Parse error: syntax error, unexpected '<' in /home/lrbaggsc/public_html/forum/archive/index.php(545) : eval()'d code on line 1
Mystery Baggs preamp [Archive] - LR Baggs forum

PDA

View Full Version : Mystery Baggs preamp



silverface
08-23-2011, 08:16 PM
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:

Input/on (1/4")
Output (1/4")
Gain slider
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!

Thanks!

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!

Bryan McManus
08-24-2011, 08:20 AM
Hi Silverface,

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 [email protected] or call 805-929-3545, ext. 111, for more info.

silverface
08-25-2011, 09:42 AM
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.

Thanks again-

Jim

F15EagleLT
06-22-2012, 08:28 AM
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!

18
19

Bryan McManus
06-28-2012, 02:51 PM
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.

20

F15EagleLT
07-11-2012, 09:41 PM
Thank you very much for the diagram! This is exactly what I needed. I will report back when I get some time to work on it. Thanks again.

geewizdaddy
11-12-2012, 09:05 AM
Hi Bryan, I have a similar request for a pre-amp EQ installaed on a Godin LRBaggs model Acousti-tele.

Looks like a 9V system with the 4 sliders. Probably an older version of the schematic above. "
Baggs DEMeter"

There is an "In" marked on one side of the board and "out" on the other but it is not obvious where the battery leads go. Looks like the ground (black) is connected to the ground from the output jack. The sleeve acts as the switch when the jack is plugged in. But I can't tell where the (+) red wire goes.

Thanks in advance.

- G

geewizdaddy
11-12-2012, 11:29 AM
This almost looks like a prototype board. Hand laid soldering ribbon instead of copper and electroplate. Between the mid and bass slider there is a pull through point to solder to the other side. Approx 3/4 of the way up the slider.

franciscofalcon
12-14-2012, 03:54 PM
Hi all! this topic was helpfull for me! I "re-bought" my old Godin Bass (1996) pre-A4 series, and electronics are broke. same problems, this diagram came as a bless!!! another problem is that gain slider is broken... can I change it? thank you!

Caleb_Elling
12-17-2012, 08:35 AM
Francisco,
I sent you an email. If you can reply to it, I'll see if I can locate some parts for you.

-Caleb Elling
Tech Support

cromorne
02-25-2013, 05:28 AM
Hi. A friend of mine gives me an old lr baggs model fretless godin bass. The battery cables are out the preamp. I don't know where to connect them on the preamp. Please can you help me ? (Sorry for my bad English).

Caleb_Elling
02-25-2013, 08:00 AM
Hello cromorne,
What model is your Godin Bass?

cromorne
02-26-2013, 01:11 AM
Hello, I don't know what model it is. It is just written LR BAGGS MODEL. On the back it is written made in canada and a number: 8799. Hope it will help !

Bryan McManus
02-26-2013, 12:55 PM
Hi Cromorne,

Did your bass' preamp have one or two battery snaps?

If there was one, it is most likely an A4 model

If there are two, it is an Acoustibass model.

In the Acoustibass, the two battery leads are wired in series. When you hold the preamp so that the battery wire contact points are on the upper left, they are soldered (-)(+)(-)(+) and yes the positive from the first lead is connected to the negative of the second battery lead in the middle of the four contacts.

Please reply here or write to [email protected] for clarification.

cromorne
02-26-2013, 02:26 PM
Hi Cromorne,

Did your bass' preamp have one or two battery snaps?

If there was one, it is most likely an A4 model

If there are two, it is an Acoustibass model.

In the Acoustibass, the two battery leads are wired in series. When you hold the preamp so that the battery wire contact points are on the upper left, they are soldered (-)(+)(-)(+) and yes the positive from the first lead is connected to the negative of the second battery lead in the middle of the four contacts.

Please reply here or write to [email protected] for clarification.



My bass preamp had one battery. Not enough place for two with the preamp. I 'll make a photo of the preamp and you'll see what preamp it is.

tbarca
03-23-2013, 09:49 AM
Thanks for posting that schematic.. Broken battery wire and not a really clear view at the green board..
Thanks TB
Pre-EQ connection diagram.jpg

Storbotte
08-26-2013, 12:18 PM
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

Caleb_Elling
08-26-2013, 03:08 PM
Staffan,
The Acousticaster used the LB6 pickup. If the LB6 isn't sitting completely flat and even in the saddle slot, there can be string balance issues. I would recommend just pressing down on the saddle evenly, to be sure that it is fully seated. Beyond that, someone at a local music shop may need to be involved in order to achieve good string balance. The LB6 can be tricky to balance, so professional input is recommended.

