Early (large) AR-2ax Tweeter Dissection

[Pete B]

I've stated that I'm interested in dissecting an AR-2ax or AR-3a tweeter

and should have been more clear to specify the .75" smaller type.

I was sent an early, larger phenolic dome style tweeter as is shown and

discussed in this thread:

http://www.classicspeakerpages.net/IP.Boar...x+early+tweeter

It is open circuit and therefore probably only good for analysis.

I removed the 3 screws and there is a black tar or putty where the flange

meets the magnet. It's not breaking free very easily, anyone know if

there is any sort of glue holding this together or do I just have to pull

harder? I want to keep the damage to a minimum if possible.

[JKent]

I've stated that I'm interested in dissecting an AR-2ax or AR-3a tweeter

and should have been more clear to specify the .75" smaller type.

I was sent an early, larger phenolic dome style tweeter as is shown and

discussed in this thread:

http://www.classicspeakerpages.net/IP.Boar...x+early+tweeter

It is open circuit and therefore probably only good for analysis.

I removed the 3 screws and there is a black tar or putty where the flange

meets the magnet. It's not breaking free very easily, anyone know if

there is any sort of glue holding this together or do I just have to pull

harder? I want to keep the damage to a minimum if possible.

Hi Pete

I had one that was fried and before I knew you were "collecting" these I took it apart. Yes--just pull harder (or pry--I think that's what I did). Don't tap the magnet--it may shatter!

Kent

[Guest ARjohn]

I have a .75" AR2ax tweeteer that I pulled from the cabinet today. I had rehabed the cabinet with new controls, and new capacitors and the tweeter still did not work. I will send it to you if you give me an address. Would appreciate any infor on where I could find a replacement. john

[Pete B]

I have a .75" AR2ax tweeteer that I pulled from the cabinet today. I had rehabed the cabinet with new controls, and new capacitors and the tweeter still did not work. I will send it to you if you give me an address. Would appreciate any infor on where I could find a replacement. john

Hi John,

.75" tweeter replacements, 8 ohm for the 2ax and 4 ohm for the 3a has been an ongoing

discussion/issue on the board. This is about the 4 ohm 3a version:

http://www.classicspeakerpages.net/IP.Boar...?showtopic=4321

Depends on what you're looking for, and your abilities.

Perfectionist restoration - buy the correct tweeter used on ebay, also ask on the board

some people have spares.

The other option is to adapt a readily available tweeter as most do not have a

large front plate, I believe there is a tweeter on ebay with an adapter plate.

I also think that Carl sells one.

I believe that an economy solution makes the most sense but certainly if these

are your main interest go ahead and use the best.

Seems that we should match the size, impedance, Fc and efficiency if possible, the

last is not so important since these designs have a tweeter level control. I'd try

this if you don't mind making an adapter plate:

http://www.madisound.com/catalog/product_i...roducts_id=8317

And I think Roy has said that this tweeter has a large enough flange so that it

bolts in, but it is a 1" unit:

http://www.madisound.com/catalog/product_i...roducts_id=1496

Some tests by Zaph are linked below. I believe that he is overly critical of the K1 tweeter.

The 2ax has a very high crossover point so the LF performance is not much of an

issue:

http://www.zaphaudio.com/tweetermishmash/

Thanks very much for the offer for the old 2ax tweeter.

[RoyC]

Seems that we should match the size, impedance, Fc and efficiency if possible, the

last is not so important since these designs have a tweeter level control. I'd try

this if you don't mind making an adapter plate:

http://www.madisound.com/catalog/product_i...roducts_id=8317

And I think Roy has said that this tweeter has a large enough flange so that it

bolts in, but it is a 1" unit:

http://www.madisound.com/catalog/product_i...roducts_id=1496

Some tests by Zaph are linked below. I believe that he is overly critical of the K1 tweeter.

The 2ax has a very high crossover point so the LF performance is not much of an

issue:

http://www.zaphaudio.com/tweetermishmash/

I agree with Pete. Our crossover frequency of interest is very high, which should minimize any issues the zaphaudio guy believes to be a problem. In fact his concerns may be associated with the higher fs of the Hi Vi tweeters, which is actually more consistent with the original AR tweeters. Also, we should bear in mind that, with the exception of the nice faceplate, the AB Tech tweeter is a very ordinary tweeter with no special "AR" sonic properties without a crossover modification. Both the AB Tech tweeter and the Hi Vi Research tweeters are manufactured in China and are nearly identical in construction quality...which happens to be quite good. Much of my interest in the Hi Vi tweeters revolves around the fact that the two models we are discussing cost less than $10 each compared to the increasingly scarce $70 AB Tech tweeter.

