AR-2ax midrange resistors Help

[charger3834]

As many of you may all ready know, I am a AR-2ax collector. I ran in to an issue with my newest pair (serial numbers 250,000 something).

I have a little too much ringing in one of the midranges, so I want to swap it out. I noticed there were 2 resistors wired in series and glued on the back of the 3.5" mid.

What changed in the crossovers that required these resistors ??

I guess I need to add these resistors to the replacement from the donor speaker(serial #180000 something.)

[dynaco_dan]

>As many of you may all ready know, I am a AR-2ax collector. I

>ran in to an issue with my newest pair (serial numbers 250,000

>something).

>

>I have a little too much ringing in one of the midranges, so I

>want to swap it out. I noticed there were 2 resistors wired in

>series and glued on the back of the 3.5" mid.

>

>What changed in the crossovers that required these resistors

>??

>

>I guess I need to add these resistors to the replacement from

>the donor speaker(serial #180000 something.)

>

>

Hi Brad;

Any chance of a photo?

Are the resistors sandcast?

What are their values?

What are their power ratings?

The resistors are wired in series yes, but are they wired in series or in parallel with the mid?

Do they appear to be hot glued or epoxied?

First time I've heard of this one.

There may have been a batch of these made.

If I am going to guess, it is a 16 ohm mid, rather than an 8 ohm, AR maybe used the resistors of ? value in parallel, to make it an 8 ohm equivalent.

Another thought is, they were 4 ohm mids and the resistors in series brought them up to 8 ohms.

An other thought is, an amateur soldered these in parallel, with the mids, they did this, to make the mid closer to 4 ohms, or louder.

Good topic and maybe there is more of these out there.

As a side note I know I have, packed up still somewhere, a 3/4" 4 ohm tweeter with a sandcast resistor glued to the back of the magnet.

Until I find it, I can only guess at this time that it was a universal replacement.

I believe firstly it is a 8 ohm tweeter, the resistor is of ? value added in parallel would give you a 4 ohm equivalent tweeter.

The opposite would be, if it is a 4 ohm tweeter, the resistor ? value added in series, makes it an 8 ohm equivalent tweeter.

I feel the first idea is engineering wise, more correct.

Perhaps Ken Kantor will comment on the feasablity of adding a sandcast resistor in series or in parallel with a speaker driver.

This would allow for only one model being in stock instead of two.

Good luck.

All the best in 2006 to you and yours, Brad, neighbour.

[charger3834]

Hi Dan,

Happy new year and thanks for your message. These resistors are in fact AR installed. I just don't know why they installed them, or what I need to do to replace that 3.5" mid with another 3.5" mid. The spare I have does not have the resistors.

Layne Audio documents these resistors and has a photo. They appear to be 3 ohms each.

http://layneaudio.hypermart.net/2axmids.jpg

http://www.classicspeakerpages.net/dc/user_files/808.jpg

Any Ideas ???

[Guest dogmeninreno]

>As many of you may all ready know, I am a AR-2ax collector. I

>ran in to an issue with my newest pair (serial numbers 250,000

>something).

>

>I have a little too much ringing in one of the midranges, so I

>want to swap it out. I noticed there were 2 resistors wired in

>series and glued on the back of the 3.5" mid.

>

>What changed in the crossovers that required these resistors

>??

>

>I guess I need to add these resistors to the replacement from

>the donor speaker(serial #180000 something.)

>

>

What you probably have is a 4 ohm driver with series resistors bringing it to the 8 ohm required for the AR2ax.

I personally have had little sucess with that arrangement.

I would replace the midrange with the proper 8 ohm driver and you could sell the 4 ohm on ebay wityhout the resistors.

I have several 8 ohm mids for the AR2ax if you are interested?

My email is duffydog1234@sbcglobal.net

Happy holidays and good luck..Dale

[Guest dogmeninreno]

The photos look like AR4x tweeters..I have never seen a midrange like shown? Dale

[charger3834]

Hi Dale, Thanks for your help.

I too have lots of 8 ohm 3.5" mids. You might be correct, I just don't understand why AR would change the impeadence of a driver that had only been in 8 ohm speakers since 1964 ! Then they would have went through the trouble of adding resistors only to put it in a 8 ohm speaker. The speakers were produced in 1974 and at that time, that driver was only used in the AR-2ax.

I guess I somehow need to know for sure.

Thanks again

[dynaco_dan]

>Hi Dale, Thanks for your help.

