Balanced & Unbalanced outputs

[JN*]

I have a Cambridge Audio DacMagic Plus 

I want to connect alternatively to separate amplifiers

One suggestion is to connect one to the unbalanced outputs and the other to the balanced using for example a "Monoprice XLR Male to RCA Male Cable"

Another is to connect both to the unbalanced outputs via splitter

Both amplifiers are NOT simultaneously ON

Comment please

Thanks John

Edited October 26, 2019 by JN*
grammar

[MLXXX]

As no one else has replied, I'll have a go.

 

@JN*, the DAC output is high (according to the specs up to 4.2V RMS, or 2.1V per phase) and it's possible that if you connect to an amplifier that is powered down that that powered down amplifier will present a non-linear load. That could lead to distortion if it affects the signal being routed to the amplifier in use.  So I'd be a bit wary about connecting "both to the unbalanced outputs via a splitter", though that could work out ok - you'd need to trial it and evaluate.

 

I note there is a headphone output. That would be likely to provide isolation, i.e. connecting one amp to that source would most likely not affect the signal going to the line level balanced and unbalanced outputs.  [There would be the possibility of an earth loop issue if using the headphone ouput for one amp, and the unbalanced line out for the other amp.]

 

It;s possible the balanced and unbalanced line outputs of the DAC are fully independent of each other -- that would depend on the circuit configuration. I haven't tried to look into that. 

[JN*]

4 hours ago, MLXXX said:

As no one else has replied, I'll have a go.

 

@JN*, the DAC output is high (according to the specs up to 4.2V RMS, or 2.1V per phase) and it's possible that if you connect to an amplifier that is powered down that that powered down amplifier will present a non-linear load. That could lead to distortion if it affects the signal being routed to the amplifier in use.  So I'd be a bit wary about connecting "both to the unbalanced outputs via a splitter", though that could work out ok - you'd need to trial it and evaluate.

 

I note there is a headphone output. That would be likely to provide isolation, i.e. connecting one amp to that source would most likely not affect the signal going to the line level balanced and unbalanced outputs.  [There would be the possibility of an earth loop issue if using the headphone ouput for one amp, and the unbalanced line out for the other amp.]

 

It;s possible the balanced and unbalanced line outputs of the DAC are fully independent of each other -- that would depend on the circuit configuration. I haven't tried to look into that. 

Thanks MLXXX

Appreciate the comment 

Experimentation begins

John

[kenwstr]

Balanced output's real strength is the ability to transmit an audio signal with no significant quality loss up to 100m or so.  It is not appreciably superior to quality RCA over short domestic runs less than 3m.  Unless you try really hard to make it so.  However, another advantage is that unbalanced cabling done correctly does not rely on the shield to provide a signal reference.  Therefore, you can easily lift the ground to isolate devices from each other.  This makes balanced connection ideal for a computer DAC.  Also, you can get Pro audio transformers (or DI box) that convert balanced to unbalanced. This would allow you to carry balanced to one amp and unbalanced to another just by using a switcher.  It also isolates the signal from direct connection as the signal is transferred by induction.  There are different quality in these transformers.  Some are very very good indeed, Pro Studio quality.  Some are not so great. 

 

Ken

[JN*]

Probably have ignored a simple solution...

Insert a 2 Way RCA Stereo Audio Switch between the DAC the amplifiers

Normally used 2 in/1 out so reverse the direction

Have I missed something?

Edited October 27, 2019 by JN*

[Guest]

48 minutes ago, JN* said:

Probably have ignored a simple solution...

Insert a 2 Way RCA Stereo Audio Switch between the DAC the amplifiers

Normally used 2 in/1 out so reverse the direction

Have I missed something?

Unless it says 2 way, it will not work. 

[JN*]

Avico 2 Way RCA Stereo Audio Switch Box CDS20A

[Guest Muon N']

Are the negatives separate or shared?

 

In a decent one they will not be shared, tied together.

 

Edit: just googled it and it is at a price point where it would not be decent kit.

Edited October 27, 2019 by Muon N'

[JN*]

Thanks Muon N’ suspected as much

[JN*]

Any suggestions for a higher end 2 Way RCA passive switch?

[rawl99]

Make one yourself if you are handy with a soldering iron.

This gives you the choice if switch/connectors which you are free to choose depending on the level you want to go to to match the quality of components you have.  The rca sockets and the switch can make a tragic difference to the performance of the switch box.

The very vast majority of off-the-shelf units I have seen have tin plated steel sockets.

The better quality ones one hopes would be at least brass connectors.

[kenwstr]

On 27/10/2019 at 8:48 PM, JN* said:

Probably have ignored a simple solution...

Insert a 2 Way RCA Stereo Audio Switch between the DAC the amplifiers

Normally used 2 in/1 out so reverse the direction

Have I missed something?

No, you haven't missed much (except as previous response).

 

 It's just that some people like to use balanced connections if they are available on both the in and out devices.  It seemed to me the OP may have had a preference for that.

[Guest Muon N']

 

On 28/10/2019 at 12:17 PM, rawl99 said:

Make one yourself if you are handy with a soldering iron.

This gives you the choice if switch/connectors which you are free to choose depending on the level you want to go to to match the quality of components you have.  The rca sockets and the switch can make a tragic difference to the performance of the switch box.

The very vast majority of off-the-shelf units I have seen have tin plated steel sockets.

The better quality ones one hopes would be at least brass connectors.

Rawl knows

 

You could make one and used pure copper sockets and a quality switch and wire it correctly with dedicated return/earths for each socket using quality wire.

 

DAC Magic and maybe the amplifiers are likely limited with their own gold plated brass sockets?

 

Even Goldpoint while maybe one of the best commercial ones uses gold plated brass sockets. So maybe the best you will get in this situation with something like a DAC Magic.

 

https://goldpt.com/sw4.html

 

But if handy, Rawl's suggestion to make you own is a very good suggestion.

[Guest Muon N']

In this thread on SH Forums is an example where someone made their own, of course that one is is 1 output and 4 inputs.

 

I'm not sure about the common ground connection he has going on there though @rawl99

?

[JN*]

Thanks rawl99 & Muon N'

This looks doable

Nice work

[rawl99]

On 31/10/2019 at 12:24 AM, Muon N' said:

In this thread on SH Forums is an example where someone made their own, of course that one is is 1 output and 4 inputs.

 

I'm not sure about the common ground connection he has going on there though @rawl99

?

Nor an uncommon approach to signal grounding.  You will see the shield is cut off at the switch end so the grounding is effectively a bus grounding approach   where the bare copper wires act as an “earth bus” for each channel.  Note that the shields are connected to the bus at each of the rca sockets.

There is no return ground signal running through the shield on the coax to the switch which is really the correct way of shielding a signal line.

Similar concept to using a 2 core shielded conductor for a mono signal ( eg analog interconnect) where the 2 cores function as signal and ground respectively  and the shield is connected at source end only.

In this switchbox to isolate the grounds for each of the sources you need a switch with another wafer to switch the grounds in synchronised manner with the signal lines.

Only then will the grounds be truly isolated from each other.