AR-4x Restoration - Where to start?

[BrianG]

I found this pair of AR-4x's at my father's house last weekend.  They were attached to a Dyanco system that he build in the 1960's, but it's long gone.  I've included some photos.

I hooked them up to a little NAD C316BEE in the bedroom and they sounded good, not great.  One of the L-Pads was dirty and I turned it a few times to get the tweeter going.  The dial on the second L-Pad is missing, as you can see on the photo.  I did not hear any tearing from the woofers, so they a probably in OK shape.  The mid's, voice mostly, felt under represented.  The soundstage was fantastic.  The cabinets are in pretty good shape and won't need a lot of work.  I noticed some small staples might be holding the grill in place.  I'm hoping that will make it easier to remove.  The cloth grills is not too damaged and I might be able to clean.  I'd like to get them sounding as they did.  If I'm really motivated I'll have my Marrantz 2235B restored for a cool retro system.

Where can to do get these back up to their past glory?  

• Tweeter?
• Crossover?
• L-Pad?
• Woofer?
• Cleaning of cloth grills?
• Batting?

I'm assuming I have to remove the grill and the drivers to get to the L-Pad and crossover if I need to.

Thank you in advance for your help!

Brian

 

[Aadams]

41 minutes ago, BrianG said:

I found this pair of AR-4x's at my father's house last weekend.

Hello Brian.   Those are some nice 4xs.  Download and read the AR3a restoration guide to get an idea of how to approach this project.  Don't touch anything until you have a better idea of what is inside the box and how to open it.   I am sure some 4x experienced members will be along to advise.  I have attached two threads about AR4x restorations. 

 

 

[BrianG]

HI Aadams, Thank you kindly for your response.  The AR3a restoration guide is very helpful now that I'm going through it in detail.  

Assuming the drivers are in good shape, do you think the underperforming mid's are related to the capacitor in the crossover not performing correctly?

Any other advice from other 4x owners?

Kind regards,

Brian

[Aadams]

Brian

The AR4x is a two way and does not have a separate mid range.  The "under performing mids" could be rotted foam surround on the woofers Playing them loud with rotten foam could damage the woofers but if they are cloth surround this is not the source of the problem. It could be dead tweeters or more likely dead pots.  The grills are attached with either glue or staples.  The restoration guide tells you how to approach grill removal.  Once the grills are off post images of the drivers in the baffle.

[BrianG]

Aadams, very helpful!  Thank you!  I'll research and start by removing the grills and inspect the surrounds.

[RoyC]

3 hours ago, Aadams said:

Brian

The AR4x is a two way and does not have a separate mid range.  The "under performing mids" could be rotted foam surround on the woofers Playing them loud with rotten foam could damage the woofers but if they are cloth surround this is not the source of the problem. It could be dead tweeters or more likely dead pots.  The grills are attached with either glue or staples.  The restoration guide tells you how to approach grill removal.  Once the grills are off post images of the drivers in the baffle.

The serial numbers indicate the woofers will have cloth surrounds. Capacitors are the least likely cause of the issue as described.

Roy

[BrianG]

RoyC, Thank you kindly for the advice.  This all makes sense.  I'll post more pictures later this week when I get the grills off.  

Brian 

 

[JKent]

Something's off with that missing pot, and those holes will have a negative effect on bass. Woofers and tweeters are probably fine but I'd replace the 20uF caps. These will work https://www.madisoundspeakerstore.com/carli-capacitors/carli-mylar-20-mfd/ and get a couple of these L-pads https://www.madisoundspeakerstore.com/l-pads-attenuators/yung-lp15-3/4-15w-8-ohm-l-pad/

Some people have been successful cleaning the grille cloth. Leave it on the frame and try gently scrubbing with a mild Oxy-clean solution. Personally, I've never had success cleaning old grille cloth. The 18 count Irish linen in "lambswool" from 123Stitch as described in the AR-3a restoration booklet is perfect.

The 4x is an excellent speaker and once yours are restored you should be happy with them. I bought mine new in 1970. Photo below shows them after restoration, with 123Stitch linen.

