55-01 Preamp change

55-01 Preamp change

Postby Ken Baker » Sun Oct 05, 2008 2:01 pm

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http://www.bassesbyleo.com/images/lakland/obp3_2.jpg

Just finished it up last night. Preliminary results are VERY encouraging. [smilie=music-smiley-005.gif] Quiet & powerful, even at 9 volts, there's a BUNCH more headroom here than with the Bart preamp.

More info later.

Ken...
...at least the doctors find me fascinating...
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Re: 55-01 Preamp change

Postby jshilgebass » Sun Oct 05, 2008 4:07 pm

Aguilar preamps are a popular choice for pairing with Nordstrand pickups. [smilie=grinning-smiley-003.gif]

We really, REALLY need to get all us modded 55-01 owners together for a SoCal minibassfest.


Joe Hilgeman
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Re: 55-01 Preamp change

Postby Ken Baker » Sun Oct 05, 2008 11:23 pm

Just a few more notes after playing and troubleshooting. I didn't get much test time yesterday. The bass made appropriate noises with everything set in the middle. WRONG!

As nice a difference as I noted above, it's even better now.

The bass had a little bit of single coil style noise to it. Mal, you may have noticed this? The blend pot was also acting a bit odd: When set in the middle, both pickups worked. It was fine when set to bridge. However, when set to neck it was effectively dead. I was scared that I broke a pickup in all the wrestling around. I went back in and checked all my wiring and it was as it should be. Mostly. It was correct given the information that I had from Aguilar, Nordstrand, and online research. Something changed, I haven't a clue what it is.

The Nordstrand Big Splits have three wires: a 22ga white, a 22ga black, and a 26ga black. The 22ga wires are connected to either end of the coil(s) and the 26ga is connected to on-pickup shielding. Online research indicated that the white is treated as "hot" and that the two black wires should BOTH be grounded. A call to Nordstrand was in agreement unless the preamp in question has a buffered input. So I connected both black wires from both pickups to ground, but that turned out to not be the correct thing to do.

The pickups I have here are relatively early versions of the big splits (based on wire color - the 26ga black is now gray), so there may be some minor internal difference. The OBP-3 could also be updated.

What I do know is that I lifted both 26ga black wires from ground and "safed" them so they can't short to anything in the cavity. Then I plugged in and tested. WAY more gain is now available and the blend works as it should. The electronics are also every bit as quiet as my L-2500, which as damn near silent. I'm going to check a couple points in the cavity tomorrow looking for appropriate continuity, as I'm now wondering if the pickups' black wire pairs are isolated. The black wire from the coil should be electrically isolated from the black wire for the shielding.

The tone is interesting with the TI Flats. They sound good on the bass, but at this stage seem to be a better match to a G&L L-series bass for me. Hell, I think they sounded better when things weren't working properly! The native midrange snarl of Leo's big soapbars, which just seems made for the Jazz Flats, isn't there with the Nords. Go figure...

===========================================
Added 10/6 after an in-depth continuity check of the neck pickup

The two black wires of each pickup should be electrically isolated from each other out of circuit. If this makes your head wobble, what I mean is this: If the pickup is not installed and is sitting on a bench, there should be NO continuity AT ALL between the two black wires. Nor should there be any continuity between the small black wire and the white wire. The large black wire completes the circuit to the coil and the small black wire provides shielding. As such in an Aguilar OBP scenario, both should be connected to ground.

The issue noted above turned out to be a problem with the entire neck pickup assembly distorting in shape as I tightened the height screws. As it distorted, the hot lead shorted to the shield. Because I initially had the shielding grounded, this effectively shorted the pickup to ground. At first I thought the pickup was bottoming on the cavity shield, but that couldn't be possible due to the foam "springs" used to provide.... spring. So I hooked up an ohmmeter and started tightening the height adjusters, and at a certain point the pickup shorted to ground. Once I realized where the problem was, I cut a couple pieces of closed cell foam that were about half the thickness of the ones I previously had in place, and a bit softer, and this allowed me to get the pickup low enough and still afford a little bit of adjustment.

