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johnnyrauder

the aillson 4 blues..help needed

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10 minutes ago, johnnyrauder said:

anyone

Be patient. Despite this being an online forum, not everything here happens within nanoseconds. Someone with direct experience will come along and help you out. Meanwhile, have you read documents in the Library? In a brochure for models 1, 2, 3, 4, 5 and 6, this 1" driver is the only tweeter shown.

5acd489fa668c_allisontweeter.jpg.a12e9db77bc379a6cfeac6f0bc9e50e1.jpg

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As mentioned on AK, the two-way and three-way system tweeters are different.  See below.

 

Les

Screenshot_20180410-210245A.thumb.jpg.311d323fa6c3edf843ad6685015de531.jpgScreenshot_20180410-210252A.thumb.jpg.b6c0cf43122afaf106f985125fd7b637.jpg

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The tweeter for a one, two or three will not work well in a four. The four is a two-way speaker, the others are three ways. The tweeters will not go low enough for a two-way. Now, a four tweeter will work in a one, two or three.

 

Brian

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3 hours ago, LesE said:

As mentioned on AK, the two-way and three-way system tweeters are different.

Hi LesE, I saw one of your posts on AK about this, but are you certain that the tweeters are in fact different drivers among these models? The graphs you've provided are in the CSP Library, too, but with the models Five and Six included. The One, Two, and Three models are indeed three-ways, with crossover frequencies at 350 and 3750 Hz. The Four, Five, and Six are two-ways with x-o at 2000Hz.

This information would suggest that the two-way and three-way tweeters might very well be different drivers, despite their identical appearance. But while I am not experienced with various Allison models, this note below from the Allison Six description led me to think that the tweeters were all the same driver part, and that the different crossover frequencies were accomplished through different crossover components (cap value?) associated with the tweeter.

Can anyone provide schematics or crossover pics of these models?  

allison tweeter response.jpg

allison six tweeter.jpg

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Physically, the tweeters may be identical but my understanding is that the two-way tweeter uses ferrofluid allowing it to operate down to 2000 Hz.  Thus the reason why you can use the two-way tweeter in a three-way system but not the other way around as was mentioned in a previous post.

BTW, there was an effort on the Yahoo Allison group to have new tweeters manufactured but I don't know if that ever materialized.   It would be best to check there for a status update.

Two-way tweeters do turn up on ebay occasionally but it takes some patience.  The earlier style tweeter with the metal flange and wires that connect to front mounted spring terminals are less common unfortunately.   But the OP hasn't identified which type he has in his model Fours.  However,  the later style tweeter can still be adapted for use in an earlier model Four.  That's what I ended up doing with with a later style two-way tweeter that picked up on ebay not too long ago.

Another possibility would be to try the SB Acoustics SB26STAC-C000-4 which was tested and found to be a suitable replacement for the Allison AL-120 two-way tweeter.  But, the OP would have to do some homework to make sure that it would fit in the model Four tweeter cut out.  I'm not aware of anyone trying this tweeter in a model Four so there is no guarantee of success.   The specs look good and it may be suitable if there are no physical installation issues.

 

https://www.madisoundspeakerstore.com/sb-acoustics-soft-dome-tweeters/sb-acoustics-sb26stac-c000-4-1-textile-dome-tweeter/

 

Les.

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Since these models came later than the original One thru Six models, I was reluctant to post this but it may be helpful to someone here. This page from the 1982 brochure cites a difference in cooling material for these tweeters: ferrofluid for the two-way model Seven, and silicone for the three-way models Eight and Nine, and this seems to be reflected in the power handling specs.

allison 7-8-9 specs.jpg

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I should also mention that the two-way tweeter is identified by a dot on the front surface of the flange. No dot on the three-way tweeter.

