Showing posts with label Mono Hi-Fi. Show all posts
Showing posts with label Mono Hi-Fi. Show all posts

Saturday, August 15, 2020

JP's Western Electric WE757A Remake


Those were the words of the late Walt Bender in Part II of his Olden Golden Components article in Issue 51 of The Absolute Sound (TAS) in the Winter of 1988. This was my first exposure to Western Electric audio equipment. I eagerly awaited TAS's promised feature of Walt's Western Electric-based audio system but that never materialized. I let my TAS subscription lapse and replaced it with Glass AudioSound Practices and Vacuum Tube Valley

My only encounter with an original WE757A was a single unit being tested on the tailgate of a Honda Civic hatchback at a ham fest in the early 90s. Keep in mind that this speaker system predates the stereo era by at least 10 years, thus, they were never available in stereo pairs.


In this day and age, the only way a mere mortal can experience a Western Electric WE757A speaker system is to build one using as many of the original parts as one can gather.


This is exactly what John Piro did. He combined a WE/Altec 728B driver with a slightly dented dust cap + the botched up KS12027 he expertly repaired to properly mount an Altec 802D compression driver. 

Then he painstakingly cloned and crafted a WE757A cabinet to house these components. Soon after the speaker system was completed, we met at the Kutztown Fall 2019 Radio Show and he entrusted the evaluation of this speaker system to me.


In keeping with JE Labs methods, I started by evaluating the drivers individually and then compared the JP WE757A to my Altec 753CI was fortunate to have had lots of time to dissect and enjoy the JP WE757A. Thanks, JP!

WE/Altec 728B


When I visited J-Rob in the summer of 2018, I spent quality time listening to his pair of WE728Bs while talking shop. The very rich harmonic overtones they produce captured my attention just like a fine violin does.

The smaller Altec decal is pasted over the larger Western Electric original. 
JP surmises that this unit started life as a WE728B which got damaged early on 
and was re-coned by Altec using an original WE re-cone kit. 

Technically speaking, the WE/Altec 728B is neither a woofer nor a full-range. It's a wide-range speaker. The RTA trace shows a seven octave range, which pretty much mirrors the original 60-10,000 kHz specification. 

WE/Altec 728B

The 728B tonal balance is very much like its smaller brother, the 755A, with an additional octave of extension in the bass and about an octave less extension in the highs. This and the Altec 414A are the only 12"-15" drivers that I've heard (so far) which don't break up in the 1-2kHz range resulting in shouty female vocals, amongst other nasties.

Dented dustcap

From the upper bass to upper midrange, the 728B has the J-Rob  coined "snap," which it shares with its 755A and 756B siblings. IMHO, these permanent magnet drivers are unparalleled to this day for their life-like midrange and ability to convey a three dimensional realism. OK, perhaps the Western Electric and GIP field coil drivers are even better but as I said earlier, this article is for mere mortals.😉

WE754A vs. WE728B


In the midst of my evaluations, I exchanged private messages with another Western Electric aficionado who's had the rare 
opportunity to compare the WE754A and WE728B drivers. He is currently assembling a pair of WE757As.


 

 With his permission, I'm sharing his valuable listening notes. Thanks, Jonas!

Just wanted to let you know what’s going on with my 757 style speakers. I was blessed to find a WE 728B in an old console in pristine condition. I was able to compare the 754A and the 728B and I liked the 728B much more. The 754A has perhaps a bit more lows but a thicker lower midrange, and less detail and dynamics, and not as smooth as 728B. Compared to other speakers they were very smooth, but when I heard the 728B with a complete absence of grain or distortion, the difference was apparent. They sounded great on things like Gerry Mulligans Baritone Sax on Night Lights. The 754A’s are made for that sort of thing and I think those who love thick midrange would really enjoy them. But they also didn’t have quite as much highs, at least to my ears. I ran them full range so it would have been nice to try out different crossovers to see if the 754A would have been better with a lower cut off. Perhaps so. 

