Power Conditioner for 15amp Amp

[Sithlord]

Hi all. I am getting a constant hum from my Krell TAS amp whenever a train goes by. I'm close to a train depot and every time a train goes by the amp makes a hum noise and then disappears. I want to know if there is a power conditioner out there that caters for a 15amp connection (Australian). I dont need many outlets as I will be only using one. The hum doesn't appear to effect sound it's just annoying. I've searched on the net but haven't had much luck. Any suggestions would be very much appreciated.

[whoaru99]

...The hum doesn't appear to effect sound it's just annoying...

It's a hum emanating from the amp itself; not through the speakers?

[David Meek]

I am getting a constant hum from my Krell TAS amp whenever a train goes by.

Okay Simon, you win the prize for most unique problem this week (or last week even).

Your amp is reacting to a large near-by moving mass of metal. How close are the tracks to your room? Close enough that the trains cause heavy vibrations? Have you tried other amps in the same location, and if so was there a similar problem? I'm just trying to figure out the cause here, and wondering if a power conditioner is the answer.

[Kevin P]

If the hum is coming from the speakers, it is probably coming from the power lines. Diesel trains are really electric trains - the diesels run generators which produce electricity that makes the train move. As a result, they produce a lot of EMI. The power lines are likely picking up the EMI from the train, especially if the lines run near/over the tracks.

In this case, a good power conditioner w/EMI filter should help.

[JonMarsh]

If the hum is coming from the amps, it's probaby due to a short term drift in the neutral line from strictly being at DC- though I don't know why that would happen from the train. When that occurs, even just 100 mV or a little more, the flux in a toroidal core transformer gets unbalanced, and the primary magnetizing inductance drops off at the peak of the AC line, causing a rise in the input current, which increases the flux, and through magnetorestrictive effects, causes phsyical vibration of the core and windings.

Why would 100 mv or more do this? The DCR of large torroidal transforms is quite low- anything putting a DC bias voltage will create an offset in the flux balance. Toroids are usually design for compact weight and size, and have a smaller core than EI types, which means the core flux can be driven close to saturation much more easily if there's an externally caused imbalance. Look at the DCR rating of 1 KVA or larger Plitron transformers, then take as little as 300 mV and devide by that DCR to get the current imbalance.

I use a DC blocking input filter on my own designs and upgrades, and some outfits actually sell those as kits, like LC Audio.

[Sithlord]

Thanks for your responses. Ok first theres no hum from the speakers only from the amp. I'm within 1km from the station and no the trains (Not Diesel) dont cause my unit (house) to vibrate I'm not that close. I'm not 100% sure if it's entirely the trains passing that causes it as it has a very light hum when there are no trains going by,it just gets louder when one does. Theres a service depot right where the station is where they work on them as well. The rest on my equipment is plugged into a power board/conditioner but the Krell is plugged directly into the wall. I dont have seperate power running my system so it shares it with the fridge which is the only thing running all the time on the same circuit. I've waited until the fridge clicks over (if thats what you call it) and that doesn't effect the amp at all. The only constant is the passing of a train that makes the hum louder. I would like to connect the Krell into a conditioner to eliminate any EMI/RFI just to cover that aspect.

David I have owned the Rotel 1095 and that as well had a constant hum to it. I sold that to a mate who doesn't have the hum problem. At the time of ownership the service depot wasn't there.


JonMarsh the only thing missing from your post is MARTY lol. Thank you all for your ideas but it still leaves me with what conditioner can I buy that supports a 15amp recepticle (wall input for Australian users)?

[Patt]

Try an internet (Google) search for power conditioners...or LC Audio as Jon mentioned.

Maybe (Richard Gray) or (Brickwall) companies have something for you...?...They are in the electrical product business.

Good Luck.

[Clive]

From the sounds of it...........you may have to do whole home conditioning along with a local unit.

[mitch57]

Sithlord,

It sounds like you have the exact same issue that I have. I have train tracks within a mile or so of my house. Although I haven't noticed my hum getting any louder when the train goes by I do have a constant hum coming from my amp.

