FU-33 Vacuum Tube Amplifier 833A 833C DIY

FU-33 Vacuum Tube Amplifier 833A 833C DIY

The FU33 electron tube is a direct-heating thorium carbide cathode glass triode, the anode cooling method is natural cooling, the maximum anode dissipation power is 350W, the maximum operating frequency is 30MHz, and the output power is 1000W. It is mainly used for oscillation in industrial high-frequency heating equipment and amplification in radio equipment.

This tube can be used interchangeably with the 833A/C type electron tube produced in the United States.

Vacuum tube FU33 is a high-power triode, usually used in communication equipment, with the characteristics of high voltage resistance. Some data of FU33 are indeed very scary. For example, the maximum anode voltage can reach thousands of volts, the maximum anode dissipation power is about 300W, and the filament current can reach 10A, which is very harsh on power supply. It seems that using FU33 to make power amplifiers is not an easy thing, but why use it? A senior audiophile said, "This vacuum tube has good pressure resistance, good sound, strong three-dimensional sound field, strong dynamic output of Class A, and freely retractable."

The DIY project spent a lots of efforts from at least 6 months ago, and now finally finished.

Here, we attached some data of vacuum tube FU-33 for you information.

Basic Parameters

Filament Voltage ……………………………………………… 10 V

Filament Current ……………………………………………… 9.4---10.6A

Inter electrode Capacitance

Grid Plate …………………………………………………… 5.5--7.1 pF

Grid Cathode ………………………………………………… 10.1—14.5 pF

Cathode Plate ………………………………………………… 6.4—10.6 pF

Amplification factor……………………………………………… 31.5-38.5

Operation Frequency …………………………………… 30MHz

Anode DC Voltage…………………………………………… 3kv

Anode DC Current ……………………………………………… 415Ma

Grid Current ……………………………………………… 40-70mA

Grid Impedance ………………………………………… 3.5/5 kΩ

Output power ……………………………………………… 1000W

Application ……………………………………………… broadcast communicate and High- frequency hearting.

Cooled style …………………………………………… wind cooled

Limit using parameter 

Maximum filament voltage: 10.5V

Minimum filament voltage: 9.5V

Maximum anode DC voltage: 3300V

Maximum anode power dissipation: 350W

Maximum grid power dissipation: 20W

Mechanical Parameter

Weight: (approximately) 0.6Kg

Installation method: vertical, anode lead up

Cooling method: natural cooling

The highest temperature of the shell: 225℃

The highest temperature at the sealing joint: 200℃

High temperature at the terminal: 200℃

Use requirements and precautions

1. When using electronic tubes, there should be no more than one limit value parameter. Exceeding the limit value is not allowed even for a very short time.

2. The lead wires connected to the electrode of the electron tube must be in good contact with the electrode, otherwise an arc will be generated, and the electrode will be melted through, causing the tube to leak.

3. The electronic tube should be handled with care during packaging, storage, transportation, and replacement to avoid damage.

4. When the electron tube is working, the ventilation should be good, the surface temperature of the electron tube should not exceed 145 degrees Celsius, otherwise, the glass bulb should be blown to cool.

5. Note: When the anode dissipation power is greater than 300W, the glass bulb is blown and cooled.

Applications

More details for vacuum tube FU33 (813A/813C), please find here.

Vacuum Tube FU33 Tube Amplifier Replace 833A/C High Power Output HIFI Audio

IWISTAO HIFI 4 Inches Full Range Labyrinth Speaker Bamboo Cabinet

IWISTAO HIFI 4 Inches Full Range Labyrinth Speaker Cabinet Bamboo

This cabinet is a hand-made product, which is made up of bamboo, which is a pair HIFI 4-inch labyrinth full-range speaker, which has a good bass with a small volume. Its full range speaker unit is made of imported high-end materials, sound better than the Lowther Fostex one, warm and delicate tone, analysis High burr-free, vocal sweet, and silky. 

For the 4-inch small caliber speaker unit, the high and low frequencies have excellent performance, good music, good at playing the violin, saxophone and other strings, for the popular and HIFI female voices and other small compilations have a good performance. The treble is exquisite and more transparent, vocal performance is real and natural, midrange is full and full of oil and rich texture, and bass is concentrated and powerful. Its overall sound quality is stable and balanced, and the HIFI sound quality style is completely.

More details, please find here

IWISTAO HIFI 4 Inches Full Range Labyrinth Speaker Cabinet Bamboo 2x60W Max 70Hz-22KHz 89dB

How to assemble super tweeter with 5 inch long brass horn

How to assemble super tweeter with 5 inch long brass horn

This super tweeter is made of brass integrated stretching for musical instruments. The curve of horn is a natural and smooth parabola with a horn design and good sound field positioning.

