Stereo Speaker Systems #1

Visonik David 80
Visonik David 80
Visonik David 80
Visonik David 80

Visonik David 80​ (Berlin, 1980) $285/pr (very rare)

Legendary German speakers, the Visonik David series came right before ADS, Braun and Canton and they all used unique and proprietary drivers & crossovers.

Made by Heco Hennel & Co. KG, the West German company that inspired Miller & Kreisel to include some of the smaller David speakers in the design of their famous "David & Goliath" ("Volkswoofer") system, the Visonik David 80 speakers are absolutely as rare as hen's teeth!  

The 3-way Heco drivers are German made and later "copied" by Braun, ADS & Canton (although each company earned their own merits with tweaks and slightly different design characteristics.)

All the drivers run directly through the crossovers which are hand-wired directly without binding posts as per the factory design.  

The main drivers are 6.5" with rubber surrounds, mids are 1.5" and tweeters are 3/4". 
The stone mineral brown exterior of the cabinets cover the high density, composite, sealed enclosures that are a weighty 25 lbs each...with radius corners and perforated metal grills.  

Designed as 4/ 8 ohm impedance with nominal load capabilities of 80 watts @ 4 ohms / 110 watts @ 8 ohms and recommended for use with 35-80 watt amp power, the frequency response (as noted on the model plate) is 28-25000Hz.  

By themselves, they are incredible...add a high-quailty sub and you've got the perfect high end sound everyone's always looking for.
As mentioned before, Visonik David speakers are a definite rarity in America and the brand is NOT related to another company using the same name that makes car speakers.

Visonik David 60/2

Visonik David 60/2 monitors (Germany, 1990) $190/pr

These outstanding Visonik David 60/2 speakers were part of the well respected lineup bearing the Visonik label.  

Produced in West Germany by Dahl Elektronik (Hamburg) for Visonik, they are surprisingly heavy considering their small size.  

Besides their obvious fantastic smooth sonic quality, the second biggest reason to consider these Visoniks is because they are beautiful...they are made of solid teak with radius edges and near perfect perforated metal grills.  

They are rated at 4 ohms for a maximum of 80 watts with a frequency range of 38-25000 Hz. 

The enclosures contain 4" German-made woofers with rubber surrounds (designed for quality rather than quantity) and peerless tweeters, all made with crystal clear depth and sound in mind.  

Best described as excellent studio quality miniature monitors (9" H x 6" W x 6" D), the built-in protection circuit will light up red LEDs on the front (behind the grills) if you are getting into the clipping range.

About Visonik David...

In 1975, the small speaker lineup named "DAVID" from VISONIK created a true sensation. The miniature David 50, slightly larger David 60 and TOTL bookshelf size David 80 all achieved the quality requirements to fulfill the German industry standard for HiFi loudspeakers - the DIN 45 500. This was ground-breaking since only big loudspeakers accomplished the standard.

The nature of the DAVID sound caused experts and studio recording professionals to change their opinion. This was the start of VISONIK's triumphant ascent around the world - yielding one award after the other.

A strong focus on research and development assured the remarkable position of VISONIK. Worldwide, from ZDF in Germany, recording studios in the USA to the BBC in Great Britain, professionals placed their faith in the VISONIK DAVID as a small monitor speaker.

The David series from Visonik is a true and exceptional original.  Designed as a sophisticated and high quality miniature loudspeakers they quickly evolved into semi-professional miniature monitors used in studios around the world due to its unique and superior sound quality. 

Whether it be the BBC, ZDF in Germany or JazzRadio Berlin - wherever a high-quality miniature monitor is needed the Visonik David is being used. 

In fact, the small David 50 was the first German loudspeaker to receive the prestigious Japanese Export Product Prize in 1977 during the 6th Japanese Audio Grand Prix for innovative technologies.

In the production of miniature loudspeakers, cabinet design has a decisive major impact on sound quality and accuracy. Often easy-to-bend plastics are used in cabinet construction. Not so at VISONIK. The Davids are robust and neutral in sound due to its stiff aluminum cabinets.
The unique efficiency (SPL) of the David also makes it possible to reach impressive levels in volume with less amplifying power. Built on 25 years of experience in the fields of miniature loudspeakers and subwoofers, the David series are truly special.  Professionals from all over the world have put faith in David miniature monitors.


