A quick look at the Altec Lansing A1 Cinema speaker.

Intro

The Altec Lansing 'Voice of the Theatre' (VOTT) range was released in 1947 in response to rapidly growing cinema attendance in the US, which peaked that year at an incredible 4.7 billion visits!

The highest grossing film at the time was 'Miracle on 34th Street', which you could see at your local cinema for 40c.

In this post we'll have a look at the first Altec Lansing brochure, and specifically dive into the A1 design.

Basic specs

The A1 was a beast, weighing in at a metric ton (1000kg) and 3.2m wide x 3m high x 1.2m deep.

It's basically a very large 2-way speaker, utilising 2 x 288C' 2.8" diameter compression drivers feeding a single '1505B' exponential multi-cell horn for the high frequencies (HF), and 6 x 16" diameter horn loaded '515' drivers for the low mid and bass. The crossover frequency was 500Hz, with the option of variable attenuation for the HF.

The A1 design borrowed heavily from the ground breaking 'Shearer Horn', which was developed in 1938 by Douglas Shearer for M-G-M. We'll cover this in more detail in a separate blog, but you will notice some similarities.

Both are very large 2-way designs, crossed at 500hz and utilise an exponential multicell horn. Additionally, both designs physically time align the HF and LF, which was a game changer in terms of improving audio quality.

The 515 bass driver used in the A1 looks not too dissimilar to a modern bass driver, featuring a permanent magnet, cast frame and wire voice coil wound around a cylindrical former, which is mounted to the rear of the paper diaphragm.

Permanent magnet speakers were only invented in 1930 by Jensen. Prior to this the industry used 'Field Coil' magnets (shown below), which fall into the 'electro-magnet' category i.e. you have to pass current through them to produce a magnetic field.

The magnets themselves were 'Alnico' back then, which was an aluminium alloy featuring nickel and cobalt. You can still buy Alnico magnet drivers these days but they are fairly few and expensive. One very nice example is the 8" Seas Exotic W8, which we may use in the future :)

Nowadays we tend to use the heavier but cheaper 'Ceramic' magnet or the more expensive but lighter 'Neodymium'.

The 288C, 2.8" compression driver used in the A1 also looks fairly similar to a modern compression driver. It too uses an Alnico magnet. Another feature is the aluminium diaphragm, which again is often used today to good effect. It is now eclipsed by titanium and beryllium in terms of pure performance, but they are more expensive options.

In modern cinema's with Dolby Atmos, you will notice a huge number of speakers to give you that immersive surround sound experience (up to 64 channels!), but back in the 40's, everything was 'mono', so you would only have one A1 speaker to cover the whole auditorium.

The sheet below states a single A1 speaker is adequate to cover a screen of up to 3,500 people.

The following sheet is a spec comparison of the models in the VOTT range.

Of note is that the 'A1X' model is identical to the A1 apart from the fact it uses a slightly larger multicell horn with four rather than two compression drivers feeding it.

You can also see the far smaller A5 speaker mentioned towards the bottom of the sheet, which we'll also cover in a subsequent post. This model has become an iconic hifi speaker, particularly in Japan.

The final sheet in the brochure lists the retail price and power ratings of the speakers. An A1 speaker would set you back $1,570 with installation supervision.

To put that price into comparison, the best selling US car in 1947 was the Chevrolet Fleetmaster, which would have cost $1,160.

The rated power of the A1 was a fairly slight by modern standards 100 watts. But then the A1 is hugely more efficient than most modern speaker designs, so the Sound Pressure Level (SPL) you would get for those 100 watts would be very high indeed!

Hopefully you enjoyed this piece and if you have any comments, questions or suggestions, we'd love to hear from you.

Please comment directly on the blog or email ceri@enton-green.com

Thanks for reading!

Ceri

Enton Green