Baldwin 801CP

[Bluebird_12]

Hey Bill;

Thanks for the info...now it makes sense. Since it is the preamp being powered instead of the pickup in the original Baldwin guitars, that is why guitars like my Ovation or guitarchuck's Zimmerman that were wired to work with an outboard amp or preamp, work just fine. You (I) may not get the total Baldwin type sound but there is the advantage of being able to mate the Prismatone to any modern preamp of your chosing.

Wayne

[Hendrik]

I made some pictures of the inside of the 22.5 volt battery box. I thought some might find it interesting.

[craigdobbins]

The Prismatone does work w/o the Baldwin preamp and power supply, but it sounds infinitely better with it. The power and depth doesn't come through with another preamp.

If you have the pickup and the internal preamp (it's mounted in a glob of reddish brown goop on the other side of the jack), you won't get anything w/o the external power supply.

Craig

[Bluebird_12]

Thanks for the pics of the battery box...I've never seen one. There was a Gretsch classical with a Prismatone?

I suppose finding an original preamp and battery box would be like finding the needle in the haystack...

Wayne

[craigdobbins]

Yes, the Dorado electric classcial, imported by Gretsch. There are a few pictures of Chet with one. You can hear it on the "In Concert" 2-LP set (Chet, Jerry, Dolly, Charlie Pride, and more).

And remember, Baldwin owned Gretsch at this time, so there's the connection.

Craig

[guitarchuck]

Here's a photo of Chet with his Dorado by Gretsch with a Prismatone pickup:

[Richard Hudson]

That looks like a dressing room at the new Opry House.

[Doug_H]

The Prismatone does work w/o the Baldwin preamp and power supply, but it sounds infinitely better with it. The power and depth doesn't come through with another preamp.

If you have the pickup and the internal preamp (it's mounted in a glob of reddish brown goop on the other side of the jack), you won't get anything w/o the external power supply.

Craig

I wonder, how big is that "glob of reddish brown goop"? I've made FET preamps with discrete components that fit inside a fat guitar plug and use a separate outboard battery box (9V), or phantom power from a board or amp. It just takes a very few dollars worth of parts and the ability to solder to make a very good preamp. If the Prismatone preamp is sealed in a 'glob' there probably isn't much to it (which is typical of 'endpin' type preamps...and/or point to point wired preamps in a 'glob'). I'd love to see a schematic for one. Anybody? Anyone want to 'de-glob' one to find out what's in there? Just knowing the particular transistor(s) they designed around (or it's specs, since the original transistors may not be available now...happens alot with older stuff) would be enough.

[Texican65]

The pre-amp in mine is covered in a "black goop" and its about 1 inch wide by 2 inch long.

Dow

[Brian Ingram]

I think that's what most people forget is that the cord coming from the battery box plugging into the jack (preamp) IS A STEREO CORD. ... I wonder if this is one thing that makes the sound so distinct to the Prismatone.

I'm new here, but am an electronics guy. The schematic Bill posted of his brother's power supply tells the tale.

The stereo cord is needed from the battery pack to the guitar because the actual guitar signal is carried on one conductor, and the d.c. power is carried on a second conductor. Of course, the shield is ground for both circuits.

A regular mono cord runs from the battery/power supply to the amp, because the cord will only be carrying the guitar signal and ground connection.

Hope that helps.

And I know nothing about the onboard preamp, so here's my guess as to why the preamp helps so much:

Any ceramic or piezo element will output a pretty strong signal when pressure is applied; so you'll get "something" with no preamp/power supply. However, these type of elements like to work into a very high impedance, and that is best presented by a preamp close to the pickup (short wiring is best).

Any amp's typical input impedance is plenty high enough for electric guitar pickups, but not enough to avoid bass roll-off with piezo/ceramic. So a preamp/buffer/booster is called for. That's exactly what Baldwin gave ya, and it obviously works. My guess is it presents a nice, high impedance for the pickup, and a fairly low output impedance to drive a long cable to the amp. I couldn't venture a guess on any corrective EQ, but it might not even be needed within the preamp.