Transformer hum!
Posted by: Mike1951 on 18 June 2018
All of a sudden, my NAP250DR is emitting a loud hum, as if I've suddenly got an earthing problem.
Much equipment switching, replugging and resiting later, it's evident that there's a mains supply factor in play.
As I'm out here in rural Spain, this could be down to any number of factors.
I'm going to monitor the situation over time to see if the problem is temporary, but if it's not, I'm probably looking at a mains cleaner.
Yes yes I know they're frowned on and I know why, but I may have no other choice.
I've seen 'Tacima' mentioned elsewhere as a quality product but there may be an amperage match issue?
In any case, I'd be looking for whatever 'best quality/minimal playback downside' cleaner that I can afford.
Given these requirements, can anybody make a recommendation?
Shuko plug/Graham's Hydra//ND5XS/XP5XS//NAC282/FLUFFY TOY/NAPSC//ATCSCM19's/Chord Epic interconnects and cable.
The one I built was on an eBay printed circuit board but with my own heavy duty components
They are available ready built on eBay for less than £85 I think ..and work well
I don't believe there is ANY need to spend hundreds or more on a DC blocker...it is just a small handful of components and that's all that's needed
Gavin L posted:................... However, if all is standby (and I am working at my desk), the hum can sometimes be intrusive as it fades in and out.
How easy is it to connect/disconnect a DC Blocker?
The fact that the hum tone & volume varies - "fades in & out" - is a very good indicator that the problem is DC Offset. If you can't link the hum tone change to electrical devices in your home powering on/off, then its on your incoming supply & a DC block filter or a balanced supply transformer is the only logical solution.
I designed & built my own & its located on my power dist board in a surface mount 25mm pattress box. Most of the filters on the market are plug in like an extra in-line power strip & are aprx the size of a 4 way power strip, balanced transformers are a lot bigger.
" balanced transformers are a lot bigger. "
And heavier!!!
And more expensive for the required power capability.
Indeed but the beauty of them is that they don't have any actual conditioning circuits. If they are good enough (and mandatory) for hospitals, they should be good enough to do a decent job at home also. And by the time you get to the Naim Classic range, their cost starts being less than a box upgrade.
I've speculated before that I'd not be surprised if Naim actually use an industrial isolating transformer on the main power inlet to the factory but they've never let on about what their mains arrangement is there.
Mike-B posted:Gavin L posted:................... However, if all is standby (and I am working at my desk), the hum can sometimes be intrusive as it fades in and out.
How easy is it to connect/disconnect a DC Blocker?
The fact that the hum tone & volume varies - "fades in & out" - is a very good indicator that the problem is DC Offset. If you can't link the hum tone change to electrical devices in your home powering on/off, then its on your incoming supply & a DC block filter or a balanced supply transformer is the only logical solution.
I designed & built my own & its located on my power dist board in a surface mount 25mm pattress box. Most of the filters on the market are plug in like an extra in-line power strip & are aprx the size of a 4 way power strip, balanced transformers are a lot bigger.
When you look what is on the market - there doesn’t seem to be anything of the quality that you would like to see with a Naim system. Ie. To run though a power strip is inconsistent with using a dedicated spur / power lines on all the equipment. Self build (only provided you have the necessary skills) seems the way to go.
Gavin L posted:When you look what is on the market - there doesn’t seem to be anything of the quality that you would like to see with a Naim system. Ie. To run though a power strip is inconsistent with using a dedicated spur / power lines on all the equipment. Self build (only provided you have the necessary skills) seems the way to go.
I’m sure you get models that can be wired in, so could go in your dedicated supply feed if you have one, or wired into a spur, or put into the cable feeding any power distribution block you may already use. (30 seconds Googling found one, (though I didn’t investigate suitability).
Emotiva CMX-2 will fix you up at a fraction of the price of most blockers. I have run 2 of them, and no negative results in SQ.
Got Hi-Fi? posted:Emotiva CMX-2 will fix you up at a fraction of the price of most blockers. I have run 2 of them, and no negative results in SQ.
they are discontinued. Very hard to find them on the market.
Got Hi-Fi? posted:Emotiva CMX-2 will fix you up at a fraction of the price of most blockers. I have run 2 of them, and no negative results in SQ.
I looked inside & its essentially a C&D mode(s) choke with a few other refinements, I am also wary of the X&Y (shunt) capacitors that are reputed to degrade SQ. (?) Is there a version with UK or Euro sockets? as all the pics I can find show the US stnd with 2x blade & earth.
tony123 posted:Got Hi-Fi? posted:Emotiva CMX-2 will fix you up at a fraction of the price of most blockers. I have run 2 of them, and no negative results in SQ.
they are discontinued. Very hard to find them on the market.
it seems anytime these things come out at a decent price they are quick to be discontinued! same with PS Audio. You are right though, I think I have seen maybe 2 hit the used market here in the last 6 months.
Mike1951 posted:All of a sudden, my NAP250DR is emitting a loud hum, as if I've suddenly got an earthing problem.
Much equipment switching, replugging and resiting later, it's evident that there's a mains supply factor in play.
What equipment switching did you do? While a ground/mains issue is one explanation, a failed component in the amp is another, especially if it comes on all of a sudden. Have you switched it out for another NAP250DR?
A failed component in the amp is not likely to cause hum fitting the OP’s description, wheras DC on the mains very much is.
Yes, it's mains-based. During the day and when playing, it's not a problem. It's just a bit weird walking into lounge early in the morning and going to bed at night when the world is quiet. I suppose I'll get used to it.
The amp is a second-hand 250 that's been refurbished and upgraded to DR.
Of course, I'm preaching to the converted here, but after other upgrades - speakers, preamp, cabling and this 'final' (probably) upgrade, all is bliss in the ears on the couch!
I think the after-care service from NAIM is fantastic. Essentially a brand-new 250 DR for the price of an internal adjustment.
Gotta love 'em. ????
PS: although, as I've just discovered, a more revealing upgrade cannot rescue the destruction of Led Zeppelin's back catalogue perpetrated by Jimmy 'cloth ears' Page...
He has been at the “song remains the same” for the 50 th anniversary......could be another botch?