Concept CE-1

Concept CE-1 (1978) not for sale at this time

Described by Concept as "constant energy speakers", the CE-1 system features *Heil Air Motion Transformers which produces sound in a totally unusual manner. The actual radiating diaphragm is a pleated sheet of very thin, near weightless plastic film. It's complicated and would require several paragraphs to fully explain the way these work...
The die cast frame 10" powerful main drivers have double surrounds that have been recently refoamed and the brand new 12" mass loaded, passive bass radiators are perfectly tuned and help to yield some extraordinary bass response.
Of course, the Heil transformers are excellent as well. The CE-1 crossovers utilize 18 dB/octave slope for the Heil transformers and they use two separate EQ controls along with two LED power monitors to adjust sound levels to the amp/receiver output capacity.
The veneer is the highest furniture grade walnut covering most of the large, heavy cabinets (85 lbs each) and the grills have three separate pieces per cabinet.
These enclosures have angled baffle boards to minimize unwanted resonance and the drivers are located for constant energy distribution. Essentially, the CE-1 cabinet has large openings for the rear, side and top radiation to enable peak performance of the Heil drivers.


Note: Because of their very wide dispersion, corner placement is not recommended

6 ohms

Type: 2 way, 3 driver loudspeaker system

Frequency Response: 30Hz to 23kHz

Power Handling: 280W

Recommended Amplifier: 20W (minimum)

Crossover Frequency: 1500Hz

Sensitivity: 91dB

Bass Radiator: 1 x 12"

Bass: 1 x 10"

Tweeter: 1 x bipolar Heil air motion

Finish: oiled walnut veneer

Dimensions: 40" x 15.6" x 15"

Weight: 85 lbs each

Year: 1978

About Concept and the ESS Heil Air Motion Transformer...

Through a contractual agreement between Concept and *ESS, it was agreed that Concept could use this system in the design of their higher-end speakers.  The AMT was originally designed by **Dr Oskar Heil in 1974.

The Heil diaphragm, made of soft, quiet mylar to reduce background noice, is bonded with conductive aluminum strips. It is the equivalent in surface area to a conventional cone type eight inch band for better point source dispersion. The low mass diaphragm is suspended in a massive magnet structure concentrating an intense magnetic field around the diaphragm.

During the mid 70's, the Heil Air Motion Transformer (AMT) was recognized by the audio industry as the most significant loudspeaker breakthrough of the previous last half-century and was licensed exclusively to ESS.

*ESS of California has used the slogan “Sound as Clear as Light” for at least 40 years, and it still holds up in 2018.  ESS has based their designs on Oscar Heil’s Air Motion Transformer since their beginnings.

**Dr. Oskar Heil contributed to the invention of the Magnetron tube back in 1947 (the old days of radar) and to pioneering work with Field Effect Transistors (FET's) that many audiophiles believe sound more like valves than bipolar silicon. Then, like so many of that time, turned his attention to audio. In 1974, he was awarded a patent for developing the Air Motion Transformer (AMT) tweeter, so called because the folded diaphragm has the effect of multiplying the surface area 5:1, much like the windings of a 5:1 transformer or a 5:1 horn. 

About Concept...

We worked at Pacific Stereo in the late 60's when they only had three stores (San Francisco, Berkeley and Walnut Creek CA). It was a heady time for the HiFi business as the tube gear was evolving into solid state. It wasn't until much later that the Concept lineup was offered as their top tier house brands. (in order, top to bottom: Concept, Reference by Quadraflex, Quadraflex and TransAudio) 

The top of the line receiver was the 16.5 (165 watts per channel, considered by many to be one of the best stereo receivers ever made). 

Basically, when a customer went into a Pacific Stereo store looking for a Pioneer or Sansui receiver the salesman would steer them toward one of the "house" brands, the best of which were the Concepts. Normally you might think that the house brand would be some cheaply made unit designed for maximum profit to the retailer. But, in this case, the Concepts (and secondarily, the Reference series) were very well built and high performing receivers and especially the Concept speaker systems. 

Research has indicated that some of the electronic Concept lineup was made in Japan by Tandy Corporation (parent company for Radio Shack/Realistic) to very exacting specs by Richard Schram of Pacific Stereo (now the CEO of Parasound). Of course they used other top notch Japanese designers and engineers that they had formed relationships with over many years.



Harman Kardon HK-50
Harman Kardon HK-50
Harman Kardon HK-50
Harman Kardon HK-50

Harman Kardon HK-50 (1969)  $165/pr

The HK-50 is a very cool omnidirectional speaker system released in 1969 by Harman Kardon.  Typically, as are most omnidirectionl speakers, these actually cover a spectrum of about 270 degrees as opposed to a true 360 degree platform. 

Each real walnut cabinet measures 11-3/4” x 11-3/4” x 18-1/4” in height and weighs about 23 pounds. These little gems radiate all reflected sound and are very efficient.