Anyway, I sold both 754A speakers to a young gentleman from NYC who's uncle is a big WE collector from Korea and it was very cool to meet such an WE enthusiast. The uncle came by to listen to them. He apparently has original 757 speakers among many others and said he uses PX-25 tube LS in his amp. With that money I found a second 728B in similar shape to my other, and they are now installed in the John Piro cabinets. 

I do wonder about the differences of the 754A and 728B in the intended applications. The 754A came before the 728B. There is some a lot of talk about it (a bit of ad copy hyperbole but very interesting still) in this issue of Oscillator Magazine, which was put out by Western Electric. Amazing that they put that much time and effort into a trade publication, and to think of what went into the design of these. 

It seems they created the 728B as an updated or “improved” version of their 754A. What I’ve heard is that the 754A has a copper wound voice coil while the 728B had aluminum. Also there’s the obvious difference in magnet structure and power handling.

They sure sound very different. The imaging and spatial depth is far better in the 728B, at least in these cabinets. The 754A seemed to beam more. Of course the published specs aren’t much different nor are the dispersion characteristics listed in the WE specs, but the 754A seemed to beam more in my cabinets. It’s almost like the 728B strip out any unnecessary frequencies and things have a nice space and clarity while the thick midrange of the 754A brought certain instruments out front at the expense of this clarity and separation of instruments. At least to my ears.

So, part of me wonders if they had just made the theater speakers earlier, designed using the 754A, if they were just trying to use up stock, or if there was a specific reason to use them instead? The 754A is slightly more efficient by 1db, and it seems to play a bit lower and have more low range frequency happening even if they go to the same rated frequency range according to their literature. (it was hard to be sure if the 754A went lower, but the lows were more filled out).

Perhaps this increase in lows, even at the expense of clarity and spacial clarity between instruments, was the reason they were used in the theater amps.

Regardless. It seems that WE put considerable thought into the new 728B. I prefer the 728B a lot myself. I wish you could compare them and do a write up! I really look forward to your future blog posts. 

Best,

Jonas Baker


WE/Altec 728B vs. Altec 414A


Altec 414A

The 414A has finally met its superior adversary. In direct comparison with the 728B, the sharp roll off around 4kHz makes the 414A sound less snappy and comparatively muffled.

Altec 414A

The main asset of the 414A over the 728B is a little more than half an octave of extension in the bass range and a couple of dB more in efficiency. In spite of the 728B's obvious superiority, my admiration for the 414A remains, much like my fondness for the 755C.😉

KS12027 vs. Altec 32C


KS12027 horn

KS12027 + Altec 802D + 20275 diaphragm

Since my capsule review last year, I learned more about the nature of the KS12027 horn. The KS12027 surpasses the 32C and Azzolina KS12024 in presenting distinctive harmonic overtones from lower frequency instruments like cellos, basses and, believe it or not, even from the tympani. Vocals and acoustic instruments are uncannily real and three dimensional, just as they are with the 728B, albeit scaled to small format horn proportions. 

When I compared the Altec 32C to the KS12024,  I noted a distinctive "in your room" presence with the latter. This quality is even more prominent in the KS12027, which is another multi-cell type horn.
 
Altec 32C
Altec 32C horn

Altec 32C + 802D + 20275 diaphragm

Comparatively, the Altec 32C sounds more laid back than the KS12027. Vocals and lower frequency instruments like cellos and basses had less of the life-like harmonic overtones rendered by the KS12027. High frequency transient speed is also slightly slower. Thus, brushed cymbals and high hat tend to have a splashy quality instead of lightning fast attack and decay coming out of the KS12027.

Although the 32C has the wispy airiness at the extreme top end which the KS12027 wasn't able to match, the addition of the Altec 3000H was not as successful as my previous experiment with the Azzolina KS12024. I think the 3000H can't quite match the transient speed of the KS12027.

I've said it before and would like to emphasize further that the KS12027 is the most natural and real sounding small format horn I've listened to. 

