How many people on the planet have played with the 12a and 13a? I know quite a few of them….and so many forum dwellers out here are saying that the 12a and and 13a we’re designed so that the 12a did the highs and the we13a the low. This is a misconception stemming from a misunderstanding of frequency range of that era….these installations were not for THX or dolby nor for soundtracks from Diehard etc…..nope!
Extensive study of the history and available documentation enabled me to have learnt that the 12a and 13a were installed in large theatres as permanent installation and placed to enable the theatre to be used for live representations with orchestra etc..
These large theatres has orchestra level seats and balcony as we know.
The 12a was installed high up at the every top edge of the scene, the 13a in the pit. The 12a was for the balcony seats and the 13a for orchestra level seats. The signal sent to all the horns was the same. Sort of multi channel mono. The frequency response in 1926 was maybe 80hz to 5000hz?….the 12a goes down to 100hz easy as I have seen from Suzuki San’s (GIP laboratory) readings…and my ears! The 13a….ever easier!
If you study (I have) the installation schema for the 12a and 13a you will notice that the 13a had an autoformer to adjust the level. This was to balance the 12a no 13a levels in the theatre. No filters were used at all.
Once you hear the 13a you will realise that it needs no 12a at all.. we did a frequency check with generator and at 45hz it is unbelievably strong and full of “guts” and then goes upto 6000hz with ease (that is the top limit if the we555).
These solid wood babies play better than the plywood we15a or metal 16a (I have both…) as they are so solid and do not vibrate. This enables better control of the lower frequencies and dynamics are not reduced because of materials….
Been asked so many times now who made these horns…..yes it’s me with knowledge, skill, patience and most of all passion…..some have asked if I can make for them….depends…!