Earth Loop Hum

Unplugging everything with the exception of the CD555 makes the problem dramatically worse.  The hum with the volume at 8 o'clock is now the same as it was with the volume dial at full.

The TT is connected to a StageLine.

i have Sky Q Silver, Oppo 203 UHD, Amazon Fire TV and Apple TV connected to the Arcam.  It outputs to a 7.1.4 Atmos system with the Front L and R passed through to the 552.

The Cinema Room was made by knocking two bedrooms together.  The Hi-Fi equipment is in one 'room' together with the Sub and TV.  The Home Cinema stuff is in the other.

Each 'room' has a Control4 network controller with IR blasters for the stuff that cannot be operated via home network.

Hmm - if you still have hum with only the 555 connected to the 552 then it looks like we can discount the AV system and TT causing the problem and just concentrate on the 3 components (555/552/300) and their power supplies. 

Did the dealer use the same Burndy cables each time or try different ones ?

As the 300 is the only thing that has not been substituted for another component i'd recommend substituting that with another Naim amp to be sure it's not the problem here. 

One more thing Bryce - when did the hum start ? I take it this has not always happened so what did you change when the hum problem started ?

James

Bryce Curdy posted:

Unplugging everything with the exception of the CD555 makes the problem dramatically worse.  The hum with the volume at 8 o'clock is now the same as it was with the volume dial at full.

The TT is connected to a StageLine.

i have Sky Q Silver, Oppo 203 UHD, Amazon Fire TV and Apple TV connected to the Arcam.  It outputs to a 7.1.4 Atmos system with the Front L and R passed through to the 552.

The Cinema Room was made by knocking two bedrooms together.  The Hi-Fi equipment is in one 'room' together with the Sub and TV.  The Home Cinema stuff is in the other.

Each 'room' has a Control4 network controller with IR blasters for the stuff that cannot be operated via home network.

Something does not add up - sorry, but what you wrote is completely counterintuitive...

Let's establish some basic facts:

Case 1: CD555 + NAC 552 + NAP 300 (and their power supplies) = horrible hum

Case 2: CD555 + NAC 552 + NAP 300 + Arcam connected to NAC 552 = less hum, but still annoying

Did I understand your reply correctly?

I've been accused at least once of not telling everything.  I forgot to mention that the Arcam 850 connects to a 4 channel Arcam power amp to feed the Atmos channels and that I have a Lumagen Radiance Pro between the four video inputs and the Arcam 850.

James N:

Not sure about burndy, need to check.

Agree about 300.

Your last question has a slightly complicated answer.  I noticed the problem after I moved house at the end of last year at which time the AV input on the 552 was changed to a balanced one.  Previously for AV I set the volume on the 552 to 9 o'clock and for CD and phono would only ever go up to about 10 o'clock.  Now the hum on the balanced AV input is obvious and if I experiment and turn the volume up higher on the CD input it becomes obvious but is absent/minimal at my usual 9 o'clock volume level and is absent at any volume on the phono input.  Hope that makes sense but I may have had the problem but not realised it for years.

Adam, you understood me perfectly.  Counterintuitive is an understatement but that's what's happening.

Bryce - i'm not sure what the balanced conversion on the AV input involved - was this a modification done by Naim or is it just a custom made cable ?

Again you say the hum is there when no other source components are connected to the 552 so this rules out the AV setup creating an earth loop. 

From what you describe regarding the hum, it sounds like it's more background in nature (rather than a loud buzz. How do you have your components arranged (i.e. power supplies kept away from the head units) ?

James

Bryce

Naim does NOT have balanced connections. 
Your Arcam does not have balanced outputs either.

But... that's not the problem 

This statement is a problem:

Previously for AV I set the volume on the 552 to 9 o'clock and for CD and phono would only ever go up to about 10 o'clock.

With an AV Bypas set correctly there is no way you can control the volume on your NAC 552. It's impossible by design.
The volume control duties are assigned to your ARCAM in this setup. Front Left and Front Right go directly (via NAC 552) to your NAP.

Bryce - can you photograph the back of your Arcam?
I need to see the connection you have used to feed the signal from Arcam to your NAC.
Also please post a photo of your input on NAP where it's connected.
Have you enabled the AV Bypass feature on your DIN input 4 or 5?

Adam

I've probably not explained myself properly.  At my old home if I was watching an AV source I would set the 552 volume at 9 o'clock.  If I wanted to increase the volume on all channels of what was then a 5.1 system I would increase the volume on my AV processor, and if I wanted to adjust the volume on front L and R channels independently I could use the 552 volume control.   Now for AV the volume setting on the 552 is preset (no light on volume control)  and I can only adjust the volume for all channels using the Arcam AV processor.

Adam - I think you misunderstood or more likely I did not explain things well.  I didn't have an AV bypass in my old house which meant the hum could have been there all along but I never noticed because it wasn't obvious on AV input at 9 o'clock and I never turned the volume up high enough on any input.

And that's why you need an isolating transformer

Adam - probably/possibly - but surely if I still have hum (more hum) with AV disconnected then I have another problem entirely unrelated and exclusive to my Naim boxes???

Bryce Curdy posted:

Adam - probably/possibly - but surely if I still have hum (more hum) with AV disconnected then I have another problem entirely unrelated and exclusive to my Naim boxes???

