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Thread: Baldwin Vintage Amp conversion

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    Baldwin Vintage Amp conversion

    Hi everyone
    Ok so I followed some threads here about converting a Baldwin Organ tube amp into a guitar amp...thing is, I found so many different models of amps, nothing looks like the one i'm getting via EBAY.

    I purchased a 1959 Baldwin Tube Amp organ model 51P, it uses 2x 6L6, 2x 12ax7 and 2x 12au7 (rectifier is 5U4)

    Anyway, here are some pics...what i'm worried about is: Am I missing a tranny here?
    This is supposed to be a big iron tranny, btw.

    Other than that, i know nothing on the matter...all i know is this thing worked great in the organ, it used to power 2x 12" speakers at 16ohm... and i'm wondering if i can use it in my 4x12' cab.

    More pics available.

    Is this supposed to be powerful at all?
    I suppose there is a preamp stage - can i hack it to add some EQ / Level things there?
    Apparently there is a gain knob on the chassis,

    K thanks for the help, people

    Jonathan
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    pineapple49
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    can you tell us some specifications about the transformers??

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    Well, the thing is I don't much about it at all.
    I'm supposed to receive the amp in a few days, at which point I can post close-up pics, and whatever else I can find with the beast in my hands.

    Now, usually I see 2 trannies on pictures of organ tube amps - and I only see 1 on mine. I also read somewhere that one should be careful in choosing amps making sure that they'd have all the required trannies.
    Also, I sent links for different amps to my brother who lives in Europe (i'm in the US), there was a pic of a Randall amp, and he told me that from the pic it was missing the output tranny, his advice was to go with a Baldwin (I think for their good reputation), which I did.

    My knowledge on the matter is close to nil right now, so any help of any sort is mega appreciated.

    Cheers
    Jon

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    Senior Member dwhutchens's Avatar
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    Looks like you've got one big a$$ed power transformer on the top with the tubes and at least one small choke and three small transformers or chokes underneath. Are you sure there aren't more power tubes besides the 6L6s? Maybe more than one power amp, one for the keys and another for the bass foot pedals. Maybe a transformer PI. Hard to tell without a schematic. If its running 2 6L6s in push pull you could get 30 to 50 watts depending on the size of the output transformer and the B+ supply.
    David

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    Yea, I'm actually looking for schematics right now...but difficult to tell which amp it is exactly.
    Seems to me that all these organs had different amps! when I search online for 1959 Baldwin organ amps, I find tons of different models...

    So do you mean this is made for 2 channels? Hence why all the tubes are in sets of 2 ?

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    Quote Originally Posted by jonton26 View Post
    So do you mean this is made for 2 channels? Hence why all the tubes are in sets of 2 ?
    No, from the look of the chassis, there seems to be the large black power transformer that fits through the chassis panel, a large choke next to the rectifier tube socket and the output transformer mounted next to the two 6L6 tube sockets.

    The other smaller transformers may be signal transformers or chokes for the pre amp and tone generator circuits.

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    Ok finally got it

    OK guys, so I got it,
    well packaged! except for a couple of little bits that fell off when taking the wrapper off, no idea where they came from, but from what i see nothing looks okk, i inspected it as much as I could.

    Input: There is a long brown wire with a sort of RCA male input - Only long wire coming off the amp. Although it's male I have a feeling this is the input, am I correct?

    Output: Top of the chassis says: "Case Speaker" right next to a socket with 4 female prongs. No idea of how to make this a proper speaker cab female jack.

    Gain: There is a gain knob mounted on the chassis, but noway to take it out and bring it elsewhere with all the point-to-point tight connectivity around it. My question is - can i hijack it with any other potentiometer that I can fix elsewhere connecting to each of the 3 terminals?

    Power: There is a 3-wire wire that has been cut clean, coming off the main power tranny, I want to connect this to a power switch then to a wall plug - any help appreciated. The 3 wires in the main AC wire are white, black and brown.
    From what I read, organ tube amps don't have a stand-by switch, so there I am, I don't think there is any way to mod that stuff, so I leave it as is i guess? Let me know what you think.

    Let me know if any better close-ups of the amp would help. Still no schematics...

    Thanks for any help.

    Jon

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  8. #8
    pineapple49
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    can you take a picture of the transformer

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    here is a closeup

    i'll be taking more pics

    thanks for the help

    Jon
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    And yet more closeups

    All I know is it was pulled from a Baldwin 51P and don't have the schematics. Any got anything that might help?

    Here is the number marked on the main tranny:

    F-C512-0237578
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    I am told that the yellow and black wires at the top right (where the output tranny is) are the output wires to the speaker outlet.

