Film-Tech Forum ARCHIVE: RCA Soundheads Mfg. Dates

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Posted by Pete Lawrence (Member # 130) on 07-24-2003, 12:10 PM:

Does anyone have a listing of the beginning and end dates during which RCA manufactured the MI-1040 types and MI-9030 types of sound heads?

And while we're at it, also the dates when NSS owned the store and produced Simplex PR1014 projectors. The Simplex history in the manuals section is a little light here.

Posted by Aaron Sisemore (Member # 145) on 07-24-2003, 01:58 PM:

NSS had owned Simplex for quite a while, I believe since the late 60's or so. Ballantyne bought Simplex from NSS in 1983.

-Aaron

Posted by Ken Layton (Member # 133) on 07-24-2003, 06:43 PM:

I think the RCA 1040 was made in 1936, the 1050 in 1938, the 9030 in 1940.

Posted by Paul G. Thompson (Member # 655) on 07-24-2003, 06:49 PM:

For what it is worth, I think the RCA soundheads were manufactured in Indiana.

Posted by Bob Koch (Member # 1062) on 07-24-2003, 07:54 PM:

Ken Layton is correct on his dates

Posted by Dan Lyons (Member # 1454) on 07-25-2003, 01:40 AM:

I run RCA 1040s at work; I knew they were old, but not that old!! [Eek!]

They work great too, original to the theatre. However I'm not crazy about that "dirt embedder" roller.

Danny

Posted by John Pytlak (Member # 331) on 07-25-2003, 06:07 AM:

Do keep that "dirt embedder" roller clean. A wipedown with a clean cloth slightly dampened with isopropyl alcohol between shows should help.

Posted by Jeff Stricker (Member # 224) on 07-25-2003, 06:46 AM:

Paul, that's the story I heard, too. RCA soundheads were built at the big RCA complex in Indianapolis. There's nothing hardly left there anymore with most of RCA's TV production farmed out to Mexico and the Far East. [Frown]

Posted by Pete Lawrence (Member # 130) on 07-25-2003, 08:55 AM:

Ken's dates sound about right to me, too. I'm really looking for the range of dates when those particular models and others were manufactured.

There is an RCA installation instruction book for the MI-9030 & 9031 in the manuals section dated March 1942. That means they were still being made then. Any idea when production stopped on the 9030?

I know that with the 9050 they added an idler gear to take the projector drive from the lower shaft instead of the upper. That was a major change. I also find references to an MI-9070. Anyone know what was different on that model?

Thanks to all for the info so far.

Posted by Bob Koch (Member # 1062) on 07-25-2003, 07:00 PM:

I remember an MI 9050 installed as a unit of the Photophone Group PG 140 in the Esquire Theatre in Sacramento in 1940.{This is now the Esquire IMAX where Adam Martin is} To my knowledge MI 9030`s were manufactured into the late 1950`s; the last ones called MI 9030B1, the difference between it and previous models was it had a 2 piece optical that you focused with a special wrench. We were still using frequency film in those days and I never saw any improvement.MI 9070 I never heard of and I`m old.

Posted by Tim Reed (Member # 137) on 07-25-2003, 07:50 PM:

Didn't the Ballantyne history book say their foundry made the castings for RCA reproducers?

MI-9070 may have been an accessory, part, tool, or something similar? Just a guess.

Posted by Pete Lawrence (Member # 130) on 07-25-2003, 09:17 PM:

The MI-9070 reference is from Strong's current parts book for the Simplex 35. The Strong G-2068 drive kit (on parts book page 2-1) fits "RCA Soundheads MI-1040 to MI-1077, MI-9030 to MI-9070".

I've never seen any other reference to a MI-1077.

Posted by Dick Prather (Member # 1136) on 07-26-2003, 12:32 AM:

My information shows MI-9030 & MI-9050 coming out in 1938. I can't find my earlier MI-1040 stuff yet. For some reason 1935 comes to mind. I found manuals to 1938 for all. I did find the PS-24 (MI-1020) introduced in 1931 and probably installations in 1932. This was the first rotery stabilizer soundhead. Not much on how long the runs were or dates per serial number. Don't forget the MI-9001 for export. A single sprocket and snuber roller without a gearbox. I have one of those. How modern.

MI-1040's came out with a felt roller from the factory. If it is dirty clean it or probably replace it. It's probably warn down a lot. They made metal, soft rubber like 4 washers, and now the solid rubber from Wolk. Should be the same as the MI-9030.

All the RCA soundheads from MI-1040 on use the same drive gears. MI-1060, MI-1070 & MI-9060, MI-9070 are "Push Pull" sound heads. That was a double track used by studios and some release prints before magnetic sound came out. It looked like two mono optical tracks except one was 180 degrees out of phase with the other. The soundhead had a twin cathode PEC and a lens splitter to seperate the tracks to each half of the PEC. There was a switch inside the soundhead to change from standard and Push Pull tracks. They also work great for Dolby seperation with almost no crosstalk. Most soundhead manufactures had Push Pull versions or adaptor kits to install in a regular soundhead.

The differance between a MI-9030 & MI-9050 was the addition of outboard gears so the projector was driven by the HBS shaft which was always in oil and to reduce vibrations caused by the projector. Other soundheads drive form the CSS shaft. The gear on the CSS shaft gets oil transfered from the lower gear while running and has more vibration from the projector. Other then being more of a pain to rebuild I never could hear any differance between them. Most MI-9050's had the new two piece optics.

These were very good soundheads every bit as good as others. They just fell from grace. A licensed soundhead to the MI-9030 is still being made in India. I ran lots of MI-1040's and have a set running in my basement.

Posted by Tim Reed (Member # 137) on 07-26-2003, 01:51 AM:

Leave it to Dick Prather to have the answers! A wealth of knowledge and expertise, thanks for clearing that up... I didn't know the push-pulls were special models.

Posted by Robert Throop (Member # 61) on 07-27-2003, 12:19 PM:

The RCA PS-24 soundhead Had the worm gear machined into the motor shaft.In the 1040 the worm was in the gearbox and driven through a coupling. I have seen 1040's with a PS-24 nameplate so it may have been an "improved" PS-24 when it was first introduced.
I didn't realize the PS-24 was out as early as 1931. I know that Radio City Music Hall had PS-24's when it opened In December 1932.

Posted by Will Kutler (Member # 770) on 07-27-2003, 01:12 PM:

Robert Throop is correct with regards to RCA 1040s having PS-24 stamped on the data plate. I have two units like this. The PS-24 is an older unit than the 1040.

I did not know that Wolk has a solid rubber roller...learn something new every day. This would difinatly be an improvement over the stacked rubber washer type, as there would be less chance of something nasty, hard to remove build-up between the washers.

John Pytlak recommended cleaning the rubber pad roller with alcohol. Now, I regularly use alcohol to clean traps, gates, sound drums and nylon platter rollers/digital soundhead rollers and have not had problems with cracking and the like. But I would wonder about the rubber sound drum pad rollers. Remember that alcohol will dry out rubber, causing it to crack, deteriate and possibly leave damaging debris on the film. I wonder if FG and lense tissue (or other lint free cloth) might work better?

For further info, there have been several other discussiion threads about servicing and rebuilding these soundheads.