Monday, July 10, 2017

How output transformer impact the sound of tube amplifier

How output transformer impact the sound of tube amplifier

Output transformer used in HIFI tube amplifier is a key component in high-fidelity audio equipment.

Tube power amplifier circuit is very simple relatively, but if you use output transformer that is produced by different manufacturers to make tube amplifier, the difference of sound is great. When output transformer in the transmission of audio signals, there will be eddy current, hysteresis, magnetic flux leakage and wire resistance loss, while the coil there is impedance, inductance and capacity resistance. These unfavorable factors will also be changed with the frequency of the audio signal changes. Therefore, the quality of the output transformer is related with its core material, quality of its core, enameled wire, winding method, size of the core air gap and so on, those directly affect the sound quality and quality of tube amplifier.

If output transformer output quality is not good, the biggest drawback is large distortion, narrow frequency response, high frequency and low frequency extension is insufficient, midrange is ambiguous, it sounds like tremble can’t achieve high frequency, bass is no powerful, orchestral instruments mixed together , There is no sense of hierarchy, the ensemble is heard is a noisy sound.

Therefore, sound quality is a decisive impact output transformer.

For tube power amplifiers, because loudspeaker is a low impedance element, the power of the high output impedance of tube must be transferred to a low impedance loudspeaker by some means. Usually use audio output transformer, which must be high quality, otherwise we try to improve the quality of amplification will come to naught.

Here, we provide you some high quality output transformers for you DIY your tube amplifier. The output transformer adopt core of Japan Z11(0.35EI) annealed silicon steel dedicated audio sheets, high quality oxygen-free copper wire coil package, and use pure pulp insulating paper between each insulated layer. Production process of output transformer defying cumbersome, adopt 2 out 3 clips or 4 out 5 clips method with hierarchical segmentation, placing paper with group by group, also with processes of meticulous, careful winding, vacuum impregnation, these lead to the transformer has good insulation and moisture resistant, transparent sound, sweet warm and mellow, excellent solution and clarity, as well as nice shape.

It is a better choice to tube amplifier audiophiles.

Friday, July 7, 2017

A Heaven-made Match Tube FM Tuner Plus 6P1 Tube Amplifier

A Heaven-made Match Tube FM Tuner Plus 6P1 Tube Amplifier
It is a finished tube FM tuner, whose tubes have been located on the same board, so it looks compact and elegant.And, it used 6N3 as a high-level and mixing, 6C11 as the unit local oscillates, IF amplification as 6J4 together with 5pcs mid cycle inductance, and it has the advantages of high sensitivity, low noise. After stereo decoded by TA7343AP, then the signal will be amplified by tube 6N2 as a preamplifier. 

Its casing is made of whole aluminum metal chassis, gold with rushed oxidation treatment, and the front panel with 8mm thick aluminum plate, the others with 4mm aluminum one. On the front panel, there are dual level meters to display audio signal level, and the digital frequency meter display FM reception frequency. Electronic tube with a modern digital frequency meter that is complementing each other with nice, classical and elegant style, maybe the frequency display board of the wireless receiver is the designer's wisdom. The lower right corner of the unit has a knob to manually tune the radio. All tubes are exposed at the top plate for heat dissipation purpose, and equipped with cat eye indicator there. The whole structure of the tuner is compact, components layout had been optimized to be more reasonable.

IWISTAO Tube FM Tuner + 6P1 Tube Amplifier

IWISTAO HIFI 4 Inches Full Range Speaker

After connected with a power amplifier and speakers, you can listen to tube taste with music sweet and mellow. Here we connected it with a tube amplifier with tubes 6P1, and HIFI 4 inches full range speakers above.
 More detail, please visit,

IWISTAO Finished Tube FM Stereo Tuner Whole Aluminum Chassis

Saturday, April 29, 2017

Enjoy CD-level Quality Sound with Wireless Bluetooth Connectivity

Enjoy CD-level Quality Sound with Wireless Bluetooth Connectivity

The new CSRA64XXX ROM series audio platform is designed for entry-level and mid-range Bluetooth speaker devices, bringing a new level of sound quality and functionality. It will be seen in the Bluetooth speakers, wireless headset, car audio, wireless hands-free products.

Bluetooth Tube Audio With CSRA64215

The audio platform supports Qualcomm's unique audio technology, including TrueWireless Stereo wireless stereo technology, cVc noise reduction technology, the sixth generation CVC voice enhancement technology.