The new 3/4"/20mm Hi Vi 4 ohm tweeter, T20-4, mentioned by Pete, is shown in the first pic.

BTW, the one inch(25mm)/wide flange model I previously tried is the X1R (second pic), not the K1.

Both Hi Vi models are available from Madisound for about $5 and $8 respectively, not including shipping.

Roy

[Guest ARjohn]

Hi John,

.75" tweeter replacements, 8 ohm for the 2ax and 4 ohm for the 3a has been an ongoing

discussion/issue on the board. This is about the 4 ohm 3a version:

http://www.classicspeakerpages.net/IP.Boar...?showtopic=4321

Depends on what you're looking for, and your abilities.

Perfectionist restoration - buy the correct tweeter used on ebay, also ask on the board

some people have spares.

The other option is to adapt a readily available tweeter as most do not have a

large front plate, I believe there is a tweeter on ebay with an adapter plate.

I also think that Carl sells one.

I believe that an economy solution makes the most sense but certainly if these

are your main interest go ahead and use the best.

Seems that we should match the size, impedance, Fc and efficiency if possible, the

last is not so important since these designs have a tweeter level control. I'd try

this if you don't mind making an adapter plate:

http://www.madisound.com/catalog/product_i...roducts_id=8317

And I think Roy has said that this tweeter has a large enough flange so that it

bolts in, but it is a 1" unit:

http://www.madisound.com/catalog/product_i...roducts_id=1496

Some tests by Zaph are linked below. I believe that he is overly critical of the K1 tweeter.

The 2ax has a very high crossover point so the LF performance is not much of an

issue:

http://www.zaphaudio.com/tweetermishmash/

Thanks very much for the offer for the old 2ax tweeter.

[Guest ARjohn]

Hi John,

.75" tweeter replacements, 8 ohm for the 2ax and 4 ohm for the 3a has been an ongoing

discussion/issue on the board. This is about the 4 ohm 3a version:

http://www.classicspeakerpages.net/IP.Boar...?showtopic=4321

Depends on what you're looking for, and your abilities.

Perfectionist restoration - buy the correct tweeter used on ebay, also ask on the board

some people have spares.

The other option is to adapt a readily available tweeter as most do not have a

large front plate, I believe there is a tweeter on ebay with an adapter plate.

I also think that Carl sells one.

I believe that an economy solution makes the most sense but certainly if these

are your main interest go ahead and use the best.

Seems that we should match the size, impedance, Fc and efficiency if possible, the

last is not so important since these designs have a tweeter level control. I'd try

this if you don't mind making an adapter plate:

http://www.madisound.com/catalog/product_i...roducts_id=8317

And I think Roy has said that this tweeter has a large enough flange so that it

bolts in, but it is a 1" unit:

http://www.madisound.com/catalog/product_i...roducts_id=1496

Some tests by Zaph are linked below. I believe that he is overly critical of the K1 tweeter.

The 2ax has a very high crossover point so the LF performance is not much of an

issue:

http://www.zaphaudio.com/tweetermishmash/

Thanks very much for the offer for the old 2ax tweeter.

Pete thank you for the information. I will try the Madisound tweeter you and Roy recommended. Will try to mail the 2ax tweeter today. I am not sure it was internally defective. I was attempting to troublshoot it and when I removed the electrical tape the connecting wire disintegrated. But it is certainly beyond my repair now. I also have inherited a pair of AR3a improved. All drivers work except the tweeters, and they pass ohm and battery scatch test, so suspect the crossover. I have looked thru much of the library and found a long thread that detailed on alternative crossover, but really only want to put it back to spec. If anyone has a wiring diagram of the 3a improved crossover it would be appreciated. john

[Robert_S]

I also have inherited a pair of AR3a improved. All drivers work except the tweeters, and they pass ohm and battery scatch test, so suspect the crossover. I have looked thru much of the library and found a long thread that detailed on alternative crossover, but really only want to put it back to spec. If anyone has a wiring diagram of the 3a improved crossover it would be appreciated. john

Hello John,

The information you are seeking may be contained in the following topics:

http://www.classicspeakerpages.net/IP.Boar...ost&p=73080

http://www.classicspeakerpages.net/IP.Boar...?showtopic=1636

If not, I'm sure someone here will offer further help.