Maxkt88
08-27-2013, 08:35 AM
Hello,
i have a Godin Acusticaster 12 string with broken preamp, the preamp ( 4 slider, 2 batteries, 1 opamp, 14 transistors) it's marked "copyright 1991 L.R. Baggs".
Is it possible to have the schematics to repair the unit?
Thanks in advance.

Caleb_Elling
08-27-2013, 09:58 AM
Hello Maxkt88,
Unfortunately, as part of our company policy, we are prohibited from distributing electrical schematics for any of our products. If you would like to send the preamp in for repair, you can call us at 805-929-3545, but I can not supply you with a repair schematic. All of our preamps are proprietary.

Storbotte
08-27-2013, 09:47 PM
Caleb, thank you for information and advice.

sangoku
12-09-2013, 11:35 AM
Hi mr. Caleb, i have this godin acousticaster. and its' preamp was broken. is it possible to buy like the who preamp? please lemme know. thank you :)

julien1410
05-19-2014, 06:33 AM
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.

20

Same kind of issue…
Just thank you so much for th scheme.

Have a nice day

TiPi Mods
09-23-2015, 04:10 AM
Hi
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.
Thanx

Caleb_Elling
09-23-2015, 03:07 PM
Hi
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.
Thanx

Hi 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?

TiPi Mods
09-24-2015, 03:29 AM
Hi 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:
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.

Caleb_Elling
09-24-2015, 07:12 AM
Ok,
On that system, you should be using a mono, or unbalanced cable. A stereo cable with a dedicated ring contact will not turn the preamp on correctly.

TiPi Mods
09-24-2015, 07:56 AM
hi, i am using a normal mono guitar cable...I just checked today different amps: with the mixing board everything works fine, with my Fender Blues Junior, sound is very low and distorted, and as said before: my Schertler Acustic amp only works, when I put the plug about halfway in the amp, just as much, as you can feel the tip touching on the inside of the jack.
but anyway I suppose, there should not be any DC Voltage on the tip.

Caleb_Elling
09-24-2015, 12:16 PM
Distortion from an electric amp, like the Blues Jr. is not uncommon. If the systems works well in a mixer, and with a certain setting on the amp, then there may not be anything wrong at all. The jack on the Schertler is the thing that is still confusing though.

If you are really using a mono/unbalanced cable, then everything should be working fine.

What model Schertler do you have? and what input are you plugging into?

TiPi Mods
09-25-2015, 04:35 PM
found out the problem: the electrolyt cap at the output was faulty. removed it..no more DC offset. (works also without it, a little less bass because of the smaller ceramic cap in parallel)

Wonderbread
09-28-2015, 07:23 AM
Does anyone have the schematic for this pre, or know the revision changes? Im trying to change the acousticaster pre back to the Pre-Amp Equalizer specs and Id like to avoid reverse engineering either of them.
Thanks!

Caleb_Elling
09-28-2015, 07:27 AM
found out the problem: the electrolyt cap at the output was faulty. removed it..no more DC offset. (works also without it, a little less bass because of the smaller ceramic cap in parallel)

i'm glad to hear that you were able to track down the issue. Excellent work!

Caleb_Elling
09-28-2015, 07:31 AM
Does anyone have the schematic for this pre, or know the revision changes? Im trying to change the acousticaster pre back to the Pre-Amp Equalizer specs and Id like to avoid reverse engineering either of them.
Thanks!

Hey Wonderbread,
Unfortunately, all LR Baggs circuits are proprietary, and have never been distributed outside of our shop.

The Preamp EQ and the Acousicaster preamp are very similar to each other, but I'm sorry to say that, due to policy, I can't go into any level of detail about the design.

I hope you understand.

norman
10-06-2015, 12:06 PM
I have a black Acusticaster LR Baggs ( No 7823) with a broken board/slider in the preamp. It's the single 9v battery type.

I'm trying to decide what's the best way to go with it. It looks pretty difficult, if not impossible, to fix the slider.

Is there a drop-in replacement preamp I could buy?

If I wanted to skip the preamp completely, is that an option. or it the pickup only functional with the rest of it?

Thanks in advance for any help.

(oh, I'm in the UK)

Caleb_Elling
10-06-2015, 12:48 PM
I have a black Acusticaster LR Baggs ( No 7823) with a broken board/slider in the preamp. It's the single 9v battery type.

I'm trying to decide what's the best way to go with it. It looks pretty difficult, if not impossible, to fix the slider.

Is there a drop-in replacement preamp I could buy?

If I wanted to skip the preamp completely, is that an option. or it the pickup only functional with the rest of it?

Thanks in advance for any help.

(oh, I'm in the UK)

Hey Norman,
If you can send me a picture or two of your preamp at [email protected], I'll see what I can do to help. We may be able to find a solution for the slider, or see if there is anything compatible as a replacement.