The top model "CSRA64215" also supports aptX audio technology that provides CD-level sound quality with Bluetooth connectivity, as well as aptX low latency technology that can listen to aptX quality audio while watching video. "CSRA64210", "CSRA64110" are facing stereo, mono Bluetooth speaker equipment, suitable for high-cost effective products.

Three are built-in 16-bit stereo codec, digital-to-analog conversion SNR 95dB, support for Bluetooth 4.0 + EDR standard specification, Support A2DP 1.3, AVRCP 1.5, HFP 1.6 (including WBS / mSBC), HSP 1.2 and other related agreements, the effective distance of 10 meters.

There are some products that built in Bluetooth module with CSRA64215,whose actual listening experience is excellent.

It is a desktop Bluetooth tube amplifier, and will be better if it matched a pair high sensitivity speakers.

Or, you can us a Bluetooth 4.2 Decoder to refresh your old amplifier to enjoy CD level quality sound with Bluetooth connectivity. It is a Bluetooth decoder with Bluetooth 4.2 CSR64215 and DAC ES9023. The Bluetooth 4.1 version CSR64215 implemented   digital signal transmission thought wireless function, the digital to analog conversion of audio output used a professional decoder chip ES9023 to play that the digital signal is decoded into an analog audio signal.

IWISTAO HIFI Bluetooth 4.2 Decoder Stereo CSR64215 DAC ES9023 Hardware Decoding APT-X

If you need the Bluetooth decoder with CSR8670, you may find here.They are 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.

IWISTAO HIFI Bluetooth4.0 Decoder Stereo CSR8670 32-bit DAC AK4490 Hardware Decoding Bluetooth Optical Inputs PCM & DSD APT-X

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

A Bluetooth 4.2 Development Simulation Demo Board Based on CSRA64215 (For study only)

A Bluetooth 4.2 Development Simulation Demo Board Based on CSRA64215 

This Bluetooth development board is used to develop related Bluetooth products for developers only, which contains 4M FLASH, it is a fast, convenient, practical, necessary weapon for product development. This development board can be used to develop Bluetooth headset, car hands-free, Bluetooth speakers and so on.

You can find the features of CSRA64215 as below.

Features of the CSRA64215 Board

1. Provide 3W amplifier output, then speaker can be used directly as a Bluetooth speaker.
2. Provide 3.5 headphone output interface, can be used directly as a Bluetooth headset when plug the headset.
3. Provide 3.5AUX-IN port, support AUX-IN switch.
4. MIC interface, can be called to call, and provide debugging dual MIC noise cancellation function.
5. SPI debug burning interface, to facilitate the use of debugging.
6. Bluetooth IO port are reserved for the PIN, for development and debugging.
7. 8 keys, 8 IO port with LED instructions IO port working state.
8. Power button MFB provides key to boot and power on two ways.
9. Three-color LED instructions, debugging LED status more convenient.
10. USB communication function, used to debug USB sound card function.
11. This development board backplane can also be used for all other CSR modules.

Introduction of board interface

More Detils, please visit 

CSRA64215 Bluetooth 4.2 Development Board Simulation Demo Boards

There is a Development Simulation Demo Board for CSR8645, 

Wednesday, March 22, 2017

A Bluetooth 4.2 Decoder with CSR64215 Plus ES9023 Hardware Decoding

A Bluetooth 4.2 Decoder with CSR64215 Plus ES9023 Hardware Decoding

After the Bluetooth decode with CSR8670 plus AK4490 DAC is launched, we would develop a similar one that is used CSR64215 plus ES9023, which is a smaller and compact, also is high cost effective. 

A Bluetooth 4.1 Decoder with CSR64215 Plus ES9023

It used Bluetooth 4.2 CSR64215 chip and DAC ES9023 chip, the previous implemented digital signal transmission thought wireless function, and support SBC, A2DPB, AVRCP, AAC, APT-X ( need your Bluetooth enabled devices support Apt-x also if adopt apt-x transmission) , the digital to analog conversion of audio output used a professional decoder chip ES9023 to play that the digital signal is decoded into an analog audio signal.

Bluetooth 4.2 Decoder's PCBAwith CSR64215 Plus ES9023

As you know, ES9023 is ESS's single-ended output DAC chip, but also  is very unique, simple one of their SABRE DAC series, is recognized the easist to sound good decoding chip. In the 3.6V power supply under our actual test, its output can be greater than 2Vrms, and no coupling capacitor structure, you will have to worry about looking for expensive coupling capacitors no longer , and do not need to worry about the capacitor to bring the audio distortion usually. In addition, we use 32ohm headphones to do actual test it can also be found very good drive, but the output will be slightly reduced. And for the connection with power amplifier, headphone amplifier and other circuits, it is just a piece of cake.

