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 Audio, Sound 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 753C. I 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 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."

JVC CD Players from the Thrift Store

Since my last CD player upload, I've acquired these three JVC CD players. It is stacked from the bottom to the top sonically according to yours truly. 😎

JVC XL-Z411 

I bought this primarily for the coaxial digital output since the price was right.

Dutch Audio Classics listed the DAC chip as a Panasonic MASH MN6623BM, but this unit sports a MN6471M bitstream DAC chip. Early bitstream sound with no nasties but also more hash than music. Not my cup of tea. 😏 

It’s a very nice CD transport though!

JVC XL-V75

If it's meant to be, it'll happen...I've been looking for this chip inside Fisher badged Sanyo CDPs only to land one in a JVC. Best of all, it only cost me a dollar!    

The Sanyo LC7881 DAC chip gives the Philips TDA1543 a run for the money. 

 If forced to split hairs, this CD player offers slightly better resolution and extension in the frequency extremes than the TDA1543 DAC'ed Magnavox CDB 492/CD2000 I reviewed here.

JVC XL-Z444

This unit shares the same Optima 4s transport as its bitstream chip'd brethren above. In case you're not a fan of the Burr-Brown family of multi-bit DAC chips, you can use it as a CD transport since it has digital coax output.

Not as warm and analog sounding to my ears than a TDA1541 equipped Magnavox/Philips or Sony but this Burr-Brown PCM56P chip'd player still gets the music right just like the older Shure SV40 I reviewed here. I will not argue with those who believe it's more extended at the frequency extremes. However, I'd argue back that the midrange of TDA1541 CDPs sound more life-like.

Happy listening and hunting!

Headphones: AKG, Grado, Koss and Sennheiser

Sennheiser HD40 from Hifi Engine

Back in the 80s, I used a Sennheiser HD40 to monitor my rehearsals recorded on a cassette deck and as a courtesy to my roommates and neighbors during late night listening. I preferred the sound of the open-backed HD40 over the heavy, closed cups of the Koss Pro 4AAs at the listening library at school.

After I left the conservatory and entered the world of classical music performance, I also did a fair bit of recording gigs. This exposed me to various models from AKG, Beyer-Dynamic and Sennheiser. However, I never really paid attention to the subtle differences in headphones. I viewed them mainly as a temporary monitor, not as an alternative form of enjoying recorded music. 

When my HD40 died in the early 90s, I acquired a Grado SR80 as a quick replacement, since I was already a dedicated user of the GTE+1 and Signature 8 phono cartridges. 

Koss Porta Pro, Grado SR80 and AKG K72

A few years ago, I bought the closed back AKG K72 for my iPad so I wouldn't be bothering Tish when I got engrossed watching a movie or listening to music until the wee hours of the morning. BIG mistake! It's a totally different animal from the K240 I had positive memories of, from studio gigs in the past. The K72 sounds harsh and compressed. It can't even properly reproduce a human speaking voice.😬

After the Darling Amp, JE Labs style was uploaded, I got a steady stream of PMs asking if the amp could be configured as a headphone amplifier. This sparked my curiosity about headphones. Although I wasn't totally clueless, I didn't realize the vastness of the headphone audio sub-culture until Google turned up pages upon pages of headphone forums and blogs. 

Being a sucker for nostalgia, I ordered a pair of Koss Porta Pros from Amazon when I found out that they're still in production. The Porta Pros confirmed my long held suspicion that something was funky with the voicing of my SR80 headphones, which I also hear from my Grado phono cartridges. 

The Grado SR80 has been displaced 😔

Using this chart, it sounds like Grado Labs tailored an upper bass boost then created a dip starting in the lower midrange all throughout the midrange, followed by an upper midrange rise for the next two and a half octaves until response drops off sharply. This curve creates an impression of tonal warmth, heightened transparency and dynamic excitement. Although it is tame enough not to be outright objectionable and quite possibly appealing to others, it is fatiguing to my ears, especially under long term listening conditions. I gave up on my pair of Altec 811 horns for similar reasons. 

