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I want to convert my M2 into an M3. I already know that i have to replace the AO-14 with an early field coil version of the AO-29. Now i have read that the resistance of the speakers may vary from 700-1000 ohms. Do i also have to consider that?
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1958 B3, 1960 M3, 1953 M2 converted into M3, 2x Leslie 122, Ventilator II, Viscount Legend Solo -
That would be the resistance of the field coil. The schematics which I have only note 700 ohm field coil resistance.
Measure the resistance of the field coil on your speaker. What resistance do you read? -
Yes, you do. And it is different depending which version of the amp (organ) you have.Comment
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Can anyone send me a list where i can read which amp version had which field coil resistance? For ao-29 and ao-14.1958 B3, 1960 M3, 1953 M2 converted into M3, 2x Leslie 122, Ventilator II, Viscount Legend SoloComment
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Just download the M-series service manual from archive.org and check the schematics. It is clearly indicated.Comment
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Remember, you will have to modify/swap the manuals. Percussion is triggered on the 1' harmonic which only goes halfway up on an M2.'60 RT-3
'69 Leslie 147RV
'77 Yamaha E-70
'4x Conn Connsonata 2A2
'6x L-133A
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'5x M2, '59 Leslie 25, '48 CV, '64 A-102, '6x M-143, '5x M3, '81 kimball stardust,
'8x Hammond Aurora, A-102, M2, another M2, Wurlitzer spinet, Wersi DX350, Thomas chordianComment
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By "modify" I believe he means add foldback to the upper manual. The M2 is lacking the key contacts and full length bus bar on the 1' harmonic. Finding spare key contacts and shoving them in/soldering ala "poor man's foldback" won't do a thing if the bus bars are too short.Originally posted by Guitarbro View PostComment
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I think he means by modify he means to change from one specification to another. In this case the modification would be from an M2 to an M3 upper manual; specifically, replacing the 1' busbar with a full length busbar, and adding missing key contacts (and wires) to take advantage of the new busbar.Comment
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Thanks Wes for the hint. I have the service manual but did not find anything yet. Now I had a look again. On page 62 I found the information I needed. M2's with serial number below 21250 use 1000 Ohms speaker field, others use 700 Ohms. The speaker field for AO-29 is always 700 Ohms. As my M2 is serial 29309, I have no problem :-)
By the way, I am planning to do the upper foldback mod.....and afterwards the conversion.1958 B3, 1960 M3, 1953 M2 converted into M3, 2x Leslie 122, Ventilator II, Viscount Legend SoloComment
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