Simple Crossover



Since I don't have access to the original WE702A crossover schematic of the WE757A, I made a simple high-pass 1st order crossover hinged at 5kHz and ran the 728B unobstructed. Definitely not optimized, but good enough for me to enjoy the speaker system.

Altec 753C vs. JP's WE757A


All my listening was conducted using the je2a3 mono integrated amp with Hashimoto H203S output transformer, fed by the following sources: Gates CB77/Gray 108B/GE RPX and Neat P58H/Calrad SV16/DL102, Magnavox CDB650 transport > Arcam Delta Black Box DAC.


Altec 753C

The Altec 753C is very lush and romantic. It gives a middle of the hall presentation compared to JP's WE757A. Its only advantages over JP's WE757A are: almost an octave more bass extension (albeit with less definition), a couple dB more of efficiency and the wispy airiness in the very extreme top end noted earlier in the 32C/802D pairing.


JP/WE757A

Typically, components with similar qualities don't complement each other because their virtues cancel out. However, in this particular case, the WE/Altec 728B + KS12027/802D was an utterly cohesive and coherent blend.

JP's WE757A sounded neutral and more analytic in a very musical way. Transients come across crystal clear and clean. Dynamic nuances at macro and micro levels are also much better conveyed. Even if the music is presented closer to the stage with greater detail and resolution, I didn't experience long term fatigue. 


In spite of the slightly less bass extension vs. the Altec 753C, definition was better. Due to a tad less efficiency, it can benefit from slightly more power. Perhaps an SE300B amp would've improved bass extension and dynamics further.

The sense of realism from its three dimensional midrange is a result of the life-like harmonic overtones produced by the 728B + KS12027/802D pairing.


The Altec 753C set a very high musical standard but JP's WE757A cabinet remake + Altec 728B + KS12027 horn + Altec 802D is more organic, finer and nobler in stature. It brought me closer to the music! 

Now I'm asking myself, how much better would it be with the original WE713C compression driver and the optimized WE702A crossover?


The WE755A, WE756A, WE754A, WE728B, WE753C, WE757A, etc. came from an era when America was at the height of its industrial might. The amount of R&D that went into these transducers will never be equalled. Sadly, these are more appreciated in Asia and Europe.

To add insult to injury, many American audio hobbyists even sneer at these foreigners who pay top dollar for these American-made classics. This gives credence to the saying, "no one is a prophet in their own land."





Wednesday, December 18, 2019

Preview for 2020


 I've become so busy the last few months and wasn't able to upload as much as I intended to. So here's what's in the pipeline for the coming year.

My one and only...

The JP757A - a John Piro (re)creation, amongst others...

Revisit MM/MI phono cartridges

American Classics 

Japanese Idler Drive(s)

'68 G401

DIY tube DAC


Tonearms are like violin bows

my camera adventures



Happy Holidays and a Great New Year to Everyone!











Tuesday, July 16, 2019

KS12027 Horn


The KS12027 horn perched on top of my repurposed Altec 861 cabinet loaded with an Altec 414A woofer should actually be residing inside a ~ 4 cubic foot slanted cabinet with a Western Electric WE713C compression driver  bolted to its throat + a WE728B 12" woofer = Western Electric WE757A monitor speaker system.

I was honored to host this KS12027 horn and provide more modest accommodations for a couple of weeks courtesy of my audio preservationist buddy John Piro.


He rescued this KS12027 horn with a damaged 0.7" aperture and repaired/modified it so that mere mortals like myself can sample its delights using a more pedestrian 1" exit Altec 802 compression driver. 

Mono Hi-Fi set up: Neat P58H + Calrad SV16 + GE RPX or DL102, JEL SE2A3 mono integrated amp with Hashimoto H-203S OPT.

All of my listening was done with the above set up.

