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Vintage tube amp Heathkit AA-71

post #1 of 10
Thread Starter 

Hey, I am hoping someone can help me find a schematic for this amp. also maybe a instruction manual. I got this thing at a garage sale a while ago it works pretty good but it doesn't have the volume I think it should there is a plug (un filled) on the front that is marked PRE_AMP POWER and i don't know what it is for it looks like a tube jack but I don't know what to put in there.

thanks any sugestions or links to schematic would be grand.

God Bless,

Bill

post #2 of 10

Hunt on Google or E-bay......Is this a tube amp??? does it have a volume control???

post #3 of 10

The AA-71 is a mono tube power amp that was designed to get it's AC power from the partnering pre-amp.  Honestly, without that, I am not sure how you got it to power up at all, unless someone had modified it.  Here is a nice picture of one that has been modded to take a standard IEC power cord, and otherwise dolled up.  Looks like it could be a nice amp, but you really need two of them...

 

http://www.audiocircle.com/index.php?action=gallery;sa=album;id=3108#

 

BTW the Heath company still exists, in Benton Harbor Michigan - you might call them and ask...


Edited by Skylab - 9/13/10 at 11:04am
post #4 of 10

Heathkit will send you a copy of the original manual for around $25. I got one for a preamp.

post #5 of 10

Data Professionals owns the IP to the old Heathkit stuff now.  They're selling the manuals and, according to the website, have a variety of parts you can purchase, too.

post #6 of 10

Very  nice, Uncle Erik!  Never knew that.  The AA-71 manual can be ordered on-line there for $5.

 

That is a nice looking amp, the AA-71.  One 6SN7GT and one 6L6/5881 per side.  Very cool.  A buddy of mine uses Heath W5M tube monos with his Quad ESL-63's.  Sublime sound, baby.

post #7 of 10

Thanks!  Though not on point, another great resource for vintage gear is Sam's Technical Publishing.  Sam's Photofacts cover almost all of the old commercial and industrial tube gear.  You get the schematics, parts lists, substitute parts, photos with labeled parts, just everything.  You can easily clone old gear from Photofacts, too.

post #8 of 10

I just came across this thread, so maybe my reply is no longer of interest.

 

But I do know about the Heathkit AA-71.  It is, in nearly every detail, exactly the same as the Heathkit W-4B

(which in turn is very similar to the W4-AM).  They are all Williamson-type amplifiers with 20 watt of output with less

than 1% harmonic distortion, using a pair of 5881 (or 6L6) output tubes, a 5V4G rectifier, and a pair of 6SN7GT

tubes.

 

I know that this is so because I have an original manual from Heath that the company shipped with a AA-71. It contains a note saying 

 

"Because of a temporary problem obtaining AA-71 manuals, we have substituted a W-4B manual to avoid any unnecessary

delay in shipping your kit.  Only a  very minor change is required in this manual to allow completion of the AA-71 amplifier.

 

Page 13 - Parts List:

Delete:  200-M244F306  1  Chassis

Add:     200-M244F569   1  Chassis"

 

Therefore, I have the schematic, and would be happy to provide free it (or a scan of the entire manual) to

anyone interested.

post #9 of 10

I have a really nice Heathkit AA-71 and would really appreciate a manual, etc. I have never powered it up as I want to let a qualified person check it out beforehand.  

post #10 of 10

Since the amp is in "really nice" condition, you can probably power it up, as long as you're careful when you do so.  It's important to use a variac.  This will allow you to begin with a very low voltage, and very gradually increase it.  This helps to "re-form" the capacitors, and it also lets you observe the amp, so you can watch for any overheating, smoke, etc.  Remember that these amps have very high and potentially lethal voltages inside, so don't touch anything of the innerds unless you truly know what you're doing.  If it's never been worked on, it most probably will require replacement of the capacitors, including the 20/20/20/20 450 volt electrolytic "can". 

 

I've scanned the full manual as a .pdf.  That way, you have the schematic, kit build sequence, parts list, and operating instructions.  Here's the download link:  http://mcnpf66cyw.1fichier.com/

 

Enjoy!


Edited by billinrio - 4/26/14 at 5:52pm
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