400w stereo audio amplifier based totally at the unique marshall leach involvement, but has made a few upgrades. Regarding the electricity supply voltage to the +-75v.
Vc comparing the overall performance of the modified leach 700w/2r on one not unusual board of each channels, as well as safety and control circuits for the fanatics. In comparison to the 700w model a chunk exclusive in wiring. Because some matters in the 700w version is absolutely tightened to perfection. 400w stereo marshall leach amplifier
700w version could criticize a couple of factors:
1st very excessive benefit output stage resulting in deterioration of sign noise distance. Therefore 700w model even greater noisy. 2d the absence of multipliers ube bias current manage and keep temperature stability diagram.
The 700w model of the thermal stabilization solved by using a unmarried transistor, that could occasionally cause a first rate loss because of power manipulate is fast enough and has a few delays. Consequently jpa400 added to this multiplier.
3rd protection blunders on board speakers,
the amplifier is much less at ease and it’s miles vital to feature this safety to the facet someplace special plate. 4th no opportunity to accurate the offset voltage of the amplifier output, this has a instead big weight in the differential pair of transistors and voltage degree. Here this is solved through trimmer linked to the input mark
5th the paintings points the individual stages are laid quite low, it’s going to also motive an growth in overall harmonic distortion as well as intermodulačního distortion.
All that is in jap400 eliminated
The input amplifier is mark with adjustable offset voltage. Mark is specifically due preamplified signal for producing the real end-impedance amplifiers and separates. The differential amplifier is a conventional symmetrical with the contemporary five ma consistent with couple, which is set 2.
Five ma each transistor
Similarly, shifted the working point voltage amplifier to approximately 13 ma. This changed motive force will provide enough power for generating terminal transistor and is tough enough. On the stop of this time is five pairs of quit-kind transistor 2sc5200 / 2sa1943. Current coverage is converted into the wide variety of transistors.
It has a negative slope and replicates the characteristics of soar terminal transistors. Modern-day protection for amplitude limitation limits the end-round transistors 7a. As has been mentioned at the thermal stabilization of the multiplier is used ube, is shaped by two npn and pnp transistors. The board also consists of an amplifier circuit for the fan control. This circuit ensures that the fan velocity manage relying on temperature.
At the temperature to sixty five ° c, fan runs for about 30%, it significantly reduces noise. After exceeding this temperature, the fanatics start walking at 100% and lighting to sign overtemperature. Enthusiasts again at decreased energy transfer at approximately forty two ° c. Thermal protection is related to protection of the speakers at cooler temperatures exceeding 80 ° c, the speaker is disconnect. On board is a relay switch that lets in stereo / bridge mode, the indikovám led on the front panel. The amplifier also consists of an auxiliary energy source to the primary board, shaped via transistor stabilizer. Because of better electric powered circuit protection circuit and fan control. There’s also an indicator of an excited, solved by the presence of the indicator sign and clip detector.
output electricity: 2x 400w/4r, 2x230w/8r
minimum excursion zázěž: 4r
slew charge: 45v/us
bandwidth: 8-one hundred fifty 000 hz /-3db
maximum permissible voltage: +-75v
filter ability: 2 x 20g / 80v
sensitivity dc safety: + /-2v
late connection: 2 seconds
fusing give up amplifier: 4 eight a / f
input sensitivity for optimum excitation: 1v