|The Audio Pages|
|Elliott Sound Products||BP4078|
The BP4078 Class-D power amplifier is now available from ColdAmp. You need only add a power supply, and the necessary hardware (chassis, input and output connectors) to have a complete working system. The module described is not a kit - it has been completely built and tested at full operating levels, and all major specifications are verified for each module. You need to add a basic heatsink and power supply.
ESP no longer supplies these modules, but they may be obtained direct from ColdAmp. Please mention that you found out about the ColdAmp products from the ESP website.
The power amplifier is suitable for powered speakers, subwoofers, or full range high powered amplifier systems. With performance as good or better than a great many conventional hi-fi power amplifiers (including some at many times the price), it has excellent bandwidth, and very low noise and distortion.
This is an excellent amplifier - and despite the qualms one may have about Class-D for full range amplifiers, there is no major parameter that suffers as a result. This amplifier is ideally suited for hi-fi, public address, bass guitar, high power subwoofers or the low frequency end of a very high power biamped system.
|Order Code||No Longer Available|
|Size||96 (L) x 72 (W) x 39 (H) mm|
|Packed Weight||250 grammes (approx.)|
Photo of Complete Module
The following specifications are typical, but may vary slightly from one unit to the next. The major parameters are very well defined, and the variations in practice will be extremely small. These are not guaranteed specifications, as the quality of the power supply will have an influence on noise and power output. All specifications can be reasonably expected to be met if assembled according to the data supplied with the module.
|Supply Voltage (+VCC and -VSS to GND) Note 1||35||-||65||Volts|
|Modulator optional external supply voltage (+ve and -ve)||8||-||25||Volts|
|MOSFET driver optional external supply voltage (referred to -VSS)||15||-||25||Volts|
|Peak output current Note 2||-||18||-||Amps|
|ON / OFF pin voltage||0||-||12||Volts|
|Minimum load impedance||2||-||-||Ohms|
Audio Performance (Measured at ±60V with 10,000uF filter caps unless noted otherwise)
|Output power, 4 Ohms||400||W||0.5% THD, 1kHz Sinewave|
|Output power, 8 Ohms||240||W||0.5% THD, 1kHz Sinewave|
|THD (Total Harmonic Distortion + Noise)||0.02||%||100Hz, 1W, 5 Ohms|
|SNR (Singal to Noise Ratio)||<100||dB||Inputs shorted to GND|
|Bandwidth (-3dB)||6 - 50k||Hz||8 Ohm load|
|Bandwidth (-1dB)||17 - 20k||Hz||8 Ohm load|
|Output Impedance Note 3||TBD||Ohms||To Be Determined|
|Output Ripple (at switching frequency)||500||mV (P-P)||Inputs shorted to GND|
Additional Parameters (Measured at ±60V with 10,000uF filter caps unless noted otherwise)
|ON/ OFF threshold voltage||2.5||V||Module deactivated below 2.5V|
|Efficiency (output stage)||93||%||400W into 4 Ohms|
|Standby power (shutdown mode)||6||W||Measured with no input|
|+VCC current at idle||40||mA||Measured with no input|
|-VSS current at idle||70||mA||Measured with no input|
|Clip LED output current||8||mA|
|Modulator supply current (external)||+35/ -20||mA||Positive and negative supplies|
|MOSFET driver supply current (external)||60||mA|
|Protect mode output voltage||12||V||0V when not activated|
|CLK output amplitude||6||V P-P||Triange wave|
1 Below ±35V, under-voltage protection is activated. Above ±68V, over-voltage protection is activated.
2 Limited by over-current protection. Once tripped, remains activated for approx. 2 seconds.
3 Output impedance is not influenced by overcurrent protection, since no series sense resistor is used in the speaker line.
You will also need a 3 pin line socket (2.54mm / 0.1" pitch) for the input header. One of these is supplied with the module. Optionally, you will need additional 2 and 3 pin line sockets for the volume control and remote On/ Off (3 pin), thermistor output, clipping LED output and protect output (2 pin).
What You Need
You will need to provide power (±56V nominal @ 2A continuous is suggested), which means a transformer (300VA for one channel with 4 ohm load, intermittent duty) , bridge rectifiers and filter capacitors. Full details of power supply requirements and wiring are provided with the module. You will also need chassis mounted speaker and input connectors, and optionally a volume control pot.
You will also require a suitable case (a 2RU rack mount case is ideal) and either a heatsink rated at around 2.5°C/W or better for each amp module, or a chassis built using a 2mm aluminium plate for the base - this will be sufficient heatsinking for domestic use.
Supply Specification (Suggested for one amplifier, e.g. subwoofer amp or monoblock hi-fi)
|Transformer||40-0-40V AC @ 3.75A (300VA) toroidal|
|Rectifier||35A 400V chassis mount bridge|
|Filter Capacitors||2 x 10,000uF 75V - 105°C electrolytic|
|Supply Fuses||5A fast blow (each supply, +ve and -ve)|
|Mains Fuse||4A / 8A slow blow (230 / 110V respectively)|
|Copyright Notice. This article, including but not limited to all text and diagrams, is the intellectual property of Rod Elliott, and is Copyright © 2002. Reproduction or re-publication by any means whatsoever, whether electronic, mechanical or electro- mechanical, is strictly prohibited under International Copyright laws. The author (Rod Elliott) grants the reader the right to use this information for personal use only, and further allows that one (1) copy may be made for reference while constructing the project. Commercial use is prohibited without express written authorisation from Rod Elliott.|