Do Allison tweeters have a tendency to fail?

[savoirfaire]

Hi, guys - I picked up a pair of Allison: Ones from someone this afternoon. He played an opera track for me and it sounded like it was working ok, but when I got it home and hooked it up, it sounded muffled when I tested out a few Alison Krauss/Union Station tracks. After putting my ear up to each of the speakers, it seems that the four mid-range speakers and four woofers are working ok, but all four of the tweeters seem to be out. Seemed a little odd so I tried with two different amps and I get the same result. Are the tweeters known to conk out on these?

 

[savoirfaire]

I managed to get the tweeters on one of them working. The wires to the tweeters weren't well connected so when I repositioned them, it started working again. That trick doesn't seem to be working with the other one though.

 

[Copa1934]

I managed to get the tweeters on one of them working. The wires to the tweeters weren't well connected so when I repositioned them, it started working again. That trick doesn't seem to be working with the other one though.

I think the leads are the more common issue. I have CD7's with no issues but the traditional pushed in dome. I can honestly say I didn't note a difference in sound as I had another pair and during A/B couldn't detect any difference. Wasn't truly "critical" listening, but if there were an issue I think it would have been apparent.

 

[savoirfaire]

Thanks for the reply, Copa. I did a little research on this and some other vintage audio forums and it was very helpful.

I bought a multimeter and tested the resistance across the tweeters. For the speaker that I got working by reseating the wires, the resistance was about 10 ohms for each of the tweeters. On the one that still isn't working, one reads about 10 ohms and one reads about 1 milliohm. Then I did the 1.5v battery test and got a crackle out of the 10 ohm tweeter but nothing out of the 1 milliohm tweeter. Looks like I've got a dead tweeter, and they must be wired in series because I noticed on the first speaker that when one is unwired, neither works.

It looks to me like the tweeters on the Allison Ones are pretty easy to replace. Just pop out the old, pop in the new, and clip the wires to the posts? Is that correct? Anyone have a suggestion for where I can find a replacement?

 

[savoirfaire]

Not sure if anyone is interested, but I had a little good news/bad news. The bad news is when I started looking for some new Allison tweeters, I quickly realized that the tweeters aren't original to the Ones. I pulled out the non-working tweeter and found out that they're Realistic "Super dome" tweeters (#40-1276A) that were made in Japan. They actually don't sound terrible, but they're not Allison tweeters.

The good news is as soon as I unscrewed the non-working tweeter, one of the wires dropped to the ground. So the reason the one tweeter isn't working is that the metal tab that one of the wires had been soldered to had snapped. I just happened to buy a soldering station at Radio Shack last year that I still hadn't gotten around to using (I've literally never soldered anything before) but I pulled it out and set it up. It's not the prettiest soldering job in the world, but it works! I put the Realistic tweeter back in, wired it up, and success!

So, yeah, I'm pretty proud of myself for diagnosing and fixing the problem and popping my soldering cherry in the process. So next question, should I replace these tweeters with something more "upscale"? I'm thinking of leaving the Realistics in while keeping an eye out for a set of vintage Allison tweeters to show up on ebay.

 

[LesE]

FYI ... Those RS tweeters are 8 ohms while the originals are 4 ohms. The tweeters are wired in series so you now have 16 ohms in its current configuration.

Congrats on finding the Allison Ones. I have a pair of Fours and I think they are outstanding. The original Allison convex diaphragm tweeters are excellent.

Les.

 

[savoirfaire]

FYI ... Those RS tweeters are 8 ohms while the originals are 4 ohms. The tweeters are wired in series so you now have 16 ohms in its current configuration.

Congrats on finding the Allison Ones. I have a pair of Fours and I think they are outstanding. The original Allison convex diaphragm tweeters are excellent.

Les.

Hm, that hadn't occurred to me. Guess I will definitely have to find a replacement for them then. What about the cheap Allison mylar dome tweeters on ebay as a temporary fix? They're 4 ohm and are only $12 a pair plus shipping.

 

[LesE]

At that price, they're worth a try. Those tweeters were used in the later Allison AL-105 and are inferior to the original Allison One tweeters. But they could be fine as an interim measure while you wait for some original three-way tweeters to turn up.

How are your woofer surrounds? If they haven't already been refoamed, then you'll need to have that addressed.

