Mystery Baggs preamp
In a trade of some effects, switches and AB boxes I received something I've never seen and can find NO info about - a L.R. Baggs PreEQ.
It's in the original box with the Nipomo address. A CE sticker on the box and no other ID except for a numbered sticker on the circuit board - 59691- and the info to follow.
It's the same brown color as my ParaAcoustic DI (never leave home without it - it's saved my bacon on more than one occasion) but just has a few controls/jacks:
Treble, mid and bass sliders
Also says Pre-Amp Equalizer above the controls
It appears to have had a battery at one time - and leakage that damaged interior paint. There are rubber pads that appear to be battery mounts.
There's a metal belt hook slipped onto one side that looks like it was originally attached to 2 otherwise useless scres on the back (the back also has a thin rubber pad.
Then it gets REAL weird - there are two 1/8" jacks unevenly mounted at the end where the battery apparently was. Both are connected to the board at different places.
Without a manual or schematic I don't want to plug in my One Spot and two adapters, plug it in and cook it. I'm not an expert at tracing solid-state circuits, but CAN read a schematic.
If anyone has a manual and/or schematic for this little gem (well, actually it's about 3/4 the size of my ParaAcoustic DI) I'd really appreciate it. I've searched the web, looked at all the Baggs discontinued items and come up empty - so I can't even test it!
loosened the circuit board screws and found more data - on the 1/4" end "Copyright LR Baggs 1991" and on the "power end each 1/8" jack is connected tip-positive to 4 respective "+" and "-" marked eyelets on the PCB. From there both seem to go to separate diodes and from there I have trouble tracing it. Hope that help with ID, manual or questions!
Last edited by silverface; 08-23-2011 at 09:29 PM.
Reason: more info -
Thanks for your inquiry. That LR Baggs product was known as the "Preamp EQ," also often called the "Line Box." The serial number you provided indicates it was made in December of 1996. It has not been produced in 12 or more years. The preamp inside the box, however, is still available. It is one of the earliest of LR Baggs' production circuits and was used in the Godin Acousticaster model guitar as well as in that Preamp EQ device.
It uses two 9V batteries for a series 18V power circuit but it sounds as though somebody wired two 1/8" jacks to where the battery leads connect to the circuit board(+/-/+/-). It's possible they made a special one-off way of connecting to the batteries externally or of connecting two AC adapters.
LR Baggs circuits are proprietary and we do not publish or distribute schematics for any of them, new or old. We can provide what info we can about the connections to and from that preamp. A replacement can also be made available. I can also offer you the option of upgrading from that old product to the nearest equivalent, the Para Acoustic DI.
Please email bryan@lrbaggs or call 805-929-3545, ext. 111, for more info.
Last edited by Bryan McManus; 08-24-2011 at 09:22 AM.
Reason: more info
Thanks much for the quick reply!
It doesn't look like a one-off as the "power" jacks are not evenly placed, the rubber battery-space padding is in place and the inside paint is a bit rusty in the area, indicating leakage. The belt clip was also unbolted, the bolts put back in place and the clip slipped over one side of the case.
My guess is a former owner was using it on the floor or on a pedalboard, had a battery leak and decided to convert it to a dual-line power supply using two filtered wall-warts (or unfiltered Radio Shack specials and enjoyed the resulting hum. ;-) ).
I'm trying to wrap my brain around the use of two of the plugs...with 1/8" adapters, and I need to check polarity as well...from a One Spot multi-pedal power supply (or Power Brick, or whatever...I just happen to use Visual Sound's One Spots). Probably need to look closely at the traces and the "sum" point to see if that would actually supply 18V or...as I've seen in a couple situations...be an odd math conundrum where 9+9=9!
The purpose of the jacks I'd confirmed just after posting when I used a mirror and jeweler's loupe (easier than pulling the circuit board) and saw the wires from the jack running to a pair of solder eyelets marked "+" and "-". I did not want to randomly plug it into 2 9V sources, though - since the person modifying it wasn't too precise about positioning the jacks who knows what other mods they may have done - and I don't want to cook it.
