New Filmosound Conversion

Discussion in 'Glowing Bottle Tube Amp Forum' started by electroman, May 9, 2021.

  1. electroman

    electroman TDPRI Member

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    My amp tech is Dave Robinson, in Georgetown, Ontario. He's done 63 of the Filmosound conversions so far and his approach as really evolved. This one is a model 285, and has a 6J7 preamp tube. That tube is magic. This is my second one of these and they are both my favorite amps of any that I've owned. The cabinet was designed and built by Derrick Bell at Veteran Guitar Cabinets in Trenton, Ontario. Single 12" speaker, and this one received a master volume after the preamp section.

    IMG_20210508_180718136.jpg IMG_20210508_180734142.jpg
     
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  2. Torren61

    Torren61 Poster Extraordinaire Gold Supporter

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    6J7 tube or 6SJ7 tube?
     
  3. gitold

    gitold Poster Extraordinaire

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    Nice looking........
     
  4. electroman

    electroman TDPRI Member

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    6J7. The original in this one was a Mullard EF37, the British equivalent to the 6J7. here's the amp before conversion. The EF37 (6J7) is the red one in the corner with the cap on top.
    https://www.tdpri.com/threads/incoming-conversion.1065251/
     
  5. Torren61

    Torren61 Poster Extraordinaire Gold Supporter

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    What happened to the original cabs? I have two of them. The gasket is a bit chincy because I don't really know what to use and they do need a gasket or they rattle at higher volumes.

    I painted this one because it was in rough condition. I still need to add a handle. Celestion Alnico Blue for the speaker.

    8FDF282A-3D89-4631-A44E-070753EB326B_1_105_c.jpeg C466C7A3-A356-4274-A9D2-EA482E5B843F_1_105_c.jpeg AC09835D-D48E-41F7-976D-70D5546F9EC5_1_105_c.jpeg
     
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  6. Torren61

    Torren61 Poster Extraordinaire Gold Supporter

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    This one has a Fane A90.

    C90D6A05-FB9D-40A6-A7C7-2514A7FE9CD7_1_105_c.jpeg 22D5C89A-47FD-44CE-9347-68BF14EF1D02_1_105_c.jpeg 817984AA-712F-4AA9-A49C-220D7F21CE77_1_105_c.jpeg


    Sorry for hijacking the thread. More pics or yours, please. What speaker did you choose?
     
    Last edited: May 9, 2021
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  7. Lef T

    Lef T Tele-Holic

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    Very nice.
    I'm outside of TO in St.Catharines.
    Great looking amp.
    Derrick does really nice work.
    Enjoy!!!
     
  8. electroman

    electroman TDPRI Member

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    You're not hijacking at all Torren61; it's a Filmosound thread. :) I bought this amp with no cabinet. The previous one that I had converted had an ugly metal cab, nothing like the nice retro one you have pictured. Here's a picture of this amp after the conversion, except we changed out that metal rectifier tube for a 5Y3, and the red Mullard got replaced with an old Svetlana 6J7, or whatever the Russian number designation is. Now it has the 6J7 preamp tube, 6SL7 phase inverter, 5Y3 rectifier, and two 6V6 tubes for the power stage.

    It's really funny how I used to be a blackface/silverface Fender guy, but now that my ears have gotten use to these old octal based amps, Filmosounds and old Ampegs, the Fenders, with their 12AX7 preamp sections sound cold and hard to my ear until they are cranked up to their sweet spot. That probably also has something to do with the fixed bias VS cathode bias of these older amps.

    20210325_164606.jpg
     
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  9. Telekarster

    Telekarster Tele-Afflicted

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    Man... that is sexy! I like the venting for heat at the top too. Really sweet amp, man! Nice.
     
  10. electroman

    electroman TDPRI Member

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    In both Filmos I have the Jensen Neo 12-100. This is their first neo design, and they got it right. Other companies had to redesign their neos after first releases didn't sound very good. One of the engineers at Jensen said that they initially tried the neo magnet on existing designs, but realized that they would have to design the speaker around the magnet. These are no longer available in North America, but are still being manufactured and distributed in Europe. I see that there is a neo 12-100K being distributed though, and I'm curious to hear how they sound. Fender is using them in at least one model.
     
