Balanced F5 Question

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Main Audio Ground.
The Chassis is not audio.
Pin1 is not audio.
The screen of the balanced impedance interconnect is not audio.
None of these NEED an AUDIO connection.

One ONLY needs to look after the SAFETY of users/operators by properly connecting the PE protected Chassis to all exposed conductive parts.
 
consider the J2 or AJ. Both ground the unused phase of the input by brdging pin 1 and 3. This allows use of the SE input on the amp. The same thing can be found in the Pass Lab amplifiers. I believe that all the circuits mentioned have a ground lift circuit in the PSU, so if pin1 is connected to the chassis, is there any chance to introduce hum?

Not trying to argue, as I have read the whole pin 1 argument and it makes perfect sense.
 
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Main Audio Ground.
The Chassis is not audio.
Pin1 is not audio.
The screen of the balanced impedance interconnect is not audio.
None of these NEED an AUDIO connection.

One ONLY needs to look after the SAFETY of users/operators by properly connecting the PE protected Chassis to all exposed conductive parts.

Let me rephrase.

Where is the input reference for each input signal when two F5 amplifiers are run in a balanced configuration and the input pair junctions are connected to Pin 2 and 3 respectively?
 
Two separated F5 do not make a balanced impedance amplifier.
I think you are describing a bridged arrangement. Bridged is not the same as balanced.
Look up F5x and the balanced versions of some of Pass amplifiers.
What does the balanced F5t look like?

You have to DESIGN the amplifier to be balanced impedance.
 
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The balanced version of the F5T amplifier is documented in the F5T document on the First Watt website. I hope you are able to find it and look at the schematic.

The F5x is documented on Patrick's thread. Once again, I hope *you* are able to find it.

The title of this thread is "Balanced F5 Question".

Maybe you should read it. The first post may shed some light. Possibly you should post a wiring diagram. Or if drawing is an issue, maybe a description.

Maybe you could help answer the TS's question for a change, instead of quoting posts out of context.

Good Day.
 
Pin1 goes direct to Chassis.
If the XLR shell is metal, then that too goes to Chassis. Either directly via the bolted connection, or via the shell/barrel tag to Chassis.

Pin2 could go to the unbalanced but insulated RCA Hot.
Pin3 could go to the unbalanced but insulated RCA Cold/Barrel.

The amplifier reads the voltage DIFFERENCE between Pin2 and Pin3
OR
the amplifier reads the voltage DIFFERENCE between Hot and Cold.

Look at a properly wired unbalanced amplifier input.
It uses TWO wires to connect the RCA to the PCB. The amplifier READS the voltage difference between Hot and Cold and then processes that signal.

Pin1 goes direct to Chassis.

Main Audio Ground (MAG) can go direct to Chassis, or can use a Disconnecting Network. The Disconnecting Network can include a switch. this switch effectively bypasses the power Diode Bridge and makes a direct MAG to Chassis connection.

Pass products should connect the balanced impedance Pin1 to Chassis, without exception.


Been catching up on my reading especially the Audio Grounds article under The Articles section here.
Everything I have read concurs with what Andrew is saying about connecting Pin 1 and its XLR shell as close to the chassis as possible. This is the theoretical best arrangement. But this works best only if all of the equipment has Pin 1 wired similarly to the chassis.

Several commercial amps have their XLR connectors PCB mounted and have no Pin 1 to chassis connection. Perhaps Pass does not connect Pin 1 to the chassis either because of compatibility issues?

Thanks. Nash
 
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Andrew is correct in saying that pin 1 goes to chassis. This assumes the input stage is balanced.

The F5, store board or otherwise cannot be used like this. The input stage will not function properly.

There is a way connect an XLR correctly, and there is a way to connect it to two F5 boards Or any two single-ended amplifier inputs. You do get fully differential operation when seen from the perspective of the amplifier output. At least in theory.
 
There is a way connect an XLR correctly, and there is a way to connect it to two F5 boards Or any two single-ended amplifier inputs. You do get fully differential operation when seen from the perspective of the amplifier output. At least in theory.

I think what you are saying is that pin 1 should be connected to board ground reference(PSU ground) in a balanced setup just like the RCA cold is similarly connected in a SE setup.
Just to be clear I am referring to the store F5T FE boards and according to the schematic posted by Nelson at the end of the F5T article, in a balanced configuration there would be two FE boards per channel with their individual feedback loops connected together.They would share the same Ground reference since they will be both tied to the PSU ground which is then tied to the chassis ground thru the CL60/ diode SLB.
Is this what you had in mind?
Thanks. Nash
 
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I have wired up a few amplifiers in this manner and they operate without issues. Personally not tested an F5 this way but hopefully soon.

The amplifiers I do use have their feedback hardwired to ground and no scope to change them, and they work fine and without any hum or noise.
 
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