 

Early two-way tweeter:

20180411_085759B.jpg.2b38a4e3395eeaef614f815bc254a0b2.jpg

 

Later two-way tweeter:

20180411_085441B.jpg.55117b31a2ce04a5fe8f2afbd0f198ad.jpg

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The only thing I could add to this would be to keep an eye out for complete, used two way systems to obtain the needed drivers and for spares.

Allison: 4, 5,6,7, all are viable choices.

The driver movement on behalf of yahoo groups could not get anywhere and was also attempted years ago with the woofers.....same outcome.

Bill

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3 hours ago, johnnyrauder said:

thanks bill i will do that.

I should mention all the two way tweeters could also be used (AL 110, 115, 120) the AL series. Excluding the 105.

Some boss cutout drilling is needed to put those in an original A4 cabinet with brass pin connectors (2 holes to internally connect the leads.)

 

Bill

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3 hours ago, newandold said:

I should mention all the two way tweeters could also be used (AL 110, 115, 120) the AL series. Excluding the 105.

Some boss cutout drilling is needed to put those in an original A4 cabinet with brass pin connectors (2 holes to internally connect the leads.)

 

Bill

Hello Bill,

In my case where I used a newer tweeter in an early cabinet, I opted to flatten the speaker terminals and extend wires from the front of the tweeter to the brass terminals.  This can be see in the second photo posted above.

Les.

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1 hour ago, LesE said:

Hello Bill,

In my case where I used a newer tweeter in an early cabinet, I opted to flatten the speaker terminals and extend wires from the front of the tweeter to the brass terminals.  This can be see in the second photo posted above.

Les.

Hi Les,

Yes, that’s the way to go with that tweeter, if you don’t want to drill.

Those newer replacements were built to handle the changes with the newer cabinets that did away with the external connectors.

Somewhere around 1990, no more tweeters were available from Allison with those fragile, external leads. By around then, all were made with the protective screens and rear connectors only. The operating specs. However, remain the same.

 If one wants to install Al 115 (for example) tweeters in the A Four, drilling the two lead holes is a must.

Bill

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1 hour ago, newandold said:

Hi Les,

Yes, that’s the way to go with that tweeter, if you don’t want to drill.

Those newer replacements were built to handle the changes with the newer cabinets that did away with the external connectors.

Somewhere around 1990, no more tweeters were available from Allison with those fragile, external leads. By around then, all were made with the protective screens and rear connectors only. The operating specs. However, remain the same.

 If one wants to install Al 115 (for example) tweeters in the A Four, drilling the two lead holes is a must.

Bill

You should be able to front wire this type of tweeter as well, no?  I've seen a few photos where the exposed terminals on the front of the tweeter are covered over with something that looks like glue and that would be a problem.  But most that I've seen are like following photo which you should be able to solder wires to in the same way as in my photo.

That said, we don't know which style tweeter the OP currently has.  If his Fours aren't first gen with the exposed brass terminals, then any of the newer style tweeters should drop right in.

 

1_f9e7d550deca74324229bad1ea31553f.jpg

Les.

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12 hours ago, LesE said:

You should be able to front wire this type of tweeter as well, no?  I've seen a few photos where the exposed terminals on the front of the tweeter are covered over with something that looks like glue and that would be a problem.  But most that I've seen are like following photo which you should be able to solder wires to in the same way as in my photo.

That said, we don't know which style tweeter the OP currently has.  If his Fours aren't first gen with the exposed brass terminals, then any of the newer style tweeters should drop right in.

 

1_f9e7d550deca74324229bad1ea31553f.jpg

Les.

Hi Les,

Yes, they can be soldered off the top as you say.

Of course, the final procedure depends on what driver he ends up  with. The reason I would advise against that is the fragile nature of the wiring of these old Allison tweeters. Drilling the two small holes in the boss cutout “upgrades” the cab. To the way all the newer ones are without risking damage to the tweeter.

The Madisound tweeter would also mean no brass pin connection. I haven’t seen the back of one of those, but the drilling in that case might not be necessary.

Bill

 

 

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