When I put it back together after being apart for troubleshooting, I put the Elixirs back on it. I'll save the JF365's for later. Mal knows his strings, though the character is different now. The strings - not Mal. [smilie=cheeky-smiley-025.gif]

So what do I gots? I gots a bass that is every bit as hot as the L-2500. It's also very flexible. Set evenly, the Nords have what sounds to me like a nice Jazz Bass vibe. Neck alone with a some drive dialed in renders what I hear as a combination of vintage Precision with the immediacy of the SB-2's split MFD. Bridge only sounds amazing like EL SUB - my poor man's SR5.

If only it had a series/parallel switch. Then I'd have it all.

===========================================

Joe! Yeah, another hookup is gonna be in order. Plus, you and Harry need to play the L-2500 again. It has a very different feel to it now that I filed the nut.

Ken...

A short post script... After banging around in control cavities from G&L, Fender, Ibanez, Hofner, and now Lakland; and with all the tangles of wires in all of them, I can now grow to like the way that EBMM does it with everything on PCBs in the cavity. The only loose wires go to pickups, battery, bridge, and jack. OTOH, you're not afforded this kind of fun & learning.
Last edited by Ken Baker on Mon Oct 06, 2008 6:21 pm, edited 1 time in total.
...at least the doctors find me fascinating...
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Re: 55-01 Preamp change

Postby hmagman » Mon Oct 06, 2008 6:10 am

OK, you guys got me excited...

I was thinking Aggie for my 55-01, tell me more!

Mini-fest? By all means. [smilie=music-smiley-005.gif]
Harry
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Re: 55-01 Preamp change

Postby Ken Baker » Mon Oct 06, 2008 8:46 am

I've actually got to get out and earn a buck or two, so will post a few details later on. The short answer is that it's do-able and leaves the bass largely unaltered physically and completely unaltered outwardly. I used the OBP-3TK/PP.

Ken...
...at least the doctors find me fascinating...
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Re: 55-01 Preamp change

Postby Templar » Mon Oct 06, 2008 9:48 am

Nice shielding job too!
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Re: 55-01 Preamp change

Postby Ken Baker » Mon Oct 06, 2008 12:14 pm

Templar wrote:Nice shielding job too!


Not really. The cavity got what appears to be a cursory splash of shielding paint at the factory, where it takes at least two coats to make it work well. I just dropped in a layer of copper on the bottom and partway up the sides. I did this, more than anything else, to provide a common ground to all the pots. The circuit should be quiet all by itself, all other things being correct.

Ken...
...at least the doctors find me fascinating...
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Re: 55-01 Preamp change

Postby 57RIP » Mon Oct 06, 2008 7:04 pm

Jeeze you've been having big fun down there in So Cal. I might not have experiences that shell distortion thing as I was using that uber-thin matting as shield - I tend to run my pickups lower into the body than many folks. Seems to me that the tone improves - truly at this point it's a habit as I haven't re-compared in years I just kinda do it that way ... Lazy bugger I...

BTW - before I plunked down for those Elixir's I pinged Arbitrary over at TB. He's a monster player and into - at least for my scene - exotic basses (Ritter, Drozd, Modulus, Alembic...) His Drozd may be the penultimate, single nicest sweetest B E S T bass I have ever held in my hands, maybe that I've heard as well. Anyway - I got the Elixir advice from him as I knew he ran them on acouple of his regular axes including the Drozd. Having heard him from out front and through a variety of rigs - I figured I couldn't go too far off. Those strings I think fit in a mix nicely. The coating seems to knock some of the overtones back making them seem 'dead' in the bedroom tone sense -

the Woody Allen scene from ??? like a pesece a morte` but when in public... she is an animal ...

From out front them seem 'focused' and with propoer EQ - they cut through and hammer... seems like a good fit for the 55-01 to me.

How do you like the Aggie voicing ?