Robert_S

[Pete B]

Pete thank you for the information. I will try the Madisound tweeter you and Roy recommended. Will try to mail the 2ax tweeter today. I am not sure it was internally defective. I was attempting to troublshoot it and when I removed the electrical tape the connecting wire disintegrated. But it is certainly beyond my repair now. I also have inherited a pair of AR3a improved. All drivers work except the tweeters, and they pass ohm and battery scatch test, so suspect the crossover. I have looked thru much of the library and found a long thread that detailed on alternative crossover, but really only want to put it back to spec. If anyone has a wiring diagram of the 3a improved crossover it would be appreciated. john

John,

The tweeter arrived here, thanks very much!

Just wondering, if you happen to measure the DC resistance of the mid

and tweeter on the AR-3a improved if you could please post them here.

[Pete B]

I agree with Pete. Our crossover frequency of interest is very high, which should minimize any issues the zaphaudio guy believes to be a problem. In fact his concerns may be associated with the higher fs of the Hi Vi tweeters, which is actually more consistent with the original AR tweeters. Also, we should bear in mind that, with the exception of the nice faceplate, the AB Tech tweeter is a very ordinary tweeter with no special "AR" sonic properties without a crossover modification. Both the AB Tech tweeter and the Hi Vi Research tweeters are manufactured in China and are nearly identical in construction quality...which happens to be quite good. Much of my interest in the Hi Vi tweeters revolves around the fact that the two models we are discussing cost less than $10 each compared to the increasingly scarce $70 AB Tech tweeter.

The new 3/4"/20mm Hi Vi 4 ohm tweeter, T20-4, mentioned by Pete, is shown in the first pic.

BTW, the one inch(25mm)/wide flange model I previously tried is the X1R (second pic), not the K1.

Both Hi Vi models are available from Madisound for about $5 and $8 respectively, not including shipping.

Roy

Hi Roy, I'm sure you had a good reason for using the X1R but if you take a look

at Zaph's CSD distortion and FR plots there is something strange going on at about

16KHz. The distortion is also highly elevated in the 1 to 3 KHz range. Note that

there is virtually no peak at resonance which is a sign that thick (non-linear) ferro

fluid is used.

The K1 on the other hand, is clean throughout it's operating range and rivals many

of the $50 to over $100 tweeters. The K1 impedance is a bit low for the 2ax, and a

bit high for the 3a, but series and shunt resistance can take care of this. Just my

opinion, but I have a strong preference for the K1.

I just dropped a K1 into an AR-11 and there is about a 1/16" gap around the edge

since it is a bit smaller than the AR tweeter. The input terminal pushes it a bit off

center so a cut out would help but is not absolutely required. Might make a nice

low cost replacement in these applications also, with of course a reasonable

crossover mod.

I bought this pair of K1s to try in Advents when I get the time.

[Guest ARjohn]

John,

The tweeter arrived here, thanks very much!

Just wondering, if you happen to measure the DC resistance of the mid

and tweeter on the AR-3a improved if you could please post them here.

I did not have a multimeter that would measure that low, but got one at Radio Shack today. Measuring the AR3a Improved tweeters and mids from the front at the connectors (drivers installed), here is what I got. Both tweeter were .2 ohm, one mid was .5 and one was .4 ohm. If I am measuring incorrectly please advise.

On the subject of the AR2ax tweeter replacement, what wire should I use to connect the HiVi tweeter (8 ohm) measured 6.5? Thanks, john

[RoyC]

Hi Roy, I'm sure you had a good reason for using the X1R but if you take a look

at Zaph's CSD distortion and FR plots there is something strange going on at about

16KHz. The distortion is also highly elevated in the 1 to 3 KHz range.

opinion, but I have a strong preference for the K1.

I just dropped a K1 into an AR-11 and there is about a 1/16" gap around the edge

since it is a bit smaller than the AR tweeter.

