Help identify a Baldwin 6L6 organ amp...

I just received a newly modified mid-'50s Baldwin 6L6 two-channel organ amplifier from a friend, and I'm hoping to have this amp identified from the experts here. My friend had this particular amp converted over to stereo-only use for my audio system by Will Vincent of Autospec (he modifies many old consumer audio tube amps and sells them on www.audiogon.com; some of you may be familiar with him and his work). The amp uses a quad of 6L6s in push-pull for the output, a pair of 12AX7 triodes as drivers, and dual 5U4 rectifiers, and is rated at about 28 watts per channel.

I've Google searched the web for info on this amplifier and so far have come up empty handed on its original design and schematics. What I do know is that it's either called a Model 40 or Model 45 amp, unless that's the actual model of the Baldwin organ or tone cabinet it came from. It was originally a two-channel mono amp in that it controlled both a high frequency driver and a low frequency woofer, and for stereo use had to have its original output transformers replaced with two new trannies to drive a left/right stereo pair of loudspeakers. It also had to have RCA output jacks and speaker binding posts added for it to be used for a stereo system, along with a power switch, an in-line fuse, and an IEC power cord outlet. After receiving the amplifier, I spoke to Will on the phone and he knows nothing of the history of this Baldwin amp since he's not an organ "buff"...he just knows electronics and basic tube circuitry and can rebuild/modify them, no matter if they're hi-fi amps, guitar amps, or from vintage radios or organs.

I'd just like to verify its model number and perhaps the year of manufacture, and whether it came from the organ console itself or from a tone cabinet, and where to find its original schematic diagram (not that it would matter much anymore since it's no longer in its original condition)...anything at all about this particular Baldwin organ amplifier would be greatly appreciated! I often wonder what became of the original instrument it used to power...how long did it survive providing music by various organists before being ripped out of its host, blah, blah, blah...obviously no one can answer those questions for me but the amplifier, and it's not sharing its secrets! It does provide beautiful music once more...it's constantly driving my loudspeakers with my favorite pipe organ recordings, and it sounds absolutely fantastic!

Thanks in advance for any assistance I receive concerning this old Baldwin organ amp.:thmbsp:

That's a nice modification on the Baldwin. I saw your previous thread at this link; it goes on for three pages with lots of pics:
http://forums.klipsch.com/forums/t/107100.aspx

IIRC the Baldwin model 40, 45, 46 etc refers to the organ model; Bogen had several similar amp model types such as PC, AD, etc. The PC model typically has 4 6L6GB tubes in mono parallel push-pull, with two 5U4GB rectifiers and either a 12AX7 or 6SL7, depending on design. However, that PC model was not 2-channel with a high frequency and low frequency output. The PC amp has a large choke and a single output transformer. As your amp has no choke (unless it is underneath) and two OPTs then, if that PC amp was used as the base model, it is possible that the choke was removed and replaced with a second OPT, a second 12AX7 added, and other wiring mods to make stereo PP vs mono PPP. However, from the layout and smaller size OPTs it looks like it may be the next option below.

Another possibility is that it was perhaps based on the tone cabinet amp, similar to the one currently on the 'bay 290250980016. This does have two 12AX7 tubes, four 6L6s and 2 5U4GBs. This looks closer to your amp and would have needed the second OPT to be added & appropriate rewiring to make the stereo PP.

I hope this helps.

I doubt the amp is from a tone cabinet. Most of the tube Baldwin and Baldwin-Leslie cabinet amps were smaller, functionally consisting of half the tube compliment (2-6L6s, 1 5U4, and 1 12AX7). Each of these were conservativelty rated at ~ 24 watts. On some of the old tone cabinet amps Baldwin had a neat feature. They had a spare, un-amplified, line out. So a pair of them could be used as stereo, or could be daisy-chained to increase the number of amplifiers for a given channel.

This amp is more likely to be a main cabinet amp. Baldwin had a couple different flavors of their early tube amps. Most often they would split the outputs of the pedals from those of the keyboards. In some of their bigger and more elaborate consoles each keyboard got its own channel.

As far as model numbers, Baldwin had quite a few variations, including different versons of their 40 and 45. But the base units of both were introduced in 1953. The 40 was a spinet model, while the 45 was a console unit.

Thanks for the info, so far...appreciate it.

From the interior pics I recently took, it looks to have a filter choke(?), and the majority of the wiring looks original (so do the caps and resistors...hope that isn't a problem later on down the road).:sigh: Maybe these images can explain more about this mystery amp.

Jim, that is a great looking amp!!!! great sounds for sure!

Bloody awesome Organ as well man!!!

Thanks for the kind words, WhiteSE...I'm lovin' this big tank of an amp!

And the organ was cool. I still miss it daily, and it was sold 2 years ago.

jt1stcav said:

Thanks for the kind words, WhiteSE...I'm lovin' this big tank of an amp!

And the organ was cool. I still miss it daily, and it was sold 2 years ago.

Click to expand...

dang man, sorry to hear bout the organ....