For the Del 'P I have an Audere 3ZB coming from TB. Vol, Blend, Mid, T stacked on B is the way it will go in. I'll have to drill a PG hole for the z-mode switch, maybe 1 inthe side of the body for the LED battery indicator. I did that in my L2500. It's down by the jack and when you plug in you get this nice brite blue glow that fades or flashes according to battery strength - the singer from The Crackertones suggested a mini-mirror ball for the end of my strap... funny guy ...
I used to look at my dog Smokey and think, "If you were a little smarter, you could tell me what you're thinking," and he'd look back at me like he was saying, "If you were a little smarter, I wouldn't have to." - Fred Jungclaus
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Re: 55-01 Preamp change

Postby Ken Baker » Mon Oct 06, 2008 9:51 pm

57RIP wrote:Jeeze you've been having big fun down there in So Cal. I might not have experiences that shell distortion thing as I was using that uber-thin matting as shield - I tend to run my pickups lower into the body than many folks. Seems to me that the tone improves - truly at this point it's a habit as I haven't re-compared in years I just kinda do it that way ... Lazy bugger I...


I've been having way too much fun, but hey... Lowering pickups is pretty common among the G&L troops, but I don't have the Nords down as far as you did. Then again, I like to have some adjustment to play with. It's that tinkering little tick that I have.

Those strings I think fit in a mix nicely. The coating seems to knock some of the overtones back making them seem 'dead' in the bedroom tone sense -

the Woody Allen scene from ??? like a pesece a morte` but when in public... she is an animal ...

From out front them seem 'focused' and with propoer EQ - they cut through and hammer... seems like a good fit for the 55-01 to me.


Agreed - very good fit for the bass and the pickups. I particularly like the smooth quiet action. I prefer the Powerbass over Superalloys for the same reason, though the difference isn't striking.

Sitting in the mix is a funny thing. G&Ls sit in the mix well; can even be over powering, but they sound good on their own. The Bongo and EL SUB don't sound so good on their own, but are great in the mix. This one is somewhere in between to my ears, and I think it's a combination of the mids and the EQ that gets it there.

How do you like the Aggie voicing ?


I just got done with an extended Cafe Walter session. A little jazz, some pop, R&R; even a couple Carpenters pieces. What I recall from passive mode pre-Aggie is excellent clarity, a very even sound across the strings, and enough mid bite to keep things exciting. Of course, the Bart preamp couldn't do anything with that. The Aggie, OTOH, can. It just takes what's there and makes it more without any coloration that I can detect, if that makes sense. Shy of a true A-B test, of course. Things sound pretty good with the EQ set flat, but not terribly interesting. Boost all three bands just a touch, and the teeth and claws come out. Mids are readily apparent, but not as snarly as G&L mids, and the highs are crystal clear. The bottom is HUGE; so huge that the bass control has to used carefully. After playing it some more and dicking around some with EQ, I think there's something to what I said earlier about the Jazz/Precision/SR5 comparison. A lot of that comes from the pickups and their locations, but the flexibility of the Aggie accentuates it.

It's a good match for what I like in a bass, for certain. I'm sure an Audere would be excellent as well, but bang for the buck is an big part of the equation and I can get 2 Aggies and some pots for the cost of one Audere. New - yes. Used onboard preamps make me nervous.

For the Del 'P I have an Audere 3ZB coming from TB. Vol, Blend, Mid, T stacked on B is the way it will go in. I'll have to drill a PG hole for the z-mode switch, maybe 1 inthe side of the body for the LED battery indicator. I did that in my L2500. It's down by the jack and when you plug in you get this nice brite blue glow that fades or flashes according to battery strength - the singer from The Crackertones suggested a mini-mirror ball for the end of my strap... funny guy ...


<Chuckle...> Kind of like the really bright flashing blue LED on my PDA/phone. It's so damned bright in the car at night that I have to remember to hide it to avoid the distraction. The BT headset is bad enough.

<edited after a more careful review of the diagram> There's an option to wire up the mid control range switch to a dual-concentric pot for high/low parametric control. Three band with para mid sweep. I may do that, but it'll be down the road as I've got push-pull for now. Thing is I'd have to stack the bass & treble to free up a body hole. It'll cost me some pots and knobs - maybe a full set of knobs so they match.

Think Carey could be enticed to do that series/parallel thing? [smilie=music-smiley-005.gif]

Ken...
...at least the doctors find me fascinating...
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Ken Baker
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