try to clean it. You can remove the contamination that occurred during transportation.

AUDIOFEEL's technology to improve the cool, thin and dry sound characteristics of silicon transistors

Amplifiers, usually made of transistors, are rated to be cool, thin and dry. To improve this tendency, we add a little capacitor to adjust the sound propensity. As a result of this tuning process, a part of the treble is cut and the feeling of opening is reduced.

So it is very difficult to hear the actual sound being played in a transistor amplifier.

AUDIOFEEL has the technology to solve the disadvantages of these transistors and it is applied to all the products that we produce now. Just like a tube amp, it is warm, gentle, clear and transparent, and all sounds are independently distinguished, full of emotion and power.

How was the technology that complements the disadvantages of silicon transistors implemented?

The principle is simple. The key is to configure the circuit so that current silicon transistors behave like germanium transistors.

"The germanium transistor has a leakage current between the collector and the base." This condition applies to the silicon transistor circuit.

In Figure 21 below, transistor (A21) is a block representing one silicon transistor. The load (CCL21) is a block that represents a resistive load or a constant current load. This is a simple representation of the transistor 1 stage amplifier.

Silicon transistors do not have any leakage current between collector (C) and emitter (E).

In other words, a silicon transistor amplifier consisting of only A21 and CCL21 is cold, thin and dry.

To use a silicon transistor amplifier consisting of A21 and CCL21 in Figure 21 as a germanium transistor amplifier, connect the constant current source NCC22 for leakage current in parallel with A21.

Then, leakage current flows through the NCC22 between the collector and emitter of the silicon transistor, and the silicon transistor A21 behaves as if the leakage current is always flowing. As a result, this amplifier behaves like a germanium transistor.

NCC21 is required to always supply current to NCC22.

Connect NCC21 and NCC22 (red box display) circuit for leakage current to the collector and emitter of the silicon transistor in parallel. As a result, despite the use of silicon transistors, it is warm, gentle, clear and transparent as the sound of a tube, and all sounds are independently distinguished, full of emotion and power. It also has the advantage of being less influenced by electromagnetic waves and external noise.

(details)

Let's take a look at the AUDIOFEEL technology, which improves the cool, thin and dry characteristics of silicon transistors.

Long ago, vacuum tube radios were produced, followed by germanium transistor radios, and then silicon transistor radios.

?Germanium transistor radio sound was good.

Silicon transistor radio, however, has the power to sound, but it is cold, thin and dry.

The problem with silicon transistors has not been improved to this day.

So what is the difference between a germanium transistor and a silicon transistor?

The answer lies in the difference in insulation characteristics or insulation between electrodes.

Indicated by Icbo in the transistor specification table.

The leakage current Icbo between the collector and base of the germanium transistor is 8uA ~ 30uA. (AC124, AC125, etc.)

On the other hand, the leakage current Icbo between the collector and base of the silicon transistor is 0.1 uA max. It is about 100 times more different.

Accurately, it is accurate to compare the leakage current Iceo between the collector and the emitter, but the transistor datasheet does not display Iceo well, so we compared it with Icbo.

The leakage current between the collector and the emitter shows that the silicon transistor is much smaller than the germanium transistor and the isolation is better.

Since there is always electrons in the vacuum tube, a fine current flows from the plate to the cathode even at the cutoff, and it is the same as the germanium transistor that the plate current is not blocked.

The FET also has a fine current flow from the drain to the source at the cutoff, and it is the same as the germanium transistor that the drain current is not blocked.

However, because of the high isolation characteristics of silicon transistors, there is a moment when collector current is cut off during cutoff. Therefore, there is a lack of sound quality in the use as an acoustic amplifier.

So why is the insulation characteristic of a silicon transistor a problem?

It takes some time until the change of the input signal coming to the base from the amplification circuit composed of transistors is outputted to the collector.

If the input signal voltage applied to the base decreases, the collector current decreases, the collector impedance increases, the moment the load resistance and collector electrodes separate, and the potential of the load resistance becomes a floating state.

At this time, the germanium transistor maintains the connection state with the load resistance because the leakage current always flows. However, since the insulation of the silicon transistor is too good, the collector current is completely cut off and separated from the load resistance. Or is easily exposed to ambient noise or electromagnetic waves. That is, the amplified signal is easily deformed.

Silicon transistors have a very good isolation between the collector and the emitter, so there is a moment when the collector and the load resistor are cut off during the amplification and the potential of the load resistor is floating. At the moment of this float, the voltage is changed to a completely different voltage than the amplified signal, and is easily affected by the ambient noise and changed to a different voltage than the amplified signal.

That is, the amplified output signal is distorted.

If it is deformed by a pulse voltage, it becomes a stimulating sound. Also, it does not follow gentle low-band signal level and can not reproduce the sound of deep bass.

In today's world, transistors are all silicon transistors, and germanium transistors are rarely produced or used. Both low-end audio and high-end audio are made of silicon transistors, if not vacuum tubes.