A vacuum tube sound wonderful also from a speaker also from headphone

Vacuum tube type headphone / speaker amplifier HA-03


It is the optimal amplifier for a direction to use both headphone and a speaker.
HA-03 is the unique amplifier which designed headphone, of course aiming at the amplifier which can enjoy itself by the best sound quality also with the speaker.
The amplifier which can generally enjoy both headphone and a speaker in the optimal state is made difficult.
In this machine, I conquered the difficulty by using the highly efficient vacuum tube C3m with one-step composition.
As for vacuum tube amplifier, the simplicity of the composition appears in sound.
In the case of this machine, the charm which simplifies the composition to a limit and the vacuum tube has was pulled out to the maximum extent.
Since it is simple, freshness sound and music can be enjoyed.
The amplification circuit of this machine is very simple.
Only one step is used by considering the pentode C3m of the vintage vacuum tube by German Siemens as pentode connection, and the moderate amplification rate and the highest quality are pulled out.
A negative return was not used for the circuit but the simplest and natural non-feedback system is adopted.
If a negative return is used, performance will become good, but sound becomes unnatural in many cases.
The number of the parts to pass is reduced to a limit, and degradation of sound is suppressed to the minimum.
The screen grid circuit and the plate circuit were used as another power supply in it, and the output as big as about 1W has been obtained by speaker load by constant-voltage-izing a screen grid circuit.


The maximum output is Headphone 1.4W, It corresponds to wide range load with Speaker 1W!
As for this machine, 1.4W is obtained by headphone load and the output of 1.0W is obtained by speaker load.
Although it may be thought that an output called 1W is small, it is said that the output of vacuum tube amplifier has force equivalent to the thing of several times as many outputs compared with semiconductor amplifier.
Please confirm the ability with the speaker usually used by all means.
If the efficiency like 90dB/1W.1m has a speaker, you can enjoy a sound almost satisfying to the volume of a degree in the middle.
Although usually so big the output at the time of headphone use is unnecessary, since the output is large, force and a feeling of a scale are added to sound.
Headphone to be used, Since a standard is 50ohms, an output is most obtained for the headphone of the impedance near it.
However, since an output had a margin, the correspondence also of the impedance of corresponding headphone to the wide range headphone from 16ohms to about 200ohms was attained.


Adoption and other high-quality sound components are adopted as a chassis for the Complite with high insulation.
The phenol resin Complite with insulation and intensity high on the chassis of this machine is contributed to adoption and high-quality sound-ization.
Moreover, careful selection use of the high-quality sound component is carried out from every country in the world, such as using the winding resistance by U.S. DALE for a resistor for an R core transformer large-sized to a power transformer.

HA-03 Specifications
Form : the amplifier use vacuum tube both for headphone and speaker
Use vacuum tube: : C3m (vintage vacuum tube by German Siemens) 2pcs. attachments
maximum output: -- 1.4W+1.4W (50ohms / headphone load) 1W+1W
frequency characteristic (8-ohm / speaker load): -- 35Hz-17.5kHz (-3dB)
remains noise: -- 57 microvolts (with A filter)
input impedance: -- 50k ohms
Input change: 2 line selection is possible.
weight: -- 5.6kg
outside dimension: -- 156(W)330(D)165(H) mm