The Koro-2011A is the basic model in the Koro Tube Components series. The M11A, which is used as the speaker system in the Koro-2011A package, is “bookshelf” size (170 x 290 x 245mm). However, despite the size, our new dual bass-reflex system (at present under patent processing) enables it to reproduce a deep, rich, and clear bass sound. The middle-high frequency is very precise. The same dual bass-reflex system is also used in other models.

What We Think

It is true that a tube amplifier reproduces electrical signals less faithfully than its solid-state counterpart. However, no perfect speaker exists that will faultlessly turn the electrical signals of a solid-state amplifier back into the original source music. Also, because the input of the middle/high frequency range signals causes the speaker cone to resonate, and because of problems in following the signal, the sound produced by some solid-state amplifiers is hard on the ear. If you have listened to a CD music source like the Mozart Requiem on high performance earphones of superior signal reproducibility, you will understand the clean and natural way that a middle/high frequency range signal can be reproduced.

In contrast to solid state, tube signals are slower and more easily matched with a speaker’s reproducibility. The tube softly filters the source music signals, making them easy for the speaker to reproduce.

Impedance matching (both electrical and mechanical) and reduction of resonance and reflection to the lowest levels are very important factors in refining an audio system. Though perhaps unsuitable for mass production, we believe that we can best do this by keeping the system simple and small. Our Single-End and Single Driver products are not so powerful, but reproduce the original quality of the music source with the highest fidelity and lowest resonance.

Special thanks to Mr. Tsuda(President of Sillicon Arts Design and M’s Unity), our technical leader and noted audio designer. His abundant talents, especially with amplifiers, have brought our products into a super-refined audio world.

The specification of koro-2011A :Opening price $1,200 The CD player is not included
A205A Integrated tube amplifier
Input* :
Output* :
Output tubes :
Input tube :
Output Transformer :
Output power :
Total gain :
Frequency :
Distortion :
Power Consumption :
AC Input power :

Weight :
Dimension :
100mV 100kΩx 1
8Ω screw/plug connection x 1
EL84(6BQ5) Pentiode mode A1 Single-End
ECC83(12AX7) Twin Triode x 1
10w x 2
4.8w/ch at 1.4V input 500Hz/8Ω/ch
12Hz - 70kHz/-3dB
0.75% 0.01w/10kHz
117V±10V 50/60Hz 1 Phase
Installed power cable.
7.0 kg
(W)285 x (H) 125 x (D)230mm

M11A Book-shelf speakers
Speaker Unit:
Rated Power Input:
Maximum Power input:
Weight :
Dimension: Speaker

MDF Piano finish vented box x 2
4” Magnetically Shielded driver 1 unit
Paper pulp cone with Rubber surround

88dB 1W/1m
4.8 kg
(W)170 x (H) 290 x (D)245mm

Package Price for koro-2011A: $1,350
Option: Speaker stand pair $100
Amplifier safety cover $150