Heathkit AS-103a Restoration questions

[Moondogtn]

I picked up some Heathkit AS-103a from a buddy and was hoping for some advice and clarification on a few things prior to getting started. I’m sure I am in the right place. 

The status of these speakers was not enviable.

Bad first. Midranges were missing. One tweeter looks to me missing the diaphragm and the one woofer was missing the Masonite ring  

The good news. Woofers were original. Also, he had two extra woofers he include in the deal. So, three of the four had the rings. 

Two woofers test good. The other two don’t test good from the terminals but do if you go straight from voice coil leads.  Corrosion or bad solder joints?  Has anyone seen this issue?  I feel like I can clean up and redo those solder joints at where tinsel wire meets the voice coil wire. This would give me a spare pair of woofers.  Actually, I’d use one of these rather than cutting my own Masonite ring  

I’m wanting to go ahead and order surrounds but was curious what current sources have the best product. I reached out to Rick Cobb and he sent me the specs of his current surrounds for AR-3a woofers.    Specs below are from Rick concerning surrounds  

 

Foam surround dimensions / AR3a woofers / p/n #610-050-1
Inside diameter (I.D. edge to edge): 8-1/8"
Outside diameter (O.D. edge to edge): 10-1/2"
Inside (inner) attachment lip size: 1/4" (angle attachment lip)
Outside attachment lip size : 5/16"
Roll size-Unmounted: 13/16" 
Cone diameter: 8-1/4" -  8-1/2"

Also, what replacement tweeter is the go to that is most well liked?  

I do have some midranges on the way. I’ll get caps ordered and check the pots soon. Not in a huge rush.

 

Note:   I’m not sure why I can’t upload pictures  I will work on getting those added  Error says file -200 but the pics are all smaller than that about 1.3 to 2 MB  

Update, pics resized and posted  

Thanks for any and all help  

Bill

 

[Aadams]

7 hours ago, Moondogtn said:

but the pics are all smaller than that about 1.3 to 2 MB. 

Sounds like your file sizes are way too large.  Save your images as a smaller size or use the windows snipping tool to make a large copy of the area you want to focus on and then cut and paste.  You can also do a screen capture if using Apple.

Proven tweeter choices are rebuilt from a couple of sources or HiVi.  There are no un-refurbished original 3a tweeters that operate correctly no matter what the seller tells you.

You should post pictures and no doubt you will get help.

Adams

[Moondogtn]

Adams,

Pictures weren’t anything special but I will try to work on posting at some point  

I noticed that many seemed to be using the HiVi Q1R successfully as a tweeter. But wasn’t sure if that was best, most current choice. 

Bill

[Aadams]

Your tweeter with the missing dome can be rebuilt. A HiVi pair is a well established alternative with differences that many listeners will neither notice nor care about.  The "purist" preference for tweeters is rebuilt and there is a difference especially if you are a critical listener of music recorded in live venues or large spaces. 

Use this search ,  AS 103 Lakecat site:classicspeakerpages.net 

Lakecat is here frequently and has multiple restored pairs of 103s.  Download the AR3 3a restoration if you haven't already done so.

Adams

[Moondogtn]

Adams, I do have the AR-3a restoration guide saved.  I also found the Heathkit assembly manual I downloaded.  At this point, I will go with the HiVi tweeters unless I stumble across some originals at a decent price.  Any idea what approximate costs for rehabbing the old ones may be? Not so much a purist but like to keep original if feasible. I will do my best to get these back in shape.  It will take me some time as I have plenty of irons in the fire.  Thank you for the advice.  I tried that search and had read some of those threads.  I was mainly curious as to updates or changes to preferred suppliers.  Thanks again.

Bill

[Aadams]

7 hours ago, Moondogtn said:

suppliers.  Thanks again.

PM sent.

[lakecat]

Hi Bill...looks like you got excellent bones for a rare and excellent speaker that is the 3a clone. I am at a loss as to why the value of these is not higher.

You see how well they did the crossover. The plate with screws is sooo much easier to remove than the stapled one in the 3a for pot repair or cleaning. The caps are fastened down with brackets....not glue...and have the Spraque caps...which are almost always in spec...so no need for immediate replacement. They fused the tweeter which is superb as we know the stories of replacement tweeters. The cabinets are furniture grade...and were made by a furniture company in N.C. The grills are gorgeous...and well made...and last.

Lastly,  they are very rare as not many were sold....due to it being a kit. I would guess for every 5000th 3a sold, there was one Heathkit sold. Most were sold to geeks who put way more time in making them nice...than the factory assembled 3a's. So yes...I would send tweeters to Chris and make these right. Congrats on getting these and trying to make them right....:)

[Moondogtn]

So, lakecat, I too noticed the screws securing the crossovers and immediately appreciated that!  I hadn’t checked those caps but planned to do so prior to replacing if needed. 

Also, pots I hear age better in these. I will test them and then clean up as needed and relube. 

