HELP - Volume drop on L2000 bass

Seeing as how we are fortunate to count Paul Gagon as a member here, it seemed like a good time to give him a home to stretch out in and relax a little. Maybe exercise the grey matter and present a little history of the guitar and bass (amps too!) from his perspective as one of the eminent designers of our time.

Got questions? Great! Good questions might be, "What kind of windings are on the S500 pickup and why?" Or, "What was the thought process behind the MJ-4?" Troubleshooting questions should remain in the regular forums (he reads those too). Finally, please be mindful of how I feel about tech questions via PM or email.

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Re: HELP - Volume drop on L2000 bass

Postby Ken Baker » Fri Apr 07, 2017 4:33 pm

Tomvl wrote:Paul is the same DC resistance for a L-2500 Pickup ? If not , which are the valued ?


Comparing the documented DCR for the L-2500 coils and the L-2000 coils, the difference would be in the neighborhood of 100Ω to 200Ω per coil. Both have 5000 turns of 42ga wire. Strangely enough, the docs I have show the L-2500 coils having the lesser DCR of the two.

Now before you jump back wanting to know how that could be, consider that several factors are in play that can affect the measured DCR of a coil for a given number of turns. The biggies are temperature and the coil wire itself (there are probably others, but these are the biggies to me even though the differences would be relatively small).

As temperature goes up, resistance goes up. As temperature goes down, resistance goes down. It might not be a huge difference, but it's there. Temperatures in Fullerton, California, USA can get into the low to mid 30°(F) range in the dead of winter (early morning) and around 110°(F) in the summer (mid afternoon). It's an old factory and temperature control isn't its high point.

Wire size tolerance must also be considered, as it will vary a tiny amount from manufacturer to manufacturer and even from spool to spool. The DCR of 2800 feet of 42ga magnet wire from one manufacturer will likely be a little bit different compared to that from another manufacturer. The manufacturer will have a published range of resistivity and/or ampacity for a given wire type that they sell, and that range is what produces the differences in DCR.

Want more? Sure! There may have been different ohmmeters used. The test leads may have been different. The test lead probes may not have been scrupulously clean. The testing method might be a little different from test to test. There may have been a raging Santa Ana Condition when the measurement was taken. Or the heat & humidity (maybe even a thunderstorm) from the summer monsoons we have here.

This isn't rocket science and never has been. Does accuracy count? Yes, of course, but within reasonable boundaries for the object in question. If you want each coil of every L-2x00 pickup to measure exactly 4.3KΩ, prepare to pay a LOT more for the bass because the cost will ramp up in a hurry.

For the sake of argument, my recommendation would be to use Paul's numbers above.

Oh! And let's get back to the topic at hand - murger's L-2000 and its volume issue.

Ken...
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Re: HELP - Volume drop on L2000 bass

Postby Tomvl » Fri Apr 07, 2017 8:37 pm

Thanks very much for your answer
Anything below 500 Hz
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Re: HELP - Volume drop on L2000 bass

Postby murger » Sat Apr 08, 2017 7:14 am

Hokay!! here goes...
1- Removed the battery - aside from active mode not doing anything (DUH!), there isn't any difference volume wise using all 3 pickup configurations - parallel mode being a little louder.
2 - All the controls function as they should, although the treble cut isn't as smooth as I'd like - most noticeable effect occurs at the bottom of the counterclockwise end
3 - Series mode resistance - Front 8.2k, Both 4.5k, Bridge 9.5k
Parallel mode - front 2.1k Both 1.1k Bridge 2.4k
Now for the fun part - this is something that I should have mentioned, but you can berate me later - I just really noticed it now (thought it was my little amp, but it does the same with the big one too - haven't used that one in a bit) - at full volume, there is a noticeable hum (actually quite noticeable - wouldn't want to run this in public)- cut the treble, hum drops - cut the bass, hum drops more - preamp on, more hum and same scenario with treble and bass - preamp on with treble boost - lots of hum and I'm thinking that Treble boost shouldn't be that harsh - it actually rings!!
There isn't a ground issue (I've had those with other guitars)
Strange that the tech I brought it to never even picked up on that :roll:
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Re: HELP - Volume drop on L2000 bass

