Azzolina Audio KS12024

Western Electric KS12024

Western Electric KS12024
Note: ~ 140° throat bend

The Western Electric KS12024 is a 2-piece cast aluminum 4-cell sectoral high frequency (800-1000Hz cut-off) horn with a 50°H x 40°V dispersion pattern. It was implemented in the Western Electric L-8  and L-9 speaker systems.

Western Electric L-8
from the Silbatone Collection

Western Electric L-8  = 1 x WE754A + 1 x KS12024 + 1 x WE713B (phenolic diaphragm)

Western Electric L-9

Western Electric L-9 = 2 x WE754A + 2 x KS12024 + 2 x WE713B

Western Electric L9
(Note: 2 x WE713B)

Images were taken from J-Rob's KS12024/Western Electric L-8 post at Hifi Haven. If you want to learn more about the Western Electric L-8 and L-9, you can download the pdf file at the bottom of Joe's post.

Read about J-Rob's musings (post #125) about the original KS12024 and Azzolina repro at Hifi Haven.

Late 40s Western Electric Brochure
from www.hifilit.com

The KS12024 horn was from the same era as the WE32A horn that included the venerable WE757A studio monitor, WE713x compression drivers, WE755A, WE756A and WE728B direct-radiator speakers.

Having been a long-time user of the Altec 755A, Altec 32A/C and more recently an Altec 756B, I consider this period as the golden age of design and manufacture of permanent magnet transducers. So when J-Rob offered to loan his personal pair of Azzolina Audio 3-D printed KS12024 horns for me to blog about, it was a privilege and opportunity difficult to pass up.

Azzolina Audio KS12024

I've been a frequent visitor to the ElectraVolt blog but never imagined I would be listening to, let alone reviewing, Charles Michlin's KS12024 reproductions. 

The original Western Electric KS12024 has a 0.7" round opening* but this Azzolina remake was optimized for 1" compression drivers like the Altec 802 that I am using for this review. As relayed by J-Rob, Charles claims the oval (rather than round) aperture sounds better. 

*All the WE horns from this era (including the 32A) were designed for use with the WE713x compression drivers and shared the same aperture size

Just like the original, this is also a true 4-cell compound sectoral horn. AFAIK, this is the model built from an amorphous plastic material. Everything else you need to know about the Azzolina KS12024 can be found here.

Testing

Altec 414A/614 + Azzolina KS12024/802 + 3000H

The Azzolina KS12024 horns were tested in the Altec 2-way system. 

Altec 414A in 614 cab 

Altec 414A woofers in 614 bass reflex enclosures running in full range mode

High-pass XO w/HF eq

Altec 802-8D compression drivers (below) with 16 ohm GPA 34852 diaphragms were mounted to the horns using the above high-pass crossover

Amorphous Plastic Azzolina KS12024 vs. Plastic Altec 32C

Altec 32C + Altec 802

This horn presents a back row perspective and may sound too laid back to those who prefer a closer to the stage presentation. The mid-range is juicy, full and vivid without a hint of shout. While the highs are feathery smooth, silky and airy, which I've only heard from its smaller sibling, the Altec 3000H. Tish (my wife) describes this horn as sublime. I think the 90°H x 40°V dispersion helps provide that holographic and lush atmosphere. 

I've written so much about this horn. Just use the search button on the right hand corner to find past entries.

Azzolina KS12024 + Altec 802

I was initially lured into the 3D-like midrange this horn produced and that lingered on. There's an uncanny realism to male and female vocals as well as musical instruments that renders an "in your room" presence. Compared to the 32C, this horn offers a front row perspective. Yet there isn't a trace of harshness or shout. Definitely a horn that will appeal to those who find the 32C too laid back yet need a horn that doesn't sound like a horn.

It is superior to the 32C in terms of articulation and detail without ever sounding analytical. There's a lot of snap, if I may borrow a term from its owner 😉, just like its stable mate - the WE/Altec 755A.

Azzolina KS12024 + Altec 802 + Altec 3000H

Tish thinks it is as good as but not quite as lush as the Altec 32C. I agree. This is primarily a tonal balance issue. Due to the prominent midrange, the extreme treble frequencies are slightly subdued giving a less airy atmosphere. Adding the Altec 3000H to fill in the uppermost octave helped in approximating the lushness of the 32C. But I still found myself wanting more "hall sound." I speculate that the KS12024's narrower 50° horizontal dispersion contributes to the comparatively austere background. Perhaps I am belaboring this point since my personal preference when I attend concerts is to sit towards the back row so I can relish equal amounts of direct and reflected sound.

