what tweeters for the AR 4x?

[JKent]

Hi all

I just picked up a pair of AR4x speakers (my 3rd pair) and they're in rough shape. pulling the grilles I found that some previous owner replaced the tweeters with some no-names. I figure I'll watch ebay for some original tweets, but I have 2 questions:

1. Besides watching for "AR4x" tweeters, are there other models (or even brands) that are correct replacements?

2. I read somewhere that early 4's had cone tweeters, but later 4's had dome tweets and the domes were superior. True? Should I hold out for domes?

I'm attaching photos of the front & back of the no-names, in case anyone recognizes them and can tell me if they are worth keeping.

Thanks!

[Carlspeak]

>Hi all

>I just picked up a pair of AR4x speakers (my 3rd pair) and

>they're in rough shape. pulling the grilles I found that some

>previous owner replaced the tweeters with some no-names. I

>figure I'll watch ebay for some original tweets, but I have 2

>questions:

>1. Besides watching for "AR4x" tweeters, are there

>other models (or even brands) that are correct replacements?

>2. I read somewhere that early 4's had cone tweeters, but

>later 4's had dome tweets and the domes were superior. True?

>Should I hold out for domes?

>I'm attaching photos of the front & back of the no-names,

>in case anyone recognizes them and can tell me if they are

>worth keeping.

>Thanks!

The 24 XXXXX may indicate it is a Becker manufactured speaker.

Do they sound okay? Are the pots not part of the problem?

I recently bought a tweeter from AB Tech for an AR 4x speaker. It fit and sounded fine. One slight problem though. It was significantly more efficient than the woofer. I had to turn down the pot almost completely to match the SPL's.

Carl

Carl's Custom Loudspeakers

[soundminded]

It's easy to reduce the sensitivity of a tweeter or midrange driver. If it's an 8 ohm tweeter, put an 8 ohm resistor in parallel with it and a 4 ohm resistor in series with the pair. This will reduce its efficiency by 6db without affecting the crossover network.

You can do the same with a 4 ohm tweeter by putting a 4 ohm resistor in parallel with it and a 2 ohm resistor in series with the pair.

For other sensitivity attenuation values, use the handy calcluator on this link;

http://www.bcae1.com/lpad.htm

Just be certain that the resistor wattage is rated high enough. Usually 5 watt resistors are fine but if they get too hot, try 10 watts. It shouldn't cost much over about $1 a speaker if that.

[JKent]

Thanks for the advice Carl, but I really want to know what other AR speakers used the same tweets as the 4x, so I can watch for some used ones on ebay. Seems to me classic speaker afficionados are like classic car buffs. Heaven forbid you should put hardware store carriage bolts in the bumper of your '56 Chevy!

I had an experience recently when I asked for advice here and on the Yahoo Allison site regarding replacement tweeters for a lone Allison: Four I'm fixing up. The gist of the comments was "There are no suitable replacements for the Allison tweeters and the originals are no longer available. The Allison tweeters were extra-special, and you can't use anything else, so you're out of luck" (or "cannibalize tweets from another pair"--not too helpful because then what would I put in THOSE speakers??). Anyway, I did buy some 4 ohm Audax tweeters and will be installing them pretty soon.

So.....What AR OEM tweets should I be looking for? Did the 4x share a tweeter with other models?

thanks

[RoyC]

Hi Kent,

The AR-4x tweeter was always a 2-1/2" cone (see attached photo). It was crossed over at a rather low point, and the same as that used in the two-way AR-2x.

Based on measuring a fair number of these tweeters, dcr appears to vary from 4.2 to 5.5 ohms, with the higher impedance showing up in post-1970 specimens. It would therefore also be prudent to acquire a matched pair if you choose used tweeters as replacements.

It is very unlikely that there is a dome type drop-in replacement tweeter for the AR-4x.

Roy

[JKent]

Thanks Roy

I checked the SN. One was missing, the other is FX276432. Opened that one up to see if there was a date stamp on the woofer (no) or a number on the inducter (no again). I did find 2 interesting things tho. There is a device(I dunno--I have almost no electronics knowledge. Looks like a cap to me--4.7 uF, but why?)wired in line with the replacement tweeter (pic attached). Then I went to pull out the pot and it is fried! Really! Melted! Check it out

Kent

[Carlspeak]

Wow, it looks like the pot took the brunt of some high voltage from a cranked up high powered amp.

That may be your whole problem with the tweeter. Have you tried bypassing the pot to see if the tweeter still works?

The 4.7 uF cap is a fairly common crossover cap for modern tweeters rated at 8 ohms nominal impedance.

It's beginning to look like you've got a bastardized speaker there. Have you checked both to see if they are outfitted the same?

For your reference, I've attached a schematic I drew from an un-altered 4ax. It had a 3/4 inch dome tweeter. The schematic shows exactly what wires go where and how to wire a new pot. Note the cap is 20 uF.

Good luck and I hope the problem is just the fried pot.

