Is there a how-to manual for repairs?

[JKent]

Decided to bring out m old AR 4x speakers and use them in my living room. Bought some "new old stock" grille cloth, re-oiled the walnut, they look like new. Trouble is, no tweeter sound from one. I'm guessing it might be the level control, but how do you know? Also--I pulled out all the "stuffing" so I could reach the level control. Do I put it back in or buy new? What about the gooey mortite-like stuff? What else do I need to know? Is there a step-by-step DIY guide on the net?

PS Here's a pic. Thanks for the tips Vern

[dynaco_dan]

>Decided to bring out m old AR 4x speakers and use them in my

>living room. Bought some "new old stock" grille

>cloth, re-oiled the walnut, they look like new. Trouble is, no

>tweeter sound from one. I'm guessing it might be the level

>control, but how do you know? Also--I pulled out all the

>"stuffing" so I could reach the level control. Do I

>put it back in or buy new? What about the gooey mortite-like

>stuff? What else do I need to know? Is there a step-by-step

>DIY guide on the net?

>

>PS Here's a pic. Thanks for the tips Vern

Hi Kent;

You are very welcome, AR-4X, MMMMMMM.

There isn't a speaker service manual at present, that I am aware of.

Use rubber gloves and mask to remove the fibreglas.

Re-use the old fibreglas as well.

A member is, I believe, composing a book or manual, un-published yet, as best as I know.

You jumped the gun with the pot, maybe.

Did you already remove it from the wiring and backboard?

Before ever removing a grill cloth, someone here would have walked you through a step by step procedure for troublshooting.

You will need to tell us what all you have done at this point, please.

The putty, Mortite, or various other names is a sealant putty which basicly doesn't harden.

You will need to apply some more, unless you were able to salvage all of the old stuff and it still very pliable.

Roll it in your hands if it is soft and if you can create a piece of spaghetti that will lay down just to the woofers hole edge of the bolt holes, that should be sufficient to reseal the woofer when you are finished.

After just re-reading your note, I thought that you now were going to replace the insulation, true?

[JKent]

>Hi Kent;

>

>You are very welcome, AR-4X, MMMMMMM.

>

>There isn't a speaker service manual at present, that I am

>aware of.

>

>Use rubber gloves and mask to remove the fibreglas.

>

>Re-use the old fibreglas as well.

>

>A member is, I believe, composing a book or manual,

>un-published yet, as best as I know.

>

>You jumped the gun with the pot, maybe.

>

>Did you already remove it from the wiring and backboard?

>

>Before ever removing a grill cloth, someone here would have

>walked you through a step by step procedure for

>troublshooting.

>

>You will need to tell us what all you have done at this point,

>please.

>

>The putty, Mortite, or various other names is a sealant putty

>which basicly doesn't harden.

>

>You will need to apply some more, unless you were able to

>salvage all of the old stuff and it still very pliable.

>

>Roll it in your hands if it is soft and if you can create a

>piece of spaghetti that will lay down just to the woofers hole

>edge of the bolt holes, that should be sufficient to reseal

>the woofer when you are finished.

>

>After just re-reading your note, I thought that you now were

>going to replace the insulation, true?

>

All I have done is open up the box by removing the woofer and pulling out the fiberglas. I thought that the tweeter pot may be the problem, since I get no sound out of this tweeter, and the pot on the other 4x is very scratchy. I read elsewhere in this forum:

"The pots can be cleaned using cleaner and/or WD-40. Put an ohmmeter on the pots to watch the resistence smoothly go from 2 ohms to about 20 as the pots are cleaned. Or you can remove them and disassemble for cleaning. The woofer should be working fine unless the surrounds are bad and I doubt if they are. Tweeters not working 95% of the time are because of dirty pots and 5% of the time due to the tweeter being blown. Infinite resistence across the tweeter terminals indicates a blown tweeter."

I thought I'd put in newer, sturdier pots and hope for the best. btw--I did save the old fiberglas, but have read about people using polyester or some such thing when refurbishing their speakers.

Here's a pic of the open box

[dynaco_dan]

>All I have done is open up the box by removing the woofer and

>pulling out the fiberglas. I thought that the tweeter pot may

>be the problem, since I get no sound out of this tweeter, and

>the pot on the other 4x is very scratchy. I read elsewhere in

>this forum:

>

>"The pots can be cleaned using cleaner and/or WD-40. Put

>an ohmmeter on the pots to watch the resistence smoothly go

>from 2 ohms to about 20 as the pots are cleaned. Or you can

>remove them and disassemble for cleaning. The woofer should be

>working fine unless the surrounds are bad and I doubt if they

>are. Tweeters not working 95% of the time are because of dirty

>pots and 5% of the time due to the tweeter being blown.

>Infinite resistence across the tweeter terminals indicates a

>blown tweeter."

>

>I thought I'd put in newer, sturdier pots and hope for the

>best. btw--I did save the old fiberglas, but have read about

>people using polyester or some such thing when refurbishing

>their speakers.

>Here's a pic of the open box

Hi Kent;

When a cleaner is mentioned, it is, an electrical contact cleaner, or to better recommend one, DeoXit, or the older name Cramolin.

There is many tv repair contact cleaners and they also may be useful, but I don't know them.

Absolutely do not use a de-squeaker, such as WD-40 on the pots contacts.

If I remember correctly, maybe 25 plus years ago, I was showing a friend, how, with my lighter, I could make a flame thrower out of an aerosol spray cleaner.

Now that you have the box empty, nice photo by the way, connect up the speaker wires again.

Be certain the woofer is disconnected or wires are not shorted together.

Play some music or sine wave signal to the AR-4X.

Rotate the pot back and forth at least 5 times.

At some point thee should be some sound from the tweeter.