Summed up

2 x KS12024 = 100° H x 40° V

These two horns share the same sonic DNA but are genetically modified for different applications. The more up-front and involving Azzolina KS12024 betrays its theatre heritage versus the mellower 32C, which was intended for near-field monitoring. I can't help but wonder if a horn design combining the virtues of both designs is a possibility.

Magnavox CDB473 and Philips TDA1541

With barely 400 CDs and just a handful of SACDs and DVD-As in my collection, I didn't invest heavily on silver discs as much as I did on LPs. Likewise, I've spent much less on digital playback hardware.

Parts Express 1" Horns and Waveguide Buy Out Specials

July was a hectic month - four 4th of July concerts with Harrisburg Symphony + two concerts at the Shippensburg Summer Music Festival. It was a welcome respite to receive an invitation from Joe Roberts to meet him at his mom's house in South Philly after I was done with all those gigs.

Leica II + Summitar 50mm f2
Ilford FP4+ in Kodak HC110

He gave me a tour of his old neighborhood, pointing out areas where he started his archeological expeditions as a kid. For lunch we stopped by this hoagie shop for really great Philly cheesesteaks. 

It was very interesting to listen to his recollection of South Philly as a kid, and how the area continues to evolve as people of different ethnicities, socio-economic and cultural backgrounds come and go.  

Before I-95 swarmed with rush hour traffic, I had to head back north with this box filled with horns from Joe. I didn't envision writing about 1" format horns again since I posted this blog entry last February. But after spotting the Azzolina KS12024s, it was hard to pass up this opportunity. Meanwhile, this post will focus only on the Parts Express horns.

Testing

I used Altec 802 1" compression drivers fitted with GPA 34852 16 ohm diaphragms mounted on top of Altec 614 cabinets loaded with 414A woofers (running full range) with the crossover below tying things together. All listening was done in stereo in the man cave.

High pass @ ~ 2500 Hz

I used these two horns as references and for the first time I was able to convince my wife, Tish, to indulge me with her sonic impressions.

Altec 32C

Tish and I love this descendant of the old school WE32A horn. She describes it as sublime.😉 

Emilar EH500

This is my favorite horn from the 70s. It was designed by Jonas Renkus who worked with John Hilliard at Altec Lansing. 

Parts Express Specials 

Round 1 

(deeper/longer exit Altec 802)

Parts Express: 299-2303

+

Altec 802

There is an ongoing thread at Hi-Fi Haven about cheap horns where this particular horn/waveguide was mentioned. Its specs are listed as a 600 Hz, 10" x 14" exponential horn waveguide with a 90° H x 40° H dispersion pattern, made out of heavy ABS plastic. Price: $12.88/ea.

Sound

Tish: Not bad, but not as lush sounding as the Altec 32C. It will eventually hurt my ears. 

JE: Tonal balance is reminiscent of the Emilar EH500. However the sound gets congested with complex musical passages (especially at higher SPLs) which can cause fatigue during long-term listening.

Community UC-1
part# 299-522
+
Altec 802

Dimensions: 10 3/8" W x 5 7/8" H x 6" D

Dispersion: 90°H x 40°V

Cut off frequency: 2000 Hz

Price: $4.48/each

 I had to DIY adapter plates to mount the 802 drivers.

Sound

Tish: Harsh and shouty👎👎👎

JE: Sounds better disconnected. What were you thinking J-Rob???🤣

Faital Pro revisited

Faital Pro STH100 + Altec 802

Dispersion: 80° H x 70° V

Dimensions: 7" W x 4 3/4" H x 3 5/8" D

Material: Metal

Price: $67/each!!!

Sound

Tish: I like this best among the three - easier on the ears compared to the other two, but not even close to the 32C.

JE: I am less impressed this time around despite the clean sound. It has less congestion, harshness and tizz than the B52/QSC clone 299-2303. But the presentation still falls far short of what I hear live. With the recent price increase, I can no longer recommend this unit.

!!!STOP PRESS!!!

Pasted below is a post by @ARX in this Hi-Fi Haven thread

Gentlemen,

Very interesting experiments with different types of horns and waveguides (the B-52 1" QSC clone is a waveguide), both vintage and more recent designs.

