Baldwin question

[cygnus2112]

Hi guys. new here and just aquired a Baldwin organ amp. It has 2 6l6's, 1 12ax7, and a rectifier tube. I have searched high and low for a schematic. Anyone know where to find one? I am converting to a guitar amp. Thanks ahead of time.

 

[steve...]

I have that amplifier and the also the model with 4 6L6 tubes.

The attached schematic is for the stereo version of the amplifier. The power supply is slightly different ( 2 rectifiers instead of 1) but the amplifier schematic for each channel is similar maybe identical to what you have. I don't know if they were identical because I modified mine. However the actual circuitry if not the values are the same.

Steve

 

[cygnus2112]

Thanks so much. I will look at it and compare. I am using it as a guutar amp build.

 

[cademan]

You will have to make sure that there is enough front end gain for a guitar pickup. Most organ amps don't have that kind of gain. Most organ amps are line level type inputs.

You might have to add another tube or gain stage to match the impedance of guitar pick ups.

 

[FlaCharlie]

The attached schematic is for the stereo version of the amplifier.

Thanks for posting that. Schematics for organ amps seem to be very hard to find. That one looks to be contained in a book of Baldwin (and perhaps other) organ schematics.

Do you have the book or know where it can be found?

 

[steve...]

I got the schematics from this thread https://audiokarma.org/forums/index.php?threads/baldwin-organ-amp-schematic-needed.197325/

This thread has good information on modifications https://www.audiokarma.org/forums/index.php?threads/curcuit-ideas-for-scratch-build-needed.197798/

I also registered on an organ site back then that had schematics. I looked through all of the information I downloaded on these amps but can't find a reference to the website with the organ amps.

If you search you will find a website with schematics for Hammond and Leslie organ amps. I acquired a couple Hammond/Leslie power supplies on the cheap and got schematics from there.

About 10 years ago I acquired one of the 2x6L6 amps, 4 of the 4x6L6 amps and 2 of the 4x6V6 amps. It was my intention to use the 6L6 versions as bass amps and the 6V6 version as higher frequency amps. The transformers in the 4x6L6 amps begin to roll off at 5khz. I did not test any of the other transformers. But, it was and still is my plan to get full range transformers for the 6V6.

Unfortunately, I had an opportunity to acquire several of the baldwin 4x6L6 amp output transformers and chokes before I tested the transformers on the ones I owned.

I did not pay very much for any of the organ amps and power supplies. The chassis are large and deep. If appearance does not matter they are good donor amps with power transformers that can provide almost 200 watts. I wired Hammond and Sansui 1000A OTs in one of the the 4x6L6 amps and got 50 watts and 40 watts respectively at full bandwidth.

Steve

 

[knockbill]

Welcome,,, Fender and other guitar amp schems are easy to find,,, and it would help you convert your amp to a good git amp,,, I'm guessing that half the 12AX7 is the phase converter, and the other half the preamp stage,, you will need more that that, as was mentioned, for git amp gain...
Here's a few to get ya started,,, Post some pics of teh amp...
https://vintagefenderamprepair.com/pages/library-schematics-layouts

 

[steve...]

All of the Baldwin amps that I have use a paraphase phase inverter.

I think they would make excellent guitar amps without any changes except maybe to the power supply. With regards to the inverter; changing to a concertina would produce different overload characteristics. I do not know which type is preferred in guitar amps.

The 4x6L6 amp power transformers also powered banks of 6SN7 tubes. The only modification I performed on the 4x6L6 was to change dropping resistors to bring down the B+.

I do not know if they used full range OTs in any of their amps. Mine were not. But, it is easy enough to test. And that would be the first thing I would do.

Steve

 

[cygnus2112]

Thanks for all the useful info guys. My goal is to use this and build a tone stack and yes, most likely another preamp tube or 2 in the gain stage. My ultimate goal is to have a super clean and lush sounding amp. I am very familiar with electronics and have done repairs, trouble shooting etc, but have never actually built an amp. I am super excited but may ask a lot of stupid questions as i have no idea how to!

 

[jagal]

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Je me connecte à cette discussion mais dirige moi si ce n'est pas le bon chemin.

Voici le sujet : J'ai récupéré 2 enceintes Bladwin Modele 2 d'un orgue que le grand théâtre de Genève vient de mettre à la poubelle (!!). Ce sont des baffles plats avec retour de chaque côté de H = 1m, L = 75cm et P = 45cm)

Ils sont équipés chacun de 2x38cm Fane 15/150 classic en 8 ohms et chacun d'un bloc amplificateur à lampes : 4x 6L6GC, 2 X 12AX7 (ECC83), 2 5AR4 (GZ34). ((Sur la plaque signalétique à l'arrière c'est 210W... pour chaque bloc d'ampli qui est mis dans chaque enceinte).

Il possède une sortie pour le premier haut-parleur (pédale haut-parleur d'orgue) et une autre pour le haut-parleur manuel du haut-parleur (clavier ?). Il y a un contrôle de volume pour chaque sortie de haut-parleur. Il ya un sélecteur de canal qui sur la position 1 (sens horaire) permet d'avoir la même tension pour les 2 enceintes et une position 2 pour un double canal qui permet un contrôle de volume séparé (et une perspective de bi-amplification ? ).

Dans les échanges sur le forum je trouve des similitudes mais pas pour le modèle Baldwin que je possède (en 210 Watts. A ce jour impossible de trouver un schéma de ce modèle d'ampli ! Et pour le moment personne en France ne connaît cet animal .

J'ai récupéré le signal d'entrée et j'obtiens un très bon résultat : très musical, assez étonnant dans le grave et qui monte assez haut dans le médium. Mais vous l'avez deviné, le plan n'est pas de jouer de l'orgue. J'ai adopté la position du sélecteur de voix double canal sans jouer avec les 2 commandes de volume.

L'idée du projet serait de s'orienter vers un 3-voix (Grave - Medium - Tweeter) (ou plus simplement un 2-way Grave - Tweeter car les HP Fane sont des médiums). La même préoccupation que la discussion actuelle.

Problème :

• Comment dois-je faire pour mettre un médium et un tweeter car j'ai actuellement 2 sorties 8 ohms pour chaque ampli ?

• Je pourrais laisser un HP bas sur une voix (coupé à 800HZ) et un sur l'autre voix l'autre Low HP plus un HP médium + un HP Tweeter (coupé à 800 HZ et 4KZh) qui maintiendra l'impédance des 2 voix à 8 ohms ?

• Les 2 sorties sont-elles vraiment distinctes (2 x105 Watts) ?

• Certains échanges sur le forum suggèrent que les 2 contrôles de volume doivent pour les hauts-parleurs hautes et basses fréquences mais dans ma configuration, ce sont les mêmes 2 HP ?

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