 From
many years we are seller for high fidelity audio equipment. Our work is our
passion and this help us to create our own definition of good sound. We
perfectly know that good sounding system is resultant of quality of each
element of it. We try to don’t favour any element, take care to keep
proportion of complete system. Searching new solutions in configurations
audio systems we decide to design Bonasus which is consistent to conception
of home use unit in high-end system. From many factors which have influence
to match amplifier to the other system components. We choose some of them
which in our opinion decide about it suitability in sound and operational
useful:
-
Integrated amplifier – that
kind of construction is optimal in home use. Compact build is for many users
principal condition of choice. Necessity to buy additional cables
indispensable in separate systems, principally raise expense of whole system
what have big influence for final decision.
- Dual mono construction – in
spit of build whole construction in one housing Our amplifier is made of two
independent circuits power supply, pre-amplifier and power amplifier.
Channels are only connected through ground loop. That kind of construction
have a lot of advantage like integration of all circuits inside of one
housing what minimize interference especially of power supply. From the
other hand electrical separation of channels increase resolution of signal.
- Output power – parameter
which is for less experience users some kind of magic rule (more watts –
better equipment), but in normal home conditions deliver a lot of trouble.
Our experience is saying that real power use at home audio system is from
0.1 to 6 Watt!!! we are convinced, that most of users have problem with „syndrome
of 11 hour”. It means that when they put volume control over „11 hour”
system stops play music and ordinary become be noisy. In our construction we
eliminate this problem put up amplifier which have “only” 16 watts power.
It forced us to build tube amp, because only tube is able to work on
low volume with full range of sound. Semi-conductor constructions have a lot
of imperfections, which principally complicate circuits in low power audio
amplifiers. Properly circuit configuration in our amplifier secure very good
linearity in whole power range. It means that independently of position
of volume knob user receive smoothness of operation in frequency range
characteristics. Important is also configuration of output stage, which work
in ultralinear A/B class push-pull. We have often questions why only 16 Watt,
when that set is able to deliver 25 watts or more? Answer is very simple –
output stage work in optimal points, which we choose after many listening
tests, and result, is output power on this level. Of course that output
power require loudspeakers with efficiency 88dB or more.
-
No feedback loop – feedback
loop is remedium for imperfection circuits with high power is not necessary
in our amplifier. To say nothing about well know bad influence of it for
sound quality we take care for another factor with have big influence on our
amplifier. Feedback loop decrease amplification what force designers to
increase output power and production of “empty watts” and have bad
influence for pick power of amplifier. There is possible to solve this
problem by increase power supply part but its complicate construction and
results are often no so good, we try to eliminate this.
- Power supply – traditional
circuit with tube rectifier and filtering use capacitors and choke, the
first stage work polipropylene capacitor after is choke and then
electrolytic capacitors, total capacity 1680 uF each channel. Past choke
filtering is divide to two circuits, one is to input stage and the second to
output stage. In input stage additionally working polypropylene
capacitors which decouple disturbance appear in this stage. All other
circuits of amplifier (logic, input selector, displays) are supply from
separate transformer.
- Operation and work check - we
equip our amplifier in “soft start” function which provide proper
warm-up of tubes before switching on anode plate voltage. This improve tube
lifetime. Bonasus have also circuit to test condition of power tubes what
give user possibility to check if is necessary change them.
- Chassis – this element,
which have very big influence for good sound is take in our construction
seriously. Very rigid steel chassis, have
big mass itself which is able to absorb inside parts vibrations. All
transformers and chokes are in shielding cans and spill special semi-elastic
damping mass. Reason is one - to eliminate vibrations appear in time of
working.
- Parts and circuit – key to
good sound of amplifier is right selection of parts. After many tests and
experiments we reach result satisfy our expectation use selected components
from Kiwame, Riken, Bourns, Mills, Audyn or Solen. Parts in signal section
are mounted without PCB but „point to point”. We use tubes like:
rectifier 5AR4, duo-triode 12BH7 and tetrode 6CA7.
 How You can find Bonasus is
construction particularly considered, guarantee high class of sound with
comfortable operate. Outside of over shown features, in shape sound of
amplifier very important is direct coupling input stage with phase inverter
or AC heating what give longer life time of tubes. Positive influence of AC
heating for the sound is well known, but using it in most of constructions
increase hum in speakers. Our recipe is very simple: the highest possible
quality main transformer and proper placing wireing give non-problem use
advantage of AC heating. Bonasus is an example of device in which use of
traditional verify solutions is join with modern technology. Result is the
amplifier which is perfect choice for demanding customers.
| Technical specification: |
|
|
| Class of operation: |
Push-Pull, A-B |
| Power output: |
26W/4W
16W/8W |
| Feedback |
zero |
| Tubes: |
2 x 5AR4 |
|
4 x 12BH7 |
|
4 x 6CA7 |
| Inputs: |
6 line |
|
|
| Dimensions: |
|
| W: |
415 mm |
| D: |
370 mm (without terminals and knobs) |
| H: |
235 mm |
| |
|
| Weight: |
40 kg. |
| Guarantee: |
amplifier - two year |
|
tubes - 3 months |
|
|
