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Old 28th February 2009, 05:57 PM   #1
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Default PC Gainclone with 14V Toroid

Hi guys,

I just spent some thoughts about getting some Gainclone inside my fathers Computer. He's got a pair of CT193, see here:
http://www.lautsprechershop.de/hifi/ct193.htm

But no amp.

I've got a Case from an ATX PSU unit here, but it won't fit anywhere in the cramped Computer.

Now I found an old CD-Rom with broken off loading plate.
The Metal is about 1mm thick (Plextor quality ) so I think it should be sufficient as a radiator.
I've got some nice 2x14V / 30VA Toroids here, they fit EXACTLY. But more than one will be really difficult to fit in there.

Will a single 30VA Toroid be strong enough? How much power do I get from +-20V DC?

Of Course this is not High End, but do I sacrifice sound quality by running the LM3886 or 4780 with such a low voltage?
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Old 28th February 2009, 06:55 PM   #2
Minion is offline Minion  Canada
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For a 30va at 14v I suggest the TDA2040 or LM1875 which can put out over 20w at +/-20v dc but at 30va would only power one channel , you would have to use 2 transformers or have a much lower output power....These chips are also very cheap to buy...

You could allways put the power supply in a different box....


Cheers
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Old 28th February 2009, 07:00 PM   #3
star882 is offline star882  United States
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You could use a DC/DC converter to run it from the existing PC power supply.
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Old 28th February 2009, 08:22 PM   #4
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Default Re: PC Gainclone with 14V Toroid

Quote:
Originally posted by Bassterror
Will a single 30VA Toroid be strong enough? How much power do I get from +-20V DC?
You will only have 20 V with no load. When the PSU is loaded you can expect about 10-11 W output power per channel with those 8 Ohm speakers. A 30 VA transformer will be sufficient.

Quote:
Originally posted by Bassterror
do I sacrifice sound quality by running the LM3886 or 4780 with such a low voltage?
No. Nevertheless an LM1875, TDA2030-2052 (mono) or LM1876 (stereo) will be fine for that task.
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Old 28th February 2009, 09:12 PM   #5
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Hi,

thanks for your replies.

LM1875 and 76 are fine but hard to get here, and no, please no car radio amp. Could run fron the atx 12V line, but i don't like the idea.

I have those 3886 here on my desk, so why not using them.

I just tied to fit 2 Toroids and, well, it would fit. I hope 10cm distance between Chips and toroids won't create any hum.

IF I use one Transformer per Chip, and someone uses a 4Ohm speaker, what do you think will happen?

Just flat bass or smoking toroids?
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Old 28th February 2009, 10:16 PM   #6
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Quote:
Originally posted by Bassterror
IF I use one Transformer per Chip, and someone uses a 4Ohm speaker, what do you think will happen?

Just flat bass or smoking toroids?
Neither. One 30VA transformer is just the right size for the ~24 W you would get with 4 Ohm from an LM3886. Flat bass would be a consequence of too small smoothing capacitors.

Use a bigger heatsink for stable 4 Ohm operation.
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