Hi all,
I’ve just started rearranging my system as I’m expecting a NAP 500 soon, and in moving the 552 I can feel the parts to be moving inside it. Is that to be expected or have a realised something needs repairing?
Thanks.
Jon
As Naim puts it, the NAC 552 has a “Fully suspended sub-chassis for superior isolation of sensitive circuit boards.”
The unit should be handled carefully so as to not unduly jostle the suspended parts. That’s why it’s supplied with transit screws installed which lock down that floating sub-chassis.
The short answer is that it’s normal to hear the subchassis knocking around if you arent very gentle when moving it. So be gentle, or install the transit bolts.
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Exactly, same with the NDS and many other Naim products having transit bolts. My CDS2 has transit bolts as well. When moving any of my Naim stuff and my LP12 I am extremely careful. These are prized possessions and need to be gently moved around!
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I got a used 552 many years ago. At the time i was also using a 52/Supercap, both of which had been recently serviced=recapped .
So i got to swap back and forth between the 52 and the 552, an in every comparison the 52 was the better preamp
But the 552 head unit had an unpleasant rattle every time I moved it , which was the loss of spring
suspensions
Naim went and reset the 552 back on the springs, and then it was very easier better than the 52/SC.
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Assuming the springs aren’t already dislodged, if you’re just rearranging your boxes on the shelves, you should be OK to move it without needing the transit bolts, as long as you take your time and keep the box level.
The SuperLine has a similar arrangement. Because I’m using phono plugs rather than the BNCs, I feel uneasy connecting and disconnecting the phono cable with the back panel moving back and forth, so I usually put in a single transit bolt to do that, a minor inconvenience.
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If you’ve received it without transit bolts in place it won’t be right. Likewise if you’ve tipped it for off level once they’re removed. I remember a figure of fifteen degrees but not where from but all the components with suspended parts need care once the transit bolts are out. Exactly how you tell if one has been mishandled in the past I don’t know.
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I wonder if it’s possible to check alignment of the sprung loaded base by trying the transit screws. If they locate easily and tighten without any resistance then presumably all is well?
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Mmm… I have great difficulty getting all three transit screws in on mine. One never seems fully engaged. This, coupled with the fact I never thought it sounded any better than the NAC52 it replaced has always left me wondering. I might have to open it up and have a look.
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If the suspension has been free to move about and for how long and how extreme is unknown then definitely get it looked over by Naim. The brass mass loading plates are very heavy and can easily do damage to the suspension and move the internal wires about. As Ron posts above, it may all seem to work, but performance may well be compromised.
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The concern here is that the current rules dictate that it needs to be returned through a retailer, which means it will be sent by courier. If I can’t be sure I’ve got all three transit screws in properly, I’d be concerned what damage might result. I used to be able to deliver items for service myself. It’s only nine years old, so not really ready for a service.
Talk to your dealer. I’m sure they can sort something out under such circumstances.
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Thanks, I’ll give him a call shortly.
The lateral and vertical movement of the PCB/brass blocks is restricted to a few millimetres, when the transit screws are not in place.
In the photo below you can see that the pins allow, but restrict the lateral movement to a few millimetres. The washers attached to the pins restrict/allow vertical movement.
There was a similar thread last year concerning moving an NDS without transit screws. It took a long car journey without any damage.
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The manual says do not INVERT without transit screws. IMO this means it is OK to move it around (gently) without transit screws but do not turn it upside down. Looking at the design above you see that it can’t actually move more than the tolerances around the screws so few mm. And when shipping the units in their boxes you cannot guarantee the unit is not inverted by the shipping company.
“The four transit screws on the underside of the NAC 552 case should be removed before use
and must be replaced if the unit is to be re-packed and shipped. These transit screws must
not be used in any other Naim product. Do not invert the NAC 552 once the transit screws are
removed.”
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I know that but I constant movement and rattling away against the stops and tugging on cables can’t be good. Peace of mind would definitely be best.
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I’d be worried if I couldn’t sense it moving on its springs.
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I’m confident Naim designers are experienced enough not to allow any cables to be pulled or strained when the PCB moves within the constrained limits. 
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I moved my 552 today from the top of the Fraim to a table close by (with the dogs in the kitchen) I very gently picked it up, kept it horizontal with no sudden movements, all is well.
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Have you seen what couriers can do?
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Many years ago I worked on communications systems and one of the customers was a large, nationwide, courier.
I was in a ‘trunking’ depot (where parcels are shipped between regions) and watching the parcels being manually sorted was an education. If it was big it was roughly pushed from one pile to another, if it was small it was often thrown.
Having seen that… I’m always very, very, cautious about shipping anything!