Tube pre or channel insert from old film projector?

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Red Favorite
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Tube pre or channel insert from old film projector?

Post by Red Favorite » Sun Nov 26, 2006 1:21 pm

Hey folks,

A couple of years back, my dad gave me this for xmas:

http://www.flickr.com/photo_zoom.gne?id ... 092&size=o
http://www.flickr.com/photo_zoom.gne?id ... 094&size=o
http://www.flickr.com/photo_zoom.gne?id ... 097&size=o


...it's a microphone input from an old film projector he rescued from the trash. He took out the preamp guts and made a new housing for it. That's the old speaker on top. I haven't used it for recording yet, because the outputs are a strange size, a little bit smaller than a 1/4" plug. It's also an unbalanced input, which I'm not too keen on. So, here's some questions I have:

1. There's a bit of low end hum, any way to get rid of it (besides notching it out with EQ)? Would it have anything to do with the transformer? The tubes were tested before he gave it to me, everything was in working order.

2. I use a Kel HM-1 condenser for recording, is there an easy way to set this up to provide phantom power? I'm guessing not...in that case:

3. Do you think it could be used as a channel insert to route tracks through? I would have to convert the 1/4" mic input to a line level input. This seems like it would be easy enough, but Google searches turn up a lot of unrelated info. This way I could use the mixer pres to power the mic & send the signal through the tubes & out to the computer or 4 track. Right?

I'm not worried about pristine audio quality, I kind of like things that sound old or worn...plus, something about the history behind it intrigues me (the projector was used for years in the mental hospital where my father works), so if I could get it in working order, that would be great.

Schematics, links, advice, anything is appreciated.

Thanks!
Jeremy

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Post by helmuth » Sun Nov 26, 2006 2:30 pm

Needs a recap?

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Post by biasvoltage » Mon Nov 27, 2006 12:51 am

a $15 female-XLR to male-1/4" transformer (which is really just a DI in reverse) from Rat Shack, and if you're really ambitious, a Rolls Phantom Power supply (about $40) will get the signal from your condenser into that 1/4" input.

When you get it working you need to record a cover version of Jonathan Richman's "hospital" using this as the vocal preamp.

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Post by brianroth » Mon Nov 27, 2006 1:30 am

Wow! A "Bell and Howell" (sp?) Film-O-Sound.

I admit to being an "AV dweeb" when I was young. Thread up the 16mm films, which was kinda cool when in elementary school, but was BAD when in Jr. High. "AV guy" was a horrible thing in Jr. High..as in getting beaten up by the jocks.

That being said...(Jr. High seriously sucked...and nowadays those guys go balliistic ...)


Those old projectors used an odd-ball I/O connector. It LOOKED like a 1/4" but it wasn't.

Switchcraft used to sell that odd-ball connector.

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Post by Red Favorite » Mon Nov 27, 2006 4:53 pm

SoftSupply wrote:a $15 female-XLR to male-1/4" transformer (which is really just a DI in reverse) from Rat Shack, and if you're really ambitious, a Rolls Phantom Power supply (about $40) will get the signal from your condenser into that 1/4" input.
Yeah, I've thought about that, but there's no way to get power to the mic unless I buy the Rolls, right? I probably don't want to sink that much $$ into it...

I did find this, which looks like what I was looking for for the channel insert idea:

http://www.epanorama.net/circuits/line_to_mic.html

I'm thinking this might be a better way to go...which leads me to another question: would there be a huge difference between the mic going through the mixer pres (which are fairly quiet & transparent), then into the FilmOSound (as an insert), as opposed to going straight into the FilmOSound preamp (presuming I had phantom power), and then out to the mixer? I mean, both ways would color the sound, right? Am I way off on this?

Thanks for the tip on the Switchcraft connector...I was thinking the most hassle free way would be to solder a 1/4" jack on the end of the cable connected to the speaker. Kind of half-assed, but hey. If I can track down the connector, I'll do it that way...

Thanks
Jeremy

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Post by ??????? » Thu Nov 30, 2006 12:50 pm

brianroth wrote:Wow! A "Bell and Howell" (sp?) Film-O-Sound.

I admit to being an "AV dweeb" when I was young. Thread up the 16mm films, which was kinda cool when in elementary school, but was BAD when in Jr. High. "AV guy" was a horrible thing in Jr. High..as in getting beaten up by the jocks.

That being said...(Jr. High seriously sucked...and nowadays those guys go balliistic ...)


Those old projectors used an odd-ball I/O connector. It LOOKED like a 1/4" but it wasn't.

Switchcraft used to sell that odd-ball connector.

Bri
They used ONE of those oddball-slightly-smaller-than-1/4" connectors on the minimoog too. Something to do with not wanting you to mistake it for an output or something.

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Post by trask » Fri Dec 01, 2006 11:02 am

brad347 wrote:
brianroth wrote:Wow! A "Bell and Howell" (sp?) Film-O-Sound.

I admit to being an "AV dweeb" when I was young. Thread up the 16mm films, which was kinda cool when in elementary school, but was BAD when in Jr. High. "AV guy" was a horrible thing in Jr. High..as in getting beaten up by the jocks.

That being said...(Jr. High seriously sucked...and nowadays those guys go balliistic ...)


Those old projectors used an odd-ball I/O connector. It LOOKED like a 1/4" but it wasn't.

Switchcraft used to sell that odd-ball connector.

Bri
They used ONE of those oddball-slightly-smaller-than-1/4" connectors on the minimoog too. Something to do with not wanting you to mistake it for an output or something.
Yeah, I'd say that should be the first mod.. take that crap out and put a REAL jack in it.. :D
off somewhere listening.

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