Active System Woes (again)...

Posted by: Tim Danaher on 25 April 2003

Hello, all

System: CD5/FC2 / 32.5 / HiCap / HiCap / NAXO 3-6 / 3x250 / Isobariks.

Problem: RF Interference/HiCap connection

Just connected the system back up in active config last night, after one 250 came back from Salisbury following service (BTW sounded fantastic driving the Briks passively -- great job!)

First, what's the correct way to connect up the HiCaps in this config? Ive got them Socket 3 to Socket 3 at the moment.

So, weird, whining RF coming from the tweeters intermittently. Swapped 250s driving the tweeters -- still there. The sound wasn't there at all today until 7:10 this evening. I was watching telly, there was a mains click and, bang! -- the whining was back. Still going on now. It rises and falls in pitch and volume and sounds like a washing machine spinning up and down. Though not as loud, it's still intrusive in a kind of cheesy-1970's-sci-fi-series-with-everybody-clutching-their-ears and-rolling-about-in-agony sort of way, and means the system must be switched off when not playing music.

I'll have to call Naim on Monday, but in the meantime, any advice would be greatly appreciated.

Cheers,

Tim
_____________________________

Os nid Campagnolo yw hi, dyw hi ddim yn werth ei marcho...

Posted on: 25 April 2003 by Jo Sharp

getting a mains click at the start might be something in your house - central heating pump coming on?

Jo

Posted on: 25 April 2003 by Tim Danaher

Hmmm...interesting, Jo.

My pump comes on at 6:00, and the system's on a separate consumer unit, but I've had my suspicions about its mains isolation for a while (loud clicks can be heard through speakers when switching off adjacent uplighters).

Thing is, this RF only happens in active setup. Passive is quiet as all get-out. Also, the quiescent 'hiss' of the amps is much louder in active setup. Just been watching the telly again, and it's like having that little Gizmo fecker from 'Gremlins' in the room with you.

Cheers,

Tim
_____________________________

Os nid Campagnolo yw hi, dyw hi ddim yn werth ei marcho...

Posted on: 26 April 2003 by Paul Ranson

One would expect a little more hiss at the speakers in an active setup since the noise generated in the crossover is passed straight to the power amps. But only a little more. Probably not enough that you would be able to tell without a careful back/back test.

So I suspect your crossover or its Hicap. I forget exactly what sockets a Hicap has, and it's changed at some point in the past, but as long as you connect an unpowered 4 pin to another unpowered 4 pin it should all work nicely.

Paul

Posted on: 26 April 2003 by Tim Danaher

Thanks, Paul

When you say 'unpowered 4-pin' does that mean that some of the 4-pin sockets carry power and others not? If so, which ones?

Cheers,

Tim
_____________________________

Os nid Campagnolo yw hi, dyw hi ddim yn werth ei marcho...

Posted on: 26 April 2003 by Paul Ranson

Early Hicaps could supply early preamps with a single supply, so used a 4 pin socket with one pin carrying 24v. Later ones may not have this socket and supply all power using 5 pin sockets (these match the 42-5/32-5 onwards preamps, so we're going back a really long time). Anyway it should be clear from the marking on the back of the unit.

Paul

Posted on: 26 April 2003 by Jo Sharp

Tim.

I had RF problems with my NAXO 2-4 and 180s. Picked up foreign radio transmissions in the early evening. When I changed to SNAXO and 250s the problems disappeared.

Try moving the units around as much as the connectors will allow you. Check that all earth connections in your mains plugs are tight.

If you have PME straps connecting variuos bits of plumbing in the house make sure they are all clean and tight. Finally, switch off your mains at the meter supply - then remove the cover of your consumer unit and ensure that all the earth connections of the earth busbar are clean and tight - if you are not sure how to do this safely, get an electrician in to do it; and he can check your house wiring and earthing at the same time.

If none of this helps, consider installing an earth spike in the garden - look at Ben Duncan's articles on the Moth and HFN/RR sites.

Jo

Posted on: 26 April 2003 by jpk73

Hi!

I never had any RFI problems. Until last week: I could hear a radio-station very clearly through my active NBLs. What's wrong? My S-NAXO is recently serviced, and the 135s are not too old...

The radio-station disappeared, but yesterday it was there again very audible for at least one minute!

Also I can hear often crackling noises, I guess they come if somebody in my house triggers a switch.

Do I need to worry...? - Jun

Posted on: 27 April 2003 by Tim Danaher

Thanks again to everyone who's replied.

quote:
Originally posted by Jo Sharp:
Tim.

I had RF problems with my NAXO 2-4 and 180s. Picked up foreign radio transmissions in the early evening. When I changed to SNAXO and 250s the problems disappeared.

Jo -

Yep, it always seems to happen early evenings.Started at 8:38 last night--LOUD.

quote:

Try moving the units around as much as the connectors will allow you. Check that all earth connections in your mains plugs are tight.

Sadly, moving stuff just isn't possible at the moment, but within the limited range of movement I could achieve, there was no discernable improvement.

quote:

If none of this helps, consider installing an earth spike in the garden - look at Ben Duncan's articles on the Moth and HFN/RR sites.

Jo

Yes, at the moment both consumer units are earthed to the same clip-on-pipe arrangement. I gather this is not ideal. Another question: given that the system has its own consumer unit with three separate spurs, should any electrical activity from the domestic circuit be audible through the system? I get loud cracks through the Briks when I switch off the uplighters, and when the washing machine and spin drier reverse direction.

Jun --

Bummer, isn't it, just when everything seems to be working properly? Think I may go over to passively tri-amping the Isobariks... "sigh"

Paul --

Hadn't realised that all-4-socket HCs existed, that's why I was getting confused. Both mine are 1 5-pin / 3 4-pin varieties, so I assuming that 5-pin socket is powered, all 4-pin sockets are unpowered?

Cheers,

Tim
_____________________________

Os nid Campagnolo yw hi, dyw hi ddim yn werth ei marcho...

Posted on: 27 April 2003 by Trevor Bennett

My system was also picking up radio stations(radio Romania) it was cured by sending the snaxo back to Naim where they put in a RF reducing thing.

Trevor

Posted on: 27 April 2003 by Jo Sharp

Just another thought....when I had the problems with the NAXO and 180s I found that the old grey SNAIC to the amps reduced the interference a lot compared to the black snaics....

Jo

Posted on: 28 April 2003 by Timbo

I had a bit of radio interference in the evenings, but cured by careful placement of the nac a5, had it all bunched up before so was acting like an antenna.

Tim

Posted on: 28 April 2003 by Tim Danaher

Thanks, everyone...

My NAC A5 is a bit of a mess, to tell the truth, but with the min. 3.5 metre requirement (x6), and the amps next to one of the Isobariks, it's difficult not get it a liitle tangled...

Cheers,

Tim
_____________________________

Os nid Campagnolo yw hi, dyw hi ddim yn werth ei marcho...

Posted on: 01 May 2003 by Martin Payne

"Hadn't realised that all-4-socket HCs existed, that's why I was getting confused. Both mine are 1 5-pin / 3 4-pin varieties, so I assuming that 5-pin socket is powered, all 4-pin sockets are unpowered?"

Tim,

no, HiCaps have always had 1x 5-pin and 3x 4-pin sockets, but one of the 4-pin sockets used to be powered, in order to run single-rail items such as 32's (not 32.5).

The connections that you need will depend on the vintage of the HiCaps. The most definitive answer is to unplug the HiCaps & read the labels on the back - this will give you your answer. Connect the two sockets which are labeled "other HiCap".

cheers, Martin

E-mail:- MartinPayne at Dial.Pipex.com