How could I have missed the Koss Porta Pro in the 80s? I'm so impressed with the Porta Pro that I also got the slightly cheaper KPH30i, which supposedly uses the same drivers. Granted, the warmer voicing on both models is a personal preference, both headphones still have a much flatter response than the SR80. If forced to split hairs, the KPH30i is tonally the more neutral of the siblings. 

Koss Porta Pro and KPH30i with Yaxi Pads

Either one can be end game to music lovers who just want to enjoy their music on a tablet, cell phone or any portable device, because they're very efficient and an easy load to drive - no need for fancy headphone amps, just plug 'n play. The Yaxi pads take comfort to another level with the additional benefit of increased definition without negating their inherent virtues. 

It should be noted that the Porta Pro and KPH30i aren't for head bangers. The sound congests at louder levels, especially on complex musical passages. That's when the listener is reminded of its maximum SPL limit. I can live with that since I owned BBC LS3/5As and still use Altec 755Cs and 755As. It's a real world compromise I've learned to accept from coherent-sounding BUT small drivers that can't defy the laws of physics.

Nonetheless, for sheer musical pleasure, one can't go wrong with a pair of Porta Pros or the KPH30i. Add a pair of Yaxi Pads and the tab is still under 50 bucks, while the retro vibe is free! 😎 

Sennheiser HD420SL + AKG K240 Monitor

Since I love traveling back in time, I hunted for an HD40 but couldn't find a survivor. So I went a model up, only to find out that the HD414 has been rediscovered by the mainstream audio press and now commands Sotheby's prices. I finally settled on HD420SLs. After a bit of cleaning and new foam pads, it brought me back to the early 80s - lightweight, comfortable and sounds very much like the HD40 with a bit more extension at both frequency extremes. I'm hoping my memory still serves me right. Typical of headphones of its era, this needs an amp for best performance. While enjoying the trip back to the 80s, the HD420SL left me looking for a 'studio monitor' sound.

Undeterred by my AKG K72 experience, I located an older, Austrian-made, AKG K240 600 ohm monitor. My particular unit looked like a veteran of the studios. I had to get a new headband and rubber bands for it to fit properly on my head. Very inefficient, it barely croaked when plugged to my iPad. So I rigged a contraption to connect it directly to the output terminals of the Darling amp or Simple 46 amp. 

JEL Simple 46 + Noguchi FM-6WS OPTs
+ headphone adapter

This classic semi-open design delivers a neutral and transparent midrange, wide bandwidth, excellent micro-dynamics with fine resolution of detail, yet is fatigue-free. But I was left longing for warmth and air as found in great concert halls.

As Covid-19 lockdown loomed and gigs got cancelled, I needed a diversion. If cost wasn't a major factor, I would've ordered a Sennheiser HD600 from Amazon. But after reading many rave reviews of its sibling, the HD650, I opted for the [Mass]drop.com 'value for money' version, the Sennheiser HD6xx. It's more efficient than the K240/600M but it still plays its best amplified. 

Sennheiser HD6xx from Drop

Compared to the K240/600M, the HD6xx has better extension in the frequency extremes. I got the warmth and concert hall airiness I longed for + a more 3-D midrange. Micro and macro dynamic contrasts are vividly rendered, making the K240/600M sound comparatively less exciting. However, at higher SPLs, for example Mahler and Shostakovich orchestral climaxes, the distinction and layering of instruments sound strained and veiled. On the other hand, the K240/600M maintains its full composure and resolves these details with ease, albeit with less dynamic impact. Should I have gotten the HD600 instead?🤔

Wait, the doorbell's ringing... 

USPS just delivered this.

I've fallen into a rabbit hole. 😆

Reality Check: Musical Instrument Frequency Chart + A Tidbit of Wisdom from Radiotron 3rd Edition

Musical Instrument Frequency Chart

This musical instrument frequency chart should serve as a reality check for those who obsess about metrics. During the triode era and up until cycles per second (cps) was replaced by kilohertz (kHz), a bandwidth specification of + or - 1dB from 30-15,000 cps was considered state of the art. That old standard actually made more sense if we look at the bandwidth of acoustic instruments in the chart above.

