Audio Database


Airtight's first monaural power amplifier in commemoration of its 5th anniversary.

6CA7/EL34 is used for the output tube, and triple push-pull is used to secure 100W or more by allowing extra space in the vacuum tube. In addition, by connecting vacuum tubes in parallel, internal resistance is reduced without increasing plate voltage, and high power is achieved.
This enables stable operation over a long period of time without applying excessive load to each vacuum tube.

Six vacuum tubes with the same characteristics selected by an aging machine are used for each vacuum tube.
In addition, each tube is equipped with an independent bias check mechanism for long-term stable operation in the best condition, and can be checked and adjusted at any time by the volume and meter on the front panel.

Equipped with a switching circuit for UL connection and 3-pole pipe connection, the operating state of the output pipe can be switched according to the speaker and sound preference.
The UL (Ultra-Linear) connection is designed to connect the screen grid of the multi-pole output tube to the tap located in the middle of the primary winding of the output transformer. In this connection method, the phase of the voltage of the screen grid is opposite to the phase of the voltage of the control grid, so it acts as a negative feedback to the output tube. Therefore, the amplification is lower than when the multi-pole tube is connected. However, due to the decrease in the amplification degree, the internal resistance of the plate rapidly decreases. As a result, it extends in the low-frequency range and exhibits the expression power of a vacuum tube. In addition, stable NFB is applied over all frequencies.
The 3-pole tube connection is 100% negative feedback applied to the screen grid of the UL connection. The plate internal resistance of the output tube is even lower than that of the UL connection, but the decrease in the output is also large. As for sound quality, the energy is stable inside and is applied to all bands, so sweet expressive power can be obtained.

High sound quality is achieved by finishing with 1.1 point wiring without using a printed circuit board.

A large transformer is used for the power transformer, making up a strong power source with good regulation.

We have adopted the highest-grade transformer manufactured by tamura Manufacturing Co., Ltd. with transformer technology that has passed the Defense Agency standards.
This transformer is a large type matched to the low impedance of the triple push, and realizes a low frequency without distortion. In addition, the constant loss is marked as 0.25 dB, which is the lowest value for an output transformer. In addition, the adoption of the Orient Core eliminates frequency shift over the entire band.

Highly reliable parts are carefully selected and used.

In order to protect the output tube, it is equipped with a muting circuit that cuts off high voltage in the output tube for approximately 30 seconds after power is turned on.

Model Rating
Type Monaural power amplifier
Effective power UL:110W
3-Line : 55W
Total harmonic distortion factor 0.08% or Less (1 kHz, 1W)
1.0% or Less (1 kHz, 110W)
Frequency characteristic 20 Hz ~ 20 kHz ± 1 dB (110W)
Input sensitivity 1V
Input impedance 100k Ω
Signal-to-noise ratio 100 dB (IHF-A Input Short)
Load impedance 2 Ω ~ 4 Ω
6 Ω ~ 8 Ω
Accessory function UL/3-connection operation selector switch
Bias adjustment function
Vacuum tube used 6CA7 : 6
12AX7 : 1 piece
12AU7 : 1 Piece
Pwer 100 VAC, 50Hz/60Hz
Power consumption Approx. 250W (Electrical Appliance and Material Control Law)
External dimensions Width 405x Height 220x Depth 340 mm
Weight 25kg