Hi Pete,

Actually I had purchased the X1R a couple of years ago to experiment with. Not knowing anything about these tweeters, I chose it based on very low cost, the wide flange, similar dcr to the 3a tweeter (3+ohms), and high fs. Not expecting much, it turned out to be a pleasant surprise. I suspect the high 5,000hz crossover point, and the fact that there is not much musical info to be heard at 16,000hz, kept me from noticing any major issues. (...and, as we have discussed, the original tweeters have there own set of issues these days). I settled on caps approximately half the value of the 3a tweeter's 6uf cap (depending on level control type), and a very small .06mh parallel inductor, so it was probably pretty well cut off from any problems in the 1khz to 3khz region.

The original 3a/2ax type tweeter naturally drops off very quickly below 5,000hz. Other than the oft mentioned (and overstated, imo) dispersion concern, there are many modern tweeters that would work in a 3a or 2ax, IF someone takes the time to devise the required crossover modifications, and deal with the wide cabinet hole. Candidates like the X1R and K1 at least have the hole covered:-).

Since a crossover change is necessary anyway, I agree that the K1 looks promising for about the same cost...especially for the later models like the AR-11, 10pi and 12.

Pete, what is your take on the Q1R?

Roy

[Pete B]

I did not have a multimeter that would measure that low, but got one at Radio Shack today. Measuring the AR3a Improved tweeters and mids from the front at the connectors (drivers installed), here is what I got. Both tweeter were .2 ohm, one mid was .5 and one was .4 ohm. If I am measuring incorrectly please advise.

On the subject of the AR2ax tweeter replacement, what wire should I use to connect the HiVi tweeter (8 ohm) measured 6.5? Thanks, john

Hi John,

I should have mentioned that you have to disconnect the tweeter and mid to do the measurement, but please don't bother if it's too much trouble.

I PMed you a link for some reasonable hookup wire.

[Pete B]

Hi Pete,

Actually I had purchased the X1R a couple of years ago to experiment with. Not knowing anything about these tweeters, I chose it based on very low cost, the wide flange, similar dcr to the 3a tweeter (3+ohms), and high fs. Not expecting much, it turned out to be a pleasant surprise. I suspect the high 5,000hz crossover point, and the fact that there is not much musical info to be heard at 16,000hz, kept me from noticing any major issues. (...and, as we have discussed, the original tweeters have there own set of issues these days). I settled on caps approximately half the value of the 3a tweeter's 6uf cap (depending on level control type), and a very small .06mh parallel inductor, so it was probably pretty well cut off from any problems in the 1khz to 3khz region.

The original 3a/2ax type tweeter naturally drops off very quickly below 5,000hz. Other than the oft mentioned (and overstated, imo) dispersion concern, there are many modern tweeters that would work in a 3a or 2ax, IF someone takes the time to devise the required crossover modifications, and deal with the wide cabinet hole. Candidates like the X1R and K1 at least have the hole covered:-).

Since a crossover change is necessary anyway, I agree that the K1 looks promising for about the same cost...especially for the later models like the AR-11, 10pi and 12.

Pete, what is your take on the Q1R?

Roy

Ah, yes I should have mentioned that even with the flaws it probably sounds

just fine as I agree with all your points. And yes it would have been difficult

to know without Zaph's tests.

I don't really know the Q1R, quickly googled and found this post by Zaph:

http://www.diyaudio.com/forums/attachment....tamp=1153505923

It has a dip at 8 KHz so I'd probably avoid it. The PE ad for it mentions that it

uses a German dome, and it does look a lot like a Morel or Dynaudio. I'd

probably take the new SB 1" dome tweeter at Madisound before the Q1R.

[Pete B]

This might work well in the 2ax for those who are so concerned about dispersion.

This Audax, as inexpensive as it is, has been noted for excellent sonics:

http://www.madisound.com/catalog/product_i...;products_id=96

I just removed the voice coil from a .75" paper dome AR-3a tweeter and the

VC is wound on a paper former, without ferro fluid of course. This Audax while

smaller in diameter does use ferro fluid which should help make up for the difference

in diameter.

Here's a Tang Band copy with a fabric dome. I've not used it or seen any tests

so people are on their own regarding this tweeter:

http://www.partsexpress.com/pe/showdetl.cf...tnumber=264-840

Pete B.

[Pete B]

Zaph tests the .75" HiVi tweeter, it does not do so well on frequency response,

this is unfortunate. He does test a few others that are better:

http://www.zaphaudio.com/tweetermishmash/

I cannot suggest the HiVi based on his tests. ARJohn did inform me that it

sounds just fine.