possibly off topic, but don't know where else to go -> voltage conversion

[davet11]

I have asked this question on recording forums, electronics forums, etc. but have not been provided with an answer that solves my problem.

I have recently moved from Canada (110v/60hz) to the Czech Republic (230V/50hz). Before I left, I managed to swap all of te appliances, power supplies, whatever, for items that had an integrated voltage transformer. Except for my 2 studio speakers.

Here is a link to the speakers:

http://www.prorec.com/prorec/articles.n...21e22c67e86256ae1000fa82a?OpenDocument

http://www.zzounds.com/item--EVE2020V2

Unfortunately I can't find a very good link with the specs, but each speaker is 200W.

I was unwilling to part with these, even though they are no longer top of the line, I still love them. I decided to buy a large capacity transformer in the hopes of using them here in the Czech Republic. Here is a link to what I bought (except I bought the 750W version):

http://tinyurl.com/8ekch

Now, my speakers are giving off a pretty noticeable buzz when I have them plugged in. And with me spending the past 6 months trying to make my PC as quiet as possible, the buzz is driving me insane.

What I need to know is:

1) is there any 'mid line' solution that I can buy to eliminate the buzz, like something that I could plug in in-between the converter and the speakers.
2) is there any solution period???
3) should I just sell these off and get something with an integrated converter?

Hopefully I can get some help here, or else off to trying to find answers elsewhere.

Thanks!

 

[BrownTown]

transformers only change the voltage of the power, not the frequency. So if your running something where the frequency of the power matters then you are screwed becasue changing frequncies is hard.

 

[davet11]

Originally posted by: BrownTown
transformers only change the voltage of the power, not the frequency. So if your running something where the frequency of the power matters then you are screwed becasue changing frequncies is hard.

Agreed, but since these are just speakers, and not something with a motor in them (aka turntables, hair dryers, etc.) that shouldn't matter as far as I know.

 

[dkozloski]

This sounds like a grounding problem. If the transformers you bought are of the autotransformer variety you might get some relief by swapping the leads. Otherwise make sure everything is grounded to a common point with no ground loops.

 

[OrganizedChaos]

probably a stupid suggestion but what about doing this: Czech power>Czech Batterycharger>Deep cycle battery>Canadian powerinverter(not sure if you can get away with a modified sine wave here)>Canadian Power>Speakers

 

[Bassyhead]

dkozloski is probably right, you probably have a grounding problem. If you look in the manual for these speakers, on the specs for the power requirements:

Factory programmed for either 120V~ 60Hz,
220-240V~ 50/60Hz or 100V~ 50/60Hz, 200VA;
Power via detachable 3 circuit IEC type linecord

Since these speakers are sold in areas that utilize 220-240 50/60Hz power, the frequency does not matter. Actually, if you have any kind of electronics knowledge and the confidence, you can look inside the speakers to see if there is wiring that sets the voltage input. Oftentimes, the same power transformer is used in products to be used in different power markets and only the way the primary of the transformer is wired is changed. If you did this yourself, you would eliminate the need for a step up/down converter. You just need to change how the transformer attaches to the power input, but be sure you know what you're doing because connecting 230V to a lower voltage input on a transformer may damage or destroy the speakers.

 

[davet11]

Originally posted by: Bassyhead
dkozloski is probably right, you probably have a grounding problem. If you look in the manual for these speakers, on the specs for the power requirements:

Factory programmed for either 120V~ 60Hz,
220-240V~ 50/60Hz or 100V~ 50/60Hz, 200VA;
Power via detachable 3 circuit IEC type linecord

Since these speakers are sold in areas that utilize 220-240 50/60Hz power, the frequency does not matter. Actually, if you have any kind of electronics knowledge and the confidence, you can look inside the speakers to see if there is wiring that sets the voltage input. Oftentimes, the same power transformer is used in products to be used in different power markets and only the way the primary of the transformer is wired is changed. If you did this yourself, you would eliminate the need for a step up/down converter. You just need to change how the transformer attaches to the power input, but be sure you know what you're doing because connecting 230V to a lower voltage input on a transformer may damage or destroy the speakers.