Adam makes a valid point that the AV system could still cause problems (when it is connected) and the simple solution to this is adding the isolation transformer. This is a separate problem which doesn't explain why you still have a hum problem when you only have your 555/552/300 running with nothing else connected. 

So...

Get those Burndy cables checked

Get your dealer to substitute another Naim amp in place of the 300 

Refer your dealer to post 4 which may help him. 

Any chance of posting a picture of your setup - I'd just like to see the placement of the items in relation to each other and anything else you may have in your rack. 

James

Bryce Curdy posted:

Adam - probably/possibly - but surely if I still have hum (more hum) with AV disconnected then I have another problem entirely unrelated and exclusive to my Naim boxes???

If there is still hum with nothing whatsoever connected to the 552 other than the CD player, then the issue has to be with the Naim boxes. That needs to be resolved first. Then add the AV amp and if there is a new hum that then needs to be fixed. 

Hopefully this is a long shot but is the household earth connection good? 

I've been away for the holiday weekend and have my dealer coming out again later.  Fingers crossed.

If he's not successful I'd been asked to attach photos.  I can see the Insert/edit image icon above but no idea what I'm supposed to do next.  What do I put in as Source?

Bryce Curdy posted:

If he's not successful I'd been asked to attach photos.  I can see the Insert/edit image icon above but no idea what I'm supposed to do next.  What do I put in as Source?

The information is here:

https://forums.naimaudio.com/to...web-into-your-post-1

Bryce,  Thank you for providing more detail, I can now understand why you're having so much difficulty with this.  

The key to diagnosing problems is to find the simplest setup that causes the problem, not just by switching inputs, but by disconnecting interconnect cables and unplugging units for the mains.  Take the system down to a minimum that could show the problem (poweramp, it's PSU and the speakers only), then add components to the system one at a time...

Reconnect the preamp, then add back the CD player (& PSU),

Disconnect the CD player and reconnect the TT & head amp,

Disconnect the TT & head amp; disconnect everything from the Arcam 850, and connect it to the preamp (& PSU); then, one by one, add back each of the components that connect to the receiver.

Leaving the Arcam connected, reconnect the TT & head amp,

Then reconnect the CD player (& PSU).

This should give you a clearer picture of which components are interacting.

I take it Dropbox would work for photo sharing.

How did your dealer get on Bryce  - Any further forward ?

He had to postpone until tomorrow.

Bryce,

It has occurred to me that you stated you need a long extension cable to get the Arcam and the 552 onto the same earth circuit.

How is the signal connected between these two?  If you have a long pair of phono leads this could be a problem as then you'll basically be hanging a long pair of radio antennae off the 552!  This could induce hum any time they are connected to the 552, even when the Arcam ends of the leads are disconnected.

Do these leads lie parallel and close to a mains cable at any point?
Does this apply to any other signal cables (including speaker cables)?

The problem is that this is the sort of detail that's needed to isolate these problems, and the sort of things a dealer should spot instantly as being a potential problem ; if they don't see this, change your dealer (but unfortunately a bit late now as you've bought all your kit).
(And long analogue signal leads from the A/V setup to the 2ch setup aren't exactly ideal anyway).

Clicking on the 2 links in bold should work if the photos don't automatically display.

Hi-Fi

LHS:

555CD

552

555PS

552PS

RHS:

Rega Planar 3 TT

300

Stageline / Control4 Base

300PS

Home Cinema

LHS:

Landline / Philips Hue Tap / Control 4 Remote

Sky Q Silver / 3 Mobile Signal Booster

Arcam 850 AV Processor

RHS:

Oppo 203 UHD

Lumagen Radiance Pro (Amazon Fire TV, Apple TV 4th gen both hidden)

Arcam 429 [4 channel power amplifier]

Hi Bryce, the picks can be displayed, just not in-line.  Right Click and <Open image in new tab> works.

[@mention:1566878603866847] - I actually wanted to see the back of the equipment, where the sockets are and see how the boxes are connected and which inputs you use. But I see it's going to be difficult

So let's have some faith in your dealer.

Adam

Huge - I've worked out, edited and tidied up.  Sorry if I was ranting.

Yes, I do have a long pair of phono leads, but disconnecting them at the Naim end makes the problem significantly worse.  I understand this may mean I have two issues rather than one but regardless I have a big issue confined to the 555CD/552/300.

I struggle to see how anybody can keep interconnects and mains leads apart for their entire length unless they have a simple system that's not backing onto a wall.

If you saw the shape of my room you'd probably agree that long AV interconnects was a necessary evil but I accept your comment.

And I think it was Alex who asked for a photo of the back of the Arcam 850 - too close to the wall to get a useful picture.

I ran long phono leads of 20ft from Denon AVR to 552, incorporating isolators.  No issues.

If the CD555 is all that is connected to the 552/300 and speakers, and you still have hum, your dealer will know the best next steps.

Interested to learn how this resolves.

Nick

Bryce - thanks for posting the pictures. Two things - 

1 - I'd move the 300 and stageline to the left hand rack. Move all the power supplies to the right hand rack. This will give you brain and brawn stacks (hopefully this won't cause issues with your turntable) and also allow you to dress the Burndy cables easily. A couple more shelves would give you more room and allow you to raise your turntable up a bit. 

2 - The wireless Control 4 thing on the right hand rack next to the Stageline. I'd keep wireless devices away from your Hi-Fi kit. 

Other than that it will be interesting to hear what your dealer finds.