Baldwin organ tube amp

[baddog]

Hi everyone

This amp is a 2 channel amp with seporate output tranys for each channel.

channel 1 has 1 12ax7 faze inverter ? tube ,1 5u4 rectifier tube , 2 6L6 output tubes and a volume control

Channel 2 has 1 12ax7 faze inverter ? tube ,1 5u4 rectifier , 2 7027 output tubes and a volume control

From what i found this amp is a 50 watt amp but it doesnt have a preamp section and i would like to add one(guitar preamp) for each channel or one for both. Any one have any ideas or sugestions. I do have some space to work with and the power transformer is huge so i dont think i will have power issue.

I did hook up a 1/4 jack to the signal input spot and the amp sounds nice and warm but very little volume.

Thanks
keith

[Gtr_tech]

It has little volume because it expects a line level input from the organ preamp circuitry. You also might have an impedance mismatch depending on what impedance that input wants to see. If there's enough real estate inside the chassis to work with you could build a guitar pre front end...may need to cut some extra holes for volume and tone stack controls. If it were me I'd just run an outboard preamp in front of it that has a line level output.

Are you sure that one side has 6L6s and the other 7027s? They're pretty much the same tube with slightly altered pinouts. Got a model # for the organ? Chassis # on the amp?

[baddog]

The organ model number is 45CP2 and the 6L6 and 7027 are stamped on the chassie. The rectifier tubes are ran together like the fender 5E6 amp. I do have enough room to work with so i could add 2 extra tubes and some pots . I dont think i need anything more than a tone and volume for each channel. I think anymore than that might get a little to complicated.

thanks
keith

[Gtr_tech]

From what you have there I'd build a preamp in a seperate chassis. Looks like its already pretty populated. FIY, don't run it without a load on the unused side. Make up a dummy load so the side thats not in use stays happy. Or just pull the rectifier tube.

I get nothing on that model#.

[baddog]

I found someone who is going to put 2 preamps in the amp for me so i can use both sides . I'm going to trade him another baldwin tube amp for the work. I plan on puting into a head configuration.

thanks for the input
keith

[tantalune125@aol.com]

To Baddog...about the baldwin amp/pre amp.

Greetings Baddog,
I just figured I got real lucky finding a mint Baldwin (4) EL84, (1)5U4, and (2) 12AX7's. Really nice...probably out of a church setting. It has the vintage plugs to console, accessories, and looks to be around 30 + watts. I would love to find the proper pre amp, either separate or internal.There is an internal pre amp, but it doesn't have the neccessary wiring to hook up a Volume,Treble,and Bass panel.
What would you recommend? Please tell me how you did it, too? My tech "friend" is running scared. He says he would have to design a whole new preamp section off of the existing one...and would need to charge me an arm and a leg. I can trade (2 Bogen CHA33's. One is working strong, with modified jacks for guitar, and I added a 16 ohm aux. out to speaker 1/4" jack also. I also have a non working Bogen CHA33...just worn out caps and and too much for my tech pal to over haul. He said it would be good for parts. The trannies, etc.
I'm a rank amateur, I use them for amplified blues harp....I have a bsaaman and love the 6L6 sound. I want a back up EL84 amp. Are the Baldwins good, once they're modified, for blues harmonica or guitar?
Thanks a ton, Happy Holidays,
and I hope you had a good Christmas, too.

[Gtr_tech]

Your friend is right. You would have to either have a preamp built or use something like a rack pre with a line level output. That chassis was intended to have a line level signal at its input....although we really don't know how hot a signal it is expecting to see. As long as you can dig up documentation on the chassis, or the input/output connectors are identified it should be no big deal. I wouldn't screw with the front end circuitry on that chassis.....just put something in front of it. I have a ton of organ chassis and they're fairly easy to work with.

[baddog]

I would find out were the signal goes into the phase inverter and re-do everthing in front of that. Find a schematic that has a simple tone & volume setup ( Matchless Spitfire) and give it a shot. Your tech friend should be able to help with that. The thing to keep an eye on is the plate voltages in the preamp. You may need to add an extra filter cap and a B+ voltage drop resistor. Is the amp a mono or stereo amp? we really cant make to many sudgestions untill we see a schematic. Do you have a model number for the organ it came from or is there a number on the chassis

One bulb goes out they all go out.
Marry X-Mas
Baddog

[Gtr_tech]

I would say mono...it has what looks like an output transformer on the top side of the chassis.....unless it has small output xfmrs under the chassis and thats a big choke on top....unlikely.