The chart is also a practical reference for all of my speaker/driver/horn articles past, present and future. Likewise, it is a handy visual aid to interpolate the pink noise + iPhone Real Time Analyzer (RTA) app traces even if in most cases they don't correlate to what we hear.😆  

In a couple of instances, an RTA trace has agreed with what I heard. In reality though, pink noise and other waveforms used for audio testing have nothing in common with musical notes and harmonies. Audio measurement is very far removed from the dynamic nature of music. To me, the RTA, audio generator and oscilloscope are tools that can be helpful if used with discretion.

Altec 755A in an Open Baffle

My adventure into high-efficiency speakers started with a pair of Altec 755Cs (and later, 755As) mounted on this very same open baffle. It was easy for me to appreciate the lack of boxy coloration, having lived with Quad ESLs for a couple of years.

Altec 755A in Open Baffle

Most open baffle detractors complain about the lack of bass response. However, the above trace doesn't pale too much in comparison to the Altec 755A + Dr. Bae/Silbatone box and Altec 755A + 618 below, even if it does look ugly!🤣

Maybe the suck out between 250-1kHz is what I hear as the absence of cabinet coloration or the "lack of snap" J-Rob heard?

Dr. Bae/Silbatone Box + Altec 755A

Despite being very compact, this empirically designed box exploits the fullest potential of the 755A driver. 

Altec 755A in Silbatone Box

This trace looks better than the 755A + OB above but not as nice as the Altec 755A + 618 trace below.

Altec 755A + Altec 618

[2 cubic foot sealed box]

A pair of Altec 618 cabinets

The Altec 618 is the classic 2 cubic foot sealed box for the 755. It has to be rigidly braced to minimize upper bass/lower midrange coloration, although some listeners may prefer that "warm" bloom.

Altec 755A in the 618 box

This trace is the flattest of all three. But subjectively, the Dr. Bae/Silbatone box + 755A sounds more neutral and tonally more accurate. I don't hear the sudden rise from 1 kHz and peaks at 1.5 and 2 kHz. 

The Altec 618 box is now loaded with 755Cs and has great synergy with the JLH 1969 clone amp.

Altec 753C

 My exposure to the Western Electric WE757A and WE753C in the late 90s inspired the Altec 2-way project. The sound of those two classic speaker systems was already familiar. They sounded very similar to the 755A with more extension in the low end + airier highs. But what really sent me on a quest to emulate them were: greater efficiency so that I can enjoy my flea powered SE-DHT amps and less congestion (more layering and instrument separation) at higher SPLs. The Altec 753C is the final destination of that journey. 

Along the way, the Altec 755A was my loyal guide for midrange accuracy and coherence, which is why I discussed the driver in its various guises above.

Altec 414A in the ported 753C cabinet

The Altec 414A woofer running in full-range mode covers at least six octaves, from 45 Hz until it starts rolling off in the 3 kHz region. Unlike most drivers of this size and type, this is very smooth-sounding and delivers a great midrange without nasty cone break up modes up to its natural roll off point.

Prior to using the 414A, I had a pair of Altec 419A Bi-flex. I also seriously considered a pair of Altec 416A but both drivers exhibited nasty peaks starting from 1-3 kHz. Now I wonder if those peaks would've been visible using pink noise + my iPhone RTA app? 

I could've studied how to filter the peaks using EQ. However, all these extra crossover circuit complications would've adversely affected the efficiency of the speaker system, which I wanted to avoid. In the end, I stuck with my original plan of keeping it simple.

Altec 414A

Fundamental frequencies below 45 Hz may look rolled off in the trace but the harmonic overtone series (hence, harmonics or harmonic overtones) of the frequencies below the roll off point reinforce the [weak] fundamental in making those lower frequencies audible in actual musical reproduction. The BBC LS3/5A is a good example of a small speaker that "reproduces" low frequencies via harmonic overtones. 

My straightforward explanation: A:27.5 Hz played on an upright piano will produce less intensity as a fundamental note compared to that from a nine-foot concert grand because the instrument is physically smaller and the length of string, shorter. However, that upright piano's A:27.5 Hz is still perceived as A:27.5 Hz by the human ear, albeit less visceral, because of the harmonic overtones produced. 

