New Toy: BGW 750 B ...playing now!

[Michael F]

I would think long and hard before I changed the ventilation (fan direction) of this amp. BGW reliability is no accident and airflow is a major contributor. Since there is no fusing on the power supplies, if the amp fails it takes out all of the outputs, emitter resistors, drivers, predrivers and smokes the board. I've seen it happen. Keep in mind these amps lived in a lot of pro racks that didn't always have ideal airflow.

Oh I have. I used to run a BGW powered Turbosound rig and they all were modified in that fashion and never experienced any amp failure . It made cleaning the amps so much easier, 6 screws and a quick brushing, you were back in business in less than 5 minutes. That also kept things very clean on the PC board side particularly around the umbilical cord connector which were no longer in the fans direct line of fire. Dust and dirt accumulation on the heatsinks was relatively uniform indicating an even airflow.
I`m sure BGW had their reasons for their choice of airflow direction but I found the reversal to be beneficial.

The important thing here is that the fan is functional. This particular amp came to me without a working fan, who knows how long it was operated in that condition?

 

[El Magnifico]

Oh I have. I used to run a BGW powered Turbosound rig and they all were modified in that fashion and never experienced any amp failure . It made cleaning the amps so much easier, 6 screws and a quick brushing, you were back in business in less than 5 minutes. That also kept things very clean on the PC board side particularly around the umbilical cord connector which were no longer in the fans direct line of fire. Dust and dirt accumulation on the heatsinks was relatively uniform indicating an even airflow.
I`m sure BGW had their reasons for their choice of airflow direction but I found the reversal to be beneficial.

The important thing here is that the fan is functional. This particular amp came to me without a working fan, who knows how long it was operated in that condition?

Yeah Mike! Who knows? Anyway, when I place my hand over the grill I can feel the exhaust from the 700B. I'll replace my fan and try your suggestion.

 

[Michael F]

Yeah Mike! Who knows? Anyway, when I place my hand over the grill I can feel the exhaust from the 700B. I'll replace my fan and try your suggestion.

You should`nt have any problems at all. You will find that a new fan is much quieter. You can experiment with the additional series resistor too but make sure the amp tolerates the PR heat and humidity.
The system I was referring to earlier consisted of 16x 750B/C`s that were driven hard and half of those bridged into a 4 ohm load tough amps!