Nak PA7 clone

bra · 6th September 2005, 01:02 PM

I think it is time to start new thread.
Maybe someone want to clone great Nakamichi PA7?
I do. I have service manual but I have to scan.

Cobra2 · 6th September 2005, 01:26 PM

I always wanted this amp...!

Arne K

jmateus · 6th September 2005, 01:39 PM

Bra
Bring it on, scan it and publish it, we are all anxious to see new amplifiers, enough of those beaten ones in other threads.
Thanks

Jan Dupont · 6th September 2005, 03:39 PM

Interested

bra · 6th September 2005, 06:03 PM

Guys scan will be tomorrow!

oPossum · 7th September 2005, 12:10 AM

Amplifier (one channel) 362k TIFF

Power Supply 156k TIFF

Unfortunately I only have a rather poor quality copy of the service manual, so some of the text is not readable.

anatech · 7th September 2005, 12:50 AM

Thanks oPossum,
That's the beast. There is still the mod PCB for the current limiter we need to find.
If the text were more clear .... Can you scan the main PCB to give others an idea of the size? 14 outputs per channel doesn't seem to convey the idea like a picture.

-Chris

anatech · 7th September 2005, 12:55 AM

You know, I'd like to have some input from N P on this. Maybe not his design, but it's his concept. Nelson may have some cool ideas.

-Chris

amplifierguru · 7th September 2005, 01:20 AM

This design has a characteristically poor HF PSRR so you will be listening to PS artefacts so best to eliminate those half wave Class AB ones in the most inelegant way possible - by wasting power running such a monster in Class A.

This type of dinosaur will be the first to go in the dawning of the new era of energy efficiency. RIP.

Cheers,
greg

anatech · 7th September 2005, 01:36 AM

Hi Greg,
Have you had a chance to hear or test these amps? Just curious.

What you say might be true, but they sound very smooth. The front end looks well isolated from the supplies. No worse than many others and better than some.

The outputs were run warm because they are not in the feedback loop and needed to be run in a more linear part of their curves - Stassis you know. I can think of a few other amps that ran at least as warm as a normal A/B with everything in the feedback loop.

True, they are not as efficient as most other amps, I'll give you that.

-Chris

6th September 2005, 01:02 PM	#1
bra diyAudio Member Join Date: Dec 2002 Location: poland	Nak PA7 clone I think it is time to start new thread. Maybe someone want to clone great Nakamichi PA7? I do. I have service manual but I have to scan.

6th September 2005, 01:26 PM	#2
Cobra2 DIY ! diyAudio Member Join Date: Apr 2002 Location: Stavanger, Norway	interesting I always wanted this amp...! Arne K __________________ Ars longa, vita brevis

6th September 2005, 01:39 PM	#3
jmateus diyAudio Member Join Date: Mar 2003 Location: US, New Jersey	New amp Bra Bring it on, scan it and publish it, we are all anxious to see new amplifiers, enough of those beaten ones in other threads. Thanks __________________ JLH 2005, Cyrus and so on...

6th September 2005, 03:39 PM	#4
Jan Dupont diyAudio Member Join Date: Apr 2003 Location: Copenhagen, Denmark	Interested __________________ Free Schematic and Service Manual downloads www.audio-circuit.dk, Company: www.dupont-audio.com, Joint venture: www.DupontMantra.com

7th September 2005, 12:10 AM	#6
oPossum diyAudio Member Join Date: May 2005 Location: Michigan	Schematics Amplifier (one channel) 362k TIFF Power Supply 156k TIFF Unfortunately I only have a rather poor quality copy of the service manual, so some of the text is not readable.


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6th September 2005, 06:03 PM	#5
bra diyAudio Member Join Date: Dec 2002 Location: poland	Guys scan will be tomorrow!

7th September 2005, 12:50 AM	#7
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Thanks oPossum, That's the beast. There is still the mod PCB for the current limiter we need to find. If the text were more clear .... Can you scan the main PCB to give others an idea of the size? 14 outputs per channel doesn't seem to convey the idea like a picture. -Chris

7th September 2005, 12:55 AM	#8
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	You know, I'd like to have some input from N P on this. Maybe not his design, but it's his concept. Nelson may have some cool ideas. -Chris

7th September 2005, 01:20 AM	#9
amplifierguru Account Disabled Join Date: Aug 2004 Location: Earth	This design has a characteristically poor HF PSRR so you will be listening to PS artefacts so best to eliminate those half wave Class AB ones in the most inelegant way possible - by wasting power running such a monster in Class A. This type of dinosaur will be the first to go in the dawning of the new era of energy efficiency. RIP. Cheers, greg

7th September 2005, 01:36 AM	#10
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Hi Greg, Have you had a chance to hear or test these amps? Just curious. What you say might be true, but they sound very smooth. The front end looks well isolated from the supplies. No worse than many others and better than some. The outputs were run warm because they are not in the feedback loop and needed to be run in a more linear part of their curves - Stassis you know. I can think of a few other amps that ran at least as warm as a normal A/B with everything in the feedback loop. True, they are not as efficient as most other amps, I'll give you that. -Chris

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