A bridge-parallel amplifier configuration uses a combination of the bridged and paralleled amplifier configurations. Zener diode D1 clamps the maximum voltage to 15V, protecting the opamp and C1 from over-voltage. The new connections for the 'added resistor' are shown with arrowheads. It should be exactly double the input voltage. It basically splits the signal into two, one of which is 180 degrees out of phase from the other. For 2 channel amplifiers, one left signal and one right signal is used to drive a mono speaker load. The same principle applies to the bridged connection shown here - no connection other than to the speakers is possible without damaging the amplifier. 2. Enter Emotiva Audio's XPA 200 watt, five-channel amplifier ($799), 1,000 watts total. Figure 2 has no such restriction. Bridgeable amplifiers are designed with an inverted channel for bridging purposes. However, these are not traditional channel-switching amps. Nearly all modern amplifiers use a long-tailed pair as the input and error amplifier (the error amp is the LTP, which detects any variation between its inputs - an error voltage - and corrects it). You will probably find that it has the same voltage, but of opposite polarity. In another of my project pages (see Project 14 - Power Amplifier Bridging Adapter), there is a design for a simple add-on bridging adapter for stereo power amplifiers. $349.99. For both these examples, only one side of the loudspeaker is driven, and the other is grounded. This is based on Project 3A, and shows only the 'slave' channel (Channel 2). First, make sure that there is no appreciable DC offset at the outputs. 4-channel amps are usually for the four front and rear speakers in a car, while subs work best with mono subwoofer amplifiers. Without using a Y-adapter, the procedure is different depending upon the Crown amplifier used. The power amps must be the same - power rating, minimum impedance rating, etc. By using bridging, close to 20W is now possible, with each amplifier driving the equivalent of 2 Ohms. Speaker level inputs are used when you want to connect an amplifier to your factory radio or an aftermarket radio that does not have low-level (RCA) inputs. Some opamps may have a relatively high DC offset if the input A transformer can be used to create the reverse-phase signal for the second power amplifier, but ideally the transformer will have dual secondaries to ensure that the signal level is close to identical for each channel. Be particularly careful with IC amplifiers such as the LM3886, as their protection circuits are easily triggered with low impedances. Amps used for bass will need a larger transformer than those used at higher frequencies (assuming the use of active crossovers). Note that if interconnect leads are to be used from the adapter to the power amp, the 100 Ohm resistors shown must be placed in series with each output to prevent instability - this is important, as an oscillating adapter will inject an AC voltage of perhaps hundreds of kilohertz into the amp's input, with the very real possibility of destruction of the output transistors. Basically, these are: Figure 1 - Basic (Conventional) Power Amp Bridging Adapter. I shall attempt to remedy the situation forthwith! To make this work, you must be able to positively identify 3 important things: Do not be tempted to disconnect the feedback attenuator network, since no power amp that I have ever seen is stable at unity gain. For those who have not used bridging or who do not understand the principles, a short explanation of how the adapter is used and how this almost quadruples the output power is called for. That results in a mono amp configuration with a power output of 2800 watts into a 6 ohm load for each mono amp. A great many amplifiers were built at the time, specifically as bridge amps, with the cross-feedback resistor and secondary input grounding built into the PCB. Soundcraftsman RP-2215R Record Playback Audio Frequency Equalizer. It should be exactly the same as the input for both outputs. For the musicians that want to recreate nostalgic music memories in your own home or studio. This technique is very common in car audio systems, because the nominal 12V (typically around 13.8V when the engine is running) of a car's electrical system is too low to obtain much power except into very low impedances. Normally, the speaker is driven from the amplifier output to ground, and the AC swing is limited by the supply voltages in the amp. If desired, a SPDT switch may be used to allow the amp to be switched from bridge back to normal mode. Project 14 - Power Amplifier Bridging Adapter, The inverting input of the second amplifier, The exact value of the feedback resistor used, The actual output point of the amplifier (where the speaker output connects, or at the input of the inductor if used). Vintage Soubndcraftsmen 410 Watt Amp PM840 Stereo Amplifier - TESTED. There is a negative though. The circuit shown in Figure 4 is about as simple as it gets, but it will still work well. The primary advantage of this method of bridging is that no additional components are needed (which means that it is cheap), and there is no requirement for a lower voltage supply to power the opamps needed for a conventional bridging adaptor. If taken from an electrically connected point that is not actually the output itself, distortion can be introduced. Good rule of thumb is to multiply that by 1.5 for class AB and 1.2 for class D. 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