Turning a dead Class-A into a GC

mikejz84 · 28th March 2004, 04:55 PM

Here is the find: A 1/2 working SAE A-205 amp at a garage sale for $10. The bad news: The non-working channel is smoked, and will not be a fun repair. I am a GC virgin and want to know how much I would have to put into this to turn it into a nice GC (100wpc) amp.

Here is the pic of what I got

Bill Fitzpatrick · 28th March 2004, 05:04 PM

What you got is a 412K photo. I lost interest while it was loading.

mikejz84 · 28th March 2004, 05:10 PM

Quote:

Originally posted by Bill Fitzpatrick
What you got is a 412K photo. I lost interest while it was loading.

I guess what you don't have is broadband

bigparsnip · 28th March 2004, 05:22 PM

Try doing a search for bridge clone, as you have more than enough heatsinking there to get you going and plenty of room to fit in the transformer and other bits and pieces.

This thread may be a good place to start:

Bridgeclone

And national have an aplication note abou this topic which is probably worth you reading too.

http://www.national.com/appinfo/audi...ation_Note.pdf

And

http://www.national.com/an/AN/AN-1192.pdf

Bill Fitzpatrick · 28th March 2004, 05:40 PM

Quote:

Originally posted by mikejz84

I guess what you don't have is broadband

Having bloated photos partly defeats the purpose of broadband. Your pic resizes nicely to 57K and still makes the point.

sreten · 28th March 2004, 05:45 PM

You'll need to bridge to get decent output.

Personally I'd fix the (far superior) class A amplifier.

sreten.

Nuuk · 28th March 2004, 06:47 PM

I'm not sure if I would recommend a bridged Gainclone as a first project. Why do you want/need 100 wpc?

Try a plain vanilla Gainclone first and to get some idea of how to achieve that, take a look at a similar project of mine.

mikejz84 · 28th March 2004, 06:49 PM

I would use the amp to drive my NHT VT-2s, they are power ******. I Bi-amp them right now 75watts for the highs and 100watts for the lows, and still that is just enought.

Nuuk · 28th March 2004, 06:52 PM

Quote:

I would use the amp to drive my NHT VT-2s, they are power ******. I Bi-amp them right now 75watts for the highs and 100watts for the lows, and still that is just enought.

"******" is the right word

Get rid of them and build something efficient.

paulb · 28th March 2004, 08:27 PM

Other than bigparsnip, you folks have been much less than helpful. I say go for it. I'm currently thinking about changing an old Class AB to a Class A. Why not?
Nuuk's suggestion is a good one, if you haven't built much before. Maybe try a bare-bones, open-frame gainclone first, you could even power it from the SAE amp power supply. Then build the real one and go nuts.

28th March 2004, 04:55 PM	#1
mikejz84 diyAudio Member Join Date: Dec 2002 Location: sarasota, fl	Turning a dead Class-A into a GC Here is the find: A 1/2 working SAE A-205 amp at a garage sale for $10. The bad news: The non-working channel is smoked, and will not be a fun repair. I am a GC virgin and want to know how much I would have to put into this to turn it into a nice GC (100wpc) amp. Here is the pic of what I got

28th March 2004, 06:47 PM	#7
Nuuk diyAudio Member Join Date: Feb 2003 Location: Somerset, SW England	I'm not sure if I would recommend a bridged Gainclone as a first project. Why do you want/need 100 wpc? Try a plain vanilla Gainclone first and to get some idea of how to achieve that, take a look at a similar project of mine. __________________ The truth need not be veiled, for it veils itself from the eyes of the ignorant.

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28th March 2004, 05:04 PM	#2
Bill Fitzpatrick diyAudio Member Join Date: Jun 2001 Location: Eugene, OR	What you got is a 412K photo. I lost interest while it was loading.

28th March 2004, 05:22 PM	#4
bigparsnip diyAudio Member Join Date: Apr 2003 Location: Cambridge	Try doing a search for bridge clone, as you have more than enough heatsinking there to get you going and plenty of room to fit in the transformer and other bits and pieces. This thread may be a good place to start: Bridgeclone And national have an aplication note abou this topic which is probably worth you reading too. http://www.national.com/appinfo/audi...ation_Note.pdf And http://www.national.com/an/AN/AN-1192.pdf

28th March 2004, 05:45 PM	#6
sreten diyAudio Member Join Date: Nov 2003 Location: Brighton UK	You'll need to bridge to get decent output. Personally I'd fix the (far superior) class A amplifier. sreten.

28th March 2004, 06:49 PM	#8
mikejz84 diyAudio Member Join Date: Dec 2002 Location: sarasota, fl	I would use the amp to drive my NHT VT-2s, they are power ******. I Bi-amp them right now 75watts for the highs and 100watts for the lows, and still that is just enought.

28th March 2004, 08:27 PM	#10
paulb diyAudio Member Join Date: Jun 2001 Location: Calgary	Other than bigparsnip, you folks have been much less than helpful. I say go for it. I'm currently thinking about changing an old Class AB to a Class A. Why not? Nuuk's suggestion is a good one, if you haven't built much before. Maybe try a bare-bones, open-frame gainclone first, you could even power it from the SAE amp power supply. Then build the real one and go nuts.

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