AR4x tweeters?

[speaker dave]

I bought a pair of AR4x. I believe they are from 1968, or at least that is what one of the tweeter datecodes says.

Both have dead tweeters but the price was right and the cabinets are really nice. I hoped it might be an L-pad (rheostat) issue but the tweeters are both open circuit.

I even managed to get a tweeter cone out to see if I could repair it. I was able to use a razor blade to cut just under the surround and get the cone edge up intact. Press hard against the basket at the right angle and you can scrape under the glue bond. With a little wiggling the cone separated from the cone. A little cutting got the dust cap off the cone. All this was without cutting through or damaging the parts. The voice coil wires come across the spider and then jump to the terminals. One of them was broken so the cause of the open circuit was obvious. I was able to splice a tiny strand to the remaining wire and now the tweeter measures 0 ohms. There must be a short in the coil somewhere.

Long story short, I am looking for a pair of replacement tweeters (see photo attached for exact model). Anybody got a pair?

When I get them running I think I will try a 2nd order filter on the tweeter for smoother response and also to improve the power handling. Should be an interesting project.

Regards,

David

[JKent]

Hi David

I have a pair I would be happy to sell. Not sure what a fair price is but PM me if you want to discuss.

Kent

[JKent]

OOPS I spoke too soon

Only have one. Can anyone else help David out?

Kent

[Tekker]

Dave,

You may want to contact Chris at reverbdmit@aol.com. He did nice job replacing voice coils on my AR3a tweeters.

Bill

[speaker dave]

Dave,

You may want to contact Chris at reverbdmit@aol.com. He did nice job replacing voice coils on my AR3a tweeters.

Bill

I think I will keep looking for a pair of used tweets as the affordable option.

I took the second tweeter apart and the coil was open circuit and had fallen off the former. I've never seen a driver with the clear voice coil gel. I assume this was meant for damping of fundamental resonance? Kind of a precurser to ferrofluid?

David

[Tekker]

I think I will keep looking for a pair of used tweets as the affordable option.

I took the second tweeter apart and the coil was open circuit and had fallen off the former. I've never seen a driver with the clear voice coil gel. I assume this was meant for damping of fundamental resonance? Kind of a precurser to ferrofluid?

David

That sounds really odd. Now I'm tempted to do surgery.

Give Audioproz a ring. You can check out some of their stock on the web, but you have to call em to order anyway. They have a lot of used AR tweeters they strip from cabinets.

Bill

[Zilch]

Long story short, I am looking for a pair of replacement tweeters (see photo attached for exact model). Anybody got a pair?

I'll check. There's at least four pair in the dungeon I haven't "fixed" yet.

My AR4x study is discretely hidden away here:

http://www.audiokarma.org/forums/showthread.php?t=123113

[speaker dave]

I'll check. There's at least four pair in the dungeon I haven't "fixed" yet.

My AR4x study is discretely hidden away here:

That would be great if you had a pair.

I read through your AR4x thread with interest. You've already tried most of the mods I was thinking of. It looks like the 2kHz dip was cabinet related in the end? (Tang Band driver had the same issue when added to cabinet.) Probably a reflection off the cabinet edge?

David

[JKent]

Aha! I knew I had read about using EPI/Genesis tweets somewhere:

http://www.audiokarma.org/forums/showthread.php?t=120634

I have a pair of the non-inverted dome type and some 10uf caps if you are interested. I really DO have these--sorry about the 4x tweet mistake!

Another option might be Zilch’s famous E-Wave mod, although once you cut the front baffle there’s no going back.

http://www.audiokarma.org/forums/showthrea...light=econowave

Zilch: What components did you use to E-Wave the 4x? Think I saw some you modded that had big square horns, like Wiredbecker’s shown here:

http://audiokarma.org/forums/showthread.ph...7859&page=2

Kent

[Zilch]

WiredGuy's are JBL OASR, the "Dr. Seuss" horn. He has BMS 4540s on them.

The elliptical 18-Sound XT120 fit best. I forget what's on the back of them; bolt-on Selenium D220Ti, maybe. Should say in the thread. Their own driver for them is an economical option, too.

The JBL 6" square one mentioned there will fit. Current favorite driver on those is Selenium D2500Ti-Nd, though JBL 2414H(-1) is a slam-dunk with the AC16 highpass filter. See pic below for how to be bad with those.

As I recall, the 8" square is too deep for AR4x, but it may fit with the Selenium Nd or JBL drivers, which are shallow. I'll have to check. That's one on the bench in the background of the pic.

The larger Dayton elliptical may fit also; I used those with D220Ti in KLH-17, and several others have built that project successfully:

http://www.parts-express.com/pe/showdetl.c...tnumber=270-316

LSR oblate spheroid will go, too, if you happen to have a couple of those lying around.

Maybe Dave'll show us all how to mate dome tweeters to waveguides for these....

[Zilch]

That would be great if you had a pair.

I have three; top two dated 1966, left one open, right DCR = 1.30 Ohms. Bottom, no date, DCR = 4.30 Ohms. You are welcome to any or all of these -- PM me your desire.