The 8” woofers and 2-1/2” cone tweeters face upwards into a specially contoured styrofoam cone shape. The sound radiates from all four sides. The tops are made of solid walnut with a circular faux marble set in the middle.
Inside each side of the walnut-frame grills there are four large openings of equal size. The actual frame material is made of multiple-layer plywood.
The speaker connection terminals are located in the corners of the bottoms of the cabinets.  System impedance is 8-ohms. An adjustable, fully operational brilliance control is for the tweeter level.
The HK-50 system sounds best when placed away from the wall or other reflecting surfaces. However, it is this very requirement that creates an advantage of very spacious sound.
The cabinets, components and grills are in remarkable condition considering they are now 50 years old! 

About Harman Kardon...

Harman Kardon's first audio products were more high style than high-tech, with easily removable faceplates available in a variety of designer colors as their principal selling point. But it wasn't long before Sidney Harman hired Stu Hegeman as HK's head designer and, the products they are most famous for the Awards Series and Citation line kits and factory assembled separates was born.

Their expertise included ventures into loudspeaker design with the now legendary HK-50 omindirectional speakers being a true vintage masterpiece.
In the late 70's the "new" handsome components were designed, built and tested with the understandings that went far beyond conventional ideas about distortion and the factors that make one component sound better than another.  HK considered the integrated series such as the HK-503 to be the most musically accurate components ever devised.  That's quite a statement!


MCS 8310 Linear Phase

MCS 8310 Linear Phase by Technics (1980) 

included with MCS stereo system bundle

"Linear Phase" was a clever way of saying the drivers are not straight up and down over each other in the enclosures.  They are set back or forward of the other drivers...the tweeters in the 8310 sit back about 2" deeper, on a separate "shelf" into the cabinet above the woofers.

Technically, this is supposed to give you an added "depth" to the sound dispersion of the various speakers.  Other models in this lineup like the 8320 were 3-way system with staggered drivers more radical then the 8310.  In any event, this was an attempt to give the MCS "Linear Phase" an edge in the very crowded and very competitive loudspeaker market.

The components in the 8310 are:

8" honeycomb disc woofers with 20 oz magnets
1-1/8" Honeycomb disc tweeters with 3.2 oz magnets
Thermally protected (circuit breakers on the rear)
Bass reflex ports on front
100 watt RMS rating
8 ohms
crossover: 1KHz-4KHz

They do a good job with very little power and the bottom end on these speakers seem very solid, no "boominess".  The highs are clean and clear.  The design is really cool, very good looking cabinets.

The walnut veneer cabinets and original grills are pristine.

About MCS (Modular Component Systems)...
MCS was the house brand for JC Penney back in the 70's and was often passed over by audiophiles simply because it was sold by Penney's.  However, in our opinion, whoever worked for JC Penney's electronics acquisition department at the time certainly had discerning taste which resulted in some very good products being offered. There is some debate over who actually manufactured the MCS series for JC Penney. Most seem to agree that it was either NEC while others mention Technics. 
Probably the different models in the MCS line were made by different Japanese manufacturers like Technics or NEC, all of whom designed great products for Penney's.  By the late 70's, it was near the end of the receiver power wars and despite the fact that most of the mid to high range MCS units had actually incorporated some of the latest technology at the time, digital was looming on the horizon and was about to change the face of HiFi.



Boston A-120

Boston Acoustics A-120 ('89-'91) $125

The Boston A-120 speakers were designed to deliver the excellent mids and highs that this series was acclaimed for.  Although the well-braced, oak veneer cabinets and grills are absolutely pristine, there was work inside that needed to be done...  

They were originally designed with 10" woofer-style passive radiators, 6" midrange drivers and 1" CFT3 tweeters and max power handling of 100 watts.
In an attempt to harness the bottom end to compliment the overall sound, Boston used a 10" passive radiator that looked exactly like a 10" woofer except without a voice coil...just the basket frame and 10" paper cone.  

Strange, like an identity crisis.  

Since the foam surrounds on the "radiator" were rotted away, rather than refoam, we completely redesigned the radiator section.  

These now have 10" tuned rubber discs mounted on the original baskets.  We also filled in the empty lower chamber of the cabinets with a fair amount of acoustic polyfill.  

The result is a well-balanced sound with a good solid "punch" to the bottom end without any trace of "boominess".

About Boston Acoustics...
In 1979, Boston Acoustics was founded as a company committed to creating products with superior high fidelity quality and design at a great value. ..Boston was a renowned leader in high-performance loudspeakers, tabletop products, and advanced car audio systems.  In 2005, Snell and Boston Acousticswere purchased by D&M Holdings which also owns Denon, Marantz, and McIntosh.