The driver unit uses a 43mm diameter neodymium copper film one with a copper short-circuit ring, a high-permeability liquid, and an ultra-lightweight 40mm diaphragm made of beryllium copper to ensure that vibration quality is lighter and more air can be pushed at the same time. Makes the music spiritual and the details more real.

An alloy of beryllium and copper. It is a flexible material in copper alloys. It has high strength, elasticity, hardness, fatigue strength, small elastic hysteresis, corrosion resistance, wear resistance, cold resistance, high conductivity, non-magnetic, and no impact. Spark and a series of excellent physical, chemical and mechanical properties.

The beryllium copper film contains 16.7% beryllium and 83.3% copper, which can make the film very thin and not easier to break than pure beryllium film. After being processed into a diaphragm, the thickness of the entire diaphragm is only 0.015 mm (1.5 wires). The 0.04mm aluminum film and 0.03mm titanium film can't be surpassed. Therefore, the analytical power is extremely strong, that is, the delicate and durable hearing with silk film, and the splendor and broadness of brass instruments.

The ultra-high magnetic circuit is composed of neodymium magnet, and it is filled with a magnetic fluid. The magnetic fluid has three functions: assisting heat dissipation, providing damping of the horn diaphragm, reducing distortion and keeping the voice coil in the center position, and acting as a centering support To find the right positioning. The speaker can also use the copper diaphragm to dissipate the heat of the voice coil into the air to increase the speaker's power. Small size and high energy, as long as you are an enthusiast, you can't miss it.

A whole super tweeter is composed of 5 components as the picture below, including to a black marble base, a holder, a tweeter component, a phase cone, and a brass corn.

When you get them, you will assemble them into a completed super tweeter, please be careful. Here, take a look how we assemble it.

1. Assembling the holder into the black marble base.

2. Dismantling tweeter component and fixing the brass horn into the nut.

3. Assembling the phase cone into the horn.

4. Assembling the tweeter into the horn

5. Finally, assembling the base that had been fixed at the first step.

More details, please find here

IWISTAO Long 5 inch Supper Tweeter 1 Pair Copper Horn Brass horns Neodymium Copper Film 6Ω 20W 1.2kHZ-40kHz

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This is a gain-adjustable passive preamplifier (audio signal boosting transformer). Using British original authentic 600:3.5K boosting transformers (second-hand disassembled one) 148H, 8DB amplification, the maximum magnification time is 2.4 times, oscilloscope test bandwidth 20-20KHz;

More details

Passive Preamplifier Audio Signal Boosting Transformer 600Ω: 3.5KΩ British Original Authentic for Smartphone PC

IWISTAO Vacuum Tube 6922/E88CC Tubes Preamplifier Stage Built-in Regenerative Power HIFI Audio

IWISTAO Vacuum Tube 6922/E88CC Tubes Preamplifier Stage Built-in Regenerative Power HIFI Audio

Many electrical appliances are converted from AC power to DC. Work at the peak of the AC, which causes the peak of the AC to be cut, causing a lot of harmonic interference. The distortion is generally up to 5%, or even higher when it become more serious. Power processing equipment can effectively reduce Interference, but it can’t be eliminated. The P20 which is recognized as the best American regenerative power supply, has an index of only 0.5%, and the sound is much better!

However, if the power of the regenerative power supply is large, the distortion is difficult to be low. If there is only power that less than 100W ten, it can still achieve ultra-low distortion power, which is applied to the pre-amplifier.

Now, many audiophiles had used a regenerative power equipment, which brings amazing changes in sound, reduces power interference, and significantly improves sound quality.

This tube preamplifier stage built-in an ultra-low distortion 60W regenerative power supply in order to achieve ultra-low distortion and ultra-high signal-to-noise ratio, its distortion is less than 0.01%, ultra-low distortion.

More details, please find here

IWISTAO Vacuum Tube 6922/E88CC Tubes Preamplifier Stage Built-in Regenerative Power HIFI Audio

IWISTAO LA1235 Stereo Radio Tuner Finished Board

IWISTAO LA1235 Stereo Radio Tuner  Finished Board

The LA1235 is recognized as a high-performance discriminator, the preparing Intermediate frequency amplification is the two-stage TA7302P, the discriminator is LA1235, after then the signal is very powerful, and finally FM stereo decoding of the LA3401 makes its sound clear and beautiful.

After the board is connected to HIFI amplifier and speakers, stereo FM radio can be played.

IWISTAO Bluetooth Speaker Solid Wood Dual 3 Inches Full Range Unit & A Bass Diaphragm

IWISTAO Bluetooth Speaker Solid Wood Dual 3 Inches Full Range Unit & A Bass Diaphragm

This vedio is a demo for IWISTAO Bluetooth Speaker, its acoustics system is made of 2 pcs 3 inches full range speaker units，a bass diaphragm，and a solid wood cabinet.