New Practice Amp Day, sort of, almost! (build in living room organ amp content)

Discussion in 'Amps and Cabs [BG]' started by NoiseNinja, Jul 3, 2017.

  1. NoiseNinja

    NoiseNinja Experimental-psychedelic-ambient-noise-drone Inactive

    Feb 23, 2011
    When not simply practicing unplugged I have been using my old living Technics living room organ with my bass plugged directly into the AUX Input of the small panel to the organs preamp.

    Beside the AUX Input, there's also a Mic Input with avolume knob for setting the input gain of the mic, a Headphones Out and a Line Out connection.

    It is equipped with a 10" speaker unit to handle the bass and a 5" or 6" speaker unit (not exactly sure which yet) to handle the treble side (got that wrong it seems, please refer to my edit text at the end of the post).

    It actually sounds beautiful, a clear, clean and defined reproduction of the bass's sound, seemingly without any low end loss, weird unwanted noises, distortion or the speakers crapping out.

    Actually it sound considerably better, than the Behringer Eurolive B212D active PA speaker with a 12" and a horn I owned until recently, which cut off the bass frequencies pretty steeply at 65Hz and beside that sounded muddy and undefined when reproducing, well, practically everything you ran through it, being it bass or guitar.

    The build in amp in the organ naturally doesn't have much wattage, but plenty and more than I ever need for home practice purposes.

    So what I pondered on for some time now, since I don't really use the actually big chunk of an organ much, and the bass keys are defect anyway, is to take it apart, pull out the amp parts and speaker units and then rehouse them into a much smaller more practical package, to turn it into a real small and good sounding practice amp.

    I figure with my EHX Black Finger in front, which basically is a tube preamp with an optical compressor put in between the high voltage (300v) input preamp tube stage and the output tube stage, and the compressor part circuit dialed out to only adding a slight bit of slow attack compression, I can make it sound even better, and maybe even start to use it as my go to bass and guitar recording amp for home recordings.

    Eventual maybe adding an EQ in front of amp as well for more tone shaping options.

    I just hope I am able to actually manage to get the amp and speakers out without breaking or messing any of the parts up, and make it work, as I honestly doesn't have all to much experience with electronics.

    Any tips and/or things I should be aware of that any of you know of, before I begin tearing the organ apart, to turn it into a small practice/recording amp, would be much appreciated mentioned.

    Edit: Just did some further research and looked up the manual or the exact model of my organ, the specs actually says it is equipped with 1 x 12" bass speaker unit, 2 x 8" mid tone speaker units and 1 x 2,6" treble speaker unit, and has a capassity of of putting out non less than 100 Watt.

    Seems like I will be getting quite a practice amp if I can manage to take it apart and rehouse it without screwing it up in the process.
    Last edited: Jul 3, 2017
  2. NoiseNinja

    NoiseNinja Experimental-psychedelic-ambient-noise-drone Inactive

    Feb 23, 2011
    An update!

    So I managed to locate the poweramp and preamp pretty fast, was a hell to get to it, but finally also managed to screw them loose from the organ chassis.

    Think I also pinpointed where the 4 speakers are connected to the amp, and it seems like the 12" and 2,6" speaker units is kind of already enclosed, so with a bit of luck and a saw I should pretty much be able to saw out an already made cabinet for those two units at least.

    Then if I haven't got it all wrong what is left to do, when I have unmounted the components in the way for me to be able to saw out the ready made cabinet, is to put together a cabinet for the two 8" units and make an enclosure for the amp and preamp and I should have my self a pretty nice practice/home recording amp.

    I figure there's still some hours work left till I get to that point, and I might have misunderstood how things are connected and it might not work after all, but at least it apparently seems it is in fact going to work this far.

    Update 2:

    Forgot to post and went on working on the project.

    Well, what do you know I tested my work, just to be sure there actually was a reason for going on.

    The speakers emitted a large hum when I plugged the amp, then it faded slowly to a less prominent hum.

    I disconnected the power again, and found out that I overlooked the volume control which I naturally hadn't disconnected was in fact not at all connected neither to the what I assumed was the preamp or the poweramp, but to one of the modules which I assumed was just an effect or sound module, seems that the oragan was wired together a bit more complexly than what I assumed.

    I then disconnected the volume control, and tried to turn on the organ again, and plugged in my bass, but all I could here was some static noise emitting from the speakers.

    Apparently some of the functions and components which you would normally assume would be integrated in the amp circuit has been allocated and instead has been put on some of the other modules the amp was connected to.

    I am still quite sure that what I isolated is indeed what hold the main amp functions, but it's all apparently a bit more complex and interchanging design than what I anticipated, and with my limited electronic knowledge, I am really unable to get any further.

    What I had imagined was that there would just be an amp and then all the sound and effect modules would be connected to that, everything pointed in that direction too at first, until I discovered the allocated volume control.

    So what I am going to do now, since it is impossible to put it all back together in proper working state after my rather careless surgery, is to keep what I still assume is the main poweramp and preamp part, as well as the speaker units, throw everything else out, and then at some point get my electronic engineer friend to take a look at the remaining parts and see if it is possible to get a working unit out of those parts.

    So no new practice amp and an organ less I guess, for now.