| waltona |
Hi all,
I'm building Brian's 3875 kit with the power supply in a separate case to the amp boards. I'm using a tranny with dual secondaies and one rectifier board. My question is how many wires do I need in the umbilical connecting the 2 boxes? Can I combine the PG+ and PG- at the rectifier board and use one connecting wire?
At the moment I was thinking of using 1 wire for each of the following:
V+ (one wire from rectifier to amp box which is then split to each amp board)
V- (as above)
Earth (for chassis only)
PG (+ and - combined at rectifier board and split in the amp box)
I know this is a very smple question and YES I have searched the forums but I'm a bit confused and thought it was better to ask and be safe.
Thanks
BIG A |
|
|
| waltona |
Thanks for the reply.
Ok I'm sorted with V+, V-, PG+ and PG-.
Now about chassis ground...do I connect the mains earth to the power supply chassis, run a second wire in the umbilical to the amp chassis and not use the CHG on the PCBs? |
|
|
| homer09 |
| sounds right, u'll know for sure when there's no hum. |
|
|
| Nuuk |
| quote: | | Now about chassis ground. |
Yes run the ground wire from the PSU chassis through the umbilical and connect it to the metal cahssis of the amp case. The connect CHG to the case via a cpa and resitor in parallel as shown in this design . ;) |
|
|
| Sherman |
| quote: | Originally posted by waltona
Thanks for the reply.
Ok I'm sorted with V+, V-, PG+ and PG-.
Now about chassis ground...do I connect the mains earth to the power supply chassis... |
If your umbilical is relatively short (say under a meter) then a five wire DIN plug works well. In the amp box use a panel mount DIN connector. Easy to disconnect and it can't be connected wrong.
Connect 1 wire each to V+, V-, PG+, PG- and earth or safety ground in the PS box.
In the amp box make the 4 power connections to the amp boards and connect the earth or safety ground pin to the chassis.
Just make sure to match the right pins to the right PS connection! |
|
|
| carlosfm |
| quote: | Originally posted by Sherman
Connect 1 wire each to V+, V-, PG+, PG- and earth or safety ground in the PS box.
In the amp box make the 4 power connections to the amp boards and connect the earth or safety ground pin to the chassis. |
That's the ticket for a ground loop.:bawling:
Bigger or smaller, depending on the distance between the two channels.
But always a ground loop. |
|
|
| waltona |
| So what would you suggest Carlos? |
|
|
| Sherman |
| quote: | Originally posted by carlosfm
That's the ticket for a ground loop.:bawling:
Bigger or smaller, depending on the distance between the two channels.
But always a ground loop. |
Built four amps exactly this way with no groundloop issues whatsoever. Remember your individual boxes each must have a safety ground within the box. The two can then be connected in the umbilical with no problem and the whole thing is safer. |
|
|
| waltona |
| Thanks for everyones help on this one. I appreciate it. |
|
|
| jeff mai |
| quote: | Originally posted by Sherman
Built four amps exactly this way with no groundloop issues whatsoever. |
You have ground loops then. They just aren't causing a problem for you. Seriously - trace all the ground wires and draw a picture. |
|
|
| scottw |
I'm also planning a separate PSU for my GC(to make more room for capacitors). This is a dual mono- two transformers, each with dual secondaries. Bridges in the PSU.
So for both channels this will be 8 leads for the power(voltages and their corresponding neutrals)-that's easy enough.
That leaves the grounding. Was planning to run a separate lead for just the amp chassis ground back to the PSU earth. Then for the power ground for the amps, should I run a single ground lead for both the amps or should each amp have its own power ground back to PSU earth?
Thanks,
scott |
|
|
|