ES9023 uses the industry's advanced SABRE digital-to-analog conversion technology, this chip set the best sound quality, cost-effective in one, making it an ideal choice for digital-analog conversion. It also can be used in Blu-ray players, CD / DVD, HD set-top boxes, digital TV or audio receiving equipment and other products.ES9023 internal use of patented technology Hyper-flow (Hyperstream) architecture and time-domain jitter elimination technology, so that it can achieve jitter-free recording level of sound quality, dynamic range of 112dB.

You may use it refresh your power amplifier or upgrade it to get CD level quality sound with wireless way, a lot of audiphiles had enjoyed it...


  1. Whole aluminum alloy casing.
  2. Built-16M memory within CSR64215 chip
  3. Adopted HIFI parts and components.
  4. Adopted imported original ST regulator, and digital power supply used independent of the LM1117 3.3 V regulator.
  5. Adopted independent hardware decoding ES9023 decoder chip
  6. Built power and signal indication on the front panel.
  7. Adopted independent external Bluetooth antenna with high sensitivit
  8. Signal flow: Bluetooth signal --- Bluetooth receiver module - digital shaping chip --- ES9023 decoder chip - output

More details, please visit,

IWISTAO HIFI Bluetooth 4.2 Decoder Stereo CSR64215 DAC ES9023 Hardware Decoding APT-X 3.5mm RCA Output CD Level Quality Sound

Tuesday, March 14, 2017

A HIFI Class B Amplifier Refer to NAP140 Circuit

A HIFI Class B Amplifier Refer to NAP140 Circuit

Power Amplifier of Named Naim is one of those products worshiped by audiophiles like as Linn turntables. Though its unassuming appearance, but it has won the hearts by warm mellow tone. Naim price is not low, people who really know what was the expert are willing to spend money to buy it. If you are truly listening to music, you will feel that once you owned and not much else for this amplifier.

I love this circuit Naim NAP140 as much love for the 1969 circuit. Because it sounds isn’t worse than 1969, and its output power is far better than 1969. One feature of NAP140 amplifier architecture is its mostly second-harmonic distortion, so the tone is somewhat like as tube amplifier charm. But the difference is that it is very rewarding that the distortion of tube amp to achieve 0.1%, but this circuit can be achieved 0.01% distortion.

We made this HIFI amplifier to refer to Naim Nap140 designing, and hope in keeping NAP140 original fine circuit architecture as same premise, to use new devices, greatly improve the operating voltage and output power, improve stability, and to Try to do something to improve the circuit (for example, the circuit adapted to work class A state). The original unit is very popular with enthusiasts respected, but also the price of its second-hand is nearly USD 2000. We do not engrave it, and cannot do it, only with reference to its excellent circuit configuration. The amplifier’s circuit is very mature, stable, ultra-low power consumption, driving and control force is very, very good, far better than integrated circuit amplifier or similar circuit at same output power, it is cannot be compared by them. More commendable is that the sound of this Class B circuit is mellow and soft as same as class A one at low power consumption.

Its output power is able to reach 80W at 8 ohms and class B state.


  1. Basically to be faithful to H140 classic circuit.
  2. Add upc1237 speaker protection system, switch absolutely no impact sound while performing midpoint of DC protection, to prevent damaging or burn your expensive speakers due to the amplifier circuit.
  3. Integrate volume control potentiometer.
  4. Integrate a two inputs switch on the front panel, you can switch the input source via the front panel.
  5. Add a midpoint adjustment circuit on differential input, generally midpoint can adjust to 5mV or less.
  6. The finished unit with about 2KG heat sink, while it is whole aluminum design, this benefit other parts of the casing become heat sink also in addition, so that the total heat dissipation area greatly increased. Its actual operating temperature up to 40 degrees, low-carbon green!
  7. Use a special custom 200W HIFI OFC toroidal transformer, ensure enough reserve power!
  8. Use a lot of HIFI elements like as ALPS27 potentiometers, high-grade RCA connect, ELNA capacitors and HIFI chemicals one. Sound’s quality is the most important thing.

