Heathkit--should I buy

Atlplasma · « **on:** 11 Nov 2008, 04:07 pm »

I have an opportunity to buy a Heathkit AA-21 for $30. The owner bought it with the ideal of doing a restoration. He's powered it on but not done anything else. (Except power it on, which is a worry.)

I'm just dipping a toe into vintage components and know knowing about this unit. Any thoughts or recommendations out there?

Audiovista · « **Reply #1 on:** 11 Nov 2008, 04:26 pm »

Can't go too wrong for $30 - even if you just open it, learn a thing or two and, if you decide it's too much work, sell off trannies for more... But, do all you can to stay safe when playing with it.

Good luck, whatever you decide.

Boris

ltr317 · « **Reply #2 on:** 11 Nov 2008, 04:27 pm »

Quote from: Atlplasma on 11 Nov 2008, 04:07 pm

I have an opportunity to buy a Heathkit AA-21 for $30. The owner bought it with the ideal of doing a restoration. He's powered it on but not done anything else. (Except power it on, which is a worry.)

I'm just dipping a toe into vintage components and know knowing about this unit. Any thoughts or recommendations out there?

Heathkit used quality components in their kits and once assembled, were very rugged. I believe the AA-21 is one of their first solid state amps. There are a lot of support on the web for the brand. And for $30, it would be a cheap investment to dip your feet in vintage gear, even if you have to recap the amp. I currently have four vintage tube amps (one is going to a friend) and they are a big bang for the buck.

Atlplasma · « **Reply #3 on:** 11 Nov 2008, 05:01 pm »

Thanks for the quick replies.

I'm also thinking of refurbishing my father's kit-built Eico ST-40 (I think it's a 40) if my brother hasn't turned it into scrap metal.

I've noticed a lot of advice on the web but was wondering if there's a such a thing as a "How to Electrocute Yourself for Dummies" book out there.

Audiovista · « **Reply #4 on:** 11 Nov 2008, 06:18 pm »

Check out these two:

http://www.audioxpress.com/bksprods/products/bkaa42.htm

http://www.audioxpress.com/bksprods/products/bkb99.htm

They are about tube amps, but have good info on construction and testing.

Wayner · « **Reply #5 on:** 11 Nov 2008, 07:00 pm »

Quote from: Atlplasma on 11 Nov 2008, 05:01 pm

Thanks for the quick replies. I'm also thinking of refurbishing my father's kit-built Eico ST-40 (I think it's a 40) if my brother hasn't turned it into scrap metal. I've noticed a lot of advice on the web but was wondering if there's a such a thing as a "How to Electrocute Yourself for Dummies" book out there.

Yes, It's a short book for dummies called "Never work on anything plugged in".

Wayner aa

S Clark · « **Reply #6 on:** 11 Nov 2008, 07:31 pm »

Quote from: Atlplasma on 11 Nov 2008, 05:01 pm

Thanks for the quick replies. I'm also thinking of refurbishing my father's kit-built Eico ST-40 (I think it's a 40) if my brother hasn't turned it into scrap metal. I've noticed a lot of advice on the web but was wondering if there's a such a thing as a "How to Electrocute Yourself for Dummies" book out there.

Join the Eico group. Also, get remember to discharge caps with a resistor on alligator clips. Even unplugged the caps can stay charged for hours.
The ST-40 is a highly thought of vintage amp.

Atlplasma · « **Reply #7 on:** 11 Nov 2008, 08:46 pm »

Thanks all around. I used to do plenty of computer mods and always (well, nearly) unplugged everything. The seller says the kit's original installation instructions are included, so that should help things.

randytsuch · « **Reply #8 on:** 11 Nov 2008, 11:21 pm »

As somebody already said, with tubes, it is more then just unplugging.

If this is an amp, there will be some large, high voltage caps in it, that can store energy for a long time. If you remove the tubes, they can store energy for days.

For all of my tube projects, if there are not some already there, I install bleeder resistors across the big caps, to discharge the caps. I normally use a pretty high resistance one, so it does not have to be high power. The drawback is that it takes longer to discharge the

And, before you work on a tube anything, use a volt meter, and make sure that the main caps are discharged before you start poking around inside of it.

Randy

Lyndon · « **Reply #9 on:** 12 Nov 2008, 12:46 am »

Everything these guys are saying, follow it like the gospel truth.
Those caps can store a LOT of punch. Got kicked pretty hard when
I thought the caps on my Krell KSA-50 project were empty.

I have a working Eico ST-40, and love it for my bedroom antique system.
Can't really call it antique, as I do have an Aiwa carousel transport, modded
into a MSB dac, and then the ST-40 into a pair of Coral speakers. Hybrid antique?

I also have an Eico HF-81 that is on the back burner as a project next year.
http://home.earthlink.net/~eico_hf81/links.htm
The original paint job is a kind of battleship grey. I much prefer this person's idea of
black with the brass.

I love the sound, but it doesn't have the punch of the Krell clone or my Pass Aleph.
Join the Eico club, those guys know all the tricks.
Heathkit has some very nice little mono amps, but you got to have a matching set.
The venerable W-5M
http://quadesl.com/refurb/refurb_heathW5M.html

Atlplasma · « **Reply #10 on:** 12 Nov 2008, 01:10 am »

Thanks for the warning. I prefer to get my jolts in other ways.

I know this is a knucklehead question, but where is the Eico club? I've heard mention of one on Yahoo.

Is there a Heathkit club as well?

dorokusai · « **Reply #11 on:** 12 Nov 2008, 02:23 am »

Quote from: Lyndon on 12 Nov 2008, 12:46 am

Everything these guys are saying, follow it like the gospel truth.
Those caps can store a LOT of punch. Got kicked pretty hard when
I thought the caps on my Krell KSA-50 project were empty.