Insulation for stuffing cabs?  I’ve been asking about drivers and stuff but...

Cabinets are in pretty decent condition except slight swelling on bottoms. 

Anyone have suggestions for this?  The veneer isn’t damaged. I am considering some good old fashioned clamps with long wooden blocks to try and slowly tighten them up?  Then inject glue once I get them close? 

 

Thanks for all the support. 

 

Bill

[lakecat]

Pots are the same so depends on location if anything. Never needed to buy insulation but there is threads here telling which kind to buy. Polyfill I think. Might be in the 3a guide.

I've used bar clamps with 1x2 oak pieces for clamping. I pour in the wood glue...getting it saturated...then clamp and really...really get it under pressure. It has worked so far....:)

[Moondogtn]

I am trying to get started.  

I ordered surrounds from Rick Cobb.  When I purchased these, the seller threw in two woofers that were suspected bad.  I am not so sure  I tried to attach pics of the two I had questions about...tinsel wires are corroded and one broke off of back of cone. The picture is a repair attempt by someone else but it almost worked. 

I was able to repair but am curious if this is a common issue? I plan to use black rtv or something to secure the voicecoil leads.   I am also considering replacing the tinsel wire completely although both of these now read about 4 ohms.  These will he used in an upcoming restoration...I hope  

lakecat, what sort of bar clamps did you find the easiest to use on this? 

I’ll keep the thread updated  

Bill

 

[JKent]

On 3/18/2019 at 11:00 AM, Moondogtn said:

Anyone have suggestions for this?  The veneer isn’t damaged. I am considering some good old fashioned clamps with long wooden blocks to try and slowly tighten them up?  Then inject glue once I get them close? 

Welcome and good luck with this worthwhile restoration.

Glenn is the expert on fixing these problems so I hope he will join in. Briefly; before you clamp and glue, dig out the swollen wood particles as best you can. I've tried clamping without digging and it did not work well. You can then squeeze some glue in there--either wood glue or hide glue. It can be thickened with a little sawdust if need be. Then, as you suggested, use long clamps and wood blocks (and wax paper to prevent the blocks from being glued to the cabinet).

I would not use polyfil. I think the AR-3a restoration guide advises against it and I know John O'Hanlon analyzed poly vs fiberglass under an electron microscope and said poly is not a good replacement.

Home Despot and/or Lowes have Johns Manville or Owens Corning fiberglass insulation in small bags. It is formaldehyde-free and therefore a better choice than the original stuff.

The Hi-Vi tweeters work well and I believe other members have said the replacements from Simply Speakers are good https://www.simplyspeakers.com/acoustic-research-replacement-tweeter-12000840.html but I would agree, if you want to do an authentic restoration because of the rarity of these speakers the best bet is to contact CSP member Chris1this1: 

 

Kent

[Moondogtn]

Kent, I did read the area regarding the insulation. I’m not that far along but will pick that up soon. 

This project is going to take some and money time but feel it will be worth it. Yes, Glenn does amazing things with cabinets!  I’m trying not to get in a rush and will continue to post progress. 

 

Bill

[JKent]

20 minutes ago, Moondogtn said:

 I’m trying not to get in a rush and will continue to post progress. 

 

Good idea, and please do

[lakecat]

Bill....I use clamps like these. You just buy lengths of 3/4" iron pipe for your needs. I have two foot to six foot pieces of pipe for use.

[Moondogtn]

Another maybe dumb question. I got the surrounds from Rick Cobb. I have never had to refoam ARs before. I do have Masonite trim rings still in place and know they should remain. The cone seems to be sitting to low and there is a gap large enough to cause me concern. I’m not fond of removing the dust cap. I usually don’t shim during a refoam but this may be the best way to do these as I have no other way to raise the cone enough to meet the surround properly. 

Im curious...has anyone tried using a heat gun to carefully removed the dust cap on these. I have done it on KLH. 

Thansk for any tips  

Bill

[Moondogtn]

Long term project update. I just used shims when replacing surrounds and it was much easier as you could adjust height of cone to make it sit correctly.  

One of the 4 woofers was not salvageable due to a concentric break in voice coil bobbin. I’m trying to come up with something but haven’t yet. 

When I asked millersound about repairing using original cone, I was told they would not do that  They suggested a complete recone as they said the voice coils on these fail shortly after new surrounds are installed. Has anyone experienced this?  

Min getting ready to work on crossovers. Do most folks completely remove the crossover from the cab or just removed the pots and caps as needed?  

I will post pics of the mids I purchased. They were damaged during shipping but I think I saved them.  I will need to dig up pics to post.  

[Moondogtn]

These pots are worse than others I have seen. I haven’t gotten to all of them but one is toast. I can’t get it to work at all...after cleaning up. 

So, for replacement pots, has anyone used these

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F264256977509

they seem to be close....25W 15ohm. 