    Is that right??

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    i just bought the whole organ today. its great to see your pics because thats definately the amp in there, but theres also more panels with over 60 tubes and mother pieces not connected thjat have tubes. it mad. but i wanna make an amp too so anything i find out i will popst here. the organ it came out of is the baldwin orga-sonic 51P. i odnt know how to post opiics here yet but i wioll post the pic of the whole inside of the organ so you can see this madness.

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    Complete organ

    I happened to come across your thread an it caught my eye. I just got a complete baldwin 51p organ from a music shop i used to work at.
    I am looking to make it into a guitar amp, as well. I noticed that you were looking for some schematics. Is there anything that my organ will help you with?

    -jefe

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    organ power amp.

    hey thanks for contacting me. i have completely gutted the organ, and have the box where the amp resides. i really have no clue what to do from here. schematics would help if i can find someone to actually rewire it? i did buy a new power tube. an Electro-Harmonics. also therer was a bad power cord that i replaced inside that box of tubes. these old things can be a real fire hazard. but since i disconnected all things plugged into it, nothing powers up anymore. which is fine, it all powered up before except the one tube. right now its in the closet until i can find someone ' in the know' on what to do with the amp section.

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    this is correct. The orginal organ has a 4-pin plug that plugged into the amp module. I think the other 2 pins acted as jumpers because the organ will not power on without the -pin plug inserted.

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    Here are some more photos:
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    yea thats what i have

    mine is sitting in a closet now. guess it isnt as easy as it appeared. oh well live and laern and save alot money for something ready to go lol

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    OK, I'm on board the Baldwin Orgasonic train too. I have '59 30-P and a '60 61-P. The amp sections appear to be identical. (Same as the 51-P in the original post) Giant iron, 2 x 6L6, 2 x 12ax7, 3 x 12au7 & RU4. My plan is to build a stereo twin monoblock for my home system. Got a million 12au7's to stack up for the preamp. Just need a workable schematic for a clean 20-30 wps. I'm not expecting to salvage much of the original circuitry, obviously. Will try to get specific info on trannys tomorrow, if anybody wants to chime in with ideas. Thanks in advance. Please ignore post count, it doesn't correlate to age or experience! Mostly age. -Rich

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    Baldwin 51P amp

    Did anyone here ever find out anything about the transformers in this amp? I just took delivery of this exact unit and I'm trying to figure it out also.

    Thanks,
    Mike

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    I just purchased a baldwin F-C512-023757 tr on ebay. Was told it powered 2 6L6s and 20 or 30 preamp tubes. I couldn't find a schematic anywhere, but I did check some voltages:

    Input 122 volts on black pair.

    726 v. on small gauge red pair
    7.2 v on larger gauge reddish pair (looks kinda brown)
    14 v on green pair
    7.1 v on yellow pair
    53 v on red/yellow wire to ground

    The red/yellow is probably center tap for the HV red wires, but I'm not sure. I will post if I find more info.
    I'd like to know the power rating of this. I'm looking to build a 40 or 50 watt amp.

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    Baldwin SE 6L6 amp

    Hey folks,

    Just got this guy last night and finding info (free) is a pain. I'm finding that this amp is from a 51P or 61P from 1961'. Did anyone find any more definative info on this amp and are you willing to swap a little knowledge on it? I'd appreciate any advice in the conversions made and I'll provide some experience/documentation if asked. Appreciate it.

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    Does anyone have any info on a Baldwin 51P or 61P amp? Nearly impossible to get any paper on this guy. Thanks.

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    Old Timer olddawg's Avatar
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    As with so many of these "conversion" projects I think the best thing to do is view them as donor amps. In this case I would just use the iron and the tubes. If you can't get the specs on the transformers, set down and meter them out. When you know what you have, then decide what known good amp configuration you want to build. You have plenty of heater current. Start with a fresh chassis and new ceramic tube sockets. Follow a known good layout and grounding scheme. You have the expensive parts. Make a new turret/eyelet board. In the long run you will save yourself a lot of time and grief with a little more investment avoiding lackluster results and unforseen cosequences. Just my opinion of course, but I have yet to see a "conversion" that was really usable and did not have wierd problems or annoying limitations.

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    Sound suggestions. I do have the service manual for a 61P and a few nice schematics. I've converted a couple of Roberts SE R to R amps with nice results (didn't do the design, but adapted what was worth it). I'm with you on the start over part. The can is too big and crowded with nonsense wave form divider circuitry. The power xfmr is a beast, though, and the choke and outputs are in great shape. I'm looking to use the 20-30 watt output for a keyboard amp for my S80, so I'm trying to keep it simple and can with the paper I have. Any suggestions on a 6L6 or 6550 layout to use with these components? I'm looking into the xfmr specs as we speak. Thanks for confirming my initial impulse to gut this guy and start from scratch.

