32v transformer suitable for gainclone?

Jerry Parker · 2nd July 2004, 05:15 AM

I've got an E core transformer from an old amplifier just sitting around (its in good condition) and was thinking I could use it to build a Gainclone. The amplifier was rated for 230watts power input so I figure that the transformer is large enough to power a gainclone. The only problem I see is that its secondaries voltage is around 30vac. After rectification and filtering, thats around 42 volts + and -42. Is that too high for the IC? If so, what (preferably easy

) methods are there to get the voltage back down to an acceptable level? I plan on driving 2 8ohm compression drivers with the amplifier, so it will rarely be pushed to max output levels.

Thanks!

aHobbit · 2nd July 2004, 05:20 AM

42Vdc is max allowed on LM3886, so this is fine. Using a regulator like the LM338 can bring down your usable Vdc to the 3886 to about 37Vdc.

Jerry Parker · 2nd July 2004, 05:57 AM

Well in another thread it says 42v is too high. So, what ways can I get the voltage down, if any?

Will · 2nd July 2004, 06:02 AM

42 volts is fine. Im using that voltage and liked the sound of my VBIGC. Just make sure your heat sinks are sufficient.

regards,
will.

MWP · 2nd July 2004, 06:46 AM

Quote:

Originally posted by Will
42 volts is fine. Im using that voltage and liked the sound of my VBIGC. Just make sure your heat sinks are sufficient.

2nd'ed.

I also run 42V... no problems in the 4 years since i built it.

aHobbit · 2nd July 2004, 09:01 AM

42Vdc will be quite too high if you intend to load it with a speaker lower than 8 ohms. However, as I said, if you want to lower it, for whatever reason it may serve you, you may use an LM338 regulator, and it can give you 32Vdc highest.

meta · 2nd July 2004, 09:48 AM

my txs' secondaries are also 30VAC - i posted a psu schem in this thread: regulated psu for gc yesterday which -I think- is okay...

hth

peranders · 2nd July 2004, 09:57 AM

Quote:

Originally posted by Jerry Parker
I've got an E core transformer from an old amplifier just sitting around (its in good condition) and was thinking I could use it to build a Gainclone. The amplifier was rated for 230watts power input so I figure that the transformer is large enough to power a gainclone. The only problem I see is that its secondaries voltage is around 30vac. After rectification and filtering, thats around 42 volts + and -42. Is that too high for the IC? If so, what (preferably easy ) methods are there to get the voltage back down to an acceptable level? I plan on driving 2 8ohm compression drivers with the amplifier, so it will rarely be pushed to max output levels.

Thanks!

I think it will do but as you know it's just about on the edge.

Note also if you have no input signal the max voltage is 94 volts (2 x 47) so if you play a little the voltage probably will drop a bit.

If you had a toroid transformer the max voltage would have been 2 x 30 VAC. The normal max voltage is 2 x 28 VAC.

2nd July 2004, 05:15 AM	#1
Jerry Parker diyAudio Member Join Date: Apr 2003 Location: Tulsa, OK	32v transformer suitable for gainclone? I've got an E core transformer from an old amplifier just sitting around (its in good condition) and was thinking I could use it to build a Gainclone. The amplifier was rated for 230watts power input so I figure that the transformer is large enough to power a gainclone. The only problem I see is that its secondaries voltage is around 30vac. After rectification and filtering, thats around 42 volts + and -42. Is that too high for the IC? If so, what (preferably easy ) methods are there to get the voltage back down to an acceptable level? I plan on driving 2 8ohm compression drivers with the amplifier, so it will rarely be pushed to max output levels. Thanks!

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2nd July 2004, 05:20 AM	#2
aHobbit diyAudio Member Join Date: Jun 2004 Location: Quezon City	42Vdc is max allowed on LM3886, so this is fine. Using a regulator like the LM338 can bring down your usable Vdc to the 3886 to about 37Vdc.

2nd July 2004, 05:57 AM	#3
Jerry Parker diyAudio Member Join Date: Apr 2003 Location: Tulsa, OK	Well in another thread it says 42v is too high. So, what ways can I get the voltage down, if any?

2nd July 2004, 06:02 AM	#4
Will diyAudio Member Join Date: Sep 2001 Location: Kuala Lumpur	42 volts is fine. Im using that voltage and liked the sound of my VBIGC. Just make sure your heat sinks are sufficient. regards, will.

2nd July 2004, 09:01 AM	#6
aHobbit diyAudio Member Join Date: Jun 2004 Location: Quezon City	42Vdc will be quite too high if you intend to load it with a speaker lower than 8 ohms. However, as I said, if you want to lower it, for whatever reason it may serve you, you may use an LM338 regulator, and it can give you 32Vdc highest.

2nd July 2004, 09:48 AM	#7
meta diyAudio Member Join Date: Nov 2002 Location: London	my txs' secondaries are also 30VAC - i posted a psu schem in this thread: regulated psu for gc yesterday which -I think- is okay... hth

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