hammond conversion questions

Discussion in 'Amp Tech Center' started by lordraptor1, Sep 17, 2021.

  1. lordraptor1

    lordraptor1 TDPRI Member

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    basically i have an old gutted hammond Ao-29 chassis with the stancor made hammond transformers.

    so here is the thing the tube in the AO-29 was a 5u4 and hte output tubes were 6v6.

    basically what i want to know is can i build a 5e3 circuit board and use the 5u4 rectifier tube with that sircuit, if so what changes might need to be made to the circuit in order to do so?

    also, the plan is to add the 6au6 tremolo circuit to this as pulled from a silvertone 1482 schematic.

    so to summarize i would like to build a 5u4 rectified 5e3 circuit with a 6au6 tube rectifier. any help would be apprreciated, all searches just bring up the usual 5e3 had a 5y3 tube, will burn up transformers, etc. which i do not think applies in this case as the ao-29 per schematic had the 5u4 rectifier on the transformer. my only other option would be just to look at peoples conversions and basically rebuild it as the only thing in it is the transformers ( pt and ot) tube sockets, and 2 wirewound resistors ( not even any wires in the thing outside of those on the transformers.

    basically a ground up build rather than a "conversion").
     
  2. Jon Snell

    Jon Snell Tele-Holic

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  3. lordraptor1

    lordraptor1 TDPRI Member

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    i didnt ask if i could use a 5y3 i know i can because the orinal tube in the ao-29 is a 5u4 which i intend to use the 5u4 that came in it and what i intend to use, i do not want to use a 5y3 because frankly i already have to buy a lot of componants as is and caps and resistors are now costing me double what they use to and i have need to buy a rectifier tube when the 5u4 that came in it is perfectly fine and tests almost new.


    my question basically is can i just build a 5E3 circuit and hook it up or do i need to modify some of the componants in the 5e3 circuit to accomodate the 5u4 rectifier tube? so far i have found so little info on in regards to what my plan is, it always turns out to be a you can use a 5y3 in place of a 5u4 but not the other way around and again i know this and am not asking that.

    basically i dont want to have to rebuild the AO-29 and waste money just to have half the work go to complete waste. what i have is chassis the 2 transformer mounted on top of chassis, tube sockets and tube shields, can caps ( wont be used), and the eyelet boards everythign else is gone so this is as bare bones as they come. i have an AO-35 converted to an 18watt which is marshally sounding so i wanted to make this one more fendery ( although i despise fender country clean tones personally i already have 2 rock rigs with the ao-35 conversion and my vintage 1987 VTM120 head and cab half stack so figured why not do somethign other than a rock machine with this build LOL.

    right now all my searching has not yielded anything, i am about at the point of just looking at and comparing other converstions and comparing to ao-29 schematic and seeing what i can do without rebuilding the ao-29 completley.
     
  4. Jon Snell

    Jon Snell Tele-Holic

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    The average DC voltage drop, under load for;
    5U4 44 - 50 volts
    5Y3 60 - 65 volts
    depending on manufacturer.

    Probably no issues as far as I can see.
     
  5. bebopbrain

    bebopbrain Tele-Meister

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    > can i build a 5e3 circuit board and use the 5u4

    Use the unmodified power supply of your AO-29 including the 5U4 to get B+ of 320VDC. Actually, it will come out a little higher. Except add an earth grounded 3-prong plug for safety.

    The rest of the circuit will not know or care what is upstream of the B+. You don't need to accommodate the 5u4. Keep the 30 ohm (R93) resistor that follows the 5u4. Probably change R92 to 5K ohms for the screens, ala Fender.

    Since the AO-29 is fixed bias and you want trem, have you considered a 6G3 Deluxe conversion instead?
     
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  6. NTC

    NTC Tele-Holic

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    I was also going to suggest a 6G3. The 5U4 is fine to use here.
     
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