I think my HDX is broken again (2 weeks after NAIM service)
Posted by: Wackymatt on 05 July 2014
Hello there,
I just received my HDX back from Naim to fix the Hard Disk. Looks like they replaced the screen as well as the new one is much brighter than the old.
Whilst the HDX was away being fixed I bought a chord QBD76 HDSD DAC. When the HDX was returned I connected the HDX to the DAC with an optical lead. This works fine. I’ve just bought a correct specification 0.75 BNB to BNC lead to replace the optical with the digital coax as this sounds better.
All seemed fine, but there is a major problem. When any light/appliance/projector is turned on/off in the house the music is interrupted. Quite clearly whatever transients being created by mains switching is effecting the interface between the HDX and QBD76. This does not occur with the optical lead. Given that no other AV electrical item in my house suffers from mains interference I am thinking there must be a fault with either the HDX or QBD76.
I’ve tried the following:
- Coax connected only. Music cuts out
- Optical only. Music is fine
- Coax and Optical connected, (Optical selected as source on QBD76). Music is fine. This test makes me believe the issue is not Ground related and the QBD76 PSU is filtering out interference. ie not the unit causing the issue. (unless its isolated when not selected)
My suspicions suggest the HDX is at fault, I’ve buzzed out the coax cable and all is fine. I’m going to first swap the cable (just in case), I’m then going to get a scope on the digital out of the HDX to see if any noise exists on either the ground or signal line. I’ll put a scope on the mains and capture the transients and measure the noise on it.
I’m going to get in touch with my local distributor to see if I can borrow some equipment to see if we can eliminate anything.
Does anyone else have any ideas? Has anyone had similar problems when using a DAC? This is a first for me.
I'm not looking forward to another 4 weeks to get my HDX fixed again. To be fair to Naim, I have never tested this function of the HDX until they returned it to me so could have been broken from day 1, but given the cost of the repair I would expect everything to be tested before it leaves their factory, the issue could of course be with the QBD76.
An XPS is also connected to the HDX, the issue occurs with and without it connected.
Matt
Posted on: 07 July 2014 by lovethatsound
Hi gmischol
So yours works ok on optical ?
You get interference on coaxial?
Posted on: 07 July 2014 by gmischol
Yes, that's right, and I have an XPS2 DR hook up on the HDX (don't know if this matters?)
Posted on: 07 July 2014 by lovethatsound
No it don't matter ive tried everything like wackymatt
Posted on: 08 July 2014 by lovethatsound
Have just been in touch with naim support about the interference problem with the hdx and they have said their r&d department r looking in to it and they will post on the forum when they have a answer. They asked 4 us 2 give them about a week . let's hope they can put it right.
Posted on: 08 July 2014 by Wackymatt
Thats great news, I contacted them at lunchtime today as well.
Posted on: 08 July 2014 by Wackymatt
I couldn't resist. I connected up a dual channel oscilloscope, the blue channel to the HDX S/PDIF output and the red to a Harmon Kardon DVD25. I generated some noise and captured the S/PDIF outputs simultaneously triggering off a noise spike (turning lamp on and off) and results are below.
Both are affected by noise but the Naim is massively more affected after the first spike, the waveform is completely destroyed. This test was done with S/PDIF outputs connected to the oscilloscope probes only. The noise is also apparent when the DAC is connected as well.
Just to re-iterate, even though there is a bit of noise on the DVD output, I haven't been able to get the music to cut out even once.
Posted on: 08 July 2014 by lovethatsound
Hi wackymatt
But what does this mean?
Posted on: 08 July 2014 by james n
Interesting. 0v line gone AWOL on one of the internal multiway connectors when it was serviced ? . I'll be interested in what you find.
Posted on: 08 July 2014 by Wackymatt
I guess it might mean there is a fault with the power supply for the HDX SPDif output, the power supply might not be rejecting noise as well as it should be, anyway something weird is going on and hopefully the Naim R&D department will workout exactly what it is
Posted on: 09 July 2014 by Paul Stephenson
We have been reviewing this issue and will post once this review is complete, any further issues which arise relating this please feel free to mail us directly at Naim support.
Posted on: 20 July 2014 by lovethatsound
I got in touch with naim support on Wednesday, they are testing a fix for the problem. So shouldn't be long now.
Posted on: 20 July 2014 by Wackymatt
Thats great news. Thanks for the update
Posted on: 28 July 2014 by gmischol
More than 2 weeks have gone by, any news now?
Posted on: 28 July 2014 by Wackymatt
Nothing as of yet unfortunately
Posted on: 28 July 2014 by lovethatsound
They asked me 2 ring them back on the 13th of august.i think naim close down 4 holidays.
Posted on: 18 August 2014 by gmischol
Time is passing by without any news from Naim, a little bit annoying
Posted on: 18 August 2014 by lovethatsound
You need 2 ring them up my friend.
Posted on: 04 September 2014 by lovethatsound
Hi Wackymatt have you had any joy yet?
Posted on: 04 September 2014 by Bert Schurink
I have currently my Nad Receiver in repair and have no expectation when it will return, annoying as well. I am happy my naim stuff is running as it would a major annoyance to live without music for a longer time, while normally the dealer should have a temp solution for you.
Posted on: 05 September 2014 by Wackymatt
I've been in contact and they are arranging to have the HDX returned for a modification. I don't know what this mod is but the HDX is being sent back next week and will hopefully be returned in 10 days time. I should know more by then
Posted on: 01 October 2014 by lovethatsound
Hi guys, have you guy's had any luck yet?
Posted on: 02 October 2014 by Wackymatt
I sent my HDX back and it took a week to have a modification made and have the unit returned. I don't have the paperwork in front of me but the mod involved removing a component from the audio board. I don't have any detailed information on what or why the mod was made.
I've now had my HDX at home and running for a couple of weeks. I've only noticed one instance where the DAC un-locked from the HDX. Although not 100% perfect this is a significant improvement over before and I'm much happier.
Posted on: 06 October 2014 by crackie
I just found this thread after my post about my home demo. of a Chord QBD76 HDSD. I am now having the very same issue with clicking then signal dropping out from HDX BNC out to Chord DAC.
Is it defiantly the HDX ? I have had a n-DAC/555PS running for 18 months via BNC digital out via a naim DC 1 digital cable and not one drop out in this time playback has been flawless, put a Chord DAC in today & drop outs straight away.
Posted on: 06 October 2014 by lovethatsound
Yes it's the hdx 4 sure.i sent my hdx back 2 naim 2 fix the problem, it came back and worked better than it did before, but not 100%.so I've sent it back again . It's been gone now for 4 weeks and naim say they are testing it with the chord hugo.i might also add the hdx also has this problem with the dac that's in the hdvd800 headphone amplifier. Plus I've tried 3 different cd players with the hugo and the hdvd800 and NO problems. I'm hoping the guys at naim are going 2 get this sorted out this week.
Posted on: 06 October 2014 by crackie
Right, thank's for the advice. I'll investigate. Anyway not sure the Chord DAC is what I am after as an upgrade sound wise, I may end up getting a 555PS DR upgrade instead, I'll see.
It's wierd the n-DAC from the same BNC out from the HDX has had zero issues, I can't get my head around that - then again I am not an Electrical Engineer 