Due to the 414A's sharp roll off past 3 kHz, the upper frequencies need reinforcement. 

Altec 32C horn + 802D + 20275 diaphragm
XO below

For many years, I struggled to make the Altec 811 horn work in this context. I started crossing it at around 900Hz @ 6dB/octave slope. Then, I cloned the Altec N1600C crossover, which effectively raised the crossover point an octave higher with a sharper 12dB/octave slope. 

None of these crossovers could blend the 414A and the 811/802D coherently to mimic my favorite full-range driver, the 755A. The "shouty distortion" was always present even with a simple 2 uf paper in oil cap + variable L-pad.

Altec 32C + 802D

After several years of frustration to the point I almost gave up, a fortuitous meeting with the Altec 32C horn opened a whole new world for the better.😄 It turned out that the objectionable "shout" I was hearing emanated from the Altec 811 horn.

The Altec 32C horn + 802D driver combo fill in the last 2 octaves of fundamentals + another 2 octaves of harmonic overtones using the high-pass crossover below. 

Sound Practices

I've learned so much from getting to know the Altec 755A, 755C, 414A, 802D and 32C intimately as well as from the other components that I ultimately rejected. 

The countless hours I spent assessing and listening to these transducers individually is a sound practice I highly recommend to audio DIYers!

Simple Crossover

Ever since I discovered the sonic delights of paper in oil as coupling capacitors in the signal path of preamp and amp circuits, I've also adapted their use in crossovers. 

Altec 753C crossover using paper in oil capacitors + Mills
non-inductive resistors
schematic

I've found the RTA to be helpful in adjusting crossover points with the help of a crossover calculator. A simple example: if the sound is harsh, move the crossover point higher. If you need more bite or presence, go lower.

Altec 414A + 32C horn + 802D compression driver  +
JP 753C ported cabinet = Altec 753C

If I were to summarize, the Altec 753C sounds lush and romantic!

Altec 753C 

Driven by 3500 milliwatts per channel of SE-DHT power, these speakers allow me to enjoy Mahler symphonies in my man cave with nuanced macro and micro dynamic contrasts. It gives a middle of the hall presentation which is my preferred perspective. The midrange is warm and coherent with a nice three dimensional quality.

Even if the extreme lows are curtailed, the harmonic overtones produced in this frequency region have enough foundation for big orchestral works. There's a wispy ribbon-like airiness in the extreme top which, to my ears, no longer need help from my pair of Altec 3000H super tweeters.

I probably could've gotten another half octave of bass extension if I chose the 15" Altec 416A woofer, but then I would've run into problems blending it with the 32C/802D horn/driver using a simple crossover. Even if I succeeded in EQ'ing out the peaks of the 416A, efficiency and midrange coherence would've suffered.

Everything is a compromise and I believe I've chosen wisely.

Wanted: smooth sounding 12"-15" wide range driver + horn + compression driver

Although Great Plains Audio is still manufacturing the 414 and 802 drivers with alnico magnets, IMHO, the listed prices are too steep to even attract the attention of the DIY community or smaller boutique manufacturers. 

I've used and highly recommend their replacement aluminum diaphragms for 1" format compression drivers. I've been told that the GPA 414 doesn't sound like the classic 414A/Z/8B/16B and is 3dB less efficient. However, I don't have hands-on experience with the GPA drivers to confirm any of those claims.

GPA is our only direct connection to the past when transducers were designed using human ears aided by measurement tools. For that alone, I want them to succeed!

Radiotron, 3rd Edition Redux

Let's (re)visit a topic that has served the interest of the entire audio industry, except the bottom-line of this hobby - the enjoyment of music!

Sad to say, no one has heeded D. Massa's advice. 

Besides, the test tones used for distortion analysis have no bearing whatsoever to the highly dynamic and complex harmonies contained in the simplest musical score.

Yup, this was 80 some years ago and there still are self-proclaimed audio pontiffs who insist on this metric!🙄