AR25 "stuffing" question

[Richard_C]

The question comes at the end if you don't want to read through the first bit, but I thought a bit of context might be useful.

First post here, stumbled on the forum while searching for all I could find about AR25s.  I'm in the UK.

Almost 40 years ago I bought a Pioneer PL512 deck, a Trio  Receiver and a pair of AR25's, the best I could afford a the time.  The AR25s are labelled AR25EP, the label has a UK and US address and serial numbers 16399 and 16400.  Looking at price lists on here, it looks like they were the "value option", priced well below some similar models. About 20 years ago the Trio began to die, and what I now know to be the foams on the speakers began to disintegrate.  I did a quick fix using rings I cut myself from thin closed cell foam, and soon after I got a Sony FA3 amplifier and at the same time some Tannoy Mercury M2 bookshelf speakers.  That suited us with young children crawling round the house.  The Trio went to recycling, the speakers (fortunately) to the loft.  The PL512 still works well, a CD player and FM tuner joined in along the way. 

This week, with a bit of time on my hands, I went up into the loft and brought down the old AR25s.  The cabinets cleaned up nicely, the grille foam is missing, I might find it but meanwhile have used some acoustically transparent  speaker cloth that I had left over from a job on my car many years ago.  They look pretty good, and sound very good to my ears - I listen to all kinds of music -  the top end is excellent with orchestral music, glock, triangle and suchlike very clear.  I have new foams and dust caps for the combined woofer/mids on order so will do a proper job on those using the advice I found in this forum.

The question: a very long time ago I remember adding some stuffing, they were in a small room with odd resonances and I was trying to kill that off.  Trouble is, I don't remember what they were like originally.  They are of course sealed cabinets, so in a range none - loose packed - tight packed, what should be in there? 

A secondary question:  there is a very small dent in the dust cap of one of the tweeters.  My instinct is to leave it well alone, what does anyone think?

 

[lARrybody]

Tonight when I get home from work I will pull out a extra pair of25's I have and weigh the amount of poly fill. The little dent in the tweeter dust cap won't affect its performance.

 

[Richard_C]

Thanks, very helpful indeed.

[lARrybody]

Sorry it took me a extra day to get back to you. This is from a pair I found last summer at a garage sale. The woofers are not original, but everything else looks right. There was no gasket between the baffle and the replacement woofer.

Two pieces of poly fill. Weighs 180 grams (6.3 ounces)  I am sure there are different densities of poly fill, but this looks like the stuff you can get a a fabric store. 

Typical red end black electrolite I see in most all ADD speakers. Notice the 1982 date. Got to love those uncomplicated crossovers. The 25 fits somewhere in between the ADD series and the S series. On my restored pair I used a 6uf Erse PluseX cap and added a lpad on the tweeter. Also replaced the spring loaded clips with some binding post.  Great sounding speakers. I listen to them a lot. 

 

[Richard_C]

Thanks for that information.  No worries about delay, I've been thinking about restoring them for 20 years so a day here or there is a blink of an eye, and we are 6 hours apart in timezone.

I have 500g in total so slightly over filled, will leave a bit out.  Foams arrived today so hope to get it all sorted over the weekend.  Mine had binding posts already, all metal ones, and a toggle switch for the 0dB, -3dB tweeter control.

[ReggaeBen]

IARrybody, I really like how you've added the L-pad to these.  It's something I'd wondered doing about if I had a poly cap in place of lytic that could benefit from attenuation.  

I picked up a pair of 25's for dirt cheap just for a spare tweeter.  They are missing the original woffers and baffle openings have been hacked a little. But maybe I'll resurrect them some day. 

Just weighed the fill and I got 7.1 oz

Ben

[lARrybody]

I misspoke about the spring loaded speaker clips, mine had or have the same screw post as Richards and Bens. I just like banana plugs on my speaker wires. Neither of mine have or had the toggle attenuation switches like your guys. I have AR 18 speaker examples with and without the switches. Ben, your stuffing appears to be fiberglass. I have European manufactured AR speakers with a blue grey polyester acoustic stuffing. AR used all three types. 

The AR 25 used the 004 tweeter which I find to be a little bright, thus the addition of the lpad. The 038 tweeter used in the AR18S and characterized by the s shaped leads is basically the same with a little higher output. The original woofer (20001-1)is a little hard to find, but the (200037-0) woofer used in the AR18S and 18B are far more prevalent and are very close in specifications. On the left is a original AR25 woofer and on the right are two AR18S woofers that I have refoamed and changed to the doubble dust cap  configuration of the previous.

 

[ReggaeBen]

It does appear to be fibreglass but its actually a very soft fill, similar to the blue grey polyester euro type.  

RichardC, your 25's cleaned up nicely and I think look great with the new grills.  Good luck on starting the refoam, we'll be here to guide you through.

