Hi Folks
I have a Boston Acoustics Soundware S 5.1 speaker system. I am facing the problem of low output on my Sub in spite of keeping gain at max i can barely feel/hear the sub when playing heavy bass content audio.
The subwoofer included in this package is a 10-inch downward firing 200W RMS (Peak power of 300W) sub. Many years back this subwoofer had failed (power supply board had burnt out) and I had taken it to an authorized service center for repair. Sure, enough they did repair it and i thought it was fine, though i did complain about low Sub output. What i did not realize was that they had replaced the power supply board of my sub with one from Boston Acoustic Soundware XS model. The XS series has a 100W RMS sub. I found all this out because the sub failed again recently and when i opened it to fix it realized the board had changed. I little search on the net i realized the swapped in board was from XS model. The problem now was a burnt zener and a dry solder on a diode. Replaced the Zener and reflowed the dry solder and problem was fixed, and Sub was alive. But output level seemed to have dropped drastically.
Could the low output on my sub be because of the under-capacity Power supply board?
There are two outputs from the power supply board one for preamp and one for amp. Power for preamp/dsp given thru a 3 pin connection -20V:0:+20V and power for amp given thru a 3 pin connection -32V:0:+32V. Assuming the low sub output is because of lower capacity SMPS board I would like to replace this power supply board with a beefier one in line with the original spec, but I don't have the original board, nor can i find the service manual for the Boston Acoustic Soundware S.
1. So does anyone have the service manual or schematic of the Boston Acoustic Soundware S (not the XS i have the manuals for that).
2. Does anyone know what voltage should be given to the amplifier section in the Boston Acoustic Soundware S Sub. I have to assume it is about 45V. I am assuming this because if i look at the driver Amp board the capacitor right next to the power input is rated at 63V. So I am assuming that the rated DC Input would be 45-50V.
Any other possible reason for the low sub output (one more suggestion is heard was to replace all the caps in the amp, while i can do this for the SMPS board i dont think i can do it for the preamp/DSP/amp board as there is so much glue used on that board to stick it to the case that any attempt to free it from the case will damage the board
Any advice would be appreciated. Thanks
I have a Boston Acoustics Soundware S 5.1 speaker system. I am facing the problem of low output on my Sub in spite of keeping gain at max i can barely feel/hear the sub when playing heavy bass content audio.
The subwoofer included in this package is a 10-inch downward firing 200W RMS (Peak power of 300W) sub. Many years back this subwoofer had failed (power supply board had burnt out) and I had taken it to an authorized service center for repair. Sure, enough they did repair it and i thought it was fine, though i did complain about low Sub output. What i did not realize was that they had replaced the power supply board of my sub with one from Boston Acoustic Soundware XS model. The XS series has a 100W RMS sub. I found all this out because the sub failed again recently and when i opened it to fix it realized the board had changed. I little search on the net i realized the swapped in board was from XS model. The problem now was a burnt zener and a dry solder on a diode. Replaced the Zener and reflowed the dry solder and problem was fixed, and Sub was alive. But output level seemed to have dropped drastically.
Could the low output on my sub be because of the under-capacity Power supply board?
There are two outputs from the power supply board one for preamp and one for amp. Power for preamp/dsp given thru a 3 pin connection -20V:0:+20V and power for amp given thru a 3 pin connection -32V:0:+32V. Assuming the low sub output is because of lower capacity SMPS board I would like to replace this power supply board with a beefier one in line with the original spec, but I don't have the original board, nor can i find the service manual for the Boston Acoustic Soundware S.
1. So does anyone have the service manual or schematic of the Boston Acoustic Soundware S (not the XS i have the manuals for that).
2. Does anyone know what voltage should be given to the amplifier section in the Boston Acoustic Soundware S Sub. I have to assume it is about 45V. I am assuming this because if i look at the driver Amp board the capacitor right next to the power input is rated at 63V. So I am assuming that the rated DC Input would be 45-50V.
Any other possible reason for the low sub output (one more suggestion is heard was to replace all the caps in the amp, while i can do this for the SMPS board i dont think i can do it for the preamp/DSP/amp board as there is so much glue used on that board to stick it to the case that any attempt to free it from the case will damage the board
Any advice would be appreciated. Thanks
The difference in power available from a 32V supply (that does not "sag" or current limit under it's normal load) compared to a 45V is almost exactly 3dB, the same difference between 100 and 200 watts.
A 3dB reduction in output power is noticeable, but not drastic.
A 10dB reduction from 100 to 10 watts could sound fairly drastic, about half as loud in the upper sub range. A "drastic" level change may be more like 20dB, reducing 100 watts to one watt.
20 volts into 4 ohm load is 100 watts, 2 volts=1watt.
Something may be limiting the current available from the SMPS board.
That's about the limit of my advice...
A 3dB reduction in output power is noticeable, but not drastic.
A 10dB reduction from 100 to 10 watts could sound fairly drastic, about half as loud in the upper sub range. A "drastic" level change may be more like 20dB, reducing 100 watts to one watt.
20 volts into 4 ohm load is 100 watts, 2 volts=1watt.
Something may be limiting the current available from the SMPS board.
That's about the limit of my advice...
Thanks did not think of it that way. What you are saying makes logical sense. Now i need to figure out which part is bad the preamp/DSP section, the SMPS board or the main amp section. My bet would be on the power board because thats the one that burnt out recently. All i need are the schematics of the same.