More Details, please visit 

Shigeru Wada Tube Preamplifier Output Quality Sound

Shigeru Wada Tube Preamplifier Output Quality Sound

Tube preamplifier is used as tone processing amplifier between sound sources and power amplifier, so it is so-called, preamplifier output quality sound, power amplifier stage output power, which indicate that a quality preamplifier plays a key role in the entire audio amplifier system. Therefore, it is very important that the sound system choice preamplifier. Tube preamplifier has its special tube soft and warm sound, its listening sense has been ranked the first reputation and praise in all preamplifier, it can be applied to tube power amplifier, transistors one, and active sound system, especially for transistor amplifier, it can make the exists boring, blunt digital taste of your original system becomes rounded, sweet, tube taste is very rich; When listening to human voice, especially for the song folk song female voice, the sound is very warm, very sweet.

Shigeru Wada Tube Preamplifier

I bought CD player that is earlier 16bit models a decade ago, for adding musical charm to the sharp and dry digital sound to improve listening sense, but also because the tube is easier to produce pre-production and high rate of return for many years also try to produce a variety of line sound effects of a variety of tube pre-level, such as Shigeru Wada and Marantz.

The two circuits of preamplifier are more familiar and well-known. Through several repeated proofing tests and contrasts, found Shigeru Wada look is extremely good from performance and sound quality. It is to keep Marantz7 mellow and rich flavor of the characteristics of music, while dynamic, transient, high and low frequency response, analysis of signal-to-noise ratio better than Marantz 7, and Keep pace with each other in the sound field, penetrating sense with Marantz7 . In fact, this is only analysis from Shigeru Wada’s circuit, it is not difficult to find that its preamplifier is made of a very good stability by high-gain double three-tube, composed of two stages voltage amplification, only one tube has 10 times signal amplification capability with a very high sensitivity.

Shigeru Wada Tube Preamplifier with Black Chassis

And its power stage is also known by most of audiophiles, a very superior performance double tube 12AU7 composed of the radio level follower which using SRPP cathode output follower circuit that is similar with SRPP, it is different with the ordinary voltage amplifier stage, it does not have the voltage gain, the role is only current amplification and to reduce the output impedance, so that the load capacity is much larger than the co-screen pole follower, whether in high frequency response or signal to noise ratio. Compared with Marantz 7, it greatly improve low-frequency response, signal-to-noise ratio is also improved in varying degrees, in terms of sound performance is more balanced and comprehensive. So the design of Shigeru Wada preamplifier is very reasonable, both a very high sensitivity, but also a very good carrying capacity, no matter what kind of power stage is more flexible, play most vividly.

Who is familiar with Shigeru Wada are known, characterized by prominent human voice, better midrange. It is appropriate to even harmonic distortion when tube working, which will not worsen listening sense, on the contrary increase the sound of beauty, make the sound be more smooth, some details will be more prominent like to do a certain optimization, especially when playing human voice, there will be some feelings of rich taste out, tube taste is very strong. It will not only play in human voice will give charm, but also playing some pieces of music, such as some indoor recording of the violin, saxophone, jazz and other music, will also have a unique style.


1.       Circuit used Shigeru Wada improved field circuit of the original version; excellent PCB circuit design, reasonable, regular, symmetrical device layout, and strictly follow the rule of single point grounding line.
2.       Whole aluminum chassis especially made for Shigeru Wada with very fine black brushed oxidation, looks shiny, extraordinary taste.
3.       And it used whole aluminum solid sand drying high-end knobs. the plate thickness of body is all 2.8mm, panel thickness is 8mm with high precision milling machine finishing, and tube seats positioning accuracy, holes-cut is smooth and sleek.
4.       Power transformer is up to 120W (EI8642 / H50 film) with a horizontal cover, and the primary and second windings of transformer are shielded strictly. Left and right channel of filament voltage has been supplied by independent winding respectively; completely eliminate mutual crosstalk, good power transformer output good sound.

Product specifications

1.       Input sensitivity : 200mv
2.       Output voltage: 2V (RMS THD <0.03%)
3.       Signal to noise ratio :> 95dB
4.       Frequency response : 10Hz-50KHz (-0.5dB)
5.       Input impedance: 250K ohms
6.       Output impedance: 150Kohm
7.       Input voltage: AC 110V or 220V/50~60Hz
8.       Whole power consumption: < 50W
9.       Dimension(W*D*H) 360mm * 190mm * 140mm
10.   Net Weight: 4.5Kg
11.   Tubes: 12AX7 * 2; 12AU7 * 2 ; 6Z4 * 2.
12.   Accessories:

Power cord x 1

More details, please visit,

Tube Preamplifier Pure with Shigeru Wada Circuit Tube 12AX7 12AU7 6Z4 Rectifier Whole Aluminum Chassis HIFI Audio 110V/220V