BSS FDS-360 Card Mods

[buildafriend]

Hi,

Looking to mod these cards so they cut off at 80hz. Not having much luck but I have the tools here to sweep them and see how I'm doing. Anyone mind taking a look at this manual and adding their 2 cents? Page 27. Looking to get good at modding these cards.

http://www.inphase.at/documents/docs/BSS_fds360um.pdf
Kindly,
- j

 

[rackmonkey]

Not sure I get it. So you’ve replaced the appropriate components per the values listed for 80 Hz in the table on page 27, but you’re not seeing the results you expect?

 

[buildafriend]

It’s not cutting the lower part of the band. It’s moving the cross over point between the mid and low bands. Each card appears to have a crossover point that moves around between the two bandwidths while the unit keeps the top and bottom cuttoffs the same

 

[Tubetec]

Page 25 , sec 17.2
subsonic filter change .
You were changing the crossover points , maybe you can modify the subsonic HPF so you get the required response .

The unit is normally set to 30hz , the option is given to change that to 15hz by using the values shown , you should be able to work out a suitable cap value so 80hz is the HPF frequency

The sub or main boards dont stand up well to repeated soldering , there was a guy on ebay selling blank as well as populated (frequency to order)sub boards for the FDS-360 . A modern pcb for the FDS sub board would be a great project .

The FDS 360 was typically used on large pa systems , one per channel but also at least one studio monitor company used them , with in house mods tailored to their product . Its a great machine very customisable to any set up , but best make sure you understand what your doing before going ahead and doing it .

 

[buildafriend]

Modifying the main board kind of defeats the purpose.

I think you’re right that maybe coming up with a new board could be the way. Would probably be a bit of a mission for me though. Don’t see why it would impossible to come up a with a low cut circuit that pops in the way the way these cards do. Would probably take more experimenting than one day of noodling.

would be super cool if someone could spot a solution that fits on the cards! There are schematic blocks on the manual right near said pages. These are analog and super cheap, could be very practical to revive them for modern use.

Kindly,

 

[Riley Casey]

If you're trying to get an 80hz high pass on the low band ( which is my read of what you're asking ) without modding the input filter on the main board you'd have to switch the unit to three way and use the mid band as the low pass on output two and output three as your high pass.