IWISTAO Blog is the official platform of IWISTAO HIFI MINIMART, dedicated to high-fidelity audio and DIY electronics. We focus on tube amplifiers, output and power transformers, speaker enclosures, and Bluetooth audio technologies, including HiFi Bluetooth speakers, headphones, and tube-based acoustic systems. The blog shares product insights, technical knowledge, and practical guides for audiophiles and audio builders worldwide.
IWISTAO 300B Bluetooth Tube Amplifier with CSR8670
This is a 300B vacuum tube amplifier with Bluetooth 4.2 technology. Built-in CSR8670 module, you can connect your Bluetooth enabled devices via wireless connect, also can play stream music.
IWISTAO FU50 Small 300B 2x8W Vacuum Tube Amplifier PCBA Kit Single-ended Class A DIY Free Tuning
Vacuum tube FU50 is known as the small 300B and close to tube 300B, but the price is much lower than tube 300B, its treble is fine, extension is very good, overtone is excellent, and the vocals are very cordial. Listening to the original sound of the Dream of Red Mansions can feel that it is super strong; listening to symphony and string music is very good, violin is very delicate, more worth playing than the tube EL34.
This kit's solution uses 6J8P for gain amplification driving, FU50 as single-ended class A output, and tube 5U4C as tube rectification. Its output power is 2x8W. Don’t underestimate its 8w output, it is a Class A state, and much better than the digital power amplifier 50WX2 output and also more powerful than the LM1875's 2x25W.
This finished board is free tuning, you need just insert the vacuum tubes, and connect output and power transformers. Also, kindly remind to connect your speaker to avoid damaging the output transformers before power on. The kits are made of fine materials and all imported high-voltage capacitors ensure safety and stability. All the seats are gold-plated to ensure good contact. High-power resistors use Panasonic, KOA and other advanced fever resistors.
Meanwhile, we provide the scheme diagram for you information. This is a channel of amplifier part below.
And, there is a power supply part below.
Here is the tubes, FU50, 6J8P, 5U4C.
After you insert the tubes into this small 300B amplifier board, you will get it as photo showed.
Upgrade version
We upgraded the FU50 amplifier with dual modes for output
Dual-Mode Operation: The amplifier board features a dual-mode design, allowing users to switch between modes using two toggle switches. For safety, the power must be turned off before switching.
A). Ultra linear Tube Mode: This mode offers a dynamic, powerful, and slightly faster sound, making it ideal for symphonic music.
B). Triode Mode: This mode provides a delicate and melodious sound, perfect for listening to vocals.
Little 7 pcs Vacuum Tube MW/SW Radio 3 Bands AM 535-1605 KHZ Shortwave 2.3-7 MHZ 6-18 MHZ
This is a pure tube 3-band radio, it can receive a medium wave and two band shortwave signal. Tube radio is built in 4-inch small speakers, which can meet listening need for 15 square rooms. If you connect an external 6-8 inch full-range speaker, then there will be a leap in sound volume.
Nobody but you from IWISTAO HIFI 4 Inch Full Range Labyrinth Speaker
Nobody but you, the song is from IWISTAO HIFI 4 Inch Full Range Labyrinth Speaker plus single-ended class A 6P1 vacuum tube amplifier. The music source of notebook is connected with a CSR64251 Bluetooth decoder via Bluetooth wireless connection, and music player is foobar2000. And the video is taken by smartphone.
The speaker cabinet is made of solid wood, and built in labyrinth structure that adopts double back guide pipe to effectively prevent the sound waves from forming standing waves, and sound quality is relatively pure. Also, its speaker unit is a full range one, is made of double 80mm magnet, tarpaulin edge, composite cone, aluminum alloy frame and 25mm coil, which is used in model AP5001 that this monitor speaker cabinet is designed by Japanese designer Mr. Kameyama presided over the design with AS100FL 42Ex speaker unit. After launched in Japanese market, AP5001 achieved very good response, and it was elected as monitor speaker cabinet by Japan's Fuji TV station. The sound is very accurate, full-range balanced, low distortion. This is from her exquisite workmanship can be realized, a large magnet, large elastic wave, long stroke, composite cone, aluminum alloy frames, that is carefully designed products when a glance.
Generally, the sound of toroidal transformer is good, large dynamic, less magnetic leakage, more quiet, and low temperature. R type transformer’s voice is warm, low internal resistance, excellent high frequency extension and also the subtle state is very good.
O-type transformer, combined with the advantages of R-type transformer and toroidal one. A completely non-cutting core made of high-flux silicon steel strip, O type transformer is made of this round-section iron core has a small volume and good electrical performance, and is an ideal transformer. The O-shaped and the ring-shaped transformer are completely different. The ring-shaped transformer is made of steel strips. The O type transfomer is a one-piece iron core. In terms of efficiency and magnetic flux leakage, the O-type has an inherent advantage. As actual listening, its performance is very accurate in high frequency characteristics, transient, and detailed.
Compared with toroidal transformer, O type transformer has the following advantages:
a. The average length of the coil is reduced by 11.4%-30%;
b. The coil has no folding angle, which makes the magnetic field distribution more uniform. For Structural features, the core has no fracture, the section is approximately circular and like as an oblate structure, also its height is short and diameter is larger with more uniform structure, so that its leakage magnetic is smaller.
Compared with the R-type transformer, its coil is not limited by the skeleton, and is tightly attached to the core, which is better coupled and more efficient. O-type transformer’s sound quality at sweet and warm aspect has a significant difference in actual comparison with the other transformers.
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