Les.

 

[Copa1934]

Not sure if anyone is interested, but I had a little good news/bad news. The bad news is when I started looking for some new Allison tweeters, I quickly realized that the tweeters aren't original to the Ones. I pulled out the non-working tweeter and found out that they're Realistic "Super dome" tweeters (#40-1276A) that were made in Japan. They actually don't sound terrible, but they're not Allison tweeters.

The good news is as soon as I unscrewed the non-working tweeter, one of the wires dropped to the ground. So the reason the one tweeter isn't working is that the metal tab that one of the wires had been soldered to had snapped. I just happened to buy a soldering station at Radio Shack last year that I still hadn't gotten around to using (I've literally never soldered anything before) but I pulled it out and set it up. It's not the prettiest soldering job in the world, but it works! I put the Realistic tweeter back in, wired it up, and success!

So, yeah, I'm pretty proud of myself for diagnosing and fixing the problem and popping my soldering cherry in the process. So next question, should I replace these tweeters with something more "upscale"? I'm thinking of leaving the Realistics in while keeping an eye out for a set of vintage Allison tweeters to show up on ebay.

That 40-1276 is a nice tweeter. http://www.radioshackcatalogs.com/html/1985/h022.html top right corner of image.

I have a set (or two?) and they have a nice sound and output. I can't honestly say they are an equivalent to the original tweeter, impedance difference aside. The Allison have a nice dispersion, sounding very good off axis. I don't believe the RS tweeter will be close in that area. I do, however, believe the "quality" of sound should be close.

Hmmm, I could swap out the drivers in mine. If I find time, this weekend, I might give that a try. Mine, of course, are CD7, but the tweeter is (basically) the same.

Yikes, just looked up the specs on the "One". Crossover points are 350hz and 3750hz. That RS driver is 6khz-20khz. You'll beat the crap out of that tweeter. Boy that allison tweeter crosses over low.

 

[LesE]

That 40-1276 is a nice tweeter. http://www.radioshackcatalogs.com/html/1985/h022.html top right corner of image.

I have a set (or two?) and they have a nice sound and output. I can't honestly say they are an equivalent to the original tweeter, impedance difference aside. The Allison have a nice dispersion, sounding very good off axis. I don't believe the RS tweeter will be close in that area. I do, however, believe the "quality" of sound should be close.

Hmmm, I could swap out the drivers in mine. If I find time, this weekend, I might give that a try. Mine, of course, are CD7, but the tweeter is (basically) the same.

Yikes, just looked up the specs on the "One". Crossover points are 350hz and 3750hz. That RS driver is 6khz-20khz. You'll beat the crap out of that tweeter. Boy that allison tweeter crosses over low.

As one would expect, their two-way tweeters go even lower. Their original series of products use a first order crossover at 2000 Hz.

Les.

 

[spkrdtr]

Some Allison tweeters have an issue with corrosion of the tinsel wire that eminates from the front of the tweeter plate, passes under the metal, mesh protective dome and connects to the voice coil leads at the side of the tweeter dome. Where the tinsel wire passes under the mesh, corrosion can and has occured. I prepared a brief paper on how to do the repair on an AL120 tweeter which consists of adding a short jumper wire to bypass the corroded portion.
The link below is to a thread on the subject. The first post has a downloadable paper (over 1000 downloads) for your review.
http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=5977&hl=tweeter

 

[Copa1934]

Some Allison tweeters have an issue with corrosion of the tinsel wire that eminates from the front of the tweeter plate, passes under the metal, mesh protective dome and connects to the voice coil leads at the side of the tweeter dome. Where the tinsel wire passes under the mesh, corrosion can and has occured. I prepared a brief paper on how to do the repair on an AL120 tweeter which consists of adding a short jumper wire to bypass the corroded portion.
The link below is to a thread on the subject. The first post has a downloadable paper (over 1000 downloads) for your review.
http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=5977&hl=tweeter

I went to download and discovered I already have it! Cool. Haven't had any failures on mine, yet.

 

[Copa1934]

As one would expect, their two-way tweeters go even lower. Their original series of products use a first order crossover at 2000 Hz.

Les.

petty wicked really. I have fun looking for mids that go that low. Well, that are reasonable and have a relatively flat response.