Switch on sequence for Naim stuff an household fuse problem

The power amp is best switched off last - just incase you get any switch on thumps from further up the chain. Most Naim pre-amps have muting relays to allow things to stabilise so it may not be such an issue. Sounds like you really do need to get your mains sorted !

If I switch the power amp on before pre, I get a loud buzzing sound from the speakers. Same thing happens if I switch the pre off before the power amp.

How long do you wait before switching on the power amp, you need to wait about 10 to 15 seconds from when the pre is switched on.

james n posted:

The power amp is best switched off last - just incase you get any switch on thumps from further up the chain. Most Naim pre-amps have muting relays to allow things to stabilise so it may not be such an issue. Sounds like you really do need to get your mains sorted !

It should read Switched ON last not OFF . 

Power amp always should be on last and off first - and when turning off it is good practice to allow a minute or two foe capacitors to discharge before doing anything that could create an input pulse.

In addition to the advice above - if you have no choice but to use the wrong sequence, turn the volume to minimum, hit the mute button, and select an unused input on your preamp. 

When you get your house rewired, get a dedicated circuit installed for your audio gear with its own consumer unit.

Hi, i had the same problem. Electrician changed the fuse, done in 5 minutes and costs 10 Euro. Christoph

Ps: identical fuse, but slower (sorry, i don't know the english terminus technicus for this, "träge" in gernan).

From your description it it seems that the electrician fitted a fuse that has a slower reaction time - same amperage, slower (or it can be faster) reaction time to blow (rupture) (open)   This can be varied to better suit the type of load on the circuit.  Its the same with the fuses installed in Naim units,  they must always be the correct slow blow to allow for the transformers startup amp load.   "träge" translates as "sluggish" (slow) in English,  

Hi,

thanks a lot for all the feedback and recommendations. I think I will try the fuse change to a "slower" type with same amperage. Have to contact electrician.
Thanks again to all of you.

Regards from Germany
Thomas

In the uk they would be a "c" type mcb, or even a "b" type if yours are the old type 2.

I had the same trouble. Cured by having the power amp on a separate double socket with nothing in the other socket. Everything else comes from a different double socket, actually on a dedicated circuit, via a distribution block. The dedicated circuit used to blow! But only since I had the 250 DR'ed – no problems before.

I think that power on/off in correct order is also an important issue to protect your speakers from such surges.

in terms of "fuses" then your electrician may well advise changing to an ELCB, earth leakage circuit breaker, which is less susceptible to such issues, and a better solution than the older mcb, miniature circuit breakers.

fatcat posted:

If I switch the power amp on before pre, I get a loud buzzing sound from the speakers. Same thing happens if I switch the pre off before the power amp.

I used to have this as well, but now that I renewed my power cabinet and have a dedicated cable (properly earthed) into dedicated wall sockets, the noise is gone. 

A slow-blow earth leakage circuit breaker fixed mine (can't remember if type b or c).  Not too expensive and can be re-used in your new creation.

But starting with the power amp switch on is not to be recommended unless you have a 552 pre - these mute everything for a couple of minutes when switched on so everything is stable by the time it opens the floodgates to the power amp... nice design !

Cbr600 posted:

I think that power on/off in correct order is also an important issue to protect your speakers from such surges.

in terms of "fuses" then your electrician may well advise changing to an ELCB, earth leakage circuit breaker, which is less susceptible to such issues, and a better solution than the older mcb, miniature circuit breakers.

I wholeheartedly agree re switching order, speaker protection actually having been the key consideration behind my earlier observation on this.

However, I'm not sure where your information on circuit breakers comes from, unless Ireland uses different nomenclature from UK: ELCB is purely an earth leakage breaker and not a current overload breaker, so used in conjunction with MCBs not in place of them. Maybe you mean RCBO (residual current breaker with overload), which combines the two and can fitted in place of MCBs in a consumer unit, providing earth leakage protection on the individual circuit, which are normally intended to limit isolation due to earth leakage faults so as not to switch off other circuits.

But other than if an RCBO with a different trigger curve is used, there should be no difference in tripping from inrush current compared to an MCB. The answer for breakers to handle high inrush currents would be to use one with a different curve, as already suggested by Mr Happy, the MCB equivalent to slow blow fuses - but you should not change the fuse/mcb characteristics without certain knowledge that the wiring is sound and that tripping is solely due to that cause, and if in any doubt a qualified electrician should be consulted before changing to any less protective a fuse or breaker.

Hey... just for future reference the switch on / off sequence is listed on the FAQ section of the forum. 

I know, because I relied on it for the first 3 years of Naim separates ownership... such is the infrequency with which I shut my gear off (to the delight of the local hydro provider).

Ah, so you were the member who visited the FAQ...

Richard Dane posted:

Ah, so you were the member who visited the FAQ...

The FAQ is a bit out of date to be fair Richard (or it was last time I looked, which was round about when Adam was a lad).

You could probably get a lot of people visiting it if you were to suggest the Forum members a) proposed new topics and b) volunteered to do a first draft of one of the Answers. Answers "owned" by forum members could be identified as such, so that Naim didn't have to worry too much about what was written.

best

David

Developing the idea further, the FAQ could be a wiki with community editing rights. Naimaudiopedia.  You don't have to give all forum members editing rights. It could be for example that you authorise as editors those forum members who you think write sense more often than nonsense!

best

David

May not be enough editors then though!

Thanks David. It may not be workable that way. The info itself never goes out of date, but sometimes needs a bit adding on and new topics added. I do edit from time to time, the last edit just recently. The idea is to cover the basics outside of networking, which had its own system on the website. What I would like is a shortcut button along the top bar..