F5 power amplifier

[WalterW]

Is this a proper way of grounding my dual mono F5's?

[tinitus]

Originally Posted by WalterW

Is this a proper way of grounding my dual mono F5's?

something doesn't look right to me

[WalterW]

You're making me curious...

Is it a good thing to twist the powerrail wires and GND wires going to the amp-board?
Or should I just twist the powerrail wires, and ground separate going to the board? Or twist nothing?
Is it wise to ground the sides of the chassis? Because the shielding / grounding is now going through a few bolds in the chassis. I don't like that.

Grz, Walter

[bnorrish]

I do not follow how you are using the 2 bridge rectifiers in the grounding. Not sure if you could sketch. Also others have said not to connect the input grounds directly to the PSU board ground. I connected the PSU ground and the input grounds to the amp board ground pads.

[AndrewT]

A sketch would help, but it looks like you have two completely separate Main Audio Grounds (MAG), one to each channel.
Then you have used the bridge + components as a Disconnecting Network (DN) to give the Fault Current route back to Safety Earth.
If that is the case then you should be able to measure Left Ground to Right Ground as twice the resistor value you used in the DN. And each MAG to Safety Earth should measure the same as the resistor value.
And as a final check when you disconnect the DNs the MAG to MAG and/or MAG to Safety Earth should read open circuit.

[noSmoking]

Hi WalterW,
Can't really make all of it out from the pics,would you post your schematic?
Regards,
NS

[WalterW]

Andrew that's correct.
The thermistors over the bridge rectifier are 5 ohm( actually when I measured them they are 7 Ohms, depends on temperature) and between the MAG's is 14.0 Ohm.

I read that you wrote a lot about this subject, do you think it is appropriate for the dual mono setup I'm trying to build? Or should I use separate earths for each amp?

@Bnorrish: I'm using the exact schematics as described in the F5 Turbo document from Nelson Pass.
Quote: "

As commonly seen in my previous projects, you will also see a thermistor /
diode bridge combination used to provide ground loop isolation between the
chassis, which is hardwired to the AC outlet ground, and the circuit ground.

An ordinary CL60 thermistor and a 35 amp rectifier bridge should suffice. "

Nelson uses only one PSU for both channels. I build two Turbo PSU's so I can upgrade to a F5 Turbo when the boards arrive at the DIYAudio store

[6L6]

Walter -

Use only one bridge as the resistance between chassis earth and audio ground... having two seems like it will only add a potential loop.

Take the speaker return (black or negative speaker connection) from the amp PCB, not the PSU - it's much quieter that way.

Also, if possible, please draw a schematic of your wiring, it will help us understand your connections.

Nice work, by the way - neat wiring, good layout, I'm looking forward to seeing more photos of your amp!

[tinitus]

[QUOTE=WalterW;3351349]You're making me curious...

just couldn't see the two diode/bridge are used only for chassis/earth connection
I have never seen this

[Rush]

Originally Posted by 6L6

Walter -

Use only one bridge as the resistance between chassis earth and audio ground... having two seems like it will only add a potential loop.

Take the speaker return (black or negative speaker connection) from the amp PCB, not the PSU - it's much quieter that way.

Also, if possible, please draw a schematic of your wiring, it will help us understand your connections.

Nice work, by the way - neat wiring, good layout, I'm looking forward to seeing more photos of your amp!

6L6,

Running the ground from amp PCB to speaker and from amp PCB to power supply? How do you purpose RCA input ground be run? What happened to single point ground?

Rush