Thursday, 9 March 2017

 First production Hadron comes together.

We have shown a bit of the cabinet detail already. Probably more than most components a loudspeaker is an entity which is greater than the sum of its parts. That said, the parts are still important. Here are some illustrations of what goes inside.

Individual parts are voiced for the crossover after initially measuring and tuning with more generic types. If there is a place for parts rolling it is here. These components operate in a highly dynamic physical and electrical envoinment. They must be robust. To reduce electrical resonance and microphonic interaction with the signal, vacuum impregnation, damping and well built components are used.

Damping material is 100% natural wool felt which is used to reduce reflections on the walls of the chamber. Nothing else is as distortion free and surprisingly the quality of wool is audible. 

Cable is simple and minimalistic. A common mistake with high efficiency speakers is to use more large speaker cables which employs much more dielectric than is needed with the penalty of high capacitance. This creates interaction with the signal in the phase or time domain - it absorbs and gives back various frequencies at various times and rates. The distortion this causes readily apparent with a high sensitivity speaker. 

Nickel core - Litz wire - from Dave Slagel

Looking in from the bottom the drivers are in place and the port can be seen. More bracing is added after assembly.

Binding posts, strutted ribs and dampening material - natural wool, quality wood with traditional bonding, acoustic architecture with varied rate curves and arches - designed for music from conception to execution - outside the box.

From the outside.

The 32 horn.

Driver/cabinet interface.

Wheels may seem shocking but greatly assist in finding proper placement in a room. Much like focusing a camera - it takes a little back and forth to find the right position in a given space. With wheels this can be done easily and quickly. Spikes can be added later if desired.

Production of the Hadron has begun and the first pair will be delivered next week. 

Thank you for looking in.

Sunday, 26 February 2017

Hadron moves forward

Hadron in production.

The Hadron loudspeaker has been in active development since September 2016. After testing and tuning we are now in production prototype phase synchronising theory with reality. This is the most work intensive phase which coordinates computer design, computer manufacturing and skilled assembly.

The design and construction methods are advanced being more like ship, aircraft or musical instrument building rather than standard carpentry. No nails or screws are used in bonding the elements which combine into a light and rigid structure. A man can jump up and down on them with no effect. The cabinet makers were impressed when this was demonstrated.

When I worked for a helicopter manufacture production prototyping was the most critical stage where proving processes included stressing parts past failure and developing operating envelopes with experimental testing. The joke was that we were crash rated. Fortunately testing loudspeakers is less stress prone. It has been rewarding to see the production cabinets improving on the test mule performance.

Not only have new design elements been implemented from what was learned with the test mules but the construction is now more comprehensive and relies less on the stressed element load path - the rigidity of the metal framed driver.

This is still incorporated but now augmented with a greater number of load paths to the cabinet from the driver. The moving element is held rigidly by a light and strong frame with great stability along the axis of motion.

It is worth mentioning the "Onken" for a moment here. It was developed for the same drivers which we are now using - the Altec Alnico 414 and 515. Future posts will feature details of these.

These Onken tunings were developed for solid state amplifiers where cabinet and port tuning includes the Rg - resistance of the total components: crossover, coils, terminals, wire, amplifier etc... . This is a large factor in the calculations and in the tuning of listening and adjusting. The L'Audiophile articles indicate clearly that while the triodes were often the amplifier type on the rest of the system the bass cabinet was driven with solid state.


The Hadron speaker was conceived by the desire to have full range deployment of SET triode power - as little as two watts of it. Dampening factor is significantly different for solid state and tubes (valves) especially SET - single ended triode amplifiers. It has been common practice to use solid state in bass amplification in mostly triode systems and thus much of the nuance (micro linearity) which a triode can provide is lost.

Most importantly, when this cabinet is tuned for solid state it is not tuned for triodes and so the traditional Onken tuning is not optimal with triodes. The best multi amp systems use identical amplifiers throughout and for us that means triodes top and bottom. Our speakers work easily with low powered triodes and not only can fill a room with bass but with with all the nuance and depth triodes provide. I am often amused when asked where the bass amplifier is when there isn't one. So few speakers are tuned for triodes that people are not used to them providing the kind of bass they are actually capable of. The Hadrons can easily run on low powered triodes and be bi-wired or bi-amped. They are better than 96db efficient and provide and easy and stable load to the amplifier.

Following posts will show installation of drivers and crossover components. 

First public showing will be Munich High End in May of 2017.

Sunday, 15 January 2017

Horn Loudspeaker Exporations

Horn augmentation of sound is a natural occurrence. Ears and vocal chords use them for the perception and creation of auditory elements. This is but the first of what could be a long list of horns found in nature. It is not much of a stretch then to assume the use of horns is helpful in the reproduction of music. In the public address and large venue application they have been used with great success from the begginig of sound reproduction until today. In the home or small venue it has also been used but with less success. This is because what was developed for the large venue was also used in the small. Many horns and related technologies were designed to disperse limited amplifier energy into large volumes of space to accommodate crowds of persons. They employed techniques to provide limited bandwidth to large volumes and to punch dialogue through heavy cinema screens. If you moved from the balcony of a theatre or concert to just in front of a loudspeaker you might expect it to be overpowering. As obvious as this might be this is exactly what has led to the audiophile perception of what horns sound like - harsh and generally without refinement. The majority of horns and drivers available have been developed for PA use.

