8mm Forum: 16mm sound quality

This is topic 16mm sound quality in forum 16mm Forum at 8mm Forum.

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Posted by Dave Groves (Member # 4685) on February 26, 2018, 06:55 AM:

I have an old Gaumont British Newsreel from the fifties and the sound is sharp and clear. Some of my newer prints tend to be less audible. Putting aside the actual prints, were some projectors acknowledged for reproducing sound better or worse than others. Was this to do with design and components used and did machines generally improve as newer models appeared?

Posted by Maurice Leakey (Member # 916) on February 26, 2018, 09:34 AM:

I have many makes and models of 16mm projectors and have never considered that any one was better than another with its sound output.
In the 50s I had a pre-war Bell & Howell 138 (American) and a wartime GebeScope L516. The sound on these used for professional shows never gave any trouble with sound quality.
It is imperative that the projectors are well maintained and that the sound optics are always kept carefully cleaned.
Regarding the latest models, to my ear, and many others, a valve amplifier gives a better reproduction than a transistorised amp. But here, I hasten to add, there's nothing wrong with transistorised amplifiers.

Posted by Robert Crewdson (Member # 3790) on February 26, 2018, 10:54 AM:

I wasn't satisfied with the sound on my B&H 601, it only has tone control, whereas the B&H 655 has bass and treble controls. One of the best sounding films for clarity that I heard was from the 1930s.

Posted by Maurice Leakey (Member # 916) on February 27, 2018, 05:28 AM:

Bell & Howell often made projectors with only one tone control. I have the last "Wooden Blimp" model which has bass and treble controls. It's the 8636BL, made in 1975, thirteen years after the "new" models, 641, 642, 643, & 644 were introduced.

It's called the Maritime as it's AC/DC model and was intended for use on ships which for many years only had a DC supply. It operates straight from the mains and has a mixture of valves and transistors in its amplifier. Also, no PEC alongside the valves, it uses the modern solar cell. The sound is excellent.

It's a single case with a small detachable speaker at the rear, this can be used in situ, or with its attached lead extended it can be placed near the screen.

The exciter lamp is the modern G29 (4v 0.75a). The projection lamp is the standard A1/53 @ 750 watts, but 240 volts. It says that it can use the A1/91 which is 1000 watts but I have never used a 1000 watt is these types of models, whilst it will give more light there is the point that the small lamp-house is now emitting one thousand watts of heat which may not be a good idea. Even the 750 watt lamp does get everything quite warm.

It's often used and I keep a record of the dates of the lubrication of its various oiling points.

Posted by David Guest (Member # 2791) on February 27, 2018, 07:27 AM:

the best projector for sound if its running as it should is the debrie d16 especially if there is a lot of music in the film valve amps were the best all the musicans like like to use a valve amp

Posted by Neil Massey (Member # 5081) on February 27, 2018, 11:47 AM:

It's an interesting question. I have ( as previously mentioned) a fully rebuilt Debrie D16 amp thanks to Bill Parsons and it sounds very good. I've noticed that it's particularly good on older films, specifically, from the 1930s through to the 1960s. I have a very good print of The Broadway Melody of 1936 and it sounds sharp, clear and very rich. By contrast, on my Elf NT2, it sounds edgy although the Elf also produces excellent sound but tends to do better with films produced in the last 35 years or so.

Films would have been in mono in the vintage era and balanced to ensure clarity of speech whereas with the rise of Dolby Stereo (and magnetic 4/6 track before it), the sound mix would have been different and would presumably have been rebalanced for the mono track, possibly losing something in the process.

The Elf does have a phototransistor rather than a photocell which may help its frequency response as the service manual quotes it as 50-7000 plus or minus 4db. I assume that the Debrie with its photocell would only manage to 6k which may have been the upper limit on old tracks.

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