>

>I too have lots of 8 ohm 3.5" mids. You might be correct, I

>just don't understand why AR would change the impeadence of a

>driver that had only been in 8 ohm speakers since 1964 ! Then

>they would have went through the trouble of adding resistors

>only to put it in a 8 ohm speaker. The speakers were produced

>in 1974 and at that time, that driver was only used in the

>AR-2ax.

>

>I guess I somehow need to know for sure.

>

>Thanks again

Hi again;

I find it amazing that this issue would just pop up out of nowhere after so many decades.

Never a mention in all of my reading, at least.

There has to be more of these out there that members may not have noticed because they haven't removed their mids.

If possible could you please take a front photo of both?

Was that not the mid driver that CTS manufactured for AR and AR adjusted with the fibreglas and screen?

It was also used as the tweeter in the original classic AR-4 speaker.

This is an interesting topic and I sure will be following it, thank you for bringing it to the forefront.

I have a another thought, maybe CTS had a batch made to other specs, or OEM customer, and it became available for AR to buy at a discount.

The Dynaco A-25 was originally prototyped as a 4 ohms system, Dynaco spec'd 8 ohms.

I won't ask you to detach one end of the resistors, but a VOM would be able to determine the drivers resistance.

Another great topic to end the year with.

Best of the new year to you and yours in 2006.

[charger3834]

>

>

>Hi again;

>

>>

>Was that not the mid driver that CTS manufactured for AR and

>AR adjusted with the fibreglas and screen?

>

>It was also used as the tweeter in the original classic AR-4

>speaker.

You are 100% on the money

>

>>

>I have a another thought, maybe CTS had a batch made to other

>specs, or OEM customer, and it became available for AR to buy

>at a discount.

>

Interesting theory, however by this time I think AR owned CTS.

I guess I will have to sort it all out with a meter like you said. I was really hoping someone had the answer. I like to know all the details all the time when it comes to AR.

[Guest dogmeninreno]

My AR parts list from 1-1-79 shows that the driver used for the tweeter was a 1200013-2.

The same 8 ohm driver used in the AR5 and LST-2..

The list also says that the driver for the AR2ax mid was a 1200008-0...

Dale..Happy New Year!!!!

[charger3834]

Thanks Dale,

I will check the part numbers. I will probably have to add resistors to the repacement driver. I just don't know why ????

[Wally]

Dale,Brad,

My AR12's whch are the successor to the 2AX's have mids in which the foam died. It's an unusual size and type so I don't know if I can find replacements. I am trying to find out if my local guy can create surrounds for them.

Do either of you have any? If not let me know what types of 8 ohm mids you do have and pricing. I would be interested in 2AX or AR5 mids. I believe the AR5 mid was basically an 8ohm AR3a mid.... or was it and AR3a mid with a resistor? I believe I saw some notes regarding resistors on other AR drivers. Please email me off forum. thx.

Sorry for the sidetrack but it does relate to a similar speaker, midrange and possibly resistors.

[charger3834]

Hi Wally,

In my opinion (not as educated as other forum members) you need to get that original driver back up and running. I think you need the correct driver to work properly in that system. This is crucial for maintaining flat power response.

Original replacements will be scarce and will probably have the same age issues.

Perhaps someone else has crossed this bridge before.

On final thing, you need not apologise for the digression. Some of the best threads of all time have been digressions.

[dynaco_dan]

>

>>

>>

>>Hi again;

>>

>>>

>>Was that not the mid driver that CTS manufactured for AR and

>>AR adjusted with the fibreglas and screen?

>>

>>It was also used as the tweeter in the original classic AR-4

>>speaker.

>

>You are 100% on the money

>

>>

>>>

>>I have a another thought, maybe CTS had a batch made to

>other

>>specs, or OEM customer, and it became available for AR to

>buy

>>at a discount.

>>

>

>Interesting theory, however by this time I think AR owned

>CTS.

>

>I guess I will have to sort it all out with a meter like you

>said. I was really hoping someone had the answer. I like to

>know all the details all the time when it comes to AR.

Hi there;

That also is interesting.

I never heard before, that AR owned CTS.

Now that this was mentioned, and if AR did own CTS, then that special deal may not have ever existed.

Now you should dig into the insulation and take some photos of the crossover board and maybe there was a onboard reason for these resistors.

The resistance of the mid is now more important to give some more answers.

Another thought just came to mind, about why there is resistors and terminal strips.

If AR owned CTS, then maybe someone made up or assembled thousands or tens of thousands of the wrong 4 or 16 ohms voice coils and the resistors and terminal strips were the least expensive way out of losing money.

I can imagine how many nails, a nail manufacturer might produce in a shift, but not how many speaker drivers could be.