I have some BGW 620B's that came from the factory without bridging switches, but I want to use a pair of them in bridged mode. I'm assuming that I can make up a Y cable that plugs into he balanced output of my preamp, (or crossover) and run the two cables to the left and right inputs of the amp and can just reverse pin 2 and 3 on one of the inputs (actually labeled High and Low on the input barrier strip) and connect the speaker to the two + outputs. Is my assumption correct?
There's nothing like checking out the specifications. Free download of service manual here: BGW 620 Manual - Commercial Power Amplifier - HiFi Engine
which shows a basic stereo commercial amp. with 6 pairs of output devices. It's rated 200W/8Ω so even though it's 35 years old, it could be be a candidate for bridging if the power supply is heavier than the 8R rating suggests.
However, the inputs are not floating or balanced and there is no facility for bridged configuration nor mention of it anywhere in the manual. You can't simply use a Y adaptor to drive the amplifiers without a balanced to unbalanced adaptor that also inverts the input to one channel. Alternatively a complete inverting adaptor but I'll leave any such modification suggestions to others who know the beast better.
which shows a basic stereo commercial amp. with 6 pairs of output devices. It's rated 200W/8Ω so even though it's 35 years old, it could be be a candidate for bridging if the power supply is heavier than the 8R rating suggests.
However, the inputs are not floating or balanced and there is no facility for bridged configuration nor mention of it anywhere in the manual. You can't simply use a Y adaptor to drive the amplifiers without a balanced to unbalanced adaptor that also inverts the input to one channel. Alternatively a complete inverting adaptor but I'll leave any such modification suggestions to others who know the beast better.
Last edited:
Hi,
With balanced drive you can bridge any common negative
single ended input stereo amplifier, hot to one channel,
cold to the other, earth as common for both channels.
rgd, sreten.
High and low on the input strip sounds like sensitivity.
With balanced drive you can bridge any common negative
single ended input stereo amplifier, hot to one channel,
cold to the other, earth as common for both channels.
rgd, sreten.
High and low on the input strip sounds like sensitivity.
If you bridge a pair of amplifiers rated as 200+200W into 8+8ohms you get a 400W into 16ohms amplifier.
You will need a pair of 4ohms rated amplifiers, if you want to drive 8ohms loads.
You will need a pair of 4ohms rated amplifiers, if you want to drive 8ohms loads.
Hi Guys
This is easy. The same as I did in many other BGW amps. The 320 & 620 amps use the same amplifier modules as the 250 & 750 amps. The GAIN is changed for the 320 & 620 amps and the MONO mode is not stuffed. By adding a feedback resistor and cap to the PCB this connects pin #7 (MONO) input. For the 620 use a 133K 1% metal file and 20pf cap. Connect pin 7 to the left amplifier output and short the right channel input. The LOAD is them driven from the HOT OUTPUTS of the LEFT & RIGHT AMPLIFIERS.
Be careful as the power transformer is not designed for an BRIDGED OPERATION in a high power modes. The thermal switch in the transformer could open.
Duke
This is easy. The same as I did in many other BGW amps. The 320 & 620 amps use the same amplifier modules as the 250 & 750 amps. The GAIN is changed for the 320 & 620 amps and the MONO mode is not stuffed. By adding a feedback resistor and cap to the PCB this connects pin #7 (MONO) input. For the 620 use a 133K 1% metal file and 20pf cap. Connect pin 7 to the left amplifier output and short the right channel input. The LOAD is them driven from the HOT OUTPUTS of the LEFT & RIGHT AMPLIFIERS.
Be careful as the power transformer is not designed for an BRIDGED OPERATION in a high power modes. The thermal switch in the transformer could open.
Duke
- Status
- Not open for further replies.