High-End Regulated Buffered Inverted GC - Page 3

ebijma · 9th June 2004, 09:03 PM

Have still one question about the tube buffer.
I want to regulated the supply of it to.
Think the LM317 will do the job, or do some of you have
a better idea?

Thanks

carlosfm · 10th June 2004, 02:05 AM

You can use the LM317.
But then, you'll need a transformer at around 2x27~2x30v, because you're regulating at 35v for the buffer.

bequerel · 10th June 2004, 03:51 PM

Quote:

Originally posted by jackinnj

I(pk) with 31 V rails wll be 3.4 Amps according to the National Semi interactive chipamp tool. http://www.national.com/appinfo/audi...gn_Guide14.xls
At best this will cause the regulators to shutdown, at worst, it will blow your regulators.

There is no need for regulating the chipamp power supply.

So if I go dual mono, with two regs per channel (one for plus and one for minus), how much current must each of the four regulators be able to handle?
3.4 amps divided by 4?

jackinnj · 10th June 2004, 04:29 PM

Quote:

Originally posted by bequerel

So if I go dual mono, with two regs per channel (one for plus and one for minus), how much current must each of the four regulators be able to handle?
3.4 amps divided by 4?

Each mono-channel is going to draw 3.4 amps, peak, into an 8 ohm load. If your load is lower impedance (which it usually is in real life) the current will be greater. The math is all worked out for you in the form of an Excel spreadsheet on Nat Semi's website.

I would like to see the square wave or pulse response of a regulated GC vs a non-regulated flavor.

carlosfm · 10th June 2004, 06:31 PM

You're talking about absolute maximum current and this is not a class A amp, an music is not a continuous tone!
The LM338 handles 12A absolute maximum, enough for two LM3875 or LM3886 chips, and MUCH better than with an unregulated PSU with 1000uf per rail (the compromise this chips need to sound good).
IMHO and whatever.

Talking just by theory may be misleading.
Try it.

tbla · 10th June 2004, 07:22 PM

carlos - try the lt1083...with 470uF on the output and 0,1uF on the 3886.........

carlosfm · 10th June 2004, 08:18 PM

tbla, I've searched on the usual places here in Lisbon and I cannot find the LT1083.

carlosfm · 10th June 2004, 08:26 PM

I'm receiving personal mails to send the schematic, so I post it here.
It was made with ExpressSCH, so no pinout for the LM3886, and the 78L18 has the pinout corrected by me.

Here it is.

tbla · 10th June 2004, 09:01 PM

http://www.rs-portugal.com and search for lt1083......

carlosfm · 11th June 2004, 12:13 AM

Gee, thanks.

Actually they are from Spain, have a site in portuguese but any store here...
I didn't search everywhere here, just two places, gonna search a little more and if I can't find them, I'll order online (not a thing I like to do...).
Thanks tbla.

9th June 2004, 09:03 PM	#21
ebijma diyAudio Member Join Date: Mar 2004 Location: Huizen	Just one question Have still one question about the tube buffer. I want to regulated the supply of it to. Think the LM317 will do the job, or do some of you have a better idea? Thanks

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10th June 2004, 02:05 AM	#22
carlosfm Banned Join Date: Mar 2003 Location: Lisbon, Portugal	You can use the LM317. But then, you'll need a transformer at around 2x27~2x30v, because you're regulating at 35v for the buffer.

10th June 2004, 06:31 PM	#25
carlosfm Banned Join Date: Mar 2003 Location: Lisbon, Portugal	You're talking about absolute maximum current and this is not a class A amp, an music is not a continuous tone! The LM338 handles 12A absolute maximum, enough for two LM3875 or LM3886 chips, and MUCH better than with an unregulated PSU with 1000uf per rail (the compromise this chips need to sound good). IMHO and whatever. Talking just by theory may be misleading. Try it.

10th June 2004, 07:22 PM	#26
tbla diyAudio Member Join Date: Jul 2002 Location: denmark	carlos - try the lt1083...with 470uF on the output and 0,1uF on the 3886.........

10th June 2004, 08:18 PM	#27
carlosfm Banned Join Date: Mar 2003 Location: Lisbon, Portugal	tbla, I've searched on the usual places here in Lisbon and I cannot find the LT1083.

10th June 2004, 09:01 PM	#29
tbla diyAudio Member Join Date: Jul 2002 Location: denmark	http://www.rs-portugal.com and search for lt1083......

11th June 2004, 12:13 AM	#30
carlosfm Banned Join Date: Mar 2003 Location: Lisbon, Portugal	Gee, thanks. Actually they are from Spain, have a site in portuguese but any store here... I didn't search everywhere here, just two places, gonna search a little more and if I can't find them, I'll order online (not a thing I like to do...). Thanks tbla.

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