IWISTAO Earphone Amplifier HIFI Solo with Bluetooth 4.0 CSR8670 32-bit DAC AK4490 Hardware Decoding Optical Inputs APT-X

After the Bluetooth decoder with hardware decoding hit market, we also have developed an earphone amplifier with  Bluetooth 4.0 CSR8670 APT-X, 32-bit DAC AK4490 Hardware Decoding, and Optical Input.

This is a Bluetooth decoder with Bluetooth 4.0 CSR867 and DAC AK4490. The Bluetooth 4.0 version CSR8670 implemented digital signal transmission thought wireless function, the digital to analog conversion of audio output used a professional decoder chip AK4490 to play that the digital signal is decoded into an analog audio signal, and finally OP amplified the analog audio signal and output it.

At the same time, the unit is compatible with optical input, optical input devices can be connected to any other optical fiber output, such as televisions, set-top boxes, projectors, DVD player, CD player, sound cards and other digital computer. 

IWISTAO Earphone Amplifier HIFI Solo with Bluetooth 4.0 CSR8670 32-bit DAC AK4490

It has the features also as below.

1. Whole aluminum alloy casing.
2. Built-16M memory within CSR8670 chip
3. Adopted HIFI level op amp OPA2604 as output.
4. Adopted HIFI parts and components at signal input and output, such as 1% metal film resistors, capacitors, audio ELNA and Nichicon capacitors, Phil ips CCB film small Signal filtering capacitors, and gold-plated RCA audio output jack.
5. Adopted imported original ST regulator, and digital power supply used independent of the LM1117 3.3 V regulator.
6. Adopted independent hardware decoding AK4490 decoder chip.
7. With op amp socket, you can exchange your favorite OP according to your needs to use different styles HIFI op amp. Currently, the output chip is original OPA2604 op amp.
8. Built power and signal indication on the front panel.
9. Adopted independent external Bluetooth antenna with high sensitivity.
10. Automatic doors to receive the first optical fiber, has a good dust-proof.
11. With an input switch to easy switch two input signals, Bluetooth and optical. The two inputs, Bluetooth + optical input, you can connect any digital device family.

a) Bluetooth module Bluetooth signals --- Bluetooth digital signal decoding --OPA2604 --AK4490 op-amp output

b) Fiber optic signal --- AK4490 decodes the received data --- OPA2604 op-amp output.

More details, please find IWISTAO Earphone Amplifier HIFI Solo with Bluetooth 4.0 CSR8670 32-bit DAC AK4490

If you want to know Bluetooth Decoder further, please find the blog 

A HIFI Wireless Bluetooth 4.0 Decoder with CSR8670 and AK4490 

What is a preamplifier?

What is a preamplifier? 

What is a preamplifier? It could be difficult to tell, the official explanation was below.

A preamplifier is the role of audio amplification, generally because audio signals are very small and cannot drive power amplifier directly, you must install a front voltage amplification circuit to amplify signal then drive power amplifier. Also, due to the diversity of input signals, such as input signal voltage level, as well as high and low input impedance, a preamplifier will fit to the strength of the input signal to set up a different magnification time. And if internal resistance doesn’t match between signal sourcing and amplifier, it makes to lose a dynamic frequency response, details! Besides adjusting the volume, active preamplifier also can be used for preliminary amplifier, reduce internal resistance difference between the signal sourcing and power stage, which is used as a buffer.

Finally, because varieties of users have various audio sources, output signal amplitude and impedance that less people actually study, there is a big difference at listening actual sounds, on the one hand it is audio output signal amplitude is different, on the other hand is internal resistance  mentioned above. This has created more songs we heard was substantially compress it’s dynamic, and detail is lost, frequency response is attenuated. Very apparently we were using computer or cell phone to connect power amplifier when listening to some music, it doesn't even feel to the low frequency and high frequency is not so bright small volume situation. No matter how good computer sound card and how good the sound system, it could not find the original tapes of the time!

