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Organ Conversions - Guitar Preamp/Master Vol/ Tone... Help!

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  • Hanger-18
    replied
    CONN541SCHEMATIC.zipLet's try Zipping it........Success!!!
    Last edited by Hanger-18; 11-29-2013, 04:10 AM.

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  • Hanger-18
    replied
    OOps file too big try again

    Here is the result of my Scan today. It got cut here and there but what you have is 2 pages of the main circuit which includes a solid state preamp for the two channels a picture of the PowerAmp and The Schematic a little cut off. The weird ovals with numbers are the plugs between circuits. Please consider sharing and helping others with conversions as These were not easy or free to get. Thank you my Friends. Hanger-18......Problem with attachment it is all together as one file at 4.89kb and exceeds forum limit of 4.7kb so I'll try again later or maybe someone more experienced at this forum can give me a better option.

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  • CBraet
    replied
    Hanger-18, do you still have the large schematics, where you able to scan them?

    CBraet

    Originally posted by Hanger-18 View Post
    Anyone out there got great ideas to convert organ's to guitar amps. Really not interested in re-making one from scratch. Just re-engineering what's needed with what's already there. I have #3 Conn 541's from early sixties and have the schems. Unbelievably they have transistors in an off-board preamp. Would like to possibly reuse the 12 au7's used for the keys in the preamp. Maybe as a second valve (cause 12au7's are about 20% amplification) I'm trying to find a way to also reuse the leslies as they would easily fit into the bottom of a 4-12 speaker cabinet along with the vintage 2-12's in the top. I need to really get the tone stack figured out, the tube preamp figured out, and a way to add a master volume and volume. Any help will clear out my garage.

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  • Hanger-18
    replied
    Thanks for reposting looks like pics are gone too.

    Originally posted by Jazz P Bass View Post
    It's not you, the server crashed awhile back.
    A batch of files was lost.
    Here you go.
    I guess I should repost pics and try to add some of my oversized Conn Organ schematics. Even the old SS ones are point to point and can give up reverb drivers and thought about using the Leslie's. in old 412 cabs with a 212 setup above the Leslie's. I am focusing on the silvertones cause they are simple and almost guitar amps. Thanks ttoThomas Organ(157.Xxxx manufacturer # )

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  • Jazz P Bass
    replied
    Originally posted by scrimpus View Post
    Does anybody have a schematic for this organ? The above links don't seem to work for me.
    It's not you, the server crashed awhile back.
    A batch of files was lost.
    Here you go.
    Attached Files
    Last edited by Jazz P Bass; 08-03-2013, 02:53 PM.

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  • scrimpus
    replied
    Does anybody have a schematic for this organ? The above links don't seem to work for me.

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  • Hanger-18
    replied
    I Just picked up a Third Silvertone Organ amp chassis and this one dates to 1969(Schumacher transformer). I tested it with a guitar through the mic input and it worked. This one differs from the others because it has a trim-pot added for the tremelo intensity. Only problem is it of course is weak as a guitar amp as the input is not matching for the guitar impedance. The Flute/string switch is just a bass/treble switch almost a 'bright' switch.

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  • Hanger-18
    replied
    Pictures of Organ guts separated from organ.

    Click image for larger version

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ID:	827215Here are some quick phone pictures of the organ teardown. The mic should help w/ conversion.

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  • Hanger-18
    replied
    Any suggestions how I could incorporate the layout of the Fender Harvard?harvard_5f10_schem.pdf

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  • Hanger-18
    replied
    Thanks for the suggestions! Flute and String=organ tones. Flute is bassy-hollow. String= higher-sharper. I wondered if it would work like a 'bright' switch? Thanks again I will research fender stacks.

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  • hasserl
    replied
    So you have a single ended 6AQ5 (electronically equal to a 6V6 but in a smaller bottle w/ 7 pins) amp with 3 gain stages and tremelo, cool. You'll want to make sure the filter caps are fresh, no sense in building something with 40 year old filter caps. You'll need to add a 1/4" jack for the input; the resistance of R1 is kind of low for a guitar amp, it will load the guitar pickups down, 1M would be better. The input stage should be converted to a common cathode style stage, i.e. add a cathode bias resistor and bypass cap; I don't know what the Flute & String marks indicate, but most of that between V1A and V2a can be eliminated, but leave C1. You could just sandwich a Fender style tone stack/Vol between V1A & V2A, that would allow you to retain the current vibe wiring and the nfb circuit. The amp should have plenty of voltage gain to drive the 6AQ5 into full saturation, could be a great sounding little amp.

    Take a look at Fender schematics and start redrawing your schematic to incorporate some of the circuits from those amps. Bring it back here for review from the group.

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  • Hanger-18
    replied
    Here's the Silvertone Organ Amp Schematics also Magnatone(Tremelo curcuit similar)

    Here is the Schematics for the Silvertone Organ. I added the Mag 410 cause the tremelo curcuit is so similar. I heard the silvertone organ was made by Thomas organ(Estey) This is my first time posting so I hope it works....... Click image for larger version

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  • Hanger-18
    replied
    The obvious!! Thanks hasserl! Should of thought of this... I got actual printed Schematics from a Organ Service Co. The Sears one is 81/2x11", but the Conn's are large fold-outs with several pages. It will take some time to figure out how to scan these in pieces, but I will post at least the Silvertone right away. It is probably the easiest because it has a piezo microphone that amplifies a Reed air chamber organ. It may have a good enough preamp at least, just need to add tone and tremelo controls. Will post these as soon as possible.

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  • hasserl
    replied
    If you could post the schematics you might get some interested folks to take a look at them and offer some ideas.

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  • Hanger-18
    replied
    Thanks, Yes I have scoured it several times before calling out for help.. It is good overview and outline for planning a build. I think it is a great source for making an almost new build. I was lost at some parts because the author is creating a broad view, but getting specific on points that would be great as wiring examples. I really think its a great article, but it has left me wanting more.... I Know it's time consuming to post hand drawn schem's, but I've spent too much time looking at pictures(speak a thousand words) than putting together a word problem in my head. With all the old organ's headed for the scrapyard now-Baby Boomers don't have room for Ma and Pa's '60's Organ- It would be cool to see "Turning Organ's into Guitar Amps for Dummies". I know it's been done but wish that there was a more meat and potatoes documentation of the process. I've managed to fix tube amps and know my way around electronics, just not as keen on theory to practical application.

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