Thursday, 14 December 2017

Western Electric TA-7331-A Baffle

Western Electric - what to say and where to begin?

My guitar teacher played violin and piano in silent movie theatres before the talkies came. Their arrival put him out of work and so he moved to the bandstand. They had live music in theatres before sound reproduction - that gives a pause. It is inevitable to inspect what the founders have done. The Far East had a head start as US Occupation forces left a trove (a store of valuable or delightful things) of Western Electric equipment abandoned in a wide variety of venues: theatres, schools, auditoriums etc..

It should be no surprise that the wealth generated by Sound in Cinema attracted performance driven research and development. The emotional response of the crowds directly related to attendance and to money. Not only was performance achieved - knowledge of it was carefully controlled - even destroyed. Ninety four years later there is still a shroud of mystery keeping all but a lucky and dedicated few at bay. It is called the sport of kings for a reason. Collectors have not only preserved artefacts which would have been lost, they have also driven prices beyond scope. It is doubtful that this will change.

There is a plethora of public information and if one lets go the objects of fetish (a form of desire in which gratification is linked in an abnormal degree to a particular object - or - an inanimate object worshipped for its supposed magical powers or because it is considered to be inhabited by a spirit.) then it is still possible to experience some of this excellence in civilised terms with a little care and diligence. 

We started with exploring the Western Electric 32A and KS12024 horns. After having them X-rayed, scanned and relief penetrated with silicone and latex we came to know them better than the collectors - or at least better than what the collectors were sharing. After successfully reproducing them and avoiding some of the common mistakes it was clear these horns we not only as good as modern equivalents but that they were easily more natural sounding. The explanation of which is for another thread. Now is the time to explore what to match them with. We begin with the TA-7331-A Baffle which was chosen because it can fit into a reasonable sized listening room. 

The original documentation is comprehensive and dense.

After sourcing the indicated quality coniferous plywood, and support lumber, construction began.

I was not going to trust a shop to do this one.

The pinewood was a pleasure to work with.

Despite the desire to improve materials and fasten with biscuits the construction method of the documentation was strictly adhered to.

This was to create a baseline for any future refinements to be compared.

I was sceptical of this design as it breaks with some of my expected notions. After assembly and before any finishing it was impossible not to have a quick listen. There were thoughts of the fire pit outside to which the several cabinets have been disposed of after testing, Onken and Ultraflex to name a few. Nothing like a glass of wine and a fire to celebrate the difference between a myth and a legend. It is amazing how large a cabinet this little pit can support while it burns and the Limousine rains clean up most of the mess... if the weather is inclement it can all be watched through six panels of glass door. Chin, chin.

The nearest items at hand were combined for a quick read on if this thing had potential - a 12024 horn/TAD driver, a crossover borrowed from the 515 cabinet,

and an Altec 414. 

Quick and dirty.

My suspicions were confirmed with a decent sound but with boomy and boxy congestion. After two alignment adjustments though we were pleasantly surprised. The elements came into place with speed and focus. It was good enough to be disconcerting - puzzling. Measurements will now follow for proper crossover development and the acoustic design will be studied more carefully. It has been noticed that every image of this baffle that could be found on the internet uses 15" or 18" driver while the documentation clearly indicates a smaller driver - the Western Electric TA-4171 of which there is scant information other than it was a 12-13". However the designated aperture is clearly 11 1/2" and thus an appropriate sized driver was implemented. The 414 12" demonstrates that the documentation might be onto something. There is a line of drivers that will be tried including 12" and 15" field coil units but this is certainly a "return to point" for measurements and listening satisfaction. The emotional connection and life like presentation are quite good.

One of the disconcerting elements is how well these two loudspeaker elements combine - quite seemless.  I look forward to what a crossover tailored for them will do.

Finishing, measuring and driver shoot outs to follow.

Until then...


  1. Hi Chuck,

    great work and interesting new project! i am looking forward to listen to these!

    best regards


    1. Hi Thomas, thank you.

      I hope then we can talk about field coil supplies!



    2. Hi,
      Nice work. Congratulations and thanks for sharing.

      Can you tell what r those "two allignment adjustments" which you done?
      Thanks n regards,
      From Mumbai, India