WOW, Nice amp

Ask the person who converted the amp for a list of what components were replaced. If there are any original resistors left in there (except the big green ones provided they are within tolerance) replace them with metal film resistors. Also if the capacitors have not been replaced or re-stuffed you need to replace them ASAP. For the coupling caps I would recommend a high grade audio capacitor. You can still get can capacitors.

Thanks for that advice, TR. I will contact Will Vincent immediately for the info.

You're welcome.

I would kinda think Will more than likely checked over everything such as caps and resistors as he made the conversion. And make sure things are up to spec before selling the amplifier.

Those Sangamo coupling caps could some NOS he had on hand. I would think he would have checked for DC leakage.

I wouldn't worry much about those green ceramic wirewound resistors, I kinda doubt they would be off tolerance. Unless they are dark and cooked looking.

1/2 watt carbon composition resistors tend to drift....but I guess he checked for tolerance and drift.... He may have had NOS carbon comps that he used, or replaced what was off tolerance.

Metal films are nice for tolerance, but if one goes too hog wild with metal fims and a simple tube amplifier circuit, it'll rob all the warmth out of it. Trust me.....

If it's a big deal, get a DMM and check these things.

Mike

Thanks, Mike. I have no reason for concern 'cause the amp sounds great and seem's in perfect working condition. I was just curious as I looked under the hood and found what looks like original components inside...I wasn't aware some people use NOS parts; just always assumed cap/resistor replacement would be with new equivalents.

When I eventually give Will a call, I'll ask him what's been done.

How do metal film resistors affect the sound?

I just noticed this post.

I'm not an 'expert' on Baldwin organ amps, but I can give you some info on this one. (Now, if it had been a Hammond I would have had a lot more info to offer)

This particular amp chassis was used on several models of Baldwin spinet organs and Baldwin tone cabinets. They made the blanks and stamped/drilled them as required. The signal input jack's position varied from being located in the front of the chassis to the top of the chassis. This was later incorporated as a minor design change but I'm not 100% sure when it went into effect. Most of these style amps were designed with two separate volume level controls; one for the pedals, and the other for the upper and lower manuals (keyboards). Then, each channel fed a separate speaker mounted in the organ.

Locations for various tube components and plugs/jacks were printed on the top of the chassis, and the printing arrangement itself sometimes indicated how the amp was to be used. I can plainly see that your amp chassis was printed in the same manner as many Baldwin spinet organ amps were. This was done to be more easily read when looking at the organ internals from 180° opposite of the upper and lower keyboard manuals.

Tone cabinet amps were often, but not always, mounted lengthwise into the cabinet from the back and printed accordingly to be able to read the print from that position. They often used this same type of oblong chassis. I'm also fairly certain that it's not from a model 45 (or 45HP2) console because they had HUGE amps in them, and they were nearly square in design. I believe most of the Orga-sonic models (that used a tube amp) also used a different amp configuration than the amp you have.

Your amp had the manual speaker & pedal speaker connectors removed (just to the right of the 5U4's) and a plate was added to cover the holes. Then, another plate was added to cover up the 8 to 10 smaller holes left by the removal of a small black tranny, a signal input jack, a remote cabinet jack, and a few pop rivet holes that were used to secure some of these components to the chassis. After that, he drilled holes for phono jacks on the top of one of the new cover plates, and for the new OPT's that were added.

The power tranny appears to be original, with the exception of the outer bell end which is painted a nice contrasting gray.

On the end where there are four phono jacks, he used one of the fuse holder holes for one of the phono jacks, then designed and drilled holes for the other three (based on that first original hole's position.) Then, he turned the fuse placement 180° to the other end of the chassis (near the power tranny), added a power switch, and another hole in the middle for the utility supply cable.

As far as the internals are concerned, I can see where he replaced the original coupling caps with Type 33 Sangamo's (most likely NOS), new jacks, etc. . . but, I can't really tell you too much about the rewiring without having photos with a much higher resolution.

. . Falcon

Will Vincent

Very nice amp indeed and congratulations. Is there a place where you can see other amps that he has built ? I see a Dynaco at Audiogon now. Any other organ amps and photos ? Thanks for your help.

Thanks, PRM. Unfortunantly, I don't think Will has his own website, and the only info I've ever found on his work are from AudiogoN and various audio-related forums such as AK, The Klipsch Forums, and maybe Steve Hoffman's. If you can find any, please let ME know...LOL!

FalconEddy, thank you for all your info...I really do appreciate it!:thmbsp:

So, I guess I can rule out that this particular Baldwin is not a Model 40 or 45 power amp, but most likely from their spinet organs...interesting. I do have the full resolution pics (approx. 1.90 MB) of its internals that I could e-mail to you, only if you wouldn't mind going over them and you're not busy (I've been to your site...loved your MP3 samples...and I know you must certainly be a very busy individual)!

Regardless, I am most grateful for what you've provided me already...actually, I'm grateful for everyone here whose given me clues as to this amp's heritage! Thank you all.

Baldwin

Hi Jim,

How can I contact Will ? I may see if he has some mono amps. Thanks for your help.

You can e-mail Will thru AudiogoN:

http://cgi.audiogon.com/cgi-bin/email.pl?0&1&membdir&zzAutospec