The 8" PT waveguide from JBL AC18 will fit perfectly, and there's just enough cab depth to use D220Ti, even, in addition to those shown. It's available in 90° x 50° ($14 from JBL Pro Parts) and 120° x 60° ($12) variants, the latter being for Howard's pleasure.

See also:

http://sound.westhost.com/articles/waveguides1.htm

[kkantor]

I think I will keep looking for a pair of used tweets as the affordable option.

I took the second tweeter apart and the coil was open circuit and had fallen off the former. I've never seen a driver with the clear voice coil gel. I assume this was meant for damping of fundamental resonance? Kind of a precurser to ferrofluid?

David

During a day trip to AR, '76?, I remember somebody there telling me about experiments being conducted with cooling fluids, but I came awat with the impression that it wasn't actually being deployed in production.

Could the gel possibly be an early FF prototype that completely precipitated? Some kind of silicone? Remains of The Blob?

-k

[kkantor]

I think I will keep looking for a pair of used tweets as the affordable option.

I took the second tweeter apart and the coil was open circuit and had fallen off the former. I've never seen a driver with the clear voice coil gel. I assume this was meant for damping of fundamental resonance? Kind of a precurser to ferrofluid?

David

During a day trip to AR, '76?, I remember somebody there telling me about experiments being conducted with cooling fluids, but I came awat with the impression that it wasn't actually being deployed in production.

Could the gel possibly be an early FF prototype that completely precipitated? Some kind of silicone? Remains of The Blob?

-k

[kkantor]

http://www.bostonaudiosociety.org/pdf/bass...-06-04-7801.pdf

Interesting discussion of FF. Apparently, silicon grease was used in tweeters. Who knew?

-k

[Pete B]

http://www.classicspeakerpages.net/IP.Boar...p;hl=dissection

[speaker dave]

http://www.bostonaudiosociety.org/pdf/bass...-06-04-7801.pdf

Interesting discussion of FF. Apparently, silicon grease was used in tweeters. Who knew?

-k

This was new to me. I have never seen silicon grease in a tweeter. I wouldn't have guessed it conducted better than Ferrofluid (but then why put it under transistors? Duh.)

By the way, the BAS references John King's paper. I worked under John at my very first industry job at Essex Cletron (later Harmon Motive). He actually held the patent on using Ferrofluid in drivers. (Never got a penny for it.) We used to razz the Ferrofluidics salesman with that fact when he came by. (Forget about lunch, where are John's license fees?)

In the two tweeters I've taken apart the silicon was a big dollop under the dustcap and a plug of FG. It is not clear that there is much, if any, still in the gap. Obviously it isn't doing a great job as we see so many open circuit AR 4x tweets!

Do you know who made these units? I thought I heard CTS but that might have been in reference to the AR2ax mid. How many cheap US systems used the ubiquitous CTS phenolic ring tweeter?

David

[speaker dave]

http://www.classicspeakerpages.net/IP.Boar...p;hl=dissection

Hi Pete,

Yes, I had read your earlier thread on the AR 4x tweeter and should have referenced it. That is what prompted me to (nondestructively) cut mine apart.

David

[kkantor]

Do you know who made these units? I thought I heard CTS but that might have been in reference to the AR2ax mid. How many cheap US systems used the ubiquitous CTS phenolic ring tweeter?

David

:- Ah yes, loudspeaker patents... If they all were honored, a basic 2-way 6.5" speaker would cost some outrageous amount, many hundreds or thousands of dollars! Oh wait. They do now.

I had thought those units were made on the AR line in Norwood?

Yeah, it's tough enough to keep FF in the gap... I can't imagine silicon grease staying anywhere useful for very long, or staying in good contact with rapidly moving surfaces. Maybe it even contributed to the long-term failure by wicking into glue joints, paper, enamel insulation, etc. Probably not a great idea in the first place...

-k

[Pete B]

This was new to me. I have never seen silicon grease in a tweeter. I wouldn't have guessed it conducted better than Ferrofluid (but then why put it under transistors? Duh.)

By the way, the BAS references John King's paper. I worked under John at my very first industry job at Essex Cletron (later Harmon Motive). He actually held the patent on using Ferrofluid in drivers. (Never got a penny for it.) We used to razz the Ferrofluidics salesman with that fact when he came by. (Forget about lunch, where are John's license fees?)

In the two tweeters I've taken apart the silicon was a big dollop under the dustcap and a plug of FG. It is not clear that there is much, if any, still in the gap. Obviously it isn't doing a great job as we see so many open circuit AR 4x tweets!

Do you know who made these units? I thought I heard CTS but that might have been in reference to the AR2ax mid. How many cheap US systems used the ubiquitous CTS phenolic ring tweeter?

David

I have to wonder if it is there more for damping of the fundamental

resonance more than anything else ....

[Zilch]

It's silicone grease, actually, and it worked wonders for Carol Doda....

http://en.wikipedia.org/wiki/Silicone_grease

[Zilch]

Shootout: