Fix-up pair of AR93Q's?

[J_B]

Hello!

First post here, hopefully I'm on the right spot. :-)

Yesterday I've picked up 2 AR93Q speakers from the street, saving them from a certain garbage-truck death. Apart from that the cloth needs some washing (I already pulled the first one off), I discovered that the foam surrounding of the bass / mid speakers are due for replacement. On one it's already fully gone and on the two others they're preparing for a single ride to the afterlife.

On eBay I've found some kits that I can have sent over from the US for 25$ + shipping (+taxes) each. If the package gets screened by customs, I might need to pay a whole lot of extra duties on it, so it could run up to 100$ to re-do all 6 of them.

I've read that letting a company service them could cost me 70$ per speaker. Apart from that, I can't find any kit or service locally in Montreal.

I haven't tried hooking them up on an amp yet to see what the result is. I'll beep the speakers to check if the coils aren't touching (so short-ciruiting the amp).

They don't need to play load; I'm living in an old apartment, so no soundproofing in walls and floor.

Will it be worth the money and hassle to get the surround foam kits? Or does anyone have a cheaper local solution I can get in Montreal or surroundings? I'm not afraid to fix them up myself, as I'm a theatre technician and I've built complete PA speaker cabinets in the past.

Thanks for the input!!

[JKent]

Hi J_B and welcome!

I have a pair of 91s that I love. The 93s are relatively rare but from what I've read they are excellent speakers. Definitely a great find (you WILL post photos, right?). Here is a page on rehabbing the apparently similar 94s: http://www.tnt-audio.com/clinica/ar94rebuild_e.html

As for the expense of the refoam kits, check M_Sound. He is on ebay as "moonlistener." Tell him you are refoaming 6 drivers and ask him to put together a kit that includes all you need to do all 6. Also tell him you are a CSP member. I'm certain the total will be less than the cost of 3 full kits.

Keep us posted.

Kent

[michiganpat]

couple years ago when some 93's popped up on the local craigslist, I contacted Msound about 6 boston acoustic style "filled fillet" surrounds for them from Msound and he quoted me a little less than $40+ ship. just use aileen's tacky glue

http://www.michaels.com/Aleene%27s%C2%AE-Original-Tacky-Glue%C2%AE/gc0040,default,pd.html

and a computer generated 30hz test tone to center the voice coil when gluing the surround to the basket.

[JKent]

Or... Ask about a kit that includes enough of the special "WD" white adhesive, some shims and 6 new dustcaps. Why cut corners? M_Sound is very emphatic in stating that voice coils should be shimmed and that WD is not the same as Tacky Glue. Not looking for an argument with Pat, who clearly knows his stuff, but I have used WD and shims/new duscaps on all my re-foams and never had a problem. If you are new to this it's good to follow the instructions exactly. 14 pages of instructions can be found here: http://www.citlink.net/~msound/refoam/page2.htm

Kent

[J_B]

Thanks for the info, definitely useful!

I'll be visiting London ON next month, so there's a Michael's to pick up some glue.

As for pictures (by popular demand):

"I will call them Thomson and Thompson!"

Thomson:

Thompson (currently undressed):

Here come the painful pics:

What came out:

/edit: wow, talking 'bout some heavy compression... As that just me, or can't I display anything more descent when storing pics on this forum?

[JKent]

/edit: wow, talking 'bout some heavy compression... As that just me, or can't I display anything more descent when storing pics on this forum?

Try sizing pics to around 100K.

Looks like you have other problems. What happened to the binding post? Wonder if there are crossover issues. The post is easy enough to replace.

Kent

[J_B]

It came in lacking a binding post. I took a look on the inside and the X-over filter looked in top shape. The bolt and nut simply got unscrewed probably (haven't found the nut yet).

Looking at M_sounds tutorial I notice that my dustcaps already have been replaced on the side speakers.

Also I read that he doesn't ship passed the border... At best I know my ex is planning a trip to NYC next week. Maybe she can pick up something at the post office there.

[JKent]

Here's one of his ebay listings. Check the shipping--he ships worldwide, except Italy & France.

http://www.ebay.com/itm/10-Premium-reFoam-Kit-Allison-Boston-EV-others-/330428545843?pt=US_Amplifier_Parts_Components&hash=item4cef137b33

Send him a message through ebay or email him: msound@citlink.net

Kent

[Tetrode]

I found mine rather easy to refoam with no shimming or 30hz signal needed.

[HarryM]

M sound ships to me in toronto ontario,no problems.He's a great guy to deal with and very knowledgeble about AR speakers.Just have it shipped USPS.It may take a week but it's the cheapest and most trouble free that I've found.

[RoyC]

Regarding the Msound WD glue vs Aleene's Tacky Glue...They both do a good job. WD appears similar to "Weldbond" glue. Tacky glue sets up more quickly.

Nothing works better than shimming, as the friction of the shims allows the cone to be set at advantageous heights, and helps maintain vertical alignment. Shimming becomes even more important when re-foaming woofers with narrow voice coil gaps. Batteries and 30hz tones are better than nothing, but not foolproof....especially with narrow voice coil gaps.

John at Msound is an excellent source for surrounds. He provides the greatest assortment of dustcaps, and the most thorough technical advice in my experience. He is also very well tuned into the needs of AR re-foamers.

Roy

[Robert_S]

Looking at M_sounds tutorial I notice that my dustcaps already have been replaced on the side speakers.

You may find that the dust caps on your woofers are original. I've seen pictures before that show some (but not all) AR-93 with what look like bright yellow dust caps (presumably made of plastic?). These were perhaps white to begin with (see the engineering file posted below), and have yellowed over time.

They are referred to in the following quote:

"The 200mm bass units have a heavy pressed steel ribbed chassis carrying a square ceramic magnet. The large diameter centring device allows considerable diaphragm travel and, as the cabinets are sealed, a gasket is placed between the speaker and the cabinet. To control the diaphragm performance, different mass dust covers are used; for example a domed plastic dust cover for the two bass units in the AR93, different sized domes of moulded paper in the AR94 bass units, and a flat cover for the AR93 mid-range driver."

Source: www.gramophone.net/Issue/Page/December%201980/131/790800/

I would guess that there was a reason for using these particular dust caps in the AR-93 200035 driver, possibly their robust nature and airtight quality under pressure. The mid-range driver, with its flat paper dust cap, is contained in and acoustically screened by a discrete internal chamber, therefore not subjected to the same physical stress.

If they were mine I would attempt the task with the original dust caps in place, using a combination of slow drying adhesive, light touch of hand, and a low frequency signal. I have yet to encounter any problems when refoaming AR 8-inch drivers in this manner—exercising due care and attention, of course.

Robert_S

AR 200035 Woofer

AR 203047 Dust Cap

AR-93 & AR-94 Specifications

[Tetrode]

The yellow dust caps are original for the side woofers.

Here are the ones I refoamed using Aleene's tacky glue.I must say I was able to do a near perfect job thanks to Aleene's.

http://www.audiokarma.org/forums/showthread.php?t=422404

[ben76]

I have worked on 4 AR93Q speakers, two dating from 1980, the others from 1982. They both had flat dark paper dust caps for the mids, and pale yellow (almost white) domed *paper* dust caps for the two side facing woofers. The 1980 woofer dust caps looked the same as the 1982 ones, but had the tendency to shed fibers (from the top side, not the bottom side facing the voice coil gap) if rubbed even gently.

I have not seen any plastic dust caps.

When I re-foamed these 4 speakers (i.e. 16 drivers) I got my surrounds from John of MSound. Since he did not have dust caps that match the originals, I have decided to reuse the old dust caps.

Even though I have had success re-foaming AR 8 inch drivers without shimming, I prefer to shim, and this is what I did in this case. I have used a very sharp X-Acto knife to cut the glue around the dust caps exactly at the seam line between the dust cap and the cone. I have not cut the whole circle, just from one voice coil wire to the other, and simply flapped the dust cap using the part that was still attached as a hinge. The keys to success are:

1. With a hot air gun in one hand soften the glue as you cut the glue with the knife in the other hand. If the air is too hot you will scorch the dust cap. If it is not hot enough the glue will not soften. Start low, and work your way up. Finding the right temperature (or distance if you cannot adjust temperature) is not hard at all. When you have the right temperature the knife simply slides through the glue, separating the dust cap from the cone.

2. Lay the X-Acto knife such that its blade is as parallel as possible to the surface of the cone. This ensures that you do not puncture the dust cap or the cone.

3. Use only the very tip of the knife. Do not let more than the tip of the blade slide underneath the dust cap as you cut (say, at most 1/8"), otherwise you may penetrate the cone.

This may sound hard but it is really very easy. The result is a re-foamed driver that looks perfect.

[J_B]

Thanks everyone!

I've had a busy week, so wasn't able to reply much.

MSound gave me a great quote for a kit with 6 foam surroundings and accessories.

I've just tried Ben's tip to keep the dust caps. Unfortunately my first cap wasn't able to just flap over like that. Trying to undo it further costed one of the contacts to break (not so much due to the knife, but the breaking of the glue). Will try to solder a new contact (I've been looking into buying a soldering kit for the last 2 years, so the perfect opportunity).

I'll try to get all the dust caps off first, before placing my order at MSound. If I need new dust caps, I rather order then at the same time, not to have to pay twice for shipping.

[michiganpat]

don't bother...use a 30hz test tone to center the voice coil. the gaps are fairly wide on the AR woofs, and I've never found it worth the risk to damage the tinsel leads to cut and shim on these. I was going to do it on the first AR18's I refoamed, but after I carefully cut off (and destroyed) the mesh fabric dustcap, I found a thick, flat paper dustcap under it, and said to myself, "screw this" and refoamed without shimming. I did it by feel, and had a minor rubbing issue with 1 woofer on a few low bass tracks. I redid that 1 woofer using a 30hz test tone, and it came out great with no rubbing issues, and I've refoamed 5 pair of woofers since (2 pair of AR 8", one pair AR 10", Becker 12", Mach ! 15" and Smaller Advent 9") all without shimming, but using a 30hz test tone to center the voice coil when gluing the basket to the foam, and have had no issues...