Remember, it's all about the music

Carl

Carl's Custom Loudspeakers

[Steve F]

The "new" AR-2x used the exact same 2 1/2" tweeter as the AR-4x.

The AR-1x used a 2 1/2" cone tweeter also, but that was a 4-ohm system. the 2x and 4x were 8-ohm systems.

No AR-4 series speaker ever used a dome tweeter.

The AR-4 used a 3 1/2" cone (as did the early AR-2x's), crossing over at 2,000Hz.

This 3 1/2" cone was also the midrange driver in the 2ax, both "old" and "new."

The AR-4x used the 2 1/2" cone, crossing over at 1200Hz.

The AR-4xa used a 1 1/2" cone (like the AR-6 and -7) crossing over at, I think, 1600Hz. My literature is in the basement, and I'm on the second floor, too lazy to walk down and up the two flights to confirm this. But 1600Hz sounds right.

Steve F.

[RoyC]

Pots don't get more fried than that!

The 4uf cap was definitely a later addition, and was probably installed by the person who plopped in that small replacement tweeter. It was likely a futile effort, given the low crossover point of the original.

To make your speakers whole again (along with new level controls) you will need the original cone tweeters. Carl, the dust cap measures 3/4", but the tweeter measures 2-1/2"...4 1/2" including the mounting flange. The 4x never used a dome type tweeter.

The only cap required is the 20uf cap as shown in Carl's drawing, and in the attached schematic (courtesy of John O'Hanlon). Your speaker serial number indicates that it is an early 70's version with a #5 (1.187mh) woofer coil, as opposed to the earlier #4 (.88mh) shown in the schematic.

Roy

http://www.classicspeakerpages.net/dc/user_files/1787.jpg

[tysontom]

>Then I went to pull out the pot and it is fried!

>Really! Melted! Check it out

>Kent

Even though this speaker is many years beyond its warranty, this is a classic example of one of the few exceptions to the AR "Full-Five-Year-Warranty" rule. AR would take care of just about anything -- and pay the shipping both ways -- but when something came along that demonstrated acute and grevious abuse ("accidental or otherwise") such as the melted, burned-out level control, AR would make the customer pay for repairs and would not reinburse for shipping. AR even repaired my lightning-damaged AR-3as at no charge (I still have the pair), but the company would not repair damage caused by obvious abuse to its products.

--Tom Tyson

[JKent]

Thanks Carl and Roy

Funny, I never listened to these. The fellow who sold them to me said they sounded good.

This will be my second 4x restoration, so I know enough about the caps and pots, and I do have a copy of John's diagram, but thank you.

Those "new" tweets are definitely going. I'll use the original woofers, cleaned up pots from my parts drawer, new Carli 20uF caps and some OEM tweets when I can get them. I also plan to replace the fiberglass, which is pretty crumbly.

So--am I correct in understanding that the AR4 and AR2 both used the same tweets? What about the 5, 7?

Looks like I have a lead on some, so I think I'll be OK.

Too many projects going on at once: two KLH Model 21 radios--one FM and one AM/FM (I also have one for sale on ebay now), a KLH 21 extension speaker, a pair of KLH Model 33 speakers, another pair of AR 4x's that will need the #4 coil in one rewound to make it a #5, and 3 Allison Fours--my own pair and a single one that needs new foam surround, refinishing and, unfortunately, 2 new tweeters. I'm going with Audax tweets because the Allis just aren't available. And my wife wants me to put it all away and get ready for Christmas! This is an obsession! Maybe I need a shrink ;-)

[Toomuchgear]

I have a pair of the 4Xs...one of my tweeters measures around 2.5 ohms...keep in mind..it was still connected to the crossover and all...neither tweeter is working...what would be the next step? Thanks to all for your wisdom

[RoyC]

6 hours ago, Toomuchgear said:

I have a pair of the 4Xs...one of my tweeters measures around 2.5 ohms...keep in mind..it was still connected to the crossover and all...neither tweeter is working...what would be the next step? Thanks to all for your wisdom

The culprit is probably badly corroded level controls. Next step is to disconnect the tweeters and apply a signal to them to see if they make sound. If they do, you will have to deal with the controls.

Roy

[ra.ra]

Hey Toomuch,

Welcome to the forum, and thanks for resurrecting a thread that's been dead for nearly thirteen years.  The 4x is a terrific small speaker, and when properly working tweeters are measured out-of-circuit, they should be closer to 4.5 ohms. RoyC's advice is excellent - - - most likely you have corroded pot controls - - - it's very possible that your tweeters are still functional, but you'll need to confirm that.

(edit: I checked a few more of these tweeters, and they measured closer to 5.0 ohms.)

Your "handle" immediately reminded me of this favorite tune which kicks in at the 1:30 mark after "Tequila". This audio is authentic musically, but sorry I was unable to locate vintage video to accompany the music - -  nonetheless, it's still great fun to watch. This song is one of the several anthems shared amongst my youthful primal tribe.   

https://www.youtube.com/watch?v=CKw0r0YBe_A