The 802D with the B-52 1" might not be an optimal combination. The original QSC PL-000446GP was designed by Mark Engebretson, former VP of Engineering at QSC, to be used with Celestion compression drivers. From the many measurements available online it's obvious this waveguide performs best with modern, pancake style compression drivers, that have a short exit instead of the deeper/longer exit of most vintage drivers like Emilar, Altec etc.

You might try B&C, Celestion, Beyma, BMS and similar 1" drivers.

There's much more to the underlying physics, but it should come as no surprise the EH-500 and Altec 32A/B do indeed sound wonderful with the vintage drivers. The gradual expansion of the wavefront from driver diaphragm to horn mouth is (almost) perfect. On the other hand, a pancake driver behind an oldskool horn, with a few exceptions, is unlikely to yield spectacular results.

Altec 802 (left) + Renkus-Heinz SSD1400-8 (right) 

The only pancake type (short/fast exit) 1" compression driver I have on hand is a pair of Renkus-Heinz SSD1400-8. This is a smaller magnet version of the SSD1800, which I got to know quite well in the attic. Hence, I had a gut feel that I was going to learn something important from @ARX. So the SSD1400-8 was pressed into service for another round of listening.

Round 2 

(short/fast exit Renkus-Heinz SSD1400-8)

Parts Express: 299-2303

+

Renkus-Heinz SSD1400-8

 According to ARX's post above, this is a clone of the QSC waveguide, which was designed to be paired with a B&C DE250 compression driver in the Econo-wave project at Audiokarma.

With the short exit R-H SSD1400-8 mounted, this waveguide was transformed. Although not quite on the same level, the sound now more closely resembles the Altec 802/Emilar EH500 pairing. The congestion I heard in Round 1 is gone with a substantial gain in midrange lucidity. Long term listening fatigue is no longer an issue since the sound has opened up with a nice airiness to it.  👍👍👍

Community UC-1

part# 299-522

+

Renkus-Heinz SSD1400-8

This horn became a lot more listenable with the SSD1400-8 mounted behind it. It sounded even better crossed over @ 5kHz. Detailed and airy but the midrange isn't quite as vivid as the B52/QSC clone/299-2303. For the record, Community compression drivers are also short/fast exit (pancake) designs.

Faital Pro STH100 

+

Renkus-Heinz SSD1400-8

Sadly, this tractrix horn became unlistenable with the SSD1400-8. Probably a mis-match? Faital Pro 1" compression drivers look more like old school Altec 802s and Emilar EA/EC175.

Parts Express Horn Wrap

Two important lessons learned:

1. Thank you very much @ARX for enlightening me! Otherwise, I would have joined the ranks of fake news bloggers. 🤣

2. My preference for matching harmonically rich-sounding components will always entail a classic pairing of units that are long out of production and are becoming more unaffordable as the years go by...😞

Raspberry Pi 3B+

The FM tuner has been a de rigeur music source in my audio system. Between the dwindling quality of FM broadcasts and proliferation of internet radio and music streaming apps like Pandora, Spotify, Tidal etc., I had to jump the bandwagon with my first generation iPad mini.

Lafayette SK98 Reunion

 

Many years ago, I wrote about vintage Japanese drivers. From that survey, the 8" Lafayette SK98 aka Pioneer PIM8L full range driver emerged as a favorite due to its vivid midrange, balanced by respectable high and low frequency extension. Thinking that I could easily find replacements, I eventually unloaded both pairs to friends who didn't have the budget for Altec 755As. 

16Ω Pioneer PIM8L with a Hamlin's badge

16Ω Hamlin's  in Altec 618 clone cabinets

Over a decade has elapsed and I am happily reunited with a pair, courtesy of my friend at Junkyard Jukebox. He believed that his treasured pair in Altec 618 clone cabinets should be in the JE Labs collection.

 Welcome back old buddy and thanks J-Rob!