If  not, what is recommended   Thanks  

 

[JKent]

11 hours ago, Moondogtn said:

So, for replacement pots, has anyone used these

Those surplus Russkie pots show up once in a while on ebay. I bought 2 but have not used them. Other members have tried them and may chime in. They appear to be well made but like the Ohmite pots they are open and therefore must be put in some kind of enclosure to keep the fiberglass out. From my experience with Ohmites I can tell you it's a PITA. But some members have made them (Ohmites) work. Here are 2 pics of Ohmite installations.  CSP member Xmas111 did a beautiful job, using an enclosure made of wood and Masonite. My XO is less beautiful. I used a standard project box.

Best solution IMHO is to follow the instructions in the AR-3a Restoration Guide and use L-pads (from PE or Madisound) with 25 Ohm 10w resistors on the mids. Also use resistors on the tweets if you go with Hi-Vi or Chris's rebuilds.

One more thought. I've never worked on the Heathkit version but I can tell you based on working on KLHs--that metal plate can be a problem. Be SURE no metal parts touch it and if you remove the terminal screws for any reason observe how they are insulated and be sure to replace the insulation. KLH used 2 rubber washers on each screw; a flat washer and a shoulder washer so the screw was isolated from the plate.

-Kent

[Moondogtn]

I got sidetracked with life and am finally getting back to this project.  I was hoping someone had tried the russian pots and could provide some feedback. I am still undecided on whether to order the Russian Pots or just use the L-pads. Both will eventually fail but either  should probably last for a good time before doing so. I may try those pots and at least would be able to see how they are made.  We all know how well those L-pads are constructed.  

I have read that the sprague electrolytics hold up well.  I checked mine and seem to be 56 for the 50uF and 156 for the 150uF.  I may just replace while in there to be done with it.  The 6uF wax in paper chicago condenser crayon is getting replaced....checked it for fun...12uF.  

I will check in soon.  Please let me know opinions on any of these items.  Thanks

 

Bill

[Moondogtn]

I’m finally getting to this. I ended up purchasing the Russian pots on eBay. They are very nice.  They do have the open back. I haven’t come up with anything to enclose them as space is limited. I’m leaning towards...don’t laugh...using silicone baking mold for cupcakes or some sort of silicone ice tray. It will be pliable and I will be able to glue it in place.

I would like to know what purpose the enclosure will actually serve?  Does it seriously get that hot as others mentioned heat and fire prevention?  Fiberglass is flame retardant but I know it can burn  

I assumed it would be to keep the pot clean from contamination. 

If this has been discussed in depth, I couldn’t find it. 

Thanks

[JKent]

9 hours ago, Moondogtn said:

I assumed it would be to keep the pot clean from contamination. 

Yup. That's it.

I'm a little skeptical about gluing silicone. Others have made little boxes with holes in the sides covered with screen. I used a plastic project box, also with holes/screen.

Kent

[lakecat]

Glad to see you are still at it...:) Little off topic but have noticed these Heathkits getting some attention. This pair on EBay that just sold for close to $400 was pretty crappy imho....and still brought good money. 

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F372853248471

[Moondogtn]

Jkent, Thanks for ideas. I saw those enclosures and they look great but mine are mounted to that aluminum plate and I don’t know what I would fit around them and make fit. I’ll see what I can come up with.....this is what is holding up my project for now....I’ll post a pic this evening to show what I mean by limited space and advice is welcome.

 

lakecat, I saw those. Something is up with the woofer surrounds for sure. My cabs aren’t in the best shape but I will refinish and hopefully be presentable. Grills are ok but maybe a little faded.  I can’t wait to hear these but holidays and family stuff seem to occupy more and more time. I will finish eventually.  

Bill

 

[JKent]

Bill,

The plastic project box used in my post of May 21 should work. It was tight in there for the Ohmite pots. Don't know if the Russkie ones are bigger, smaller or the same.

I'm surprised Heathkit used those stupid metal plates (like KLH). In general I think the Heathkit cabs are superior to AR but they goofed there! Anyway, the plastic box is of course non-conductive and should work. Sorry but I don't have the box size written down.

[ra.ra]

The Ohmite controls do indeed have very open backs but their use as replacements in restorations should not require re-inventing the wheel. If preventing fiberglass or mineral wool fibers from interfering in the proper operation of these controls is the sole concern here, I see no reason why carefully draping a piece of Kimpac (or cheesecloth or.....) over the wired controls would not achieve this goal with far less effort. After all, this is exactly the intent of the Kimpac placed underneath the woofer in early AR speaker models. I do really enjoy seeing all of the creative solutions to this issue, but there are times when the KISS principle is often the most appropriate solution. Because of the rear metal plate used in the Heathkit version, this may be one of those times. 

Additionally, the original Aetna-Pollak pots used in hundreds of thousands of AR speakers do not have fully open backs, but they do have several open slots around the perimeter, and without additional screening, did allow for fibers to enter the working mechanisms.