 

[ra.ra]

On 12/8/2018 at 8:04 AM, lARrybody said:

The AR 25 used the 004 tweeter....

This is a fine little summary from Larry, but I think this note was meant to say the 014 tweeter for the AR-25.

I guess I had not realized how large the dimensions of the AR-25 cabinet are - - its size is identical to the AR-15, which has nearly twice the internal volume of the popular AR-18. With the 1-1/4" tweeter and simple crossover, the AR-25 seems squarely situated between the AR-17 and the AR-15, IMO. The 25 does not show up in much literature (this AR-25 info was from Euro brochure), and I think it was SteveF who noted this was a model marketed (in 1978 or 9) to designate the 25th anniversary of Acoustic Research.  

[lARrybody]

15 hours ago, ra.ra said:

I guess I had not realized how large the dimensions of the AR-25 cabinet are - - its size is identical to the AR-15, which has nearly twice the internal volume of the popular AR-18.

These 25's are how I acquired the near perfect foam grills for my AR 15's. With a 1982 date stamped inside the cabinets, the 25's must of bridged the time gap between the ADD series and the AR9 series bookshelf speakers. To bad they did not have the wood veneer of the AR 15 and 17.

[Richard_C]

All done, straightforward apart from one last minute near disaster on a  tweeter wire.

I have added pictures and gone into some detail on the tweeter fix.  For those AR fans who like detail, here are some numbers:

AR25EP, serial numbers I've already posted above, 164399 and 400.
Inside is another numbered sticker, Ingham MItrefold AX9399 and 9401, I take them to be the cabinet numbers.

Units are 200001 woofer/mid, and 200014-3 tweeter, both "made in USA".

Crossover is set in a lot of epoxy resin, toggle switch for 0db/-3db tweeter adjustment, capacitor is ELCAP 6MFD.

So to work.  It took along time to clean up the cones and spider, not difficult but painstaking.  My home made foams of 20 years ago were a mistake, using hot melt glue was an even bigger mistake!  Remember back then you couldn't use ebay or amazon to find the proper things.  The dust caps looked in very good condition, the new ones hadn't arrived yet, so I decided not to cut them off and use shims to center the cone but instead to use the clothes peg and rock method which was fine.

I know most of you will know far more than me about how to re-foam but I have put a bit of detail in below for those who are about to do it for the first time.  Skip it of you've done it before.  Foam was fixed to the cones with some care, you can use feel as well as eye to make sure they are even, squeezing round  you can feel the  edges.  Once set, you need 8 pegs, the extra 4 help.  Use a pair of pegs opposite each other to fix the foam to the rim.  Using thumbs on the cone near the pegs,  rock the cone and feel it foul the coil on each side.  Adjust the pegs until the 'rock' needed to touch the coil is equal each side,  Then push the cone up and down near the center, nice and free.  The add 2 pegs at 90 degrees the to the first, repeat.  With them in all place check that the cone moves freely.  Smear some glue under the foam in the sections between the pegs, let it set for a few minutes until tacky then put the 4 extra pegs on where you have glued.  That holds it all in place while you take the original 4 pegs off and glue there as well, then put them back on.  Gently push cone done to check it is free.  That's  it - leave to set.

Reassembly was going well, 180g of stuffing in each one, then the mini disaster.  The spade terminal on one tweeter popped out of it's body as I was re-fixing it, breaking through and breaking the wire where it went across the cone.  Looking carefully, the small plastic mount had disintegrated probably through age.  I tried to fix it and surprised myself by succeeding.  First step make a scissor cut in small piece of white paper and slide it down the side of the cone so that the tiny wire sticks through.  That means you can see it and it protects the cone from solder drips.  Then cut a length of lighting flex and pull out a couple of strands of the thin copper, twist them together.  Magnifying glass time, solder the new bit to the old bit.  Then run the new bit through the hole where the old terminal was, insulate carefully (I used self amalgamating tape) so it can't touch the metal body, fix to the old spade terminal which is now floating rather than secured to tweeter body, job done.   I fixed the old bright solder spot on top just for cosmetic purposes.

Last act was to cheer the cabinets up with Danish Oil, polish and enjoy.

They sound good and the sealed cabinet design means you don't have to worry about resonances from a back port.  I can see that the top end might be too much for some, but my living room is fairly dead acoustically.  I might do the -3db cut in summer when the curtains are open so there is a lot more glass in the room.  In dark winter evenings big heavy curtains kill any nastiness.  I do wonder, people who spend ££££££ on a piece of wire to make their speakers sound better might get a bigger impact by moving a few cushions on the sofa.  Few of us can afford a 'listening room'.  

Altogether a satisfying project, 2 old speakers restored to everyday use.  Here are some photos, covers off  - first post showed them on.  The second success this weekend was to de-hum my old Pioneer PL512 turntable.

