NAC 552 - occasional POPing...

I have the same through the 282/HCDR 200 and assumed it to be the central heating thermostat.

G

It is usually RF pick-up through either mains or radiated. Things that switch on with high current can generate it (I had it with an old Fridge), or a noisy switched supply. A friend into Armature Radio had a strange interference that turned out to be some fairy-lights recently installed in his garden - he blames the cheap and nasty SM supply for the LEDs from China. LED Bulbs can do it too - people plug them in and forget what is actually inside them.

After the DR you will resolve more of this stuff that you may not have noticed before perhaps. A process of elimination will eventually locate it, usually it is in your house on your own mains circuit, and you can suppress it.

DB.

if you can borrow another pre-amp from your dealer then you can check and confirm whether its really the 552 or something else... 

enjoy

ken

If nothing in your system has changed, and the pre didn't pop before the upgrade, I would guess that it was the recent visit back to Naim that has caused a problem. My advice would be to send it back from whence it came.

You are looking at roughly a $45,000.00 dollar product after the DR upgrade, no way should you experience anything but bliss for that kind of money.

badlands posted:

You are looking at roughly a $45,000.00 dollar product after the DR upgrade, no way should you experience anything but bliss for that kind of money.

Life would be so easy if money could buy bliss ... (or love). Especially for audiophiles, more so for wealthy audiophiles.

Reality is not that simple and Darke Bear seems on the right tack.

Darke Bear posted:

It is usually RF pick-up through either mains or radiated. Things that switch on with high current can generate it (I had it with an old Fridge), or a noisy switched supply. A friend into Armature Radio had a strange interference that turned out to be some fairy-lights recently installed in his garden - he blames the cheap and nasty SM supply for the LEDs from China. LED Bulbs can do it too - people plug them in and forget what is actually inside them.

After the DR you will resolve more of this stuff that you may not have noticed before perhaps. A process of elimination will eventually locate it, usually it is in your house on your own mains circuit, and you can suppress it.

DB.

I hear what you're saying, DB, but my audio is on a separate supply from the ring main, and there's no new appliances or equipment, (or fairy lights) in the house or garden... it does deserve some thought though as you never know what SWMBO may have sneaked into the home.  However I couldn't afford anything new after the DR upgrade, and she's as broke as I am!  So although the things you mention would be culprits, I'm still left suspecting the 552 or its power supply. Thanks for your thoughts DB.

Have you tried powering down for a while, then powering back up? This can often clear strange niggles as everything nowdays seems computer controlled.

badlands posted:

If nothing in your system has changed, and the pre didn't pop before the upgrade, I would guess that it was the recent visit back to Naim that has caused a problem. My advice would be to send it back from whence it came.

You are looking at roughly a $45,000.00 dollar product after the DR upgrade, no way should you experience anything but bliss for that kind of money.

I absolutely agree, badlands.  The problem is that it isn't what's called a 'solid' fault... I can't tell you when it's going to occur.  I've tried noting the time whenever I hear it, hoping to hear the next occurrance and thus be able to say 'every xx hours', but so far I've failed to determine this.

When I was responsible for computer systems, the worst problems were when a user reported a fault that began "Sometimes it goes like this..."  the intermittant fault.  I'll eat my latest vinyl purchase if the same is not true in Naim's customer service department !   They aren't going to allocate someone to sit for a few hours waiting for my 552 to say 'pop', or do they have a computer that will do this, perhaps?

There have been some useful suggestions (for which my thanks), so armed with these thoughts, I shall have a chat with my dealer when he opens again tomorrow and see what his advice will be.

Roger

PS - I love the sound of the dollar value of my kit, badlands... it sounds much better when you say it than when I say it in £   

Mr Happy posted:

Have you tried powering down for a while, then powering back up? This can often clear strange niggles as everything nowdays seems computer controlled.

Thanks Happy, I've power cycled it a couple of times, but switched it back on within a few seconds (about 30 seconds).  I've not left it for any length of time.  How long does it take for capacitors to completely discharge after powering off, do you know?  Could certainly be worth a try.