Postby Paul Gagon » Sat Apr 08, 2017 8:13 am

murger wrote:Hokay!! here goes...
1- Removed the battery - aside from active mode not doing anything (DUH!), there isn't any difference volume wise using all 3 pickup configurations - parallel mode being a little louder.
2 - All the controls function as they should, although the treble cut isn't as smooth as I'd like - most noticeable effect occurs at the bottom of the counterclockwise end
3 - Series mode resistance - Front 8.2k, Both 4.5k, Bridge 9.5k
Parallel mode - front 2.1k Both 1.1k Bridge 2.4k
Now for the fun part - this is something that I should have mentioned, but you can berate me later - I just really noticed it now (thought it was my little amp, but it does the same with the big one too - haven't used that one in a bit) - at full volume, there is a noticeable hum (actually quite noticeable - wouldn't want to run this in public)- cut the treble, hum drops - cut the bass, hum drops more - preamp on, more hum and same scenario with treble and bass - preamp on with treble boost - lots of hum and I'm thinking that Treble boost shouldn't be that harsh - it actually rings!!
There isn't a ground issue (I've had those with other guitars)
Strange that the tech I brought it to never even picked up on that :roll:

OK, let's go through your numbers.
1- Glad all the pickups work but usually people find the series mode a bit louder and more powerful then the parallel mode. Wonder if we have a bit of mis-wiring going on here. Check the wiring diagram that Ken has posted here on the site and compare it to what you have.
2- Glad the controls all work. The pot taper controls the "smoothness" of tone transition. Some people like linear tapers and others prefer audio tapers. It's a personal thing. The taper in the L-2000 treble control is audio.
3- The coils seem to be OK, however, you have one of those "over wound" bridge pickups. There was a period of time when someone on the pickup line decided that the L-series pickups needed to be hotter and more bassy sounding. Not sure how long it went on but the moment I became aware of it, I made them switch it back.

On the hum issue. Does the hum get louder when you take your hands off the strings and are not touching anything metal on the bass? If so, you are dealing with a shielding issue. If the hum stays basically the same, you have a marginal ground on one of the controls. Even though it might look like you have a solder connection to the back of a pot, sometimes it has a bit of corrosion under the connection and isn't quite up to snuff.

This is one of those times when I wish I had the bass in front of me. For a volume drop like you are describing I would suspect either a funky solder connection or a bad control. Try this. Re-solder every control connection and check the wiring with the diagram Ken has on this site and report back.

Oh, thanks for doing the ohm meter thing and sharing the results.

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Re: HELP - Volume drop on L2000 bass

Postby murger » Sat Apr 08, 2017 8:38 am

The hum stays the same regardless of whether I'm touching the bass or not - looks like it's time to warm up the soldering iron.
That may not happen for a while, seeing as we're in the middle of tax season (I own a bookkeeping business) - hopefully I can get to it between now and the end of April!
I'll let you all know how this turns out!
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Re: HELP - Volume drop on L2000 bass

Postby murger » Wed Jan 17, 2018 5:30 am

Here's the update you've all been waiting for :D Sorry for the delay, but I finally got a chance to work on the beast just recently. I actually sat down and resoldered EVERYTHING before Christmas (I actually had a weekend to myself!). Result - no difference, aside from a burnt finger. I suspect the IC board may be the culprit, so I got pissed and ordered the whole thing, pots and all! One hour later - The BEAST is BACK!! I had forgotten how loud this thing is. I had bought an Ibanez Soundgear as a temporary replacement (I know, I know), and it's not quite as punchy. It may get retired!
I'd like to thank everyone for the input and suggestions.
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Re: HELP - Volume drop on L2000 bass

Postby Paul Gagon » Thu Jan 18, 2018 6:15 am

murger wrote:Here's the update you've all been waiting for :D Sorry for the delay, but I finally got a chance to work on the beast just recently. I actually sat down and resoldered EVERYTHING before Christmas (I actually had a weekend to myself!). Result - no difference, aside from a burnt finger. I suspect the IC board may be the culprit, so I got pissed and ordered the whole thing, pots and all! One hour later - The BEAST is BACK!! I had forgotten how loud this thing is. I had bought an Ibanez Soundgear as a temporary replacement (I know, I know), and it's not quite as punchy. It may get retired!
I'd like to thank everyone for the input and suggestions.

That’s great news! Congratulations and thanks for the update.

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