Some horn devices have been developed for home or small venue application but have been lost or misunderstood as time passed and public awareness went toward less sensitive devices. The Voit/Lowther is one of these. Originally it was a horn driver - not for direct radiation and coupled with a rear horn as it is often used as today. It is no wonder that it developed a reputation as "shouty". Altec theatre horns suffer much the same misapplication in the home. They were designed for large venues. Western Electric collectors fair better as the tricks to get different dispersions were not yet employed on these earlier designed horns. Where does this leave the common person who desires fine music in the home? It seems it leaves them without the most natural of all sound augmentation devices - the horn and so higher distortion devices have traditionally been employed. Paul Klipsch declared that lack of sensitivity equals distortion - it is an axiom which is unavoidable.

This oversight can remedied although there are always concessions. Size and frequency are inevitably related. Researching the quest of horn systems which were designed for small venues revealed often repeated errors, innovations and rediscoveries of lost technologies. Predictably, knowledge was lost as other speaker technology displaced horns. As home application was never the main body of commercial knowledge - these two elements marginalised the development of home horn systems. One of the great exceptions and greatly overlooked horns is the Western Electric 32 horn which was patented in 1935. Not only are the Western Electric 753, which uses this horn, one of the most costly and rare of collectable speakers but musicians and recording engineers used the same horn for near field monitors until it went out of production in 1984 making it perhaps the horn in longest production - ever. This then was a natural starting point when seeking a small horn for average sized listening rooms. The more that came to light about this unusual and well developed horn the more interesting things became and this is primarily because it sounds particularly good.

D.G. Blattner of Bell Laboratories was granted US Patent #1,996,743 for this type horn in 1935. It first became known as the Western Electric 32A and later, when WE was broken up by anti trust legislation, it was licensed to Altec which changed it slightly into the 32B/C, casting it in plastic, shortening it, and adding external braces to make it more rugged for stage touring and roadie handling. Listening comparisons between the two reveal a similar character with the earlier model being dryer and the later being a bit richer. The earlier version was originally used with a phenolic diaphragm known for less extension but more natural vocal range. The plastic horn appears to be an adjustment for the later AL diaphragm which has greater high frequency extension but less rich vocal range. In any case there is no question this little horn has a remarkably natural presentation in the near field and is a pleasure to have in the home. It brings many of the virtues of the horn - nuance and dynamics -  without the harshness and distortions many horns have.

Ladies and Gentlemen  - the 32 horn:

One the more unique horns in Altec's inventory and one of the longest in production. The design originated with Western Electric and was available to Altec as part of the 1938 consent decree that established the firm. 

Western Electric used it with 713 driver in the the 753 Loudspeaker.

Altec used it in systems with the 802 and other 800 series compression drivers. 

The most famous such system was the A8 Voice of the Theatre speaker which was widely used in movie theatres. 


It was also used in 9849 studio monitor

The late 70's saw its incorporation in the Model 15 home speaker system. 

A variety of Pro Audio stage monitors used the horn such as the Pro R&R Stage Monitor N482 which had a cult following among stage musicians.

We have incorporated this horn into the Hadron Loudspeaker for the home because of its natural sound field and refined response.

Azzolina Audio Hadron Loudspeaker

Happy Listening

Sunday, 20 November 2016

European Triode Festival 2016

Wave 1

This was my first year at the ETF and so, as is inevitable to initiation in any tribe, wore a name tag with an imaginary "newby" highlighted over the actual name. This is as it should be and it was mesmerising to see the differences in this event to any other show or meet - it is unique. The wide variety of approaches, real time building and modifications and non-commercial sharing of information was WAY too much fun. It could not all be taken in, too much going by too fast so the best thing to do was just ride the wave you happen to have caught at the moment. In the spirit of that here is a first batch of pictures.

 Super Sexy and Rare RCA speaker. Check out the (tweeter?) petals.

Vintage city.

Reel to Reel madness - Telefunken no less.

What is it? 

A microphone umbrella! To give the mics a shadow from the room bounce.
Made from unwashed, lanolin laden fresh wool.

All preparations for the shootout which was the taping and playback of a live musical event.

More on this later...

Modified (recreated?) compression driver.

Norwegian Wallflower of Sound.

Made especially for the event.

Amazingly life like and rich. From Joni Mitchell to Deep Purple. 
Hats off gentlemen!

More to follow... on the next wave.

- Photos curtesy of Camila Barcha, Copyright© all rights reserved.