AV2 Hiss coming from speakers

Posted by: dan scott on 18 January 2007

Hi everyone,

Well I went racing home last night with my 175 in the back of the car all excited. Got everything hooked up and got the Nait5i running in unity gain mode on the AV input ready to be used properly (I was waiting on a modified Chord Chrysalis DIN-Phono cable to get this working)

There is a problem however (Pretty big one too!) there is a loud hiss (Kind of like static ish) coming from the all the speakers, the two fronts especially when the nait is in AV unity gain mode. If I put it back to CD (and hence the volume goes down) it goes away. Now I understand there may always be a bit of background noise in a loudspeaker from the power amp but this is a lot and much more than i've ever had from any reciever i've ever used, it's OK in loud sequences but in dialouge or normal TV prgrams it's awful

(Have to say didn't expect a problem like this!)

My Naim setup is as follows -

AV2
Nait5i
NAPV 175
CD5 (Into Nait5i)
Ariva, n-Sats, n-Cent (All on NACA5 and Naim plugs)
All Naim equipment is using the Naim Crabtree mains leads

Any ideas of what I do now? My plan for tonight was going to be to unplug all equipment from the power and the AV2/Nait5i then only plug in the Naim kit and see if I still get the problem. Any ideas anyone i'm really not feeling great here, thought i'd be in home cinema heaven today but sadly not the case....

Posted on: 29 January 2007 by AV@naim

Gain on a 5i power amp stage is roughy +11db over stadard amps, this may account for the extra noise level you are hearing.

Was a SPL meter used to set the channels up (using the white noise function on the AV2:- TST ON)?

Use the AV unity gain input as per before, set the speaker levels on the AV2 using an SPL meter and then you will probably find the front L/R channel levels need to be dropped by 11db

Posted on: 30 January 2007 by General Skanky

FYI.

I once had the problem of hiss on my rear speakers.

They were active ATCs.

Modded cables added some resistors and it was completely cured.

Posted on: 30 January 2007 by dan scott

to be honest the whole SPL meter adjusting idea is something I have yet to undertake (So far i've just done it audibly...

)

I'll look into getting myself an SPL meter and how to do it all and then shall report back again with what I find!

Thanks again
Dan

Posted on: 31 January 2007 by Roy Donaldson

Dan,

I'd highly recommend getting an SPL meter a perhaps Digital Video Essentials DVD (though you can just use the n-Vi / AV2 test tones too).

I set all mine up by ear and then got a SPL meter later on. Found out I was wayyyy out.

Setting the levels correctly makes a big difference to the sound stage. Very worthwhile doing.

Roy.

Posted on: 01 February 2007 by dan scott

Roy could you recommend an SPL meter, I googled it but they seem to vary a lot in price? If I remember correctly digital video essentials is available on Amazon.

Thanks
Dan

Posted on: 02 February 2007 by Roy Donaldson

Dan,

There used to be a Radio Shack SPL meter you could buy from Maplin, or Lektropacks, but I can't see it online at the moment.

Roy.

Posted on: 02 February 2007 by AV@naim

http://www.maplin.co.uk/module.aspx?ModuleNo=46362&doy=2m2

I purchased this, but it was "On sale" at the time.

Posted on: 02 February 2007 by Roy Donaldson

This is the one I've got:

http://www.amazon.co.uk/Radio-Shack-33-2055-Digital-Sound/dp/B000A1EHGW

Can't see where else to buy it online though at present.

Roy.

Posted on: 23 February 2007 by dan scott

Well my AV2 looks like it's going to have to go on holiday to Salisbury for a while. The hiss is still present although with a NAC202 upfront it's a lot better than with the 5i (Most likely due to the 11db gain and me not yet using an SPL meter)

Now i've got a new issue - it sounds like there's a storm going on in my front 2 speakers when going through the AV2!

Sounds weird, like rain falling - happens on all inputs so not source based and disappears when the volume is muted.

After speaking to someone really helpful at Naim a while back it looks like the volume control circtuitry could be the culprit - this latest development would lend to that as the problem goes away when I mute the AV2

Now I've got my 202 I can send the AV2 away and run everything in 2 channel while it's away, I couldn't send it back before as then I'd have no sound at all...

I hope everything gets resolved, quite worried for my poor AV2!