whaT is this old preamp/mixer /tape machine/projector amp. ?

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whaT is this old preamp/mixer /tape machine/projector amp. ?

Post by johnblue » Thu Oct 31, 2013 2:16 pm

I scored, I already know i love it, even though i havent ran audio through it....it plugs in, lights up and everything seems minty... but it has no name.

the rundown...

2 transformer mic inputs, 1 audio input, 1 narrator input . 1 master volume control. 1 projector input 1 projector output. 1 mixer output?

tube compliment, 1 6x4 3x 7025 2x 12au7

all the transformers were made by NyTronic, the input transformers are sweet =) 50-150-600 taps input - 75k ..... 30-20k +1db theres a third transformer i assume for the audio, or its an output 75k -600 ?

and from what i can gather, its from a company called viewlex. i am fairly certain its a military piece. viewlex made all types of old projectors, and had patents on sound and film combo's very early on...

i am trying to figure out the best way to utilize this gear, should i isolate the 4 outputs and add pots/attenuators?

it has bias and audio adjustors up top, and it has non locking buttons for them on front... what are the buttons for? they are next to the VU, so i assume they are for monitoring?

anyways, anyone have any info on this thing? maybe some breadcrumbs for a schematic?

maybe you have rebuilt something kinda like this?

and finally, what would you do with it?

preamp 1 by fiftiethshade, on Flickr

preamp 3 by fiftiethshade, on Flickr

preamp 5 by fiftiethshade, on Flickr

preamp 2 by fiftiethshade, on Flickr

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Post by Scodiddly » Thu Oct 31, 2013 5:29 pm

If it was mine, and I wanted to do something with it, I'd put some music on and spend probably several hours following wires and making my own schematic.

Looks very cool. Somehow the color of the chassis and the component labels make me think "DuKane".

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Post by johnblue » Thu Oct 31, 2013 5:47 pm

Yeah, I plugged it in... I used the mixer out, and I think its a main out... the narrator pot and channel 3 work in conjunction with that...

Channels one and two work as one would assume, and the master works as one would assume.

The audio and bias pots up top work well, i think the front bias buttons bypass them? I don't understand those aspects of circuitry, I am going to study that.

I am pretty pumped up.

Channel 2 sounds better than channel 1,

First things first, full recap.

Those big silver ones stacked up on the right are sangamo oil caps, they should be good right? Replace the disks?
I am John Blue.

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Post by bluesman » Fri Nov 01, 2013 6:48 am

I used to believe that paper in oil caps did not go bad. My Klipsch cornerhorns had these type caps & after 40 years, they were definately bad. As a result the speakers sounded harsh & spitty, very fatiguing to listen to. I did a re-cap of the crossovers & the cornerhorns are now singing sweetly. Your mixer looks like a product of the 1950's...I think I would replace them.
Very cool looking unit by the way.
"The digital future sucks the boils off my white ass." McHugh

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Post by Nick Sevilla » Fri Nov 01, 2013 12:13 pm

Does it have any brand markings anywhere?

It looks like an RCA PA system.
Howling at the neighbors. Hoping they have more mic cables.

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Post by johnblue » Fri Nov 01, 2013 9:53 pm

the only other identifier, other that, Viewlex, and NyTrontic, there is a CP Clare Co. relay in there

is the honeywell VU meter, model 55x, and its a gigantic VU. i read on another forum its a The meter is a relabeled Weston 802 .

what i want to do is isolate the preamp outputs onto 2 more pots, but still have it work as a mixer, also tap the input trafo's and make selectors for the impedance.

i think i have to remove the oscolation circuit in there, i see something like that, generally, how is it removed/bypassed?

as is i think i have 3 or 4 good preamps with a little work.

o.k. the question about the bias,

there is a pot up top, for bias and one for audio, both screw type, and move nice, and they both sound the same when adjusted, but the buttons for those on the front, are non locking, and they both "make it louder" so i assume, they bypass the biasing ? why would that be such a prominent option on the front of the board?

i could just hang out while recording and use it as a semi distortion button =)

i understand the bias pot, but why the audio pot? have you seen 2 seperate bias things labeled this way before? i guess one bias is for the mic preamp circuits and one is for that d.i. type circuit.

i also like that the tubes and bias pots are all right up front and just remove that grill easy and get at it =)
I am John Blue.

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Post by emrr » Sun Dec 01, 2013 10:48 pm

Part of a military issue film projector set, should also have a portable cased projector and portable cased speaker with it. These were made by a lot of different companies, mostly identical.
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