I have the Rotel RMB 1095 and it has a slight hum/buzz almost all the time. Sometimes it buzzes louder then it does at other times. I haven't been able to pin point what causes it to get louder or for that matter what causes it to buzz in the first place.

I've considered taken it in to my dealer to see if it hums when they plug it in. My dealer is located 75 miles south of where I live so that should ensure that it's on a different power grid.

As far as a power conditioner eleviating the problem... I doubt it. I have my 1095 plugged into a Richard Gray power conditioner and it still hums/buzzes.

Since you sold your 1095 which hummed/buzzed at your house and didn't at the persons house you sold it to, I would conclude the problem is with the power in your home or the power grid you are on.

Mitch

It appears I have the same problem. Please let me know if you ever find a solution to this problem. There's at least one other person on this forum that has the same issue that you and I are having and I'm sure he would like to know if a fix is available as well.

[Anton]

An all Oz solution

Sithlord,

I've been chatting to a local group in Brisbane about power conditioning and protection units from Surge Shield (they have come up in this forum before).

They sell power boards, in wall cavity units and DIN rail units that come with active voltage tracking and filtering to keep the power clean and steady.

I've just purchased a new home and have been talking directly to them about putting in a dedicated circuit for my HT and they love a challenge.

The CM90 is a good solution to your problem if you want real all 'round protection and filtering, it mounts in your wall cavity (link below) they sell for AU$395 and will have to be installed by an electrician.

http://www.surgeshield.com.au/cm90.htm

I really recommend speaking to the guys at Surge Shield, have a chat to:

Roy Stokes
Director Technical & Training
0410 493 000

or

George Forster-Jones
National Sales Manager
0438 438 210

If they don't have the answer they will get the R'n'D dept to track one down for you.

Good luck

[Sithlord]

Anton that sounds like the solution for me. I currently own their A2 power board which Aussie Geoff from this forum recommended to us and I'm extremely happy with it. I will enquire more information from the contacts you have provided and again thank you for informing me of this. I'm currently renting so I hope the device can be removed when I leave. I will let you know how I go.

[Anton]

Sithlord,

You will be able to take it out no probs when you move if you use a sparky to do the work.

Good luck the guys at surge shield are fantastic!

[mitch57]

Sithlord,

Please let us know if that solves the hum/buzz problem.

[Sithlord]

Mitch you can count on it. I read your thread regarding the buzzing your having with your 1095 very frustrating. When I owned the 1095, I had the buzzing from day one to when I sold it. It never seemed to effect sound but I did have a slight buzzing from my speakers which I dont get with the Krell. Like you my amp can be dead quite particulary on weekends as there are less trains. But come Monday it's back to buzzing all the time. It's a public holiday today (Monday) and the amp is dead quite. As soon as it starts I listen and sure enough a train is going through the station then it goes back to being silent. I hope this surge shield will rectify my problem but at $395 plus Electrician costs it will have to wait a month or so. I will keep you posted if it becomes sooner.

[Anton]

Eh Sithlord,

Why don't you try your A2 with the amp first befor going and spending the cash on the cavity unit and labour. The filter is exactly the same for both products, this a quick experiment will tell you if the cavity unit will be a winner. Might save you $500.

[Sithlord]

Anton that option is not available to me as the Krell users a 15amp connection meaning that the 3rd pin is larger than the ones used on most electrical devices which are 10amp. Believe me if it was that simple you can count on it that I would have tried. I had to get an electrician to install a 15amp wall socket just so I could plug the amp in hence no power board. The link below shows a 20amp female plug and thats what mine looks like when you plug the cord into the Krell. I couldn't find a 15amp male one to show you. As you can see it's different than the one you use for your 1095.

http://www.dedicatedaudio.com/inc/pdetail?v=1&pid=2759

This is why I'm having trouble trying to find a power filter to cater for a 15amp connection. Your suggestion (Surge Shield) is the best that has been offered so far but it's going to have to wait unfortunately.