What's in a NAIM?

Grounding one of the source components - in this case the phono stage completely eliminated the hum

Thanks for all your input

Williewonka, are you still having this problem or have you resolved it?

I can confirm there is no problem with the NAIM equipment and this is HiFi only system so there is no connection to any video component - except for the DVD player that is being used only as a CD transport

I spoke with NAIM support and they confirm that their design philosophy is different from that of the consumer electronics manufacturers, which causes this problem to occur.

Grounding the neutral to the earth will fix the problem, but will it cause the source to perform differently?
- if not - why don't they ground the neutral via a three pin main plug?
- why doesn't "consumer electronics" use three pin plugs at all?
e.g. My Denon A/V Receiver only has two pins also

I have a feeling that common occurrences of bad domestic wiring led to the design decision not to ground consumer electronics, because most consumers do not posses the required knowledge or equipment to track down a bad connection/earth/neutral. Audiophiles tend to posses more knowledge in this area.

The solution offered by NAIM was to insert a stereo Ground Loop Isolation device between the DVD and the AMP.

They were not keen on employing any ad-hoc connections to either ground or neutral or between Chassis - i.e. connections not supported by way of the leads supplied with the equipment manufacturers.

These isolation devices are commonly used in disco and music amplification circles, mainly because the power supply at some venues can present problems of this nature.

Behringer has this type of product available, but it does not have phono plugs - so I might have to get creative

http://www.behringer.com/EN/Products/HD400.aspx

Having had Behringer gear for live music mixing I can confirm they are high audio quality components

Other solutions I have found are:
http://www.directproaudio.com/product.cfm?directid=55211
http://www.xitel.com/usa/prod_gli.htm
http://www.jkaudio.com/pureformer.htm

I'm not going to rule out that the Naim might have a problem, but when video is a part of a system, it opens the door for all kinds of hum and noise. Naim is one of the most reliable and dependable brands I've ever worked with, especially their "two channel" models. It might be the Naim, but just make sure to isolate the video first.

If the system has coax connected from the cable box or to the TV disconnect it. If it is the cause, you need a ground loop isolator.

Try this...it solved a similar problem for me w/ a Denon universal.

A short run of solid copper wire (bell wire - Home Depot) from the center screw of the electrical wall plate to a CHASSIS screw on the Pioneer should solve your problem.

Good luck.

I have also posted a related question here, but it is more a question regarding the design of various sources

http://forum.audiogon.com/cgi-bin/fr.pl?htech&1277418935&openusid&zzWilliewonka&4&&

The sources that hum are the ones where an AC signal can be measured.

I have an old AKAI and a Luxman amp and there is no hum aparant on either of them with these units

I have gone as far as switching all the breakers off except the dedicated line to the amp - it still hums - so I do not think it is from an external source

Lost for things to try...

Seems that the NAIM is very sensitive

I am using the DVD as my CD transport, since it also plays SACD.

I have tried isolating just the amp and the DVD - still hums

I route the DVD for normal play via optical link via Cambridge Audio DAC - no hum.

But the DVD only plays SACD via the left/right channel audio output and that's when the hum starts.

I measured an AC signal (i.e. the hum) of around 1.5 V AC between the neutral on the interconnect and the ground at the outlet - but I also found this with 3 other DVD players from other manufacturers, so I think this is normal, since it has no effect with other amps I have.

There are other reports on the web of similar problems with NAIM amps, so I am wondering if anyone encountered this before and had a fix for it.

Does the NAIT5i produce the same hum when you connect another source? Does the Pioneer produce the hum when connected to another amp, TV, etc....? Could the television/monitor produce some feedback through the video or audio connections? Are you using multiple audio outputs on the Pioneer? Do you have any kind of "conditioner" or "protector"?

I know this doesn't answer your question, but after 20+ years of doing custom systems, I've had to do my share of trouble shooting with such issues.

You might read the Naim manual to make sure the settings are right. I have designed/installed several Naim systems through the years it seems like there are some settings on the NAIT that allow preferences such as RCA and DIN connections.

Also look at the video settings and connections on the Pioneer. Video outputs can have a lot of audio problems when not setup or hooked up correctly. Don't rule out the fact that there could be a technical issue with the Pioneer and/or video system.

http://www.naimaudio.com/support/manuals

Here is a link to the Naim manual site. I hope it works out for you.