Nak PA7 clone - Page 7

anatech · 15th October 2007, 01:16 AM

Hi John,
Both of those amps are nice. The PA-7 is a class A-B design where the feedback is taken from before the final output transistors. It's a great amplifier, but due to the lack of feedback around the actual outputs, it "likes" 8 ohms loads much better than 4 ohm loads. Low impedance will not in any way hurt these amps. It's just that the outputs get less linear as the load impedance drops. They all do, but there is nothing to correct here.

When testing these amps, they would merrily blow 20 A breakers in the shop before protection kicked in when driving 2 ohm loads. It was useless to attempt to try to test these at full power into 2 ohm loads. Never ever had one fail in this testing either.

-Chris

reddish75 · 12th December 2007, 08:04 AM

i have what looks like the full manual for the pa7 and the pa7e if anyone is still interested in building this amp?

AMV8 · 13th December 2007, 03:23 PM

Hi

I am interested in building the amp.

Is it possible to post the manual or e mail to me on Don.Whittle @kbr.com or post me a copy - I live in Walton on Thames and will pay for postage.

Don

15th October 2007, 01:16 AM	#61
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Hi John, Both of those amps are nice. The PA-7 is a class A-B design where the feedback is taken from before the final output transistors. It's a great amplifier, but due to the lack of feedback around the actual outputs, it "likes" 8 ohms loads much better than 4 ohm loads. Low impedance will not in any way hurt these amps. It's just that the outputs get less linear as the load impedance drops. They all do, but there is nothing to correct here. When testing these amps, they would merrily blow 20 A breakers in the shop before protection kicked in when driving 2 ohm loads. It was useless to attempt to try to test these at full power into 2 ohm loads. Never ever had one fail in this testing either. -Chris __________________ "Just because you can, doesn't mean you should" © my Wife

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12th December 2007, 08:04 AM	#62
reddish75 diyAudio Member Join Date: Aug 2006	i have what looks like the full manual for the pa7 and the pa7e if anyone is still interested in building this amp?

13th December 2007, 03:23 PM	#63
AMV8 diyAudio Member Join Date: Jan 2005 Location: near london	Hi I am interested in building the amp. Is it possible to post the manual or e mail to me on Don.Whittle @kbr.com or post me a copy - I live in Walton on Thames and will pay for postage. Don