If after 5 attempts you have no sound, even temporary, find yourself a tweeter or any small fullrange driver of any kind and try that across the tweeter leads.

It now should have some highs coming from that temporary speaker, if the original tweeter is dead.

If not still, let us know, I haven't assumed that the tweeter is dead yet.

Re-use the old fibre-glas stuffing, as you cannot just replace it at random, the quality and quantity is critical.

[Guest tgw]

While some advise not using WD-40, but rather a specific contact cleaner, I have tried both and had success with both.

I prefer to replace the fiber glass fill with new material. I don't think there is anything magical about 35 year old fiber glass. However, if you don't mind handling it then you can certainly put it back when you are finished cleaning the potentiometers. I replaced the original fill with my AR-3's and put new fill in the AR-4x's I have worked on.

I use 3M #77 surface adhesive when replacing the grill cloth. I stretch the grill material by using thumb tacks on a soft wood panel and then place the frame onto the material after having sprayed the adhesive on the frame. Make sure you use the adhesive in a well ventilated room or apply outside and then bring the frame indoors.

I find the grill frames are held in place just by friction.

I fabricated new AR emblems using .020 brass plates I purchased from an engraving shop. Unfortunately I had to purchase 100 as a minimum order. These new emblems combined with new grill cloth make the speakers look like new.

In my opinion (and on this forum I am speaking to the choir) the amount of work required to bring back to original specs these classic speakers gives you sound that would cost considerably more if duplicated using newly purchased speakers of the same quality.

While inside the speaker it is good to check using a capacitance meter the values of the cross over caps. Some prefer to replace them regardless of the reading.

[RoyC]

>I replaced the original fill with my AR-3's

>and put new fill in the AR-4x's I have worked on.

Did you replace it with fiberglass or some other material? I agree that there is nothing "magical" about the original nasty fiberglass, but fiberglass itself has different acoustic properties than other materials (such as Acousta Stuf). These materials cannot be substituted for fiberglass in a 1 to 1 ratio.

Roy

[Guest tgw]

Roy:

I have used both acousta fill and polyester stuffing in AR-4x's that I have worked on. I just use enough to fill the entire cavity as did the original fiber glass. This might have changed the output, but nothing that I can notice.

[JKent]

Very interesting. So speaker refurbishing seems to be more art than science

Anyway--I bought brand new pots and am awaiting their arrival. I saved the old fiberglas but have not decided whether to re-use it or not. Any more input on stuffing material?

[Guest tgw]

Experimenting with different methods of restoration is in my opinion half the fun of this type of restoration. Sometimes we make things better and sometime we make things worse, but that is how we learn.

[johnieo]

>Anyway--I bought brand new pots and am awaiting their arrival.

>I saved the old fiberglas but have not decided whether to

>re-use it or not. Any more input on stuffing material?

Greetings:

I have measured fc (cabinet resonant frequency) and Q of an AR-4x cabinet with two stuffings- fiberglass and Legget & Platt FiberLoft trilobe-cross-section polyester fiber (close to that used in the AR-18). With the correct amount of fiberglass, fc was 55 Hz. With poly, fc remained at 60 Hz. It did not decrease as the poly weight was increased from 6, to 7 to 8 oz; only Q continued to decrease. The woofer tested in this experiment had an fs of 32.5 Hz.

These results I discussed off-line with Ken Kantor who indicated it is his experience that one cannot substitute new materials in older speakers <> and obtain the original design performance.

It would be prudent to retain fiberglass and retain the speaker's lowest possible bass performance. You may choose to install new, if the old is very broken and dusty; just maintain the same weight. The early serial numbered 4x (up to somewhere around sn 180,xxx to 220,xxx used an AR #4 coil (0.88 mH) and 18 oz of fiberglass. After that the inductor was changed to a #5 (1.18 mH) and the fiberglass weight was reduced to 12 oz. It makes no difference whether it be brown, yellow or pink. Nor does "R value" have any significance for this application; just the weight.

Enjoy them; they are an absolutely wonderful little speaker!

[dynaco_dan]

Hi John;

A great write-up as always, thank you.

[Rlowe]

>These results I discussed off-line with Ken Kantor who

>indicated it is his experience that one cannot substitute new

>materials in older speakers <

>with fiberglass>> and obtain the original design

>performance.

I have AR6 & 14 speakers that have a diferent fill that looks more like "matress" fill. I understand this was used in Euro and late US cabinets, does anyone have more details on the material and its equivalence to fibreglass/poly in term of equivalent weight?

Is it 1:1 ??

[JKent]

Thanks to a lot of help from John and a lot of trial-and-error (a lot of error), things are moving along. I bought a pair of L-pads from Larry Lagace and went to work on the speaker with the dead tweeter. The L-pad did the trick. I suppose I could have cleaned the pots but it took more than a squirt of WD40. I pried it open and after trying emory cloth resorted to a wire brush chucked in my Dremel, followed by a blast of contact cleaner. That got the guts nice and shiny, but still pitted. I think I'll stick with the new L-pads. Had to put longer leads on the wires so I could work with them, and I used stakon crimps on the speaker and the L-pad instead of solder.

Next step is to install a Zen capacitor to replace the antique original. Then I'll re-stuff the box and see how it sounds compared to the "unmodified" one.

Any comments are welcome. btw--anyone have a suggestion for replacing the paper that goes between the woofer and the stuffing to keep the 'glas off the woofer? I saved the original, but it's not completely intact.

[JKent]

Finished the project and put the speakers in my living room. That was fun! Here's a pic of the inside of spkr 1. The cap is hot-melt glued in place. I later snipped the leads from the old cap off. On spkr 2 I rearranged things so I could have shorte leads. Next project: Replace the passive radiator in my VMPS subwoofer and install a "plate amp." I'm on a roll ;-)