Comparing OEM and HiVi tweeters in restored pairs of AR2ax speakers

[Vern48]

 

In February 2021 I posted the restoration of my first pair of AR2ax speakers:

https://community.classicspeakerpages.net/topic/13241-my-ar-2ax-restoration/#comment-134198

A couple weeks ago I was able to complete restoration of the second pair of 2ax’s referenced in my last post of that thread. I did follow through and install a pair of restored OEM tweeters by Roy C.  Dayton caps were used in both – 4uf on the OEM tweeters and 3uf on the HiVi tweeters. Did not use 25 ohm resistors on the tweeter L-pads, did install them on the midrange controls along with the Dayton caps.

I was now interested to see what the difference might be between the two sets of tweeters.

I used tracks from the following CDs for my listening:

            BY REQUEST John Williams and the Boston Pops

            COPLAND Bernstein & New York Philharmonic

            DUETS Tony Bennett

            THE LOOK OF LOVE Dianna Krall

            GREATEST HITS BeBe & CeCe Winans

            THE VERY BEST OF Erich Kunzel & the Cincinnati Pops

            THE PLANETS Charles Dutoit & Orchestre symphonique de Montreal

 

I want to be clear about one thing: my hearing acuity is not what it used to be-my upper range diminishes at around 6-7-8K, so, my thoughts and observations may not be the same as someone else.

 

I did the listening in my living room with the speakers on short stands about eight feet apart, placing the tweeters and midranges at about ear level. The stands were located about two feet away from side and back walls. My sitting position was about eight-to-ten feet away. I periodically switched the speakers between the “inner” and “outer” position on the stands. I would often listen to the same track several times, switching back and forth between pairs.

To make level adjustments easier, I installed AR3 type knobs on the L-pad shafts so that the knob pointer lands at the cabinet “dot” at the center of their rotation, the twelve o’clock position, if you will. I tried many mid/tweeter level combinations. I ended up with the mids at eleven o’clock and the tweeters at one o’clock, on both pairs. Those settings sounded good to me, but again, it may be my hearing deficiencies skewing the results.

So, eventually, I drew the following conclusions:

1. On some tracks, I was not able to discern a huge difference, if any. Occasionally, I lost track of which pair I was listening to.

2. Both pairs were satisfying in longer duration listening sessions.

3. I could hear differences on some tracks that I thought were just that, different, but not necessarily better or worse.

4. However, I eventually concluded the OEM tweeter had an edge over the HiVi tweeter.  I thought this was most evident on the Tony Bennett and Dianna Krall tracks. There seemed to be a quality of clarity and realism to such instruments as the cymbals and brushes. The pronunciation nuances on the Krall vocals also seemed smoother.

What would I recommend to others wanting to restore their AR’s?  If absolute originality and a drop-in replacement are the priority, go with the OEM. If lowest cost is the absolute priority, or the originals are unavailable, then the HiVi.  If I was doing this again – restoring two pairs of 2ax’s, I think I would go the OEM route for both sets, although I would have to say the HiVi does make for a slightly cleaner look without front wiring.

Roy’s work in designing the HiVi/inductor combination is to be highly commended. I was satisfied listening to my first restored pair for the last two years.

So, all in all, I’m a happy camper. I have two pairs of restored AR2ax’s and am satisfied with both.

[JKent]

Thanks for the write-up. One question: Is that poly-fil in one pair? Some years back Prof John O'Hanlon wrote a scholarly paper on the microscopic and sonic differences between fiberglass and acousti-fil. He found significant differences as I recall so I wonder whether that would be another variable in your comparison, besides the obvious Hi-Vi vs OEM difference.

Kent

[RoyC]

40 minutes ago, JKent said:

Thanks for the write-up. One question: Is that poly-fil in one pair? Some years back Prof John O'Hanlon wrote a scholarly paper on the microscopic and sonic differences between fiberglass and acousti-fil. He found significant differences as I recall so I wonder whether that would be another variable in your comparison, besides the obvious Hi-Vi vs OEM difference.

Kent

It appears to be poly batting over the original, later type of AR fiberglass. If so, it works very well.

Roy

[JKent]

Ah. I've done that myself (your suggestion as a sub for Kimpac). Thought maybe Vern's was completely stuffed with poly.

[Vern48]

Sorry about the lack of clarity of my attached images.  Both cabinets are filled with 20 oz. of fiberglass.  Interestingly enough, to me at least, was that originally, one cabinet had 20 oz. of fiberglass and the other had 16 oz.  The image with the white fabric is crinoline I picked at Jo Anns to place between the fiberglass and back of the woofers.

[RoyC]

47 minutes ago, Vern48 said:

Sorry about the lack of clarity of my attached images.  Both cabinets are filled with 20 oz. of fiberglass.  Interestingly enough, to me at least, was that originally, one cabinet had 20 oz. of fiberglass and the other had 16 oz.  The image with the white fabric is crinoline I picked at Jo Anns to place between the fiberglass and back of the woofers.

Crinoline works well too.

It isn't unusual for original stuffing amounts to vary a bit. We conducted many measurements when putting together the AR-3a restoration guide, and found such differences to be insignificant.

Roy

[Jim Pearce]

I would be interested in hearing everyone's take on the black tweeters that have been rebuilt.

Also, I would like to put a fuse in the circuit ahead of the tweeter...between the crossover and the tweeter. Any recommendations as to amperage?

I guess I should have placed this comment right after the original post, sorry.