what is this preamp/mixer/projector thing?

Discussion in 'Tube Audio' started by johnblue, Oct 31, 2013.

  1. johnblue

    johnblue Active Member

    Messages:
    267
    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?

    [​IMG]
    preamp 1 by fiftiethshade, on Flickr

    [​IMG]
    preamp 3 by fiftiethshade, on Flickr

    [​IMG]
    preamp 5 by fiftiethshade, on Flickr

    [​IMG]
    preamp 2 by fiftiethshade, on Flickr
     

     

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  2. battradio

    battradio Electron trainer

    Messages:
    5,211
    Location:
    Near ST. Louis MO
    Well it is most likely a pre amp for some type of tape machine and projector because it looks like it recording bias . It has a 1968 date code on one of the caps , so that would make made around that date , the 75k impedance would be the output . To use it for straight audio you will need to disable the bias oscillator .
     
  3. Trio

    Trio Super Member

    Messages:
    2,207
    Likely made for schools, or for small production houses that recorded voice tracks to the movie format. Super 8 had a magnetic stripe as I recall, and I think the 70mm format may have used it as well. 16mm was a light modulated sound reproduction.

    If it had been made for military, it would have a contract number and which branches used it.
     
  4. s-petersen

    s-petersen Scott Subscriber

    Messages:
    4,483
    Location:
    Middletown,New York
    In the meter,it says Honeywell,Model 55X? They made lots of AV gear
     
  5. johnblue

    johnblue Active Member

    Messages:
    267
    Thanks, Mic-preamps is what I got it for, and as its already doing the trick, via mixer-out phone jack :)

    Now if I can't find schematic, guess ill try to draw one :(

    Never done that before. :)
     
  6. johnblue

    johnblue Active Member

    Messages:
    267
    Yeah, the meter is honeywell 55x ... it is now the most gigantic VU in all of my gear.

    That is a good breadcrumb to follow! Thank you sir!
     

     

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  7. battradio

    battradio Electron trainer

    Messages:
    5,211
    Location:
    Near ST. Louis MO
    The meter is a relabeled Weston 802 , and one of the best VU meters every made .The Lighted Version was the standard of the industry for over 30 years .
     
  8. s-petersen

    s-petersen Scott Subscriber

    Messages:
    4,483
    Location:
    Middletown,New York
    I thought the preamp may have been made for/by Honeywell,as a possible way to find a schematic.it is not uncommon for two or more companies to put together a piece of equipment.
     
  9. Trio

    Trio Super Member

    Messages:
    2,207
    Honeywell at that point (1967) was making largely test equipment and HVAC gear. It is possible, but remote that they built the item. They may have assembled the meter and stamped their name to it under contract with the company who made the larger unit, which, if the builder of the larger unit made it under a government contract, it is likely Honeywell was the ordained subcontractor who modified the Weston Meter. In 1967 they were heavily involved in the space program and some military oriented things like Torpedos, cluster bombs, avionics and test gear for the military. They did have some cooperative agreements with some companies to produce photo strobes, and some other items. The strobes they did make, but some of the consumer items that bore their name were not made them. They did flirt with Yashica, Pentax, and 3M's consumer electronics foray (Wollensak).

    But it is most likely an orphan, and you will have little to no luck finding the schematic for it in all likelyhood

    The silk screened lettering does suggest the company that made the item was a military contractor. On the bright side- no fungicidal varnish appears to have been applied, which would have been the norm for something like that if it were a military piece.
     
    Last edited: Nov 1, 2013
  10. kevinmasters

    kevinmasters Well-Known Member

    Messages:
    674
    Location:
    Riverlea, Ohio
    I don't know what it is either but my heart would start pumping if I saw it at a yard sale!
     
  11. johnblue

    johnblue Active Member

    Messages:
    267
    the date on the big cap cans is 11-66, the rca 7025's are dated 9 67 cant tll on the sylvania jan 12au7s or 6x4wa

    but one thing i was thinking about is what i read about 7025's... when were they in general use?

    other people look at this thing and they almost all say 50's but mid 60's is what it looks like.

    i have to say, from here, the most relevant information is the trafo's, seem to be made for viewlex by NyTronix,

    another notable thing is the way its grounded, it has these lugs on top of it, and holes on bottom, the ground is connected to the lugs, so they are stackable, or rack stuck up with other things and ground connect.

    $75 on ebay, i was the only guy that bid on it... he hadn't sold alot of things, and it did seem too good to be true, i have a home recording studio. and i cannot afford anything remotely like this under normal circumstances... so it was kind of a gamble, it paid off and i am really happy.

    I am telling you, the tube gods have been smiling on me lately, in the last 6 months i have aqquired alot of very useful things for dirt cheap.

    i only really need one channel right now, so i think i am going to hold off on anything other than tube rolling right this moment, and if i can find the schematic, i will wait till after this album to mess around with it. i am also going to change the big cap cans, as they have started to develop a wierd crystal growth on the bottom after using it a bit.
     
    Last edited: Nov 2, 2013

     

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  12. Trio

    Trio Super Member

    Messages:
    2,207
    Viewlex is the likely main manufacturer of the item. The date coding is 1967

    Tubes like the 7025 were used in industry into the 1970's. I have a 1968 vintage Dumont scope identical to what you see in Kutherpali's apartment (the Raj mahal) on the shelf in the background. Tektronics scopes that had tubes were in use in industry into the 1980's, but the tubed test equipment was made into about 1973 not counting what Heath or Allied had offered nor other kit makers.

    So the production of those tubes lasted into the 1980's.

    That crystalization is the electrolyte of capacitors leaking- the cap is kaput.
     
  13. jsguitar93

    jsguitar93 New Member

    Messages:
    2
    *Bump

    I just got 3 of these things from a wear house and want to overhaul them. Anybody have any idea on schematics?

    best,

    J
     

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