Testing tweeters and mids on AR 2ax

[JMiP]

Is there a way to test how strong the tweeters and mids are on AR 2ax speakers with a digital multimeter? I know I can just use my ears to check how strongly they are putting out sound, but (at least my) ears can be somewhat unreliable for such tests. There is definitely a difference in the output of each of those components when adjusting the pots on them, but it seems like the tweeter is performing stronger on one of the speakers and I want to do some sort of test to verify that feeling.

 

[rothwellaudio]

Is there a way to test how strong the tweeters and mids are on AR 2ax speakers with a digital multimeter?

No. But you can test any resistors in the crossover to check they're as specified. Some multimeters will allow you measure capacitance too, which would be useful.

 

[ra.ra]

Full functionality from these drivers is dependent on: condition of driver; accuracy of cap; and range of pot control. If these speakers have not been previously restored, the pots definitely require attention and the caps most likely will benefit from replacement.

When the drivers are unwired and out-of-circuit, a multimeter can easily measure DC resistance (in ohms), and this might begin to provide information of the driver's condition. A listening test is still the best subjective test, preferably using a tube held to your ear to isolate each driver. The 2ax mids are robust small cone drivers and typically age very well. The 2ax tweeters (which version do you have?) are known to provide diminished output with age due to stiffening of the foam suspension blobs around the dome. Many of these can be-re-built to restore the upper frequencies that these drivers are known for.

 

[JMiP]

Yeah, I forgot to mention that I updated the caps and pots with new materials from ar-vintage a few weeks ago and I know I was successful because the sound coming from these speakers went from sounding like they were wrapped up in sleeping bags to something wonderful that lives up to the Acoustic Research hype. But then, a friend noticed that one speaker seemed to have just a bit better highs than the other other one. I didn't really hear it at first, but now I tell the difference. On the weaker tweeter speaker, I can turn that pot all the way down and there's no high end at all, and then I turn it all the up, and while there is high end coming out, it's just not quite as prominent as the speaker with the better tweeter.

After reading @ra.ra's response, I did some reading up on the tweeters for these speakers and I think s/he is on to something with their idea of the diminished output due to time. BTW, I have the version of 2ax that had the grill cloth on a removable grill frame as opposed to the style with the cloth glued to the speaker front.

 

[ra.ra]

The primary differences between the early and late versions of 2ax are:

Woofer: early has cloth surround; later has foam
Tweeter: early has 1-3/8" phenolic dome; later has 3/4" paper dome
Badge: early is square "AR"; later is rectangular "AR-2ax"

Which version of tweeter in your pair?

 

[WaynerN]

I use a 1.5 volt AA battery to see if the drivers are working. If they all sound about the same level with the click of the battery, then all is good. (Hint): all you need to do is touch the terminals together momentarily to get some kind of clicking noise out of them. At least then, you will know if they work or not. If they sound close to the same loudness, proceed farther at the restoration. Of course the sound level pots are always the problem.....

 

[RTally]

Is there a way to test how strong the tweeters and mids are on AR 2ax speakers with a digital multimeter? I know I can just use my ears to check how strongly they are putting out sound, but (at least my) ears can be somewhat unreliable for such tests. There is definitely a difference in the output of each of those components when adjusting the pots on them, but it seems like the tweeter is performing stronger on one of the speakers and I want to do some sort of test to verify that feeling.

An easy way to see how drivers in a speaker perform is to use a RTA (real time analyzer). For quick tests I use a signal/noise generator and an analyzer app on my phone (Decibel X).

Depending upon the system I am testing, I use a signal generator app on a phone or I use a website on a computer connected to my audio system. The phone with the analyzer app is held in front of the speakers. I sometimes use a yardstick to ensure that the phone is at the same relative distance from the speakers under test. The phone app is not very accurate, but it gives me a good indication of relative differences.

 

[JMiP]

Here are my tweeters. The one on the right is the better one.

 

[JMiP]

Why do mine look so different from @ra.ra' s tweeters? Weird.

@RTally that looks pretty cool, but I have no idea how one would do that to measure the strength of an individual driver. Something I would like to investigate further. Thanks for the tip on that.

 

[kirk57]

Here are my tweeters. The one on the right is the better one.


View attachment 1590535 View attachment 1590536

Are you sure that the potentiometers controlling the tweeter output are tracking the same for both speakers?
One way to check is to swap the tweeters between the two speakers. If the low output remains on the same one, then it’s a pot/wiring issue.

Another consideration is that those little blobs are some sort of foam that was used by AR when building the tweeters. As I understand it, this foam degrades over time and that can affect the performance of the tweeter (this also applies to AR-3 and AR-3a tweeters). I am aware of no cure for this issue. I ended up replacing the tweeters on my AR-3a with HiVi units as recommended in another thread here and at Classicspeakerpages.net.

 

[RTally]

Why do mine look so different from @ra.ra' s tweeters? Weird.

@RTally that looks pretty cool, but I have no idea how one would do that to measure the strength of an individual driver. Something I would like to investigate further. Thanks for the tip on that.

To test one driver in a speaker and to compare it to another driver in the other speaker, just play a tone in mono with the same signal going to both speakers. With a single tone in the middle of the range of the driver, only that driver will be making sound. Then you can measure the sound level from each speaker to see if they are the same or not.

 

[ra.ra]

Why do mine look so different from @ra.ra' s tweeters? Weird.

Your tweeters are entirely original, and the same ones I have in my 2ax speakers. The one I showed in post #5 is simply a later version that allows for internal wire connections from the rear, whereas yours are clearly connected through the front terminals.

I am aware of no cure for this issue.

The Hi-Vi replacement is a great solution, but there are now at least two people who are able to restore these old 3/4" dome tweeters, and I believe you are correct - - the foam blobs harden over time and lose their suspension ability.

 

[JMiP]

I looked into the Hi-Vi replacements, but it looks like some modification is needed when installing the new tweeter. I also see that Mr. vintage-ar is selling replacement tweeters all ready to drop into place, but at a significant price hike. Is that modification easily done myself? Keep in mind that I updated the crossovers myself and didn't have much trouble doing so. If it is something I can do myself, is there a set of step-by-step instructions with a parts list that I can ready somewhere?

 

[baco99]

You can download a free app for your phone to measure SPL.

 

[don philipe]

I went with the HiVi replacements on mine,it's the best solution. Watch those fine wires on the tweets,you don't want to break them,almost impossible to resolder.
A side note,For a great sounding speaker and well built they sure look ratty with the grills off.

 

[ra.ra]

...but at a significant price hike...

The Hi-Vi tweeter typically requires the addition of a small inductor coil, and these parts purchased directly through a place like PE will result in cost $aving$. It is a fairly simple installation, and has been discussed at great length on the Classic Speakers website. The other two accepted solutions - - re-building original tweeters or purchasing other new replacements (not Hi-Vi), are also discussed at length on that site.

...I updated the crossovers myself....

How much work did you do here?

 

[JMiP]

I installed the vintage-ar kit which consisted of removing the old block that housed the two original caps, I then clipped off the existing wires, removed the old pots, and then I installed the two new caps and the new pots. With his non-soldering kit, I didn't have to do any of that type of thing. I'm not averse to doing any soldering, but it would have kind of sucked doing that in a cramped space.