The Heathkit AR-15 Stereo Receiver: Cool to look at, difficult to service.
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- Опубликовано: 11 фев 2016
- I fixed up a Heathkit AR-15 with a serious case of bad caps in the preamp, power amp and power supply that were causing insane distortion (15%+!) in one channel and a loss of most of the audio in the other channel. Expect such a unit to consume nearly a whole day of time due to difficult to access components. At least it looks cool.
In the end, I got 55W/ch with both channels driven into 8 ohms with 0.1% THD+N at 1kHz. Not bad, but nothing to write home about and typical of cap coupled amps. (OCL circuits are far superior!)
Apologies for the sound, I inadvertently muffled my mic a few times. 
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Great Video ! My father and I took 2 weeks to built one of these from a kit in 1968, and paired it with the AR-2AX speakers and a Dual 1019 Turntable. I still have an emotional connection to the look and sound. About 10 years ago bought a spare for $10, and then found 2 more AJ-15's( the tuner) with cabinets. It is on my bucket list to get one of the A5-15's to work. Both tuners work fine. I'm surprised that you didn't open the little silver front panel to adjust the stereo phasing.-- remember how odd it was that that the stereo subcarrier was not locked. In the day, the AR-15 was at the top of the heap ! and affordable by comparison if you built it from the kit -- Thanks for doing this young student a favor I It's super vintage and he/she should have fun with it !
I tried playing with that off camera but it still wouldn't lock. The tuner likely needed a more extensive service and they really didn't want to invest in it since most Dallas radio stations basically play the same 20 songs on a loop.
Alignments and even used tuners are a tough sell to people my age and younger and we can blame the consolidation of the media industry for that. Just look at the entry level hi-fi market to get a glimpse of what younger folks want in a stereo...you'll be practically tripping over a cargo ships' worth of integrated amps but only a few stereo only receivers are still made and none are from the new Chinese entrants to the market like Topping or SMSL.
I would get one of these just for the put-on :"Hey, wanna see my AR-15 ?"
I know I’m very late to this party. I have restored a few of these receivers. And although they may be quite a bit of work to do, I believe that they are still worth doing. Paying to have one restored is expensive, but you’ll end up with a receiver that will motor on for another 50 years. Plus it is an extremely cool looking machine that puts the modern plastic disposable junk to shame.
the "manual" for the AR-15 is the assembly instructions, which includes the setup for the IF and all that. it's a kit and came in pieces with step-by-step build instructions. there's been an archive of most of the instructions online for a long time
Heathkits were really Hi-Fi. At a Mcintosh demonstration at a Pacific Stereo store, the tech offered $100 to anyone who brought in an amplifier that could beat the Mcintosh on a square wave test. The Heath AA-29 amplifier equaled the McIntosh on the oscilloscope test. No factory built unit by the big companies even came close.
Have the AR-29 which is the receiver version and agree, sounds awesome
I find that sometimes,you lose a little in one job and then gain tremendously from it in the long run.This student will tell all of his friends when they hear it who did the work.Word of mouth is very under rated in today's society,it can make or break a business.Good work and good luck.
Good work. Love old Heathkit ham gear. Just acquired a mint AR1500a...with service manual. At first did not want it....but did not want to see it go to landfill....so ...$20 later I lugged it to van...Sweet sound. All in spec. But what a bear weight wise. 54 lbs...are you kidding me.....Jeez...had to take off face plate for minor adjust of dial needle....its a solid piece of aluminum....christ...I could bench press it...lol. NO one builds like this anymore....No regrets.Set up it man cave with my original Yamaha NS 670 speakers( 1976)and yamaha turntable. Haven't stopped playing records for 3 days....
AA-15 amp published THD spec was .5% from 20Hz to 20kHz at 50 watts. Less than .2% at 1000Hz with 10 watt output and less than .2% at 1000Hz at 1 watt output. AFAIK AA-15 is identical amp as AR-15 only without the tuner. When I complete the project I will post results obtained from my old HP8309A. Funny you mentioned it took you most of a day to repair. I'm on the most of a week plan. I make about 5 cents an hour! Having the Heathkit manuals is a big help for somebody like me.
In a lab test for Stereo Review magazine the Heath AA-29 measured .08 per cent distortion at 35 watts per channel from 20 hertz to 20 kilohertz.
Let's not forget that this receiver is still one of the best designed and beautiful units for it's time and still admired now. I still own one and still admire it. The only contender that comes close is the Tandberg 2080 which I still hope to own one day.
I restored one of those in 2015, fully recapping it, and some other things as well as replacing the hard to find driver transistors. and removing the tuner assembly IS fun along with the preamp. also all the green mylar caps were falling apart as well. Sad.
I have a copy of the original construction manual for my AR15 (which still works at 52 years of age-again except for the FM Stereo DEMUX which is funny since I invented the PLL FM Stereo demodulator used in all systems after 1971)
That thing really does have a pretty face. Nice job on the repair. Not sure I’d consider NOS tantalums as new. Old electrolytics are old electrolytics as far as I’m concerned, used or not.
Wet tantalum with a glass seal has a practically indefinite life in this application. There are quite a few of them in my older HP test gear and I have not had to change one ever....the same cannot be said about the electrolytic caps in my test gear. Since the seal is glass, they aren't prone to drying out and I installed so much voltage headroom that shorts are highly improbable.
The tuner was best. I bought it because it was the best receiver ever tested at the time better than marantz etc. By consumer reports. Used it to run speaker columns I borrowed from theme park skating rink. For graduation class pa years later.
Profit it's a very lame excuse for sloppy work.
Thanks for the video. I have an AA-15 amp with AJ-15 FM tuner. Basically same as AR15, but separates. You can find the complementary pair RCA 40409/40410 drivers on ebay. Will probably have close to $100 in the amp just in new parts. I bought 4000uf computer grade caps for the outputs. Got them on sale, but still paid almost $15 ea landed. What series and voltage of 4700uf Nichicon audio grade caps did you use?
I suggest using 50V capacitors as originally specified by Heathkit, these were Nichicon KW if I recall. Use of 2" diameter "Computer Grade" caps facilitates mounting but costs *significantly* more and was not in the budget for our customer unfortunately.
I see that you substituted a 5600 uF cap for the original 8000 uF, what affect does this have on the sound ? what other effects will that have, i.e. power draw, heat, increase of hum ???
Craig Yuen Despite what the schematic shows, this one had a 5000uF cap in it from the factory. There is no hum and it actually beat spec by 10%. Watch the video to the end; seeing is believing! I got 55W/ch at 0.15% THD+N, spec is 50W at 0.5%. If we had an inadequately filtered supply, those numbers simply would not have been possible. What's also vital besides bulk capacitance for supply filters is ESR and the new cap has *way* lower ESR than the stock one had even new.
I had one i widh i kept it
How would i get you to do some work for me?
Send me a private message or find me on Facebook.
The AR-15 was acclaimed to be the BEST receiver available at the time of its introduction. Bad caps come with age and lack of use by the owner. Not the fault of the original design.
I never said it was a bad receiver and of course any receiver this old will likely need significant service. What is most definitely a fault of the original design is how difficult it is to service. A few tweaks to how this thing was laid out internally would have greatly improved serviceability.
Been digging around in old B&O systems. They can be real pigs to service some times. Great fan of modular builds where you can pick out the boards reasonably easy.
When someone do not know how to do a job, and still want to do it, charges all the extra learning time on the customer. Sorry for the customer. Regards.
ya thats nice, not!
never herd anyone cry as much