Kent

[lARrybody]

Brian   just want to add a few things to what Aadams and JKent have said.  You can discontinue the wax block cap and push it back slightly to make room for the new 20uf cap. That way you wont have to mess with the inductor. 

 

You don't really want to mess with the original pots, just install new L-pads. You wont have any problems that way.

The 18 ct. lambs wool from 123 stich is some excellent material but a bit pricy. I went another way and used the Charles Craft Irish Linen from Michaels. Less than $5.00 with the 40% off coupon. It is a tea dyed tint so I soaked it in some diluted bleach water to lighten it up a bit. It does look very presentable. 

 

Two last recommendations. Use the sealer available from RoyC  and Vintage AR on the woofer cloth surrounds. Don't use anything else no matter what you read.  Make sure the woofers and tweeters are properly sealed to keep the cabinets air tight.  You should really enjoy these speakers.  

[BrianG]

lARrybody & JKent,  Thank you!  Lot's of helpful advance.  

My first task is getting the grills off.  After reading RoyC's restoration guid I understand they glued not stapled in place.  The staples are to hold the cloth in place.  When I get them off I'll post some updates before proceeding.

lARrybody, the cloth looks great.  Mine are discolored, not really stained.  I'm going to try to clean them first.  

You guys have been so fantastic.   See you in a few days!

B

[BrianG]

I'm planning on running these with a NAD C316BEE, 45 WPC, in the bedroom, not really loud.  

I also have a Marrantz 2235B that needs some work that I could use.  (I'm the original owner.)

NAD going to be good?

[JKent]

The NAD is plenty. I ran mine for years off a Dynaco ST-35, 17wpc. Sounded great.

[BrianG]

Grills are off.  They were attached with staples.  All the drives look in good shape.  Looks like cloth on the surround.  Oddly, it looks like some screws are missing on one of the 8'' drivers.  Please let me know if you want me to post more detail.  

[Giorgio AR]

22 minutes ago, BrianG said:

some screws are missing on one of the 8'' driver

Hi, two notes on the screws: the original screws should be black, not with the clear galvanic treatment that should appear in the AR4xa late, circa 1974, probably the woofers have previously been removed from the cabinets, so either screws have been lost and replaced, or the female insert may have come off posteriorly, so there was no possibility to insert and tighten the screws.

[RoyC]

1 hour ago, BrianG said:

Grills are off.  They were attached with staples.  All the drives look in good shape.  Looks like cloth on the surround.  Oddly, it looks like some screws are missing on one of the 8'' drivers.  Please let me know if you want me to post more detail. 

There are no missing screws (they are original), and it does not appear that the woofer has ever been removed. Many of the earlier woofers, like yours, had more screw holes than were used. There were over 400,000 4x's manufactured in the US with a variety of versions of the 8 inch woofer. The later ones had 4 screw holes.

Roy

[BrianG]

RoyC,

Thank you.  It looks like the surrounds are cloth as expected.  All the drivers look to be in very good shape.  At this point I'm assuming my issues in in the electronics.  The next step should be to remove the woofers and look at the capacitors, crossover and LPads.  

I'm assuming I should do the following:

1. Test and likely replace the capacitors
2. Order and replace the LPads
3. Re-paint the cloth surrounds with the recommended glue?

Thank you for your help!

Brian

[Aadams]

Still nice with the grills off.  Provide images of the inside.

25 minutes ago, BrianG said:

I'm assuming I should do the following:

Things to keep in mind.

