Noob Question: Wiring a battery system

[Buehgemeiste]

For my current setup i use five 6V SLA batteries, which gives a total voltage of ~32V when fully charged.
These drive single supply class d amplifiers (like TAS5611 or TDA7498) and an active crossover preamp (single supply).

Now i want to switch to dual supply, as my speakers can take much more power than those small amps deliver.
I have IRS2092 boards here and want to power them with eight 12V SLA batteries.
This should provide about +-50V which should be good the amplifiers.
Now i have some concerns:

So far i always just connected all amps and preamps to the same supply...no diodes, just one fuse.
I had no problems with it, but i think it could be done better / safer ......but how?

So far i simply connected the audio GND from the source to the batteries '-'.
All my previous amplifiers have audio GND to power GND connected onboard.
So i just fed the amplifiers with the signal '+' (no GND-connection from preamp to amp).
All of the single supply class d modules i used so far were BTL.
Speaker '-' is not equal to power '-'.
With my new more powerful dual supply modules that's not the case.
They have speaker '-' connected to what will be the center tap of my batteries.
Most likely i will change the preamp to +-9V (two 9V batteries) supply.
But that is still giving me a headache.
I have no idea how to wire it.

I started a thread in the class d-forum , but get no response there.
I quote what i have written there.
The sketch i attached should serve as a special case, from which i can derive other cases (hopefully).

I'm going to upgrade my battery driven soundsystem.
I use sla batteries.
It is the first time i implement dual supply amps (IRS2092).
I attached a sketch that shows a possible scenario:

There are 3 amps and a preamp that use different power supplies.

Amp1 and the preamp are connected to a single 32V supply.
This is basicly the setup i was using all the time (sometimes with more amps on the same supply).
Would it be better/safer to put filters or diodes in front of each amplifiers power inputs?
Amp1 has BTL outputs.
The preamp is working with a 'virtual ground' as bias voltage.
Signal GND was no problem here.

Now Amp2 and amp3 will be connected to an dual 50V supply.
The amp modules have power GND (center tap of the batteries), signal GND and Out- connected together on board.
What is the right way to wire this system?

 

[Sorento]

Herr Bürgermeister:

since you are using independent batteries for Pre- and Pwr- Amp you need to connect pre-amp gnd (which is <-> of 32v batt in your sketch) to pwr-amp gnd (which is center tap of +/-50v batt)

that's all ...

fuses are used to prevent fire or wire meltdown, they will not protect semiconductors
I would fit
- a low rated fuse from +32 batt to the pre-amp
- a higher rated fuse from +32 batt to amp1
- connect a high rated to +50 top batt and connect the other end of that fuse to both +50 of amp2 and amp3
- connect a high rated to -50 bottom batt and connect the other end of that fuse to both -50 of amp2 and amp3
- no fuses in any gnd or <-> wire

mind: wire cross section must be adequate for fuse rating

 

[AndrewT]

fuses are used to prevent fire

why don 't they teach this @ school?
It is fundamental to safe living in our electrical age.

wire cross section must be adequate for fuse rating

All wiring (that is not protected by a further fuse) downstream of any fuse MUST be rated at greater than the fuse rating.

If one changes to a lower rated cable then one MUST insert a lower rated fuse to protect this smaller cable.
This fuse can an an extra that only feeds the lower rated spur, or can be back at the fuseboard.