Thanks all for help and words of encouragement.

 

 

 

 

[JKent]

1 hour ago, Richard_C said:

instead to use the clothes peg and rock method which was fine.

OK. I know Brits & Yanks are separated by a common tongue but I have no clue what the "clothes peg and rock method \" is ?

They look great! One critique: Those black & red capacitors are notorious for leaking and drifting. I'd replace them.

Kent

[Richard_C]

This might help explain, I guess its the easiest way to do it of you don't want to cut off the dust caps.  The centering starts at 7.15 sec.

https://www.youtube.com/watch?v=boVURbet11g

I looked at a few you tube re-foam videos, and picked the method that made the most sense to me in my situation.  I found a better example of this method but can't find it again.

I guess I should replace the capacitors, unlikely to get the originals so presumably any 6 MFD will do.  In the UK we had a store called Maplin, sort of Radio Shack, but it went bust last year so there are no more walk in stores for this sort of thing, needs to be amazon or ebay so you need to know exactly what to order.

Richard

[JKent]

Ah! I figured clothes pegs are clothespins but couldn't figure out where the rocks came in. I was thinking noun but you meant verb 

Yes--almost any 6uF will do, as long as its voltage rating is equal to or greater than the original, and it's bi-polar. So either an NPE (non-polar electrolytic) or any film cap.

-Kent

[Richard_C]

Useful thanks.

I can't see the voltage on the ones I have.  Looking online I can order the following from UK  distributors, the Solens are more expensive but that's not a problem, I only need 2 and its a trivial expense in the scheme of things.  

6uf 50V Alcap Bipolar Axial Electrolytic Capacitor (10% tolerance)

Solen 6.00uF 400v DC polypropylene capacitor (2% tolerance)

Plan to order the Solens unless anybody shouts "bad idea" ........

 

[Mike Godden]

On 12/5/2018 at 11:16 AM, Richard_C said:

The question comes at the end if you don't want to read through the first bit, but I thought a bit of context might be useful.

First post here, stumbled on the forum while searching for all I could find about AR25s.  I'm in the UK.

Almost 40 years ago I bought a Pioneer PL512 deck, a Trio  Receiver and a pair of AR25's, the best I could afford a the time.  The AR25s are labelled AR25EP, the label has a UK and US address and serial numbers 16399 and 16400.  Looking at price lists on here, it looks like they were the "value option", priced well below some similar models. About 20 years ago the Trio began to die, and what I now know to be the foams on the speakers began to disintegrate.  I did a quick fix using rings I cut myself from thin closed cell foam, and soon after I got a Sony FA3 amplifier and at the same time some Tannoy Mercury M2 bookshelf speakers.  That suited us with young children crawling round the house.  The Trio went to recycling, the speakers (fortunately) to the loft.  The PL512 still works well, a CD player and FM tuner joined in along the way. 

This week, with a bit of time on my hands, I went up into the loft and brought down the old AR25s.  The cabinets cleaned up nicely, the grille foam is missing, I might find it but meanwhile have used some acoustically transparent  speaker cloth that I had left over from a job on my car many years ago.  They look pretty good, and sound very good to my ears - I listen to all kinds of music -  the top end is excellent with orchestral music, glock, triangle and suchlike very clear.  I have new foams and dust caps for the combined woofer/mids on order so will do a proper job on those using the advice I found in this forum.

The question: a very long time ago I remember adding some stuffing, they were in a small room with odd resonances and I was trying to kill that off.  Trouble is, I don't remember what they were like originally.  They are of course sealed cabinets, so in a range none - loose packed - tight packed, what should be in there? 

A secondary question:  there is a very small dent in the dust cap of one of the tweeters.  My instinct is to leave it well alone, what does anyone think?

 

Hi Richard. I know this reply is 4 years later!! I also have AR25's also in the UK. Inherited (23 years ago) from my late uncle.  They have been in use every day since. The foam surrounds were perished when I got them and I had Wembley Loudspeakers professionally redo them. A few years later one if the tweeters got damaged (Cat Attack!) Also trashed the foam grills. I tracked down what I think was the last pair of New replacement tweeters on the planet from a HiFi shop somewhere in the US. And like you have fabricated new, acoustically transparent grill. Since the cat incident they have become wall mounted using Martin Audio / Powerdrive, mounts.   I am a professional sound engineer, for the past two decades they have been my reference, incredibly flat sound, very natural. I have periodically looked to replace them, but to get something as good would be £1000+. I have other speakers RCF reference monitors in my office and a warehouse full of Pro-Audio Concert systems but to chill at home and just enjoy music they are the business. Hope yiubarevsill enjoying yours. If you ever want to connect just give me a shout. Google MG Event & Sound & you will find contact details. Mike Godden. UK