  11. electroman

    electroman TDPRI Member

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    It's cathode biased, so runs pretty hot. The tubes face forward and the vent is directly above them. Derrick Bell routed a shallow cavity so the vent would be nice and flush. That way the vinyl fold can still be secured against the wood.
     
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  12. Sequimite

    Sequimite Tele-Meister Ad Free Member

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    I have that exact FilmOSound cabinet. I haven't done anything with it yet. Found it at an antique mall a few years ago and stuck it on a shelf. I was disappointed that there was no amp in the cab.
     
    Last edited: May 10, 2021
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  13. Torren61

    Torren61 Poster Extraordinaire Gold Supporter

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    I have the original Jensen that came with one of them. It's an alnico with the Amphenol plug. I have the retractable cable and mechanism as well. But no amp. :(
     
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  14. Sequimite

    Sequimite Tele-Meister Ad Free Member

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    Has the original speaker worked out for anyone? P1030490.JPG P1030491.JPG P1030492.JPG Here's mine:
     
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  15. gusfinley

    gusfinley Tele-Afflicted

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    Halton Hills is a beautiful place and that is a Beautiful amp!
     
  16. Mowgli

    Mowgli Tele-Meister

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    I like the octal preamp tube sound, too. Those early Ampegs and Gibson amps sound great!

    I've got a couple of questions for you and/or your amp tech. --

    The Filmosound 285s, IIRC, didn't come stock with Power/isolation transformers or 6.3 volt filament voltages (didn't they use power tubes with 25 volt filaments - 25L6GTs ?).

    How did your tech effectively eliminate the potential shock risk besides installing a polarized plug?

    How did he use 6V6s instead of 25L6GTs?

    The Filmosound 385, IIRC, were the models with the Power/isolation transformers, not the 285s.

    A polarized plug, by itself, does not isolate the line voltage; it just keeps the chassis from being connected directly to the "hot" side of the line outlet.

    Am I missing something here?
     
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  17. Mike Simpson

    Mike Simpson Doctor of Teleocity

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    I have a Film-O-Sound cabinet I use with my Mark DV, it has an Eminence neo Lil' Texas speaker in it.

    IMG_2440.JPG
     
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  18. electroman

    electroman TDPRI Member

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    Sorry for the late reply. The old 179 models had stock power/isolation transformers, like most paging amps of the era. If you see a 285 with the power switch located between the vol. and tone knobs, those ones had no transformer attached to the chassis, so might be what you are referring to. My tech won't accept those for conversion. However, some of the 285 models were almost identical to the 179s, and have 6v6 power tubes, power and output transformers located on the chassis, etc. the 385s have 12aX7 type preamp tubes and the earlier 179 and 285 models, at least the ones I have, use octal preamp tubes.

    I almost bought one of the 285s with the on/off switch located between the vol and tone knobs, but fortunately I ran it by my tech and he explained the problem. So, if anyone is looking, just steer clear of the 285s with the switch between the knobs.
     
  19. Mowgli

    Mowgli Tele-Meister

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    Thanks for the information! Much appreciated. Mystery solved!

    FWIW, I attended an estate sale a while back and on its last day - everything was priced to sell - I walked out with some great deals including a Fender PA-100 for $50.

    For $3 each, I snagged two 285s without the trannys (thinking about modding them into stereo Hi-Fi monoblocks) and two 385s which I plan to mod into guitar amps. At the time, I was unaware of their potential. I just noticed that there were some tube amps in these projectors and made them an offer... no one else was interested so they let me have them for $3 a piece!!!

    From the clips I've heard online these little amps sound amazing when modded appropriately.
     
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  20. electroman

    electroman TDPRI Member

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    Great deals on the Filmos. Some of the 385s have EL84 power tubes, and for those who like a more Vox/Marshall type of sound, those are the ones. I personally prefer the 6V6 ones. Regardless, the sound and response really comes down to how they are converted. Dave Robinson guts them, for the most part, keeping the chassis, transformers, tubes, some wire, etc., and uses his own designs, but I've heard of people salvaging original caps, etc. Good luck with the builds and post 'em up when you start.
     
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