Kutztown Radio Show Fall 2023

 What I saw...

...and heard 😊

JE Labs Choke-Capacitance Coupled SE2A3 amp

Canon P + Canon 50mm f1.8 LTM 
Foma 100 in Rodinal

Inspired by my plate choke-loaded 76 line stage preamp adventures, I was curious how a similar driver circuit configuration would sound in an SE2A3 amp. So I pulled out my Radiotron Designer's Handbook, 3rd Edition to gain a better understanding of choke-capacitance coupling (aka plate choke loading) vis-à-vis resistance coupling.

Below are highlights of relevant information I gathered.

Shoten R50 Pentax K to Leica M adapter

Inasmuch as I love music and retrotech high fidelity music reproduction, I think it's healthy to take periodic breaks from hifi. Frequent visitors know that I also enjoy photography, especially using black and white film loaded in old school manual focus cameras. 

So today's blog is about the Shoten R50 lens adapter that's designed to take a 50mm (Note: a 35mm, 45mm, 55mm or 58mm, etc. won't focus accurately) Pentax K bayonet mount lens and fully couple to the rangefinder focus cam of a Leica M body from 0.7 meters to infinity. 

Japanese Idler-Driven Turntable Part 5: Lafayette PK300

I bought this Lafayette PK300 idler-driven turntable because it looked like an improved Shield MO-19 (aka NEAT P58H) with the added feature of an eddy current pitch control as found in the Garrard 301/401 and Thorens TD124.

Shield MO-19 vs. Lafayette PK300

Comparing them side by side, the PK300 turned out to be proportionately smaller in all dimensions and lighter in weight. Hmmm🤔…let's travel back to the late 50s.

Ortofon STM-72 + Weller WTCPS repair + Hakko FX-888D

One morning, I discovered the right channel of my Ortofon STM-72 was dead. While waiting for the Weller WTCPS soldering station to heat up, I carefully peeled the foilcal to pull apart the 2-piece tubular housing so I can resolder the broken cable connection(s). 

General Electric A1-400 Speaker

It was past lunch, so I took one last sweep at the Kutztown Spring 2021 radio meet before heading home. That's when I noticed this cabinet with a familiar looking metal-grilled driver partially hidden behind a huge pile of equipment. Without haggling, I handed a couple of ATM bills to the seller and we shook hands.

As soon as I got home I went through my Japanese audio magazine shelf and pulled this Stereo Sound Special Issue about Vintage Speaker Units, published in 2002.

Not exactly the General Electric A1-401 featured in the magazine but the slightly earlier A1-400. Pretty good memory for someone pushing 60, huh? 😉

GE A1-400 specs

As stated in the spec sheet, the perforated metal grill functions as a mechanical roll off filter for the 12" driver and the non-polarized wax and paper capacitor filters frequencies below 1800 Hz from reaching the 2 3/4" cone tweeter.

I also recognized this period correct DIY tuned pipe enclosure designed for corner placement. It was built based on an article published in the May 1955 issue of Audio (go to page 18), authored by Norman H. Bates. 

BTW, AFAIK, he's not related to the lead character in Hitchcock's thriller. 🤣

Vocals are nicely rendered! The transition between the low and high frequency drivers is very coherent, as to be expected between two paper coned transducers. If I were forced to split hairs, I hear a tinge of nasal coloration in the lower region of male vocals, which I never notice with any of my Altec speakers. 

Musical instruments and percussion are also well reproduced! Bass extension and definition of the A1-400 in the tuned pipe corner cabinet is at par with the Altec 756B in a 2.5 cf box, if not a couple of Hz more extended. Top end overtones are silky smooth and airy. Even if this cone tweeter lacks the ultimate transient speed and shimmer of a fine horn/compression driver combination, it's probably the finest I've ever heard!

I guesstimate its sensitivity to be in the high 90s/W/M because it'll boogie, driven by the 1250 mW SE triode connected 46 or 1500 mW SE10 amp. Although I can also listen to my Altec mini 757 with those aforementioned amps at respectable SPLs, it needs at least an SE2A3 for full dimensional monaural listening pleasure. 

Kudos to Mr. Bates' corner loaded tuned pipe cabinet for the aforementioned impressive bass performance and my perceived easy-to-drive/high sensitivity nature of this speaker system. Kids, this enclosure was designed during the slide rule era!👍

Now I'm inspired to pursue my 285mW SE112A mono amp project.😊

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I really enjoy this speaker with a GE RPX or VRII phono cartridge tracing Atomic/Space Age/Exotica Lounge/Bachelor Pad mono LPs from the 50s by the likes of Martin Denny, Arthur Lyman, Walter Wanderley, etc. 

After 21 years of hunting, I finally got a satisfying taste of the GE co-ax. I've seen this on eBay between $150-175, which I believe is a fair price for a unit with intact cones and no voice coil rubbing. A couple of my Instagram contacts even expressed fondness and admiration for this speaker when they saw a glimpse of it in my posts!

I now regret leaving my RCA 501-S1 in the attic 😔 because it would have made for a very interesting shootout. If I can trust my sonic memory though, the RCA didn't have the nasal coloration in the lower midrange I noted earlier. OTOH, the top end of the RCA could be deemed more reticent or refined depending on the listener's taste. 

I debated whether to refinish the cabinet
but the patina grew on me.😊

In the context of my monaural hi-fi system, it shall remain second only to the Altec mini 757 because when I played a young Sinatra LP for my buddy Ding, he initially thought it was Bing Crosby.😄 Sinatra only sounds like Sinatra LIVE or on an ALTEC!👍😎

Let's see what the gentlemen at Stereo Sound thought of its younger A1-401 brother two decades ago...

The scan below is from Stereo Sound Vintage Analog 2, 2014

I can drink to all that!🍻