which chip for my transformer

dre · 24th June 2008, 09:53 AM

Hi, another which chip question:

I've bought a transformer of plus and minus 16Volt.

Which chip should I use for my gainclone with this transformer: LM3875, LM1875 or other?

DC Dave · 24th June 2008, 11:27 AM

First, how big is the transformer?

The voltage will work with either chip. I would try both 1875 and 3875. It will only cost an extra $20 or so to test out which you like better. The transformer is usually the most expensive part. Build a couple amp modules and compare them.

dre · 24th June 2008, 02:21 PM

The transformer is rated 5 Ampere
So 32 * 5 = 160VA

Nordic · 24th June 2008, 02:32 PM

That is ok for LM1875...

AndrewT · 25th June 2008, 09:44 AM

most of the chipamps will run well from a 160VA 16-0-16Vac transformer.
You could even wire up a two channel amp from this transformer.

korben69 · 26th June 2008, 11:18 AM

Hi jacking the thread....

So a 330Va - 2x18v is suitable with LM3886 too ?
Thanks

AndrewT · 26th June 2008, 11:21 AM

Quote:

Originally posted by korben69
Hi jacking the thread....
So a 330Va - 2x18v is suitable with LM3886 too ?
Thanks

yes, look up the datasheet.

amo · 7th July 2008, 05:15 PM

Any suggestions on how to use 30-30 output trans (460VA) for 3886 or 3875? I can get these for USD $35!! besides, major outlets have a standard config of 30-30... I was planning to run several modules from such a tranni.

AndrewT · 7th July 2008, 05:37 PM

I suggested 28Vac as the maximum for 3886 on moderate 8ohm speakers, but some came back saying 25Vac was a more sensible maximum.

wg_ski · 7th July 2008, 05:41 PM

+/-42 a bit high for a chip amp, but you can add a few turns of #14 THHN and put it in series with the primary - that will drop or raise the output depending on polarity. You could add turns to the secondaries, but that's a bit tricky if they need to be well balanced.

BTW - those are some nice trafos that Tanners has. GET THEM BEFORE THEY ARE GONE. That's not a threat, it's a promise

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24th June 2008, 09:53 AM	#1
dre diyAudio Member Join Date: Mar 2002 Location: Netherlands	which chip for my transformer Hi, another which chip question: I've bought a transformer of plus and minus 16Volt. Which chip should I use for my gainclone with this transformer: LM3875, LM1875 or other?

24th June 2008, 11:27 AM	#2
DC Dave diyAudio Member Join Date: Feb 2004 Location: Washington DC	First, how big is the transformer? The voltage will work with either chip. I would try both 1875 and 3875. It will only cost an extra $20 or so to test out which you like better. The transformer is usually the most expensive part. Build a couple amp modules and compare them.

24th June 2008, 02:21 PM	#3
dre diyAudio Member Join Date: Mar 2002 Location: Netherlands	The transformer is rated 5 Ampere So 32 * 5 = 160VA

24th June 2008, 02:32 PM	#4
Nordic diyAudio Member Join Date: Sep 2005	That is ok for LM1875...

25th June 2008, 09:44 AM	#5
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	most of the chipamps will run well from a 160VA 16-0-16Vac transformer. You could even wire up a two channel amp from this transformer.

26th June 2008, 11:18 AM	#6
korben69 diyAudio Member Join Date: Nov 2006 Location: Near Lyon	Hi jacking the thread.... So a 330Va - 2x18v is suitable with LM3886 too ? Thanks

7th July 2008, 05:15 PM	#8
amo diyAudio Member Join Date: Apr 2003 Location: Texas - USA	Any suggestions on how to use 30-30 output trans (460VA) for 3886 or 3875? I can get these for USD $35!! besides, major outlets have a standard config of 30-30... I was planning to run several modules from such a tranni.

7th July 2008, 05:37 PM	#9
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	I suggested 28Vac as the maximum for 3886 on moderate 8ohm speakers, but some came back saying 25Vac was a more sensible maximum.

7th July 2008, 05:41 PM	#10
wg_ski diyAudio Member Join Date: Oct 2007	+/-42 a bit high for a chip amp, but you can add a few turns of #14 THHN and put it in series with the primary - that will drop or raise the output depending on polarity. You could add turns to the secondaries, but that's a bit tricky if they need to be well balanced. BTW - those are some nice trafos that Tanners has. GET THEM BEFORE THEY ARE GONE. That's not a threat, it's a promise