I'll pull the board, make sure there are no anomalies, and if I get a good connection reading from the two outside +/- eyelets I should be OK. In fact, I may just pull the board from the case, remove all jacks and hard-wire it in a routed "effects well" on my bizarre Fender pedal steel (which has 9V power hard-wired...I'm sure I can get 18v in it).
Other subjects emailed privately.
Godin Acousticaster where to solder the 9v battery connectors to LR Baggs circuit?
Hey guys - I was given a non-working guitar a long time ago from a band-mate (I am a drummer
who plays a little bit of guitar as well). I knew nothing about this guitar, except it had broken electronics and he failed in trying to repair it. It has sat in one of my closets for years until recently one of my daughters has shown an interest in trying to play it. I would love to fix this thing up for her since it is a very cool looking guitar. In hopes of repairing it myself, I finally did some research on it and found out it is an old Godin LR Baggs Acousticaster. The guitar's internal circuit board says "LR Baggs 1991" and has 4 slider potentiometers (Gain, Treble, Mid, Bass - I think it is the same board which you guys are discussing here in this thread). Since there are no publicly available schematics, I need to see if I could get some help.
It has two individual corroded 9v connectors which have become completely seperated from the circuit board. I can solder and would have no problem buying a couple of new 9v connectors and soldering them into place, but the problem is that I cannot figure out where exactly they would need to be soldered to the board. I can see an area of the board where my band-mate tried to solder them but he burned up the area pretty good (looks like he tried to solder it with a freakin' blow torch).
Do the 9v connectors get chained to each other thus leaving one positive wire and one negative wire to connect to the guitar\board? Or is there really 4 seperate solder points for the two connectors? Also, one or two of the wires coming from inside the guitar look like they are supposed to be attached to the board also (but who knows where)? If I post a couple of pictures could one of you guys show me where to solder the connections? Are we allowed to post pictures here?
Thanks in advance!
The attached image shows where two battery leads connect into the left side of the top edge where it says "- + - +." The first pair is one battery lead, the second pair is another battery lead and the middle two wires are joined by the terminals in the circuit board.
Pre-EQ connection diagram.jpg
Thank you for the diagram. I bought an Acousticaster the other day and now it works after some solder works. The are still some things to do in order to get it sound well. The 6th string is too loud and maybe 3rd and 4th are a bit weak. Do you know if you can ajust these things in a way? I first tried bronze strings, then magnetic steelstrings. I think that the sound level is à bit more even with steelstrings. What is recommended? Hope you can give some advice. /Staffan
Same kind of issue…
Originally Posted by Bryan McManus
Just thank you so much for th scheme.
Have a nice day
some mystery on my Godin LR Baggs preamp: on the output there is a voltage of about -5V on the tip of the plug. my Schertler Amp naturaly does not like that. Only works, when I put the plug halfway out of the amps input. otherways there's only a little bit of hum and no sound.
Someone knows what could be wrong? ( its the 18V preamp, all the connections look like on the pictures posted on page 1 of this thread.
Last edited by TiPi Mods; 09-23-2015 at 06:19 AM.
Hi TiPi Mods,
Originally Posted by TiPi Mods
When you say that the output voltage is -5V, are you referring to the output level? Or are you actually getting DC voltage to measure on your guitar cable?
If you have to unplug the cable half-way from the amp, then there may be something in the guitar jack that is not connecting correctly. That's my first thought at least. I assume you are using new batteries as well, right?
Thanks for your answer:
Originally Posted by Caleb_Elling
yes, I m getting DC voltage on the guitar cable tip...maybe I should say it the other way round,: the guitar cable ground ( ring) is 5V positiv. As the output is blocked with a capacitor there should not be any DC on the tip of the cable, I suppose.
And yes: fresh batteries, I measured about 18,6 V
when I unplug it half from the amp, it seems that there is no more DC comin in, so it works perfectly, sounds great and loud.
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