Where in Brisbane can I get a transformer for my Chinese amp - diyAudio
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Old 15th February 2008, 12:17 AM   #1
data is offline data  Australia
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Default Where in Brisbane can I get a transformer for my Chinese amp

I have a EL84 integrated amp purchased from Hong Kong, and it has 220v mains input, at the moment I am using a stepdown transformer in order to use it.

Who in Brisbane can replace the power transformer in it so I can run direct from our 240v mains?

It might have a weaker left channel compared to the right also, that I would like looked at.

Thanks
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Old 15th February 2008, 02:23 AM   #2
mach1 is offline mach1  Australia
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Getting a 240v transformer with the same specifications and mounting footprint as the original is going to be extremely difficult, if not impossible. Your best bet is probably a Hammond 300 series, but their cost in Oz ($270 - 350) is probably around what you paid for your entire amp.

As an alternative you could try running it straight into 240v and putting in voltage dropping resistors for the filaments. If the amp has a tube rectifier, you could try replacing the original with one that drops a bit more voltage. However, reliability could be a big issue, as Chinese amps are not well known for using overspecified transformers.

Continuing to run it with the stepdown may be your best option.
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Old 15th February 2008, 04:25 AM   #3
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Default mach1

Thanks for the run down on possibilities, yeah the amp was only $290AU shipped, so I agree that a new transformer would be bad economics at those prices.

Wish I had enough understanding to build one from scratch.

Cheers
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Old 17th February 2008, 12:04 AM   #4
rastus is offline rastus  Australia
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Evatco are in Rosewood but are mail order only.

http://www.evatco.com.au/hamptprice.htm

I recently ordered a R0080-043 240V R-core transformer (should be suitable for a EL84 amp) for AUS$76 including EMS shipping (3-5 days) from:

http://www.vt4c.com/shop/program/mai..._id=7&hit_cat=
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Old 17th February 2008, 12:25 AM   #5
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Default Chinese amp transformer

Hi
Get yourself a transformer with a secondary winding of the voltage you wish to remove ie 10 voltsabout 3 amps should do and connect it in bucking fashion.you will find out how to do this on Triode Systems web page.
Regards David
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Old 17th February 2008, 04:43 AM   #6
data is offline data  Australia
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Thanks guys

I'm very new to doing modifications, so I sometimes get lost on what is needed to be done

I'll defiantly look at those options, and post anything I'm unsure about, I'm waiting for a schematic from the guy I bought it off.

By the way, this is a Mengyue Mini
http://i8.photobucket.com/albums/a19/df69/Inside.jpg
http://i8.photobucket.com/albums/a19...08-07_2116.jpg
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Old 17th February 2008, 08:47 AM   #7
rastus is offline rastus  Australia
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Thank you for posting those photo's !!

I have seen these on ebay and in China a few times. I have been thinking of buying 2 or 3 as a basis for a valve surround sound system but every time I go there I end up with too much luggage already (read: parts and stuff the missus wanted).

For the price you paid, especially the external cosmetics and the fact it is a valve stereo amp, it is a bargain.

As mach1 stated, if you don't have much modification or amp building experience, you may well be better off using a step down transformer.

From the underside view it is fairly obvious that it is built to a cheap price and fast assembly (but that doesn't necessarily mean it has a cheap amp sound, some of the parts used don't look too bad at all), but, having said that, I wouldn't really recommend running it at 240V.

It looks like it might have some fairly dodgy solder joins as well. It might be worth getting someone experienced in soldering to touch them up for you and maybe fix up the wiring.

Probably the first thing to do if you want to replace the power tranny with a 240V one is to get someone experienced in amp building/modification to measure the power parameters.....measure the physical size of the power tranny including bolt spacings and go from there. The biggest problem is that these are probably built in lots of 100's and 1000's for the amp manufacturer.

It is possible to get trannies custom made in China, particularly Shenzhen, reasonably cheaply. I have had some made there as one off's before. If you know someone who speaks Mandarin or Cantonese, it is easy to get a quote from a lot of places there.

If you don't...perhaps try Harbuch's
http://www.users.bigpond.com/harbuch/
They make very high quality transformers and can modify existing ones.
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Old 17th February 2008, 09:50 AM   #8
data is offline data  Australia
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Thanks rastus

I have a friend that is very good, he put those big Teflons in, and the bypasses with the oils on the driver valve caps, as well as the ground wire. (made a very noticeable difference in the sound)

The photo below is it in It's original state.
http://i8.photobucket.com/albums/a19...07-07_2053.jpg

I haven't heard from him for a time so I thought I would get help from here.

Only real issue of a sonic nature needing to be corrected is a difference in the volume levels of the two channels, the left is noticeably lower than the right, this puts the sound stage out of whack. I have no clue where to start in finding this fault.


Any particular points where the solder looks sus?

Is it a complex or difficult thing to measure the power parameters of the power transformer?

edit: Typo fixed at request of poster by dhaen
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