AR2ax (Early) Tweeter Dome Suspension

[ReliaBill Engineer]

Well, after months of listening, I’ve decided I’m going to replace the midranges in these. They just don’t produce the level of detail I want. After a long search, I found the midrange drivers I’ve been looking for. They have very similar DC resistance and impedance, and sensitivity to the original paper cone midrange drivers. Also, a very similar frequency response, extending out to 10 kHz from 500 HZ, and flat with very good dispersion, varying only 6 dB at 45 degrees off-axis. So I won’t be changing the crossover, nor pots. They aren’t a drop-in replacement, so I’ll have to modify the faceplate to fit in the existing mount hole in the baffle. 
 

Once done, I’ll post results. I’ll document my work. I’ll also make comparison recordings, by doing one speaker at a time. 
 

My goal is to make these sound very similar to the early AR-3a’s.

[RoyC]

51 minutes ago, ReliaBill Engineer said:

Well, after months of listening, I’ve decided I’m going to replace the midranges in these. They just don’t produce the level of detail I want. After a long search, I found the midrange drivers I’ve been looking for. They have very similar DC resistance and impedance, and sensitivity to the original paper cone midrange drivers. Also, a very similar frequency response, extending out to 10 kHz from 500 HZ, and flat with very good dispersion, varying only 6 dB at 45 degrees off-axis. So I won’t be changing the crossover, nor pots. They aren’t a drop-in replacement, so I’ll have to modify the faceplate to fit in the existing mount hole in the baffle. 
 

Once done, I’ll post results. I’ll document my work. I’ll also make comparison recordings, by doing one speaker at a time. 
 

My goal is to make these sound very similar to the early AR-3a’s.

Bill,

Have you ever heard the AR-3a?

You really should post your project(s) in the mods and tweaks section of the forum

Roy

[ReliaBill Engineer]

I’ll make a new post there. But I felt it necessary to bridge this thread to a new one.
 

But i see many mods and tweaks in the AR-3a rebuild section. Certainly not all original. 

[ReliaBill Engineer]

On 7/23/2023 at 1:33 PM, RoyC said:

Bill,

Have you ever heard the AR-3a?

You really should post your project(s) in the mods and tweaks section of the forum

Roy

Yes I have. A good friend had a pair. Fact is, he has posted in here. Unfortunately he passed away a few months ago. It was my listening to his a couple of years back that got my attention to vintage AR speakers. His had the HiVi tweeter, but his repair shop that installed the mod didn’t do it correctly, so he didn’t get the full benefit. 

[ReliaBill Engineer]

I have no idea how/why this ended up in tweaks and mods. But ok.

[Aadams]

12 hours ago, ReliaBill Engineer said:

no idea how/why this ended up in tweaks and mods

I think because you wrote the following. Your intent clearly is not to preserve or restore the 2ax designed performance and appearance.

On 7/23/2023 at 1:40 PM, ReliaBill Engineer said:

They aren’t a drop-in replacement, so I’ll have to modify the faceplate to fit in the existing mount hole in the baffle. 

 

On 7/23/2023 at 1:40 PM, ReliaBill Engineer said:

My goal is to make these sound very similar to the early AR-3a’s.

Not saying your project isn't worthwhile.  If you devise a credible solution that is not too complex or destructive you could have a hit on your hands.

The third most visited thread on this site, with 44k views, is about modifying the AR4 to improve its sound.  First is ADS 1590 maintenance and performance.  Second is AR3a RESTORATION.

You might include this driver as a candidate.  It would be readily accepted as credible.  There is plenty of speaker engineering talent here, you haven't yet heard from, that could offer advice on the electronic adaptation.  When used in the AR9 or 90 it covers the 1200hz to 7000hz band, very close to what you are trying to cover.  When used in the 10 inch AR92 it covers 700hz to 7500hz. 

https://www.midwestspeakerrepair.com/shop/home-audio/midranges/others/mw-audio-mm-2044-acoustic-research-copy-midrange/

Adams

 

[genek]

To clarify, the criteria is the intent to change the original sound. Otherwise, every instance of someone replacing the tweeter in an AR-3a with a HiVi QiR - or even the tweeter from an AR-11 - could push a discussion over the line.

So for this topic, the decisive moment was:

On 7/23/2023 at 10:40 AM, ReliaBill Engineer said:

Well, after months of listening, I’ve decided I’m going to replace the midranges in these. They just don’t produce the level of detail I want. 

 

[ReliaBill Engineer]

I won’t be using the “approved” midrange replacements. I’ve selected and listened to my choice already. As for crossover, I’ve already designed it, and am waiting for parts. I will assemble it, then listen to it extensively and make any modifications needed. I’m going to leave the existing mid in place, positioning my replacement outside (on top) of the cabinet for comparing. Wire the replacement directly to the external terminals, and turn the pot for the existing mids to zero. This way I can do a very close comparison, A/B them. 
 

Ultimately, the new mid and XO will be a drop-in replacement without corrupting the cabinet, nor original XO circuit. 
 

It will be for those wanting to upgrade the sound, yet not be irreversible from original drivers or crossover. If later sold, both pairs of drivers can be included with the speaker pair; a choice of performance.

[ReliaBill Engineer]

Original tweeter, woofer, crossover capacitor values. These have the sound I was looking for. Airy, clear. Not “laid back”, but very musical over long listening sessions.  Perfect for my tastes.