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    Old Timer olddawg's Avatar
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    Then all you really need is a power amp right?

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    Yep. Got this huge piece of iron, a fair amount of good bumble bees and spragues, a peerless 7532 for power backup (probably use for something else), an altec output tranny (still crunching the numbers on him), the three little trannys that are in this amp (one obviously the choke), and all kinds of little goodies from this baldwin and in bins. I'm getting the bug again and will probably piss off the household with a lack of appearance for days on end (or evenings at least). I'm still a tone freak, even after all these years. Any suggestions appreciated and I'll attempt to let go of what little brain matter I still retain.

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    Member RWood's Avatar
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    Quote Originally Posted by nvaeth View Post
    The baldwin amp used two 6l6GCs and the power transformer has 12.6 and 6.3V fil lines and 335VAC going to a 5u4, and putting 350V on the plates of the 6l6s
    Here's the PT info people have been asking for, as well as the elusive schematic. Disregard the part about the Champ conversion:

    http://music-electronics-forum.com/t21323/

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    Baldwin Conversion

    Thanks RWood. Any input is better than none. I don't think I'll waste a great output transformer on this project. This isn't audio quality stuff and a keyboard amp doesn't justify using one up. Also, came out to Planet Utonia (Utah) from Chesapeake. Have a bunch of relatives in Richmond. Kinda missin' old VA. Thanks again

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    Yw. Maybe not audiophile stuff but there are dozens of great musical instrument circuits that could be whipped up, point-to-point, under that chassis slab. The 5E5 Pro is what I'd like to build with mine. Amp chassis in the bottom of the cab, controls up top.

    Yep, Virginia is rat purty this time of year; it probably misses you too.

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    Baldwin organ transformer

    Quote Originally Posted by jonton26 View Post
    Hi everyone
    Ok so I followed some threads here about converting a Baldwin Organ tube amp into a guitar amp...thing is, I found so many different models of amps, nothing looks like the one i'm getting via EBAY.

    I purchased a 1959 Baldwin Tube Amp organ model 51P, it uses 2x 6L6, 2x 12ax7 and 2x 12au7 (rectifier is 5U4)

    Anyway, here are some pics...what i'm worried about is: Am I missing a tranny here?
    This is supposed to be a big iron tranny, btw.

    Other than that, i know nothing on the matter...all i know is this thing worked great in the organ, it used to power 2x 12" speakers at 16ohm... and i'm wondering if i can use it in my 4x12' cab.

    More pics available.

    Is this supposed to be powerful at all?
    I suppose there is a preamp stage - can i hack it to add some EQ / Level things there?
    Apparently there is a gain knob on the chassis,

    K thanks for the help, people

    Jonathan
    I just bought a transformer, but not yet paid for it, and I hate my 18watt amp as I got tinnitus(ear ringing for days) from it. I was wondering about a solid state diode arrangement and was wondering if anyone knew about that. I find there are 1 amp diodes and 3 amps diodes and I know what a diode bridge is. I can also figure to put in a 5u4 rectifier. I am thinking the transformer I should rewind and use Formvar(spelling) wire as to get rid of the enameled wire. That is something for you to think about too. rectifier winding is very difficult, one round wire on top of the other and 67 feet is the wire length and if you do a center tap it is 67 feet in the either directions.

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    I recently acquired a working Baldwin 51P from the DUMP of all places. It sounded a bit muddy at first but really came alive after about 15 mins. I want to convert this to a guitar amplifier, however, I want to be able to preserve all of the sound effects from the tone generator, i.e., vibrato, sustain, clarinet, oboe, etc.

    One thought I had was to (conceptually) replace the two keyboards and set of pedals with a guitar jack (3), and drop the signal into the appropriate spot on the schematic (I bought a copy online). It appears that certain 'effects' apply to either the solo keyboard, accompaniment keyboard, or the percussion pedals.

    Then I would remove the keyboards and pedals from the organ, creating a flat, rectangular profile to the unit and leave everything else in place as far as speakers, expression pedal, etc. Maybe even wire in a tone circuit. There are about 50-60 12A_7's that generate the individual notes that I would like to bypass altogether, but I'm not sure if that's option. For example, if I remove that circuitry, do I need a dummy load there for things to balance out?

    I am thinking about contacting one of the local university electrical engineering depts (Duke and/or NC State) to see if a professor or student would be interested in looking at this with me. Please let me know if anyone would like to see the schematics and if there is any interest in working on a similar project. Thanks!

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