Here, 6N2 tubes we used the most common one, we specifically tune the circuit for computer sound source without expensive components piled up, but a reasonable configuration, we choose the most suitable work point, and precisely matched the key components to ensure circuit work at the best.

Circuit Diagram

More details, please find here!

IWISTAO Tube Preamplifier with Matisse Fantasy Line Stage GE 5670W for Your Upgrading Car Audio

It is a Tube Preamplifier with Matisse Fantasy Line Stage GE 5670W, and its power supply is DC 12V, you may use it to update your car audio system from the DC12V.

The main feature of Matisse Fantasy Line Stage is sweet mellow sounds, calm and powerful low-frequency sound field is very open, like a sense of the scene, and here it goes without saying! Since tube preamp birth, it is well known as its design concept for distinguished from commonplace, pure and transparent sound quality to really spotless, and become a world-class reference.

The circuits adopt British famous circuit of Matisse Fantasy Line Stage, and with 12VDC power supply (Recommanded Power supply: DC12V / 1A ). The HIFI Tube Pre-Amplifier is made of HIFI imported components like as United States AB resistance, which can bring a sense of warm and soft vocals, Philips filter capacitor charging and discharging more reliable, Germany ERO coupling capacitor to that make the sound more balance, ALPS potentiometer sound good but also durable, gold-plated contacts Cinch make the connection more reliable and greatly reduce transmission of resistance signals.

Also there is vedio to paly music and it is taken by iPhone 5S.

More details, please find http://www.aliexpress.com/store/product/Free-Shipping-DC12V-HIFI-Tube-Pre-Amplifier-with-Matisse-Fantasy-Line-Stage-5670W-Tubes-HIFI-Component/725205_1610495358.html

What is an Operational Amplifier?---OpAmps Tutorial Vedio

What is an Operational Amplifier?---OpAmps Tutorial Vedio

Operationl Amplifier, especially OP IC had been used in Power Amplifer as preamplifier or other functions. 

There is a excellent OP IC with metal seal, this is LME49720,which is ultra-low distortion rate; it is a professional audio op amp that is able to achieve total harmonic distortion and noise performance under 0.00003% or less in the world's only, and pursued and loved by many audiophiles around the world.

LME49720HA is one of the most top HIFI op amps IC in the world, low noise, high slew rate, wide operating voltage range and output current, etc., high overall performance is unprecedented, and can easily meet the most demanding audio application requirements. Ideal for professional and high-end audio system, it can be widely used in high fidelity buffer amplifier, high-fidelity active filters, high-fidelity headphone amplifier, high-fidelity phono equalizer amplifier, high-quality audio amplifier, high-fidelity preamplifier, high-fidelity multimedia, high-performance professional audio, high-fidelity balanced network, high-performance line drives, high-performance line receiver, mixer, etc. with the division.

LME49720HA is National Semiconductor's new generation of "op-amp of the Emperor", LM4562HA upgrade, sounds beautiful noble, comprehensive and balanced, clean sound at the end, natural, high analytical, dynamic large, low dive deep, IF full, people sound sweet and moist, high frequency transparent, delicate soft, contagious.

Specifications

Operating voltage: ± 2.5V ~ ± 17.0V

Harmonic distortion: 0.00003%

Noise Density: 2.7nV / √ ^ Hz

Conversion Rate: 20V / μs

But,do you know know-how of Operatial Amplifier. If you want to know more, please find the vedio below.




Also, there is a Closs A Headphone Amplifier and it is a preamplifier with OP IC LME49720HA, its sound is great.

http://www.aliexpress.com/store/product/Headphone-Amplifier-Discrete-Component-Pure-HIFI-Class-A-Amp-Lehmann-Upgraded-Version-Plastic-sealing-LM47910/725205_1931445868.html

Metal seal LM47910

Headphone Amplifier with OP LM47910