Altec 414A + mod'ed KS12027 + 802 + GPA34852

From the moment I mounted the KS12027 + Altec 802 combo above the Altec 414A woofer, the first adjective that came to my mind and stuck for the rest of its stay was, natural! Just like its WE/Altec 32 and KS12024 relatives, this is also a horn that doesn't sound like a stereotypical horn. In fact, the articulation (attack and decay of notes) and overall presentation of harmonic overtones via the KS12027 is even more natural and realistic. It made the Altec 32A/32C and Azzolina KS12024 sound merely like very high quality Hi-Fi which mainstream audiophiles may find more appealing. These findings were echoed by my friend Ding during his recent visit to the man cave.

Altec 32C, KS12027, Azzolina KS12024

Even if I loved the KS12027 so much, I didn't want to get attached to something I may never be able to own. So this past weekend I met up with John at a ham fest and handed back this valuable piece of audio history. After giving him my rave report, which is hardly representative of what most audiophiles like nowadays, he was not dissuaded. He is still seriously considering reproducing them. 😎














Friday, December 14, 2018

Friday, June 1, 2018

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. 😇


I no longer aspire to be as lucky as my buddy Ding with his Gray 108 and Gates CB77. 😞 But I recently found a transcription length Gray clone 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!






Friday, July 28, 2017

Noguchi Finemet: FM-3WS-H + FM-6WS output transformers


This was the last extensive testing and listening session I did in the attic before the stereo and mono systems were rescaled. I misplaced some data and just recovered them recently. So as promised in a previous blog entry, here's the write-up on the two entry-level SE Finemet OPTs from Noguchi.

WARNING

These are bonsai-sized output transformers. If thumping bass frequencies is your idea of high-fidelity you should stop here right now. Otherwise, please proceed with caution ;)

Noguchi FM-3WS-H

Noguchi FM-3WS-H + Tamura F7004

David vs. Goliath - indeed, the FM-3WS-H is tiny. I had to mount it on a perf board so that it wouldn't fall from the square mounting hole left by the Tamura F7004 ;)

JPY 13,910 or US $124

Noguchi FM-3WS-H
100Hz (top left), 1kHz (top right)
 and 10kHz (bottom right)

Technical and listening tests were done with the output transformer mounted in the SE10/VT25 amp, which resides in the attic mono system.

Noguchi FM-6WS

Noguchi FM-6WS + Tango U808

The FM-6WS is not that much bigger either.

JPY 16,000 or US $142

Noguchi FM-6WS
100Hz (top left), 1kHz (top right)
and 10kHz (bottom right)

Technical and listening tests were done with the output transformer mounted in the Radiotron SE2A3 stereo amp in place of a pair of Tango U808 OPTs.

Color Chart in Kanji
for wiring
transformer leads

Subjective evaluation of both OPTs


I have to admit that given the Lilliputian dimensions of these OPTs, I was predisposed to expect poor bass performance in spite of the claims from their respective spec sheets. The 100Hz square waves verified the manufacturers' claims and the quality of bass I hear more than compensates for the lack of ultimate extension which, in my experience, can only be had from OPTs the size of a Tango XE60/NY15s or Tamura F2000/F7000 series. In fact, when I invited my seasoned DIY Audio buddies for a listening session, none of them noticed significant bass deficiency.

Back in the 90s, there were two types of exotic transformer core material vying for the best - Permalloy and Amorphous. I learned then that the virtue of exotic core material shone through the mid-range, rather than at the frequency extremes. I never quite made the leap to Amorphous because I was already satisfied with the life-like mid-range abilities of Permalloy. I heard the Amorphous Tamura F5002 in a familiar circuit and system context, and thought that in spite of its edge in resolving detail, it sounded clinical compared to Permalloy. Finemet is supposed to have evolved from Amorphous. However, the mid-range performance from these two entry-level Noguchi Finemet OPTs have the warmth and lucidity of Permalloy without the antiseptic quality of Amorphous.

With such fine midrange performance I didn't expect any high frequency aberrations and the two 10kHz square wave oscillograms above confirm the smooth falling response beyond 20kHz (no ringing or phase shift), as shown in their respective spec sheets.

If I didn't already have Tamura and Tango Permalloy OPTs the bigger Finemet offerings from Noguchi are very tempting!