1.  Don't remove the tweeters unless you must, the flanges can be delicate.

2. Be patient in removing the woofer, the old putty can be stubborn.

3. Use adhesive gasket tape instead of putty when reinstalling the removed drivers.

 

[Giorgio AR]

1 hour ago, RoyC said:

There are no missing screws

Roy, if you look closely at the photos of the 2 speakers, in those of the first (you can see better in the photo of the woofer only), on 4 fixing screws there are only 2, in one seat, the hole is covered by the sealant, in the other one sees the screw passage hole.
It is clear that the screws present are original, but if you look closely, both on the woofer and tweeter the screws are mostly clear, on the woofer with the 4 complete screws, 3 are black, one is clear.
In my ARs (22 pairs), the only pair that has screws equal to those with clear galvanic treatment are the '74 AR4xa, from the early AR4xa I have, 3 pairs of AR7, 2 pairs of AR4x and pair of AR6 are all black.
I am attaching photos of an AR4x Woofer circa 1969 and below of AR4xa 36/74

Left AR4x, on right AR4xa

[JKent]

On 12/14/2020 at 10:38 AM, BrianG said:

RoyC,

Thank you.  It looks like the surrounds are cloth as expected.  All the drivers look to be in very good shape.  At this point I'm assuming my issues in in the electronics.  The next step should be to remove the woofers and look at the capacitors, crossover and LPads.  

I'm assuming I should do the following:

1. Test and likely replace the capacitors
2. Order and replace the LPads
3. Re-paint the cloth surrounds with the recommended glue?

Thank you for your help!

Brian

1. Don't bother testing the caps--just replace them. One 20uF cap per. You can leave the originals, just cut the leads.
2. Yes on the L-pads. The terminals don't correspond to the originals. I'll post a photo when I find it.
3. I like Roy's authentic goo for re-doping cloth surrounds but some have said it's not really necessary on the 4x so you may want to wait and see.

Kent

PS: Found it. I think this is Roy's pic. Note that on the L-pad, tab 1 = tab 3 on the pot. L-pad 2 = B and L-pad 3 = 1. 

 

Edited November 23, 2022 by JKent
Removed pictures

[BrianG]

5 hours ago, Aadams said:

Still nice with the grills off.  Provide images of the inside.

Things to keep in mind.

1.  Don't remove the tweeters unless you must, the flanges can be delicate.

2. Be patient in removing the woofer, the old putty can be stubborn.

3. Use adhesive gasket tape instead of putty when reinstalling the removed drivers.

 

Is there adhesive gasket tape you can recommend?  

Thanks!

Brian

[JKent]

19 minutes ago, BrianG said:

Is there adhesive gasket tape you can recommend?  

Thanks!

Brian

https://www.parts-express.com/parts-express-speaker-gasketing-tape-1-8-x-3-8-x-50-ft-roll--260-540

[BrianG]

I want to order some parts.  Are these the right ones?

Is this the right L-Pad?  https://www.parts-express.com/speaker-l-pad-attenuator-15w-mono-1-shaft-8-ohm--260-250

Is this the right capacitor?  https://www.parts-express.com/solen-20uf-400v-polypropylene-capacitor--027-582

Thanks Kent for the gasket tape!

Is there anything else I should order?

Kind regards,

Brian

[BrianG]

JKent, 

Outstanding and Thank you.

IBrian

[JKent]

That's what we're here for 😉

Regarding your L-pad and cap selections, those are fine. Some people use the L-pads with shorter shafts https://www.parts-express.com/speaker-l-pad-attenuator-15w-mono-3-8-shaft-8-ohm--260-248  If you use the 1" shafts you'll need some kind of spacer so the shaft doesn't protrude too far. But many of us do use the 1" shaft model.

The Solen caps are good. You could use any of these: https://www.parts-express.com/cat/metalized-polypropylene-crossover-capacitors/294?N=22074+4294967118+4294962381&Ne=10166&Nrpp=99999&Nrs=collection()%2Frecord[endeca%3Amatches(.%2C"P_PortalID"%2C"1")+and+endeca%3Amatches(.%2C"P_Searchable"%2C"1")]&PortalID=1  Many of us here use the Dayton 5% 

Kent

[BrianG]

Kent, Thank you!  Are there any other parts I should be ordering?

Also...I uncovered the mystery of the missing screws after talking with my father.  One of the speakers was serviced.  It looks like who ever did the work left out two of the screws and did a less than perfect job on the gasket tape.

I'll order some parts and be back in a week after I pull out the woofers.

Kind regards,

Brian