I doubt there's enough real estate inside that chassis to mount pots for a redesigned front end....pretty crampy lookin' topside. Which is why I recommend to just stick somethin' in front of it.

[tantalune125@aol.com]

Gtr tech...and Baddog,
Thanks for the previous posts.

My reasoning is, if a 14 watt head amp from a console stereo cab (Admiral Model Number SS649 w/ (2) EL84's), which sounds awesome, then, (4) EL84's should be perfect for bigger venues. Much like a 59 Bassman (RI). I am hoping I made a good investment.
But this Baldwin pre amp thing is really bummin me out. Like i said, I'm a rank amateur.
Just a couple more questions, please.

- Can you recommend a company, or individual, who has experience, and who can do rack pre with line level output?

- Any suggestions as to type of outboard pre amp? I just missed a heathkit pre amp...there is one on Ebay now, but the item is also paired with the main amp as well. I don't think the Seller will split up the auction. Just recently, the last person I asked to split up the auction, did so, but he got back to me waay after he re listed it with a B.I.N. of $25. I was sick!

- And is there a way to find out how hot a signal it is expecting to see?

I have the Baldwin original 2X12 Jensen C12R's. The whole deal was practically free. I am so inclined to invest a little more. Who knows if it kills I'd probably make it my favorite. It's hard to beat a 59 Bassman (RI) for harp, or guitar. The head room and tone for Blues is amazing. My guess is the EL84's might give an as good or better sound. thanks....

[tantalune125@aol.com]

Gtr tech and Badddog...

Gtr tech...and Baddog,
Thanks, for the help and previous posts. It's truly hip to have this kind of forum.

I'm not seeking outrageously loud amplification. I do like around 30 watts. It offers the head room, more than I'll ever truly need, and amazing independance from egotistical guitar players...who are loud, passive aggressive (with harp players), and often think they're not loud enough......lol!
My reasoning is, if a 14 watt amp from a console stereo cab (Admiral Model Number SS649 w/ (2) EL84's), which sounds awesome, then, (4) EL84's should be perfect for bigger venues. Much like a 59 Bassman (RI).... hoping I made a good investment.
But this Baldwin pre amp thing is really bummin me out. Like i said, I'm a rank amateur...a vintage mic builder for blues harp is more my hobby.
I love my gear and a (4) EL84 amp would be the icing on the cake.

Just a couple more questions, please.

- Can you recommend a company, or individual, who has experience, and who can do rack pre with line level output?

- Any suggestions as to type of outboard pre amp? I just missed a heathkit pre amp...there is one on Ebay now, but the item is also paired with the main amp as well. I don't think the Seller will split up the auction.

- And is there a way to find out how hot a signal it is expecting to see?

I have the Baldwin original 2X12 Jensen C12R's. The whole deal was practically free. I am so inclined to invest a little more. My guess is the EL84's might give good sound...but at what cost?
thanks....here's some pix of the trannies and the i.d. numbers...hope it helps..

[tantalune125@aol.com]

more pix of Baldwin amp

Forgot to attach..here some shots which may help anwer some questions I sent you....
K

[baddog]

Its hard to give advice if you dont have a schematic od the model munber of the organ the amp came from. Do you now what the organ model number is for the amp?

Baddog

[tantalune125@aol.com]

Baldwin Organ (4) EL84's 30 watt...no schematics

Lookin' again here for some random acts of kindness. I am seeking tube tech who (might know someone) can take on this modification for me....Or offer some advice. The best advice yet was to find a schematic....no luck. Which is why I got such a good deal...
Perhaps someone who knows the score and has the time to help. I have a Bogen CHA33 I can trade...and it works real well. I've had it for several years and has given me no problems.

[PRNDL]

I've done a bunch of organ amp conversions and have some advice for you.

By far, the simplest method is to choose an amp that has the same output tubes and make a replica using the parts from the organ amp.

It's possible to rearrange things in the existing chassis.

In yours, you would move the OT and choke onto the top, and move the preamp tubes in line with the output tubes. The circuit board is then mounted where the preamp tubes were.

You'd make the circuit board using the template from an existing amp (AC30), except it may have to be a bit thinner than normal to fit.

Next would be drilling holes in the front. Use a template for the amp you're copying (AC30) with the idea of buying a faceplate later on. Same thing with the rear.

If you were nearby, I could help with this.

Ron

PS
The comments about moving the preamp tubes were for the first amp chassis.

The Baldwin 4xEL84 is much more challenging because there is little room, and the chassis is square.
In that case, it might be easier to make or purchase a new chassis.