@jea48
I am in the USA
I will talk to the electrician when he comes back from vacation to find out what exactly he did, I may say things that are misunderstood since I am no electrician by any means, but for what I know is that I have an isolated 20 amp outlet that has it's own grounding and that's pretty much all I know and I know that there is a copper poll in the ground by the outside electrical wiring. I can tell you more once I talk to him. |
You got a bit of bad advice.
Mechanical transformer hum comes from having DC on the AC line.
Isolated lines or ground do not help you.
First check your AC for DC. An electrician should do this.This can be caused by lights and dimmers elsewhere in the home, so you may diagnose this by shutting off everything but your amp.
Fixes include:
- Switching to other phase
- Using a balanced power conditioner.
Most power conditioners are not balanced so won’t help.
Best,
E
|
@erik_squires
But what makes one transformer to buzz but another not. Wouldn't you think that when you spend this kind of money for an amp to be quite even if there is a little DC offset in the AC line, plus there was another guy that said there is no such thing as DC in AC line, so which advice should I go for.
Even my electrician was confused as to what I was trying to fix, and when I told him how much money I paid for the amp he was laughing his arse off.
He was trying to make me happy and do whatever I asked him to do even though he did not wanna do anything because everything looked fine to begin with.
|
@ tomiiv30 As for DC on the AC mains. Nelson Pass
If you are experiencing mechanical hum from your
transformer, it is often caused by the presence of
DC on the line. Usually this comes from some appliance
using current asymmetrically, such as a lamp dimmer.
The hum comes usually from toroidal transformers, which
saturate easily with DC, and when they recover, they
draw an extra pulse of current, causing the noise.
You can put a pair of back-to-back electrolytics in series
with the AC power line to block this, and it works fine.
Makes sure the current rating of the electrolytics is
high enough, and the they are joined at a like polarity,
such as + to +. https://www.diyaudio.com/forums/solid-state/2080-dc-filter.html Re: Not trying to start a flame but.... "If your not comfortable with a meter get an electrician or tech that knows his way around test equipment. " If you read the comments in the AA archives, you would have seen the ones from real engineers (Jon Ricsh, John Curl, etc)who have measured this. They report that most hand held DVMs cannot measure this (John Curl tried three different Fluke models with mixed results). If you really want to try and measure the DC off-set on your AC line with a cheap hand-held DVM, try the following: Put a 100K resistor in series with a 100µF cap (this is called an integrator). This now goes in parallel with the AC line. Measure the DC voltage across the cap. Even a few tens of mV DC off-set can make a toroid buzz, especially low priced ones. The image here is a PA Audio DC blocker. Note the two series connected bridges, this gives four forward diode drops vs the two of the Bryston circuit. Note also that the caps in parallel with the diodes are very small, just for RF suppression. The original LC Audio filter was similar to this PA Audio one as well, only they used three forward diode drops, and only small RF caps.
http://db.audioasylum.com/mhtml/m.html?forum=tweaks&n=140383&highlight=integrator+djk&r=...JMHO, if the mechanical buzzing on one of the transformers is caused by DC on the AC mains, then both transformers would be buzzing. . |
Not all transformers will respond the same. Try taking the amp to another building and see what happens.
|
