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Humming hicap dr

meridian 508

pfm Member
Looking to acquire a hicap dr to go with my supernait2....going to buy blind ,used or ex dem but worried about reports of humming.
Any thoughts please...
 
I think you'd be unlucky if your hi-cap noticeably hummed, it's usually the bigger PS beasts that have more of a problem. I noticed it first with a 250. However as the Smiths sang "some girls are bigger than others" and some transformers certainly hum more than others.

I have to use an isotek thingy due to fluctuations that sometimes sounded like a Honda 50. This is with a 552 PS and 300 PS.

Never had hum with my hi-cap but now that I think about it it was an Avondale version so maybe that's the reason.

.sjb
 
I got fed up with humming from Naim transformers and bought Teddy Pardo equivalents instead. (This was before e the DR range)
 
They all hum to some degree. If you are lucky, it will only be audible up close in a quiet room. If you can hear it when music is playing, something is wrong.
 
They hum and buzz very noticeably. At one time I had 4 Hi-Cap DR in an attempt to find the quietest one for a customer but all were unacceptable, being clearly audible across the room. Naim considered them "within spec".
 
I have a CB Hicap and SC2 DR that are silent. Sometimes when there are other things on in the house like the fridge when it chills, i can get a light hum through my XPS2. Once the interference of the mains has stopped, so does the hum.
 
The SuperUniti I recently bought NOS/x-dem hummed for a about 8-10 weeks. Then miraculously one day it became virtually silent. My Rega Elicit (clamshell version) had two transformers which would hum (at times) to a point where It could be heard when not even in the room! Rega changed the amp twice, third time I got one that didn't hum as much. That amp also took about 4 months till both transformers stopped humming. Its inherent with toroidal transformers, if your mains is anything less that clean. DC on the mains from other/commercial/3 phase buildings on the grid is usually the cause.
 
Don't think I had any Naim amp. or Supercap etc. which didn't buzz/hum from time to time. That it was not consistent directed me to think it was the fluctuations of mains supply (or DC on it) which was responsible and that both the H &F trannies and their successors were overly susceptible.

Never bothered me and never influenced the sound, as far as I could tell over a 30 year period. I have never heard hum from my 01 p/supply, however, dating from '81. I can't imagine that filtering of any description would be anything but deleterious to s.q.

I have had fully dedicated mains supplies for 15+ years, so think it's in the supply rather than internal appliance interference.
 
Mains hum depends on both the transformer and the quality of the mains supply, so unfortunately there is an element of luck involved. Naim transrormers are noisier than most, it seems. I've had three different amps in my present listening room, two were somewhat louder that I'd have liked, the other (latest) one is virtually silent. If buying from a dealer I would always make it clear that I would want to return any amp that I wasn't happy with, for that or any other reason.
 
Have you listened to a hicap?...I've had the s/n2 about 3 weeks now and it sounds great ..I was thinking down the line of getting a used one to see the difference between with or without . If it turned out no difference just move it on..
 
Hi-Caps make a good/positive improvement IMHO, it did with my SN1. Its quite logical why; The internal power supply becomes dedicated to the power section and the Hi-Cap becomes the dedicated power supply for the pre-amp section. IMHO this is better than a pre/power arrangement coz the audio signal is still on one circuit board rather than going from one box to another.
 
I've had my Hicap since buying it new in Saudi in 1998. The only time it has hummed noticeably was in Saudi (filthy mains) and very occasionally in the last house we lived in which had poor quality wiring. Since moving here, nothing, no hum detectable even with my ear on it. Hicap serviced about six years ago.
 
It is possible to make a large toroidal transformer that does not hum or mechanically buzz. You just have to know how to make it so it is quiet in operation and find a good manufacturer who will make it to that spec. Unfortunately this costs money and some manufacturers can't/won't pay for this, so the upshot is that the transformer will be noisy. The transformers in our 50watt Convergence monos and 50watt Convergence stereo amplifier are very large and are totally silent.

Also be aware that DC on the mains can cause the transformers to mechanically hum. You only need a few volts of DC and that can cause significant mechanical noise.
 
So hum is not allways related to bad or insufficient mains ?

Correct. I always recommend, where possible, to isolate the DC element by using an isolation transformer between the electronics and the mains. It is also possible to design and make a transformer that will not mechanically buzz, even with a little bit of DC on the mains. However it is always best to isolate the DC to start with.
 
(Snipped).....IMHO this is better than a pre/power arrangement coz the audio signal is still on one circuit board rather than going from one box to another.

How does that square with the Naim strategy of taking a perfectly clean
signal from the pre-amp thence down a cable carrying DC current, into
an area of EMC noise - the Hicap and finally along yet another cable
carrying DC into the power amp.?
 
How does that square with the Naim strategy of taking a perfectly clean
signal from the pre-amp thence down a cable carrying DC current, into
an area of EMC noise - the Hicap and finally along yet another cable
carrying DC into the power amp.?

Surely you are itching to answer your own question? :)
 


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