L2000 preamp version dates

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L2000 preamp version dates

Postby DBStodd » Fri Apr 03, 2015 7:06 am

Hi All,
I'm sure this information is posted here somewhere, but I can't find it:

What years correspond with each L2000 preamp version?

Thanks for the help.
Todd
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Re: L2000 preamp version dates

Postby Ken Baker » Fri Apr 03, 2015 7:50 am

Edit: Turns out I've a fairl amount of data. See below.

Just curious... Why?

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Re: L2000 preamp version dates

Postby DBStodd » Fri Apr 03, 2015 8:03 am

Doing some comparison shopping, so if I know the dates ahead of time, I won't need to have the sellers check the preamp for me.
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Re: L2000 preamp version dates

Postby Glazenn » Fri Apr 03, 2015 1:33 pm

Just an indication.
My L-2500 is dated Jan 1997: REV 1.0
Year 2000 instruments are with REV 1.1
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Re: L2000 preamp version dates

Postby Ken Baker » Fri Apr 03, 2015 2:47 pm

Just remembered something.

A few years ago I tried collecting preamp photos & such from L Series players. USA & import. I ended up abandoning the whole thing due to lack of info. Still, I got a few. Here they are, with as much info as I have:

From my own L-2000 from 2000, now gone. Same as my 2008 L-2500.
Image

An unlabeled 1991 preamp
Image

From 1994, a v1.0 preamp
Image

From 1996, a v1.0 preamp
Image

A Korean Tribute preamp of unknown vintage
Image

An Indonesian Tribute preamp of unknown vintage
Image

2008 Tribute preamp from an L-2500
Image

A 1981 preamp from an L-2000 Series E
Image

A little more rooting around finds that I actually have a bit more info.

The v1.0 preamp is Leo's. I don't have a schematic for that one that I can actually call a v1.0, but I do have this and this. I have no idea as to the meaning of the "Ver 2" on the second one and how that might dovetail into what we see in the wild.

The v1.1 (L-2000, L-1500, Climax) preamp is Paul's. It hit paper in 1997. I have no notes when it went into production, but would assume 1997.

The v1.2 (L-2000, L-2500) preamp is Paul's. It hit paper 10/20/2011. I have no notes when or if (see next) it went into production. May be an "Oops! Excuse me" kinda thing.

The v1.3 (L-2000, L-2500) preamp is Paul's. It hit paper 10/28/2011. I have no notes when it went into production, but would assume 2011/2012.

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Re: L2000 preamp version dates

Postby Paul Gagon » Mon Jun 06, 2016 6:05 am

I did a post on a similar topic but maybe it's more appropriate here. It went something like this......

You know, I don't think I have ever explained the various versions of the G&L Bass preamp or why the changes were made. Seems like a good time to do that. The original preamp that G&L was using before BBE took over used an LM4250 chip and very large resistor values around the circuit. These resistors were of the carbon film type and were typically 5% or 10% tolerance. I was told that there were some complaints about the preamps being noisy (circuit noise, not 60Hz hum. Think hiss vs hum). This was primarily caused by the large resistance values coupled with the type of resistors used.

Rev 1.0 was the first preamp to address the noise issue. It was done in September of 1992 and used the LF441 chip and value scaled down the resistors. These resistors were made from metal film and had a tolerance of 1%. The frequency response was the same as the original but the circuit noise was quite a bit less. I took great care in evaluating the sound of this preamp against the original with a ton of bass players. No way was I going to mess with the sound of the bass. I just wanted to reduce the circuit hiss.

Rev 1.1 was done to go back to the LM4250 chip because it was being so difficult to get the LF441. Besides, with the proper value of the bias resistor that connects to pin 8 of the 4250 you can achieve the same noise spec as the 441. This version was done in October 1997.

Rev 1.2 was done in February 2011. This revision switched the position of R8 (1K) to the output side of R9 (100K) to reduce the voltage divider effect at the output (a very minimal change) and to bring the external 10K gain controlling resistor on to the PCB under the name of R11. Also, the on board high frequency boost resistor (R7) was changed from a 21.5K resistor to a 27.4K resistor to reduce the treble gain......a very small amount

Rev 1.3 was done in October 2011. This revision was to address complaints of picking up radio interference in the preamp. An RF input filter was added to the front end by using R12 (1K) and C7 (220p). This blocks any radio frequency signals from entering the input circuitry of the preamp.

There isn't any real difference in the sound of the various versions of the preamps. All these revisions were done to address a variety of noise, RF, or availability issues. From the excellent pictures Ken provided you can see that the PCBs were different colors. The dark green ones with the "G&L bass preamp" silk screen come from the Southern California Almatron company and are assembled in the G&L factory. The light brown/cream colored PCBs are from Cort and are used in the Tributes. The preamps from Cort have recently gone to using the TL061 chip and 5% carbon resistors so it's very easy to tell when you have a preamp from the Indonesian factory.

If I've left something out that you are curious about, let me know. By the way, all of this info is as of September 2014. I was laid off from G&L at that time so things may have changed since then.
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Re: L2000 preamp version dates

Postby bdgotoh » Mon Jun 06, 2016 11:40 pm

This is really great Paul, thanks very much. This doesn't really involve the preamp, but do you remember when they stopped putting the big green capacitors on the series/parallel switch? I'm guessing it was sometime in 1998 or 1999. Do you know why they stopped using them?
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Re: L2000 preamp version dates

Postby Paul Gagon » Tue Jun 07, 2016 6:44 am

Hi bdgotoh,

That date sounds about right. I'm not sure of the exact moment but the change came, as usual, from requests that came in from dealers and customers. There was a time when marketing received a lot of complaining about the noise/hum from the basses. This was when the bass had its pickups in the single coil mode (actually the mode is really more like series HB with one coil very heavily loaded down). Anyway, the request was to just make the pickups remain in humbucking mode in all positions so the decision was to have a two position switch that went from series to parallel HB.

As I'm sure you know, there is a "K" wiring for the basses (this was a request from Kurosawa the distributor in Japan). This switching allow for series, parallel and single coil. There have been several experimental wirings through the years but most never saw the production line.
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Re: L2000 preamp version dates

Postby bdgotoh » Tue Jun 07, 2016 5:15 pm

Thanks Paul, very cool to know what the K stands for!
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Re: L2000 preamp version dates

Postby TDR1138 » Wed Jun 08, 2016 10:19 am

Paul Gagon wrote:There have been several experimental wirings through the years but most never saw the production line.

Curious... what were some of the things that were tried?
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