Hissing NAP 500

Posted by: KC on 13 April 2002

Anyone has any experience with hissing on NAP500? I am running active 500 on SBL. The amps do not hiss when they are turned on. The hissing occurs on the left channel (Tweeter) after playing 1LP. No hiss on the right channel. The volume control has no effect on the level of the hiss. Hissing stops as soon as I power the affected amp down and power it up again. However, the hissing returns after a few LPs.

The same amp felt hot to the touch one morning, the fan was blowing at full speed and hissing occured on the left tweeter. No music was played prior to this occurence. Now I turn the amps off when I am not playing music to avoid this problem.

Is it a defect in the manufacture? But then again the other amp does not display this problem.

Posted on: 13 April 2002 by Andrew Randle

Get it sent for servicing (it should be under warrantee) immediately, before it blows up your SBLs

This kind of fault seems very serious, particularly if it runs really hot with no signal. Often it is down to a flakey component that needs replacing, although that kind of fault has the potential to generate surges into the loudspeakers.

Andrew

Andrew Randle
Currently in the "Linn Binn"

Posted on: 13 April 2002 by DAVOhorn

Sounds like there is afault with the amplifier.

If it is a class A/B amplifier then it should run reasonably cool and running hot is a sure sign that there is a fault with the amp.

You must without further ado get it back to NAIM for repair.

Your dealer will be pleased to sort this out for and may provide a loaner while yours is away.

If you dont do this and the amp lets go then your speakers could very well be damaged.

Let us know what happens and what the fault is.

regards david

Posted on: 13 April 2002 by Roland Huu

Hi KC

Sounds like the left 500 amp is acting up. So far the only time my fan come on is when I drive it really hard.

Have you troubleshoot? I know it's a pain with an active setup to be sure that nothing else (eg SNAXO and SuperCap) is contributing to the problem.

Did you try switch the left 500 for the right 500 amp? If the hiss switch to the right/follow the amp then I think it's pretty sure.

How about going back to passive set up? testing the left 500 first and then the other 500. Does the hiss exist for both channel tweeters?

If it still persist, then it's a call to you know who.

Good luck... would be interested in finding out what was the cause.

Regards
Roland

Posted on: 14 April 2002 by KC

I have since switched the amps around and now the hissing noise has moved to the right tweeter channel. I have also tried to turn off the preamp, SNAXO, and CD player just to eliminate any possible signals from these sources, the hissing remains on the right channel.

Also, tried to play with Mono engaged on the preamp and switch between left and right channel using the balance control, the treble is definitely missing on the right channel compared to the left channel.

Would Naim like to comment? These are expensive pieces of equipments and I do not expect such faults for such a new sets (less than 2 months old)

Posted on: 14 April 2002 by dave simpson

Hi KC,

Man that's gotta be frustrating. Especially with something like a 500. Unfortunately, even billion dollar aircraft break-down "new and just out of the box". Personally I think it's time to contact your dealer- it's time for him to take over now.

Though an "infrequent" customer of Naim's service department (NANA), I can assure you, they are the best...period.

keep us posted....

dave

Posted on: 14 April 2002 by Derek Wright

In the thread
http://forums.naim-audio.com/eve/forums?a=tpc&s=67019385&f=48019385&m=4401981892

you asked a similar question to my current one on Fraim height.

How did you resolve the issue

Sorry for thread crashing
I hope that the Singapore 500 rescue service are helping you out

Derek

Posted on: 14 April 2002 by Roland Huu

I think it's advisable to (1) call for service (2) send a mail to Naim Audio directly at info@naim-audio.com

You should get an answer. They can also coordinate with distributor for servicing your 500.

I would leave the 500 out of your system for now if you want to continue to listen. I've heard many stories of tweeters blown in active system when amps go funny.

checkout... http://sound.westhost.com/tweeters.htm for explanation why they do. useful info site for me.

Regards
Roland

Posted on: 14 April 2002 by Paul Stephenson

Switch off, contact your dealer asap. I am sure they will be able to help solve this problem fast.

Posted on: 15 April 2002 by KC

1. Fraim too high

Derek, I just followed Paul's advice, bought an extra base and move half the tower down to the new base.

2. 500

Thanks for all the advice. I have switched the amp off since the problem started and only switch it on when I need to listen to some music. 500 active is addictive!! As soon as the problem reoccured, I turn it off again. But now I won't turn it on again until I have it looked into.

I have absolute faith in the local dealer here. Bunch of great guys who are very dedicated to what they do and supportive. The best I have known in the industry.

Posted on: 15 April 2002 by Alex S.

remove asp asap.

Alex