Sound bleed into power amp when headphones inserted

shinobi76

Novice Member
I have a Arcam C49 pre amp > P49 power amp setup connected with XLR

When I plug headphones into the pre amp, the output to the power amp is supposed to mute. However there is some bleed into the power amp as music can still faintly be heard through both speakers - slightly more on the left channel.

I do have the option to manually turn off the speakers on the power amp when I listen using headphones but I shouldn't need to do this.

Muting the volume on the pre amp with or without headphones inserted works as it should - no sound at all through the speakers.

Was wondering is someone on here might know what the problem might be.
 
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Helix Hifi

Well-known Member
I have a Arcam C49 pre amp > P49 power amp setup connected with XLR

When I plug headphones into the pre amp, the output to the power amp is supposed to mute. However there is some bleed into the power amp as music can still faintly be heard through both speakers - slightly more on the left channel.

I do have the option to manually turn off the speakers on the power amp when I listen using headphones but I shouldn't need to do this.

Muting the volume on the pre amp with or without headphones inserted works as it should - no sound at all through the speakers.

Was wondering is someone on here might know what the problem might be.
I don’t own the Arcam setup, but it can be crosstalk. Sound can be heard from another input if you have several sources connected to the amp.

I learned this by mistake many years ago. Volume was on max, switch to an input, phono button I believe. I could fairly hear the sound from tv.

However I never experienced it when using headphones.

Exactly how loud is it?
 

Helix Hifi

Well-known Member
Unplug all other sources you have connected to the amplifiers, then try and see if it changes.

Try different headphones, try different XLR cables. It could help-doubtful it would.

There are many expert here, they we’ll too. But what you are hearing is crosstalk.
 

shinobi76

Novice Member
The sound from the speakers is the same sound being played through the headphones - not crosstalk from a different RCA input.
I only use 2 inputs on the pre amp - a DAC and a CD player. Only one is being used at a time.

As I increase the volume, the sound will increase through the speakers also.

The sound through the speakers is loud enough to be noticeable to anyone in the room, but not if wearing headphones.

I have tried different XLR cables and different headphones and the issue is the same.
 

noiseboy72

Distinguished Member
I would suggest there's a fault in the headphone muting circuit and it needs some attention.

Probably worth contacting Arcam in the first instance and take things from there.

Just out of interest, if you connect the pre and power amps together using an unbalanced connection, does the fault persist?

These pre-amplifiers are rare in that they feature a fully balanced signal path through the whole signal path. The exception to this is the headphone amplifier, so this may be the cause of the issue.
 

shinobi76

Novice Member
I would suggest there's a fault in the headphone muting circuit and it needs some attention.

Probably worth contacting Arcam in the first instance and take things from there.

Just out of interest, if you connect the pre and power amps together using an unbalanced connection, does the fault persist?

These pre-amplifiers are rare in that they feature a fully balanced signal path through the whole signal path. The exception to this is the headphone amplifier, so this may be the cause of the issue.
If I connect the pre-amp and power amp using unbalanced connection the issue persists but to a lesser extent in that the volume through the speakers is not as loud in accordance with the headphone volume. It is much less noticeable.

The 2 gain settings on the power amp are 25db and 31db. For unbalanced RCA I have it set to 25db, for balanced XLR to 31db.

I have also changed the speaker outputs I'm using from A to B and it made no difference.
 
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shinobi76

Novice Member
Reply from Arcam:

"This sounds as though the C49 is working correctly, when headphones are connected the main speaker outputs will not be muted fully. Due to the way the unit is designed you can get cross talk to the pre out stage, not normally issues us it is very quiet, but as you say can be noticable.

I would recommend turning off the power P49 at the wall if this is a concern, this will stop any output."
 

Phildick

Active Member
That's an interesting response from Arcam.

I have just tested my a49 which you probably know is the same amp but in one box. I plugged some phones in and turned it up to 60 on the volume, which is very loud. Nothing but silence from the speakers.
 

shinobi76

Novice Member
That's an interesting response from Arcam.

I have just tested my a49 which you probably know is the same amp but in one box. I plugged some phones in and turned it up to 60 on the volume, which is very loud. Nothing but silence from the speakers.
Maybe so, but you're not comparing the same thing. I expect there are differences considering they are dedicated separates as opposed to an integrated.
 

Phildick

Active Member
Maybe so, but you're not comparing the same thing. I expect there are differences considering they are dedicated separates as opposed to an integrated.
Yes there will be minor differences. But if you look at the photos on line you will see they have the same circuit boards, transformers, layout etc.

Anyway all I'm saying is mine should be potentially worse as it's all crammed into one box.

Also, Arcam's advice about switching it off at the wall? Really? What's wrong with the power button?
 

shinobi76

Novice Member
Yes there will be minor differences. But if you look at the photos on line you will see they have the same circuit boards, transformers, layout etc.

Anyway all I'm saying is mine should be potentially worse as it's all crammed into one box.

Also, Arcam's advice about switching it off at the wall? Really? What's wrong with the power button?
I have no idea, but their response does acknowledge the issue I have happens as the design means the speakers are not fully muted. I don't know what reason they'd have to give false info about it.
 

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