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PostPosted: 17 Jan 2010, 18:09 
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Joined: 25 Dec 2009, 16:44
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I have managed to get 4 x 120VA, single secondary 24V toroidal transformers. My idea was to use these for a power supply for a power amp of 50W into 8 Ohms. The total amount of 480VA for the transformers seems to be a little excessive, but I have them and they were cheap. The power amp modules are 24-48VDC so the voltage of the transformers should be ok. Is there any problem in using 4 smaller transformers as opposed to one larger unit?


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PostPosted: 18 Jan 2010, 14:21 
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Joined: 08 May 2009, 08:20
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Location: Duesseldorf, Germany
Hi and welcome,

it shoudn't be a big problem to use your transformers. Which amp modules do you plan to use? Do they need a symmetrical (+ and -) DC supply? It might be helpful to post some further informations ;-)

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Tom.

Some of my projects: TDA2050 Chip Amp, the LM3886 Gainclone Thread and the Szekeres Headamp Thread.


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PostPosted: 19 Jan 2010, 15:23 
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Joined: 25 Dec 2009, 16:44
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The amp modules are copies of Musical Fidelity X-A50 MK II's. I have two of these modules, each has a VEE- and VCC+ on the PCB. There does not appear to be any voltage regulation, I take it that this is normal?
I also have several 10,000uf caps, over the top yes, but cheap also. :-)

The PCB's look like this...

Image


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PostPosted: 20 Jan 2010, 01:41 
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Location: Duesseldorf, Germany
Hmm, nice boards ;-)

A voltage regulation doesn't make a sense on this "high power" amps.
The losses would be too high and a regulation would be a bit on the slow side (imho).

Now, a simple but useful way to use the transformers is to stick one transformer pair together, to get a V+ and V- supply with an Centre tapped ground. 2 transformers for 1 board... Your 10.000uF caps are ideal for an unregulated supply. You'll need 2 rectifier bridges for two supplies (One for one channel). Then you'll have the advantage of two monoblocks...
The current from each supply should be OK, to get enough power out of the boards.

Do you have an idea how to do this? Feel free to ask, if you need some more help!

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Cheers,
Tom.

Some of my projects: TDA2050 Chip Amp, the LM3886 Gainclone Thread and the Szekeres Headamp Thread.


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PostPosted: 20 Jan 2010, 15:37 
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Joined: 25 Dec 2009, 16:44
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Tom,
Your help is greatly appreciated. I have just found a transformer from an old Pioneer A605R, so I may use that, if the outputs are suitable.
Here is the PSU circuit that I shall be using.........

Image

Thanks to Dejan Veselinovic - TNT-Audio for this design.


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PostPosted: 21 Jan 2010, 01:06 
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Hi again ;-)

Dejan's supply is very good and nearly similiar to the often used layout from BrianGT...
The Dejan supply also has some very useful tweaks. You can't go wrong with it!

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Cheers,
Tom.

Some of my projects: TDA2050 Chip Amp, the LM3886 Gainclone Thread and the Szekeres Headamp Thread.


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