I have a working Eico ST-40, and love it for my bedroom antique system.
Can't really call it antique, as I do have an Aiwa carousel transport, modded
into a MSB dac, and then the ST-40 into a pair of Coral speakers. Hybrid antique?

I also have an Eico HF-81 that is on the back burner as a project next year.
http://home.earthlink.net/~eico_hf81/links.htm
The original paint job is a kind of battleship grey. I much prefer this person's idea of
black with the brass.

I love the sound, but it doesn't have the punch of the Krell clone or my Pass Aleph.
Join the Eico club, those guys know all the tricks.
Heathkit has some very nice little mono amps, but you got to have a matching set.
The venerable W-5M
http://quadesl.com/refurb/refurb_heathW5M.html

That's very nice but I really like woodgrain when it comes to vintage gear.

Mark

ltr317 · « **Reply #12 on:** 12 Nov 2008, 02:58 am »

Quote from: Atlplasma on 12 Nov 2008, 01:10 am

Thanks for the warning. I prefer to get my jolts in other ways.

I know this is a knucklehead question, but where is the Eico club? I've heard mention of one on Yahoo.

Is there a Heathkit club as well?

It's not an Eico club; it's one of the groups on Yahoo. I subscribe to the group. There are a lot of knowledgeble subscribers in the group and they can teach you everything you want to know about the ST-40.

Atlplasma · « **Reply #13 on:** 12 Nov 2008, 03:11 pm »

I found the Yahoo Eico group and have applied to join.

Lydon, your ST-40 looks terrific.

Niteshade · « **Reply #14 on:** 12 Nov 2008, 03:23 pm »

Vintage tube equipment is good to get IF it doesn't have printed circuits. Old PC boards get brittle and discolor from the heat. Some of Heathkit's amps have PC boards.

Atlplasma · « **Reply #15 on:** 12 Nov 2008, 04:12 pm »

That's good to know. I can always take a peek I guess. This unit was manufactured in 1963, so it might be early for a printed circuit board, don't you think?

Atlplasma · « **Reply #16 on:** 12 Nov 2008, 10:22 pm »

aa Okay. I have the unit along with the original assembly manual. (It even has instructions for soldering.)

The seller said he plugged it in and the front panel lit up. I'm reluctant to do that with a component that's almost as old as I am.

I'm considering using the manual to do a step-by-step rebuild. Based on the little I know, replacing the resistors and capacitors would make sense. Not sure about the transistors. How does that sound?

Of course, I could just plug it in and wait for something to go "poof."

Atlplasma · « **Reply #17 on:** 14 Nov 2008, 03:46 pm »

Well, here's an update on the AA-21 from the guys at Radio Shack who volunteered to test it out for me.

It seems the unit is complete dead.

So my options appear to be do a complete rebuild or put the unit out for parts. The RS guy thought the
parts would run $200 at least. I bought this more as a learning project than anything else but am really more interested in tube audio
than solid state.

I'm sure other enthusiasts jumped in and found themselves in this situation. What would the "old hands" advise?

slbender · « **Reply #18 on:** 17 Nov 2008, 05:17 pm »

The AA-21 is an early Germanium Transistor Integrated Amp, and I believe that none of its original transistors are available from any source at present, even if you could get the eight 2N2147 output transistors, assuming it needs them, they would be much more leaky than they were forty years back, and likely would have problems thermally ( getting worse as they heat up ). Substituting silicon for its 2N2147's, or other specific Germanium parts is a bad idea, and will change every aspect of the amp's original operating points, as well as the sound and distortion. Back in the 1962 - 65 time frame, these Germanium devices were somewhat leaky, and variable, and likely to get worse over time.

Taking the advice of a Radio Shack minion is very likely to be bad advice, as I guarantee they know less than you do at this point. I have an AA-21D, there were several slightly different versions, and I have never plugged it in, but I'll bet with some cap upgrades ( probably less than $10. worth ) it would work and sound like new, or maybe not, however good or bad that might be. Mine also cost me ~$30. and a long trip to go pick it up.

The AA-21 is really a bargain at $30. - buy it just for its neat Art-Deco 1950's design, but if you want a Heathkit Amp to listen too, then get an AA-50 (later silicon circa 1972) or even an AA-151 (Tubes), avoid the AA-100; pray for an AA-40 and AA-11 companion Preamp - but you'll never be able to afford it, for many reasons, or get an AR-15 Receiver or the AR-1500.

Many vintage sets are often available on ebay, craigs list, or other places such as Goodwill stores, there is a world of this stuff to choose from. Start collecting today!@! Most need well under $50. in repairs or parts, I've been given so many sets for free, or just the cost of shipping, I've got 'em piled up to the ceiling in several places. If you were local, I'd give you one or two to have fun with, but today the cost of shipping a 25 to 35 lb., vintage set often is double its actual sell-able value as a "set needing repair".

-Steven L. Bender, Designer of Vintage Audio Equipment

Quote from: Atlplasma on 11 Nov 2008, 04:07 pm

I have an opportunity to buy a Heathkit AA-21 for $30. The owner bought it with the ideal of doing a restoration. He's powered it on but not done anything else. (Except power it on, which is a worry.)

I'm just dipping a toe into vintage components and know knowing about this unit. Any thoughts or recommendations out there?

Atlplasma · « **Reply #19 on:** 17 Nov 2008, 07:48 pm »

Thanks for the sage advice on this and other Heathkit units. Maybe the guy I purchased from knew more about these things than he let on.

And I like the idea of buying a bunch of transistors and then seeing what happens. If nothing else, it would be a good opportunity to learn a thing or two about desoldering and soldering.

Steve