I would leave it about half hour, although im sure they would discharge quicker than this. 

Hi RJ,

Another thought - try switching off, then unplugging and replugging all the cables. Maybe a connection's slightly dodgy. Oh, and don't forget to switch it back on afterwards.

tonym posted:

Hi RJ,

Another thought - try switching off, then unplugging and replugging all the cables. Maybe a connection's slightly dodgy. Oh, and don't forget to switch it back on afterwards.

This has got to be favourite course of action at the moment, Tony.  I was planning to rearrange my Fraim/lite so as to move the NAP500 up from the bottom to the second shelf and to put more space between the 'brain' stack and the 802 Diamond speaker that is very close to it.  So the system will be down for the best part of a day when I do that and of course all the cables will get re-plugged.

And just for good measure, I'll tie a knot in my handkerchief to remind me to switch it all back on

tonym posted:

Hi RJ,

Another thought - try switching off, then unplugging and replugging all the cables. Maybe a connection's slightly dodgy. Oh, and don't forget to switch it back on afterwards.

Make sure the powerline is really firmly pushed in. Easy to miss the final claiming of the internal connections.

Or even clamping......

A possible good call from Basel Boy - I seem to recall a similar issue some years back that was down to some arcing due to incorrect fitment (not pushed in beyond the initial resistance) of the power line IEC.

Hi Roger - I once had a similar issue with soft popping - and it was cured by ensuring the signal ground to the NAC had at least and only one earth. Have you got this setup on your 552 inputs?

I doubt its RFI (as opposed to radio breakthrough)  as that would typically more constant and tends to be more of soft background modulated buzz or whine or even a hardening of the sound. Noisy mains such as from a thermostat could cause it - but tends to be a more of a soft click type sound in my experience

Simon-in-Suffolk posted:

Hi Roger - I once had a similar issue with soft popping - and it was cured by ensuring the signal ground to the NAC had at least and only one earth. Have you got this setup on your 552 inputs?

I doubt its RFI (as opposed to radio breakthrough)  as that would typically more constant and tends to be more of soft background modulated buzz or whine or even a hardening of the sound. Noisy mains such as from a thermostat could cause it - but tends to be a more of a soft click type sound in my experience

Thanks Simon, no I haven't paid proper attention to grounding. A new CDX2 arrived recently and I just plugged it in without paying attention to the ground settings on all the other boxes.

I mentioned to Tonym a couple of posts ago that I was intending to rearrange my Fraim stacks, so I will do this, taking care to ensure ground switches are where they shoud be and that, following BaselBoy and Richard's observation, all the powerlines are well seated too.

With thanks,

Roger

Proper grounding is quite fundamental to getting the best performance out of the kit it's not just about hum and earth loops

Darke Bear posted:

It is usually RF pick-up through either mains or radiated. Things that switch on with high current can generate it (I had it with an old Fridge), or a noisy switched supply. A friend into Armature Radio had a strange interference that turned out to be some fairy-lights recently installed in his garden - he blames the cheap and nasty SM supply for the LEDs from China. LED Bulbs can do it too - people plug them in and forget what is actually inside them.

After the DR you will resolve more of this stuff that you may not have noticed before perhaps. A process of elimination will eventually locate it, usually it is in your house on your own mains circuit, and you can suppress it.

DB.

I bet your old fridge got "upgraded" pretty rapidly

Graham Clarke posted:

I bet your old fridge got "upgraded" pretty rapidly

When I was younger our 'fridge' was called a Keptcold... you had to pour water into the top every day and the evapouration kept the contents inside cool, not an electric cable in sight.

I remember the excitement when we 'upgraded' to a gas fridge.  Once again, evapouration provided the cooling, but it was evapouration of the coolant within a closed system ...not an electric cable in sight.

And then along came your electrical fridges with their compressors, their thermostat clicks and their mains spikes and that's buggered up your hifi systems ever since... I ask you, this is progress?

Roger