Ortofon SPU #1S and the Enigmatic Spherical Stylus

Garrard 301 + Ortofon RMG309 + SPU Classic GME

It seems like yesterday when my SETUP friends Joel, Nonong and William gifted me with an Ortofon SPU Classic GME cartridge for helping them get rid of the upgrade syndrome afflicting their high-end audio sensibilities back in the mid 90s. Within the same time frame, I was frequently talking shop with Sound Practices editor and publisher, Joe Roberts, regarding my Homebrewer article. At some point, the conversation segued to the virtues of the spherical or conical stylus based on the research done by Reto Luigi Andreoli (published in German by Christian Rintelen in Hi-Fi Scene Schweiz). Looking back, and at the risk of sounding ungrateful to my friends, would the humbler Classic GM have been a more appropriate gift? 😇

In the process of hunting for an original SPU with conical stylus, I instead landed three Denon classics - a ca. late 80s DL103, DL103S and DL103C1- for the price of a then brand new DL103R. Compared to a regular DL103, the DL103S is sweet and most extended in the high frequencies but least dynamic, the DL103R most detailed. The DL103C1 emerged as my favorite for combining all the virtues of the aforementioned models. These are very competent MC cartridges, which, along with the SPU GME, have been invaluable tools in voicing my audio system through the years. However, none of them could match the vivid midrange presence of the SPU.

Meanwhile, my spherical SPU hunting got sidetracked by Monaural playback and Retro Cool Tonearms and Cartridges.

Ortofon SPU Classic GME

In the intervening years, I had been fortunate to listen to higher-end Ortofon SPU models in familiar systems. Inasmuch as the SPU Royal, 85th Anniversary, Meister and Synergy offered better detail retrieval and extension in the frequency extremes to satisfy contemporary audiophile standards, I was never convinced that they were presenting a tonally more accurate sound overall.

Ortofon SPU#1S

After over 20 years, the idea of owning a spherical stylus-equipped SPU still haunted me. Fortunately, Ortofon introduced two entry level SPUs in 2016. I bit the bullet and ordered the cheaper SPU#1S with a bonded spherical stylus last year and couldn't be happier. Even if the #1S has slightly less top end extension than the Classic GME, the midrange is even more organic and soulful because the harmonic overtones are more akin to what I hear in a live music-making environment.

It's been known for decades that a conical/spherical stylus is kinder/gentler to the grooves. Thus records in less than perfect condition become more listenable traced by this type of stylus. Granted its technical inadequacies can be measured, which in turn has pre-conditioned audiophile beliefs for several generations, what matters most to me is still the enjoyment of music, and a measuring tool for that has yet to be invented.

While perusing various audio forums these past couple of years, I noticed that compared to 20 years ago there are a lot more vinyl aficionados who recognize and appreciate the musical merits of the humble round profile stylus. In hindsight, if the Retro Cool Tonearms and Cartridges article I wrote before my hair turned gray contributed to this trend, my efforts have not been in vain.

Velvet Touch, Calrad SV12 + SV16

I may have shot myself in the foot when I spilled the beans in the original Retro Cool Tonearms article many moons ago, before collecting all the desirable models of viscous damped tonearms. 

But it's all good - more good karma to come, hopefully. 😇

Gray Research 108 on an HF500 turntable + Velvet Touch (rear)

The Gray Research and Japanese clones all operate on the same exact principle as depicted above.

 

This is a transcription length Gray clone I obtained locally, a Calrad SV16 complete with original box and instructions. 

Calrad SV16
Pivot > spindle = 276mm

Neat P58H + SV16 + GE RPX 

Top: Calrad SV16
Bottom: Velvet Touch (aka, Calrad SV12)

Courtesy of Ben C

Here we have the instruction manual for the Calrad SV12 which is also applicable to the Velvet Touch.

Neat P58H + Velvet Touch (aka SV12) + GE RPX

Velvet Touch or Calrad SV12
Pivot > spindle = 8 3/8"

Musicmaster Model 12 installed as per the above 8 3/8" pivot to spindle distance. Sounds okay. But read further...

This is my Realistic Mk VII idler turntable with a factory mounted Realistic A-3 viscous damped tonearm, which is identical to the Calrad SV12 and Velvet Touch.

 Pivot to spindle distance = 220 mm or 8.66142" or between 8 5/8" and 8 11/16".  

This is my preferred setting after listening to the following cartridges: Denon DL102, GE RPX and VRII + low cu stereo cartridges like the PickeringV15/Stanton 500, Shure M7D & SC35C.

Neat P58H + Calrad SV16

I've also gotten good feedback from ears I trust regarding brand new Gray 108 clones from Karmadon. Serge has come up with variations on the viscous damped tonearm theme. This route is well worth pursuing since prices on eBay for the original 108 and clones have become ridiculous.

Happy Listening!