I have contacted Event about this actually and I would need to order a replacement part for the speakers which they advised me would cost around the same as a new set. Is there any way to troubleshoot a grounding problem so that I could be sure that that was the problem? How could I solve it?

 

[Bassyhead]

I don't know the model converter you're using because your link doesn't work anymore (post the brand and model # instead). If you can switch the polarity try that.

 

[davet11]

Sorry here is the one I am using:

http://bargainoffers.com/catalog/product_info.php?products_id=154

the model number is THG-750U/D

 

[OrganizedChaos]

another stupid idea: if it is a grounding problem how about disconnecting the speakers ground wire from the converter and hooking it straight to a waterpipe.

 

[herm0016]

use a ohm meter between the ground on the speakers and the ground on the transformer, should have a reading of 0. and use a volt meter between your ground and a known good ground to test for a ground loop problem

 

[Bassyhead]

I don't know much about international power plugs, but it looks like you can plug the European one either way. Try switching it around if you haven't done so already. Also, looks there's no ground prong on an European plug/receptacle.

I'm assuming you flipped the switch on the power supply of your computer to 230V over from 110V. If you want to try something, try plugging your computer into the converter along with the speakers (of course switching the power supply to 110V from 230V first). This will allow you to run everything off the same source and see if the buzzing noise lies in the design of the transformer itself or a grounding problem like dkozloski suggested. You should be able to eliminate any problems that should arise from using different power sources. 750 watts should hopefully be enough for your speakers and computer just to temporarily experiment with.

 

[bobsmith1492]

Since you're running at a lower frequency input, there will be more ripple on the output of the power supply in the amp, resulting in more noise on the output of the amp. You could get some bigger filter caps if you want; that might be the only way to fix it. Also, try isolating your input signal; if it shares a common ground, you could be getting some strange ground return along your input signal resulting in a lot of noise.

EDIT: I noticed that is supposedly a "cheap" amp (although it doesn't look like it to me! ). That means they likely used cheaper/lower capacitance filter caps, as they are a good chunk of the cost of an amp, which reinforces the idea that the power supply ripply increased with the lower frequency.

 

[davet11]

Originally posted by: bobsmith1492
Since you're running at a lower frequency input, there will be more ripple on the output of the power supply in the amp, resulting in more noise on the output of the amp. You could get some bigger filter caps if you want; that might be the only way to fix it. Also, try isolating your input signal; if it shares a common ground, you could be getting some strange ground return along your input signal resulting in a lot of noise.

EDIT: I noticed that is supposedly a "cheap" amp (although it doesn't look like it to me! ). That means they likely used cheaper/lower capacitance filter caps, as they are a good chunk of the cost of an amp, which reinforces the idea that the power supply ripply increased with the lower frequency.

Hmm, well, the speakers are self-amplified, so I'm not sure if there is any way i could resolve the problem that you suggest?

 

[bobsmith1492]

If you open it and find the amplifier/power supply, you probably could. They're easy to find - the biggest cylindrical doohickies in the amp.

 

[davet11]

I've narrowed it down to a problem in the transformer, could anybody suggest a decent quality transformer that I could use for this application?

 

[bobsmith1492]

How do you know it's the transformer? You'd have to figure out what output voltage you need. Ebay has some good ones usually; look up toroid and there's one guy who always has a ton of them (toroidal transformers - the best kind for amps.)

 

[davet11]

Originally posted by: bobsmith1492
How do you know it's the transformer? You'd have to figure out what output voltage you need. Ebay has some good ones usually; look up toroid and there's one guy who always has a ton of them (toroidal transformers - the best kind for amps.)

The converter gives off a slight hum when plugged in, as soon as I plug the speaker in, the frequency hum coming from the speaker is the same as from the converter. I don't think the converter was really meant for audio applications.