White background noise

1. disconnect the earth tag from the lp12
2. try experimenting with the way your cables are dressed
3. borrow another preamp and powersupply

if it is the mains, do nothing and hopefully it will pass.

yours in paranoia,
dev

Thanks for the suggestions. I will try some experimentation tonight. My initial thought is a fault in the pre-amp/supecap. I will try to borrow a 82 from a dealer here in town to (hopefully) rule that out. My cables are fairly well dressed and separated. However, I will connect/disconnect all cables to remove dirt/oxide. Hopefully this will solve this (annoying) problem. Last resort: book a time with a psychologist...

What would be an acceptable level of hiss in a Naim system anyway?

Regards
Anders

ps. not sure what acceptable levels of hiss is, i sit about 13ft from my sbls and can't hear any hiss at all

i dont hear any hiss from my system, unless i actually put my ear by the speaker drives -- and even then, i have to try hard to hear it.

let us know how you get on with your borrowed pre. and also if your system is still playing music.

enjoy

ken

Naim amps do tend to produce a small amount of hiss, and it's audibility is affected by several factors, of which the most significant is speaker sensitivity. It's unaffected by muting the preamp or adjusting the volume (with the exception of listening to phono stages) since all of the gain is after the volume control / switching.

Newer amps (e.g. 112/150) are quieter, but I don't hear anything at the listening position, even with my 42/110's, but I'm using insensitive Kans.

It has no effect on the musicality of the system, but if that does seem worse you could be suffering from interference or possibly a fault.

Andy.

If your amps are 5 years old or more this can be the first signs of the main capacitors going - both my 250's got hissier as the caps wore out, and both went noisy at the same age (5 and a half years), although bought at different times.

Recapping is not too expensive and restores everything to the way you remember it!

Regards

Henry

It may be worthwhile mentioning that I now use 500/NBL rather than 135/Isobarik, so Dev, the Naxo is ruled out, and Andrew, the 500 should be far more quiter than the 135s, even if NBLs are much more sensitive than the Isobariks, and Henry the amp is brand new so it could (should) not be a recapping issue. Ken, yes, the system still plays music, but the key issue is the, as Wai-lon pointed out, the recent and clearly noticable hiss from my listning position about 10 feet from the speakers. I agree with James about the humming from transformers and the fans of the 135s. It does not bother me at all! The white noise is another story altogether as it introduces a filter between myself and the music.

Last night I did the following:

1. Removed all source "interconnects" from the pre-amp (source's power cables still plugged in the wall socket and powered up) : hiss still there unhanged
2. Removed the "interconnect" between the 52's Supercap and the 500 (source's and pre-amp power cables still in the wall socket and powered up): hiss still there unchanged

This made me conclude that the problem may lie in the power amp section. Is this a fair conclusion or do I need to power down the disconnected (sources, pre-amp) units before reaching this conclusion?

In addition, I will also connect a pair of Kans to check if the speaker sensitivity will affect the hiss level.

Any other thoughts or suggestions?

Regards
Anders

i may not have understood the full background to this hiss issue. if you have changed both the speakers (isobariks to nbl's) and the power amp (135 to 500), and the hiss is still there, then i would say the source of the problem is unlikely to be the power amp or the speakers.

you were going to try a different preamp -- (you were going to borrow an 82??) did you do this?? what was the result?

enjoy

ken

cheers

Dev

Dev, I will have to return later on this one as it takes some time to adjust to the Naim speaker sound. Both are excellent combinations with their specific strangths (and weaknesses). In any case, the 500 is a magnificent amp.

Regards
Anders

When I first installed the 500/NBL (in June), there were no audiable hiss.

so you know how the 500/nbl system sounds then -- and the normal level of hiss, i.e. as good an inaudible.

if you have a nearby dealer, you might consider taking your 52 and 500 to try one at a time on his/her NBL's and see if the excessive hiss appears.

what does your dealer say anyway?? assuming you bought this superb system from him/her, he/she should be bending over backwards to help surely??

enjoy

ken

Muting the pre-amp: hiss dissappeared entirely...

Not sure what to make out of this

Regards
Anders

may main suspect so far is the pre-amp. can u swap this? take it to your dealers? etc etc

enjoy

ken

one word of caution - your power amp may be on the blink. If this is the case it may fail catastrophically, and is quite likely to also destroy whatever speakers are connected. My dealer learnt a very expensive lesson this way when a customer brought back a faulty amp.

I suggest you leave the NBLs disconnected until you get to the bottom of this!!!!

BTW, despite the best of quality control, electronic components are most likely to fail during their first few days of operation. My money is on the new power amp, or on any cables which may have been disturbed during the upgrade.

Naim power amps are likely to hum (low buzz through the speakers) when no preamp is connected or is switched off.

I wonder if you have a complete earthing failure? Does anyone know if a tuner would be affected by an earthing fault?

cheers, Martin