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PADA-300B English

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PADA-EL34 パーダ

EL34 triode PP Power amplifier

PADA-300B

300B-PP Monaural Power amplifier

PREDA

Solid-state Pre-amplifier

VIDA Supreme ヴィーダスープリーム

LCR Phono stage amplifier,4CH configurable

VIDA ヴィーダ

LCR Phono stage amplifier, option averrable

VIDA prima ヴィーダプリマ

NF+CR Phono stage amplifier

HEADA ヘッダ

Balanced drive Headphone amplifier

SP03L

MC Step-up transformer

 

 

PADA-300B
PADA-300B

Direct Heating Triode tube, 300B push-pull
Inter-stage transformer drive
Discrete transistor front-end, Hybrid construction

Key features

1. Output stage, 300B push-pull.
28W@8ohm

2. Front-end, made in Japan discrete
transistors.

3. Hybrid construction combined by
inter-stage transformer.

4. No negative feedback loop in total
signal path.

5. Full balance signal structure.

6. Lundahl output transformer.

7. Solid rosewood body with oil finish.

8. Large size EI core power transformer
and very low noise high stability
independent power supply section
for front-end and output stage.

9. Bonnet cover is bundled.

 

PADA-300BBlock Diagram

PADA-300BBlock Diagram

 

PADA-300B Top View


PADA-300B Top View

 

PADA-300B Close Up

Bonnet cover (bundled)/Two units for Stereo Solid Rose Wood with oil finish
Bonnet cover (bundled)   Two units for Stereo

Solid Rose Wood with oil finish

Rear side Sideview
Rear side Side view


Inside

Inside

 

PADA-300B Explanation

 

Design Philosophy

Conventional hybrid power amplifiers are constructed using  vacuum tubes in the front-end and transistors for the output stage, the transistors doing the power amplification with the tubes just adding a flavor of the classic tube sound.

However, the PADA-300B is designed in the opposite way – the transistors in the front-end and the tubes for the output. The PADA-300B design leverages the transistors to achieve low distortion, high SNR and wide frequency range, and then utilizes  an inter-stage transformer to drive the output tubes. The inter-stage transformer matches the signal level and supplies the voltage difference between the transistors and tubes. This construction makes optimum use of both the advantages of transistor performance as well as the warm tube sound.

 

Noise Prevention and Control

Thanks to the excellent linearity of the 300B tubes and Lundahl transformers the PADA amplifier has no negative feedback loop. The tube filament is driven by AC voltage. In many of today’s conventional amplifiers, DC filaments driven by high-current diode devices is used because of its low cost, which often results in low hum noises. DC-driven filaments have other disadvantages, such as unevenness of electron emission in the filament wire due to its resistance factor, which can  damage tubes in long term use. PADA-300B AC drive technique cancels hum noise thanks to its push-pull design and simple center adjustment by its pod trimmer. AC is by far the best method for achieving  optimum performance from 300B tubes.

 

Self-Biasing

The PADA-300B employs self-bias methodology for operating the tubes, providing long-term stability. The user can change to different brands of 300B tubes by simply plugging them in - no need to re-adjust bias current with a monitoring meter. Self-biasing circuits usually use electrolytic capacitors due to need of large capacitance and small footprints. The PADA-300B, however, uses highly reliable precision polypropylene film capacitors, taking advantage of their superior high frequency response and longer lifetime in high temperatures.

 

Front End Circuitry

The PADA-300B’s frond-end circuit utilizes NEC and Toshiba Japanese transistors that were developed especially for audio applications from 1970-1980, the golden age of analog audio. Those transistors have been discontinued due to lack of demand in the digital era, but have excellent audio performance compared to the current chip-sized transistors made in China. Aurorasound has a large quantity of new-old-stock of those Japanese transistors from the 70’s and utilizes them in all Aurorasound products.

 

Power Supply

The PADA-300B’s power supply section has independent regulators for both the front-end and output stage. The front-end regulator Is the same high quality regulator as the Aurorasound VIDA’s, which ensures stability and low noise. The output stage regulator uses super-low-noise silicon carbide Schtokky diodes with large size film capacitors instead of common electrolytic capacitors, once again taking advantage of their superior high frequency response and longer lifetime in high temperatures as in the self-biasing components.

 

Output Stage

In general, when music plays in fortissimo (very loud) or sequential percussive phrases, common output stages consume a large amount of current power, causing the front-end to suffer. However, PADA-300B system of independent regulators prevents this from happening, managing dynamics extremely well.

 

Chassis

The chassis consists of 25mm thick solid oiled Rosewood, hand made by a woodworking artisan in Japan’s Shizuoka prefecture, home of Mount Fuji. This rosewood is used for finger boards and sides of acoustic guitars, in which it provides a very robust foundation to support the guitar top board and strings. The effect of the rosewood on the PADA-300B’s is the same as that of the guitar construction. The top of the PADA-300B is made of 4mm thick solid aluminum, a completely anti-magnetic material.

 

PADA-300B Specifications

[Specifications]  
Input RCA or XLR balance
Input impedance 56kΩ (RCA/XLR)
Output power 28W, 8Ω load
Signal sensitivity 400mV/RCA,  800mV/XLR,  max power
Frequency response 20Hz – 45kH,  +0db/-3dB
THD+N 0.08%   A-weighted
Residential noise 0.09mV以下. A-weighted
Functions RCA/XLR input selector, MUTE Switch
Vacuum tubes PSVANE WE-300B
Size W310 xD480 xH248mm with bonnet cover
Weight 19.8kg
AC power supply AC115V  or   AC230V
Power consumption 180W

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