Rotel ra-1062 transformer hum...

[SGT]

Hello all,

just joined the forum after desparately googling out a solution for my problem: brand new Rotel ra-1062 (integrted amp) has developed audible hum near the transformer area. It can be heard from about 10-15cm (4-6in), but it changes the pitch to a higher frequency and level and in that case can be heard from about 2-3m (80-120in). It stays there for about 4-5sec and then winds down.
I didn't pick up any rule as to when this occures. Tried correlating it to a light dimmer usage or fridge, washing machine... etc, but couldn't establish any connection. I was disconnecting all appliances from the wall sockets, too, with no correlation to the hum. This is all done in a quiet room. Can't hear it while music is playing (haven't tried very low volume, though).

Please note - it is not speakers related hum - I don't hear it in speakers.

This is, actually, my second ra-1062 in the lost month, after first was replaced by my dealer because of the same problem :cry: They say it worked fine at their location, but I'm not sure what they've been testing it for. Both amps worked fine out of the box, but a couple of weeks in the use, the hum showed. That's why I believe it's not location, but componentry related. Or ?

An advise to sort out this *annoying* :M issue would be very much appreciated.

Best regards and thanks in advance to anybody taking time to reply,
SGT 8)

[lvhung]

Sell 1062 and get Arcam A80 intead (800USD)

[soundhound]

Get you're hands on a multi meter and watch you're line voltage, sure does sound like poorly regulated power.

[ironchef]

Sell 1062 and get Arcam A80 intead (800USD)

Not so sure about this advice. I audtioned both when I was shopping for an integrated, and decided on the 1062.
Although there is certainly some subjectivity involved here (the speakers and source were different, although at similar price points), it appeared that there was substantially more power available in the 1062, and I just liked the sound better. The A80 was too laid back. Might be better for lovers if classical music, though.

As for the original question, it sounds odd that two 1062s should develop the same problem. Are you conditioning power?
FWIW, my 1062 has been completely silent.

[mitch57]

I have the same problem but with two different amplifiers. A Rotel RMB-1095 and a Parasound Halo A51. Both transformers buzz most of the time but sometimes they are dead silent. Neither amp buzzes at the dealer. I have narrowed it down to being some sort of eletrical noise on my power line. I even turned off every breaker in the house except the one the amp was plugged in to.

[NewBuyer]

PS Audio has the UPC-200HB which will remove DC on the powerline. This will sometimes totally cure the problem you are describing. Here's a link.

[SGT]

g'day all and thanks for your suggestions.

Hum is not *always* there. Last night I have enjoyed very quiet night, for example. My concern is more in terms of "it was ID-ed and more likely than not, it will only get worse". So, I'd better do something about it. That has initiated my search and queries here.

From my further googling, it crystalized as candidate no.1 that I got issues with my power supply (i.e. someone in the area runs some funy fridge or dishwasher or... that poisons the ac line with dc signal, or some of my household devices does it - needs to be figured out...). One of the promising finds (still haven't tried it) is Humbuster OR UPC 2000HB from PS Audio (http://www.psaudio.com/products/humbusterac.asp ; http://www.psaudio.com/products/upchb.asp). There're some good articles on trannies mechanical noise and troubleshooting.
I'm currently trying to make a dc suppression/filter device as posted on one of the diy forums. People have tried it and it worked for them. Heaps cheaper than from PS Audio (but that's a professional product, hey).

The moral: keep an eye on your dc levels in your ac lines. If present, remove it!

Cheers,
SGT

p.s. Oops, sorry NewBuyer, didn't see your post...
p.s. Thanks for the Arcam suggestion. Tried 75+ and 80, but preffer Rotel sound.

[thyname]

Sell 1062 and get Arcam A80 intead (800USD)

I was wondering what are you doing in a ROTEL forum then?!!!

[lvhung]

I own 1068/1095 Rotel
it does not mean I must to compliment and clap all things
Like these: 1068 pop, 1080 fuses, 1095 humming

[SGT]

<
it does not mean I must to compliment and clap all things
Like these: 1068 pop, 1080 fuses, 1095 humming
>

...hmmm... second that... 1062 contour knob does pop and scratch. Very rarely used here (might be an argument for someone...), but *when* used it should be silent. Period.

[ProStereo]

lvhung had this to say: "Sell 1062 and get Arcam A80 intead (800USD)"

Come on Ivhung, that isn't an answer! We are here to help solve issues when asked, not suggest a product of your endorsement. Many times hum can be fixed by tracking what is causing it. The Arcam is not exempt from hum problems.

[thyname]

I own 1068/1095 Rotel
it does not mean I must to compliment and clap all things
Like these: 1068 pop, 1080 fuses, 1095 humming

Did you actually have problems with both your Rotel pieces? It is strange to notice that you had a fuse problem with 1080 even though you actually DON'T own a 1080!!!

It is very unfortunate you had encountered those problems, however, Rotel has a five year warranty, but I am not sure for Rotel authorized dealers in Vietnam and warranties they offer.

[lvhung]

My 1068/1095 is no problem in working
the only problem is that I wish I could have more headroom for 200W of 1095
1095 seem not ideal at lower volume

[SGT]

ok,

I've built the diy dc suppressing filter and, so far, I'm happy to report that my trannies are QUIET !

It still is early days (got parts yesterday, soldered last evening), but in the last 12 hours I didn't notice even the "normal" hum/buzz that I got used to. Now, some room has to be left open for the possibility that my power supply was clean and 1062 wouldn't hum even without the filter, but *this* level of quietness is something new to my exeprience with Rotel!

Will keep you posted and if there is interest, will attach the schematic of the filter.

Cheers,
SGT