Neck pickup volume lower

[Mlazarus]

Hello everyone. I hope you are enjoying the weekend. I read this 2007 topic called: Low volume on bridge pickup". So, with this Series 1 bass player, he stated that the pickup gains on the back were maxed but did not understand why the bridge was sounding lower. Now, in my case, the pickup gains are maxed on my 82' Series 1 as well, yet the NECK pickup volume is lower compared to the other pickup (The opposite of the other player's situation). Mica, explained, based on his picture that the pickup connectors were on backwards and that the fangs need to be facing up. In my case (as you can see in the picture) my connectors don't have fangs to indicate the direction of connection. So how will i know if the connectors or on correctly. Note: These are the MK-11 2695 connections. Thank you for any input.

[JimmyJ]

Hey Michael,

I believe your connectors are the "right way up" even though they don't have obvious "fangs" and are not marked with the traditional "T", "B" and "H".  Nor do not have the color coded stickers used in later years.  But the underside of these connectors have two visible slots (as you can see in that other thread) so it looks like yours are correct.

FYI, the connector furthest to the right in your picture (closest to the edge of the board) should be the bridge pickup.  Hum canceller in the center.  And Neck pickup closest to the center of the board.

But I did notice something else... The opamp for your neck pickup (black muilt-pin chip closest to the center of the board) is a "5534" but doesn't match your others. Though I can't see the opamp under your ribbon cable, that center one has definitely been replaced at some point and is not the same as the other 4 chips on your board. Now I don't know enough about the specs of these chips to know if that would make any difference - though probably somebody in here does - and I'm not even sure Alembic still uses the NE5534AN.  But these chips are not expensive so you might think about getting a matching one for that socket.  Just a thought.

Jimmy J

[Mlazarus]

Thank you, Jimmy. Where would i get that NES5534AN? If I'm looking at the correct one, it's the one that is closest to the rainbow strip, correct? BTY, what is that rainbow strip for?

[Mlazarus]

Oh, it's to the right of that one. sorry.

[Mlazarus]

Here is a much better picture of the series 1 electronics. I circled the 5534 chip. Also, what is the object circled in  blue? It looks different and smaller than the two on the left. Is that normal?

[JimmyJ]

Yes, you can see that one you've circled in red doesn't match the others.  But I don't mean to send you on another long thread of concern and worry about your axe!  This tiny detail we've noticed may have nothing to do with your differing pickup volume levels because I would think all 5534 chips would have similar amplifying gain specs.  So this may not mean anything.  DON'T PANIC!

I expect this has already been mentioned in one of your other threads but, swapping the outer two pickup connectors is a great way to diagnose how your board and pickups are working.  If you swap those and the difference in gain also changes making the neck pickup (coming through the other channel of the board) much louder than the bridge pickup, then you may be on to something.

Not sure where to find these original NE5534AN chips because they may have been discontinued...  D'OH!!  And I don't know what the best current replacement chip might be.  So wait for somebody in here who actually knows what they're talking about (maybe even Mica) to pitch in and make some suggestions.  That advice may also be to ignore this little anomaly and just sit down and play that bass!!

The little metal can you circled in blue is a JFET or - in my layman's terms - a hi-fi, fast, low-noise, dual-transistor audio amplifier which is the first stage of our preamp board. 

Jimmy J

[gtrguy]

Your various 5534s should be pretty much the same. You can carefully pull them (instructions online show how easy it is) and swap them around if you want to compare them). Note the alignment notch for reinstalling them.

[Mlazarus]

Thank you. Yes, i will not panic. I'll just wait for others and Mica. I will do the Upgrade though (for the hum and to update what is needed.). I'm sure Ron will notice and clean up things like that and more. It's worth it to me. In the meantime, I Will play my bass! Lol. It sounds great. Has potential for more. 

[Mlazarus]

If i were to get a new op amp online. Ive seen one from phillips:https://www.ebay.com/itm/202692816005?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=DeH9N6xGRA-&sssrc=2349624&ssuid=VO-aAtw4Ry-&var=&widget_ver=artemis&media=EMAIL.

It looks like a plug and play, but i would want direction from Alembic to do it or not. All i know there is a difference in both pickup volumes. I just turn up the neck volume. Perhaps,  the bridge is set brighter and higher and i just notice the difference.

[JimmyJ]

See, I was afraid my observation might have this effect on you.  Don't obsess over this!  And maybe hold off on buying any EBay parts for the moment.  (That is not an "AN" chip you pointed to.  Here are 5 closer for $1 each: https://www.ebay.com/itm/401500440826?hash=item5d7b4a88fa:g:8Z8AAOSwmgJY5Kal.  But it's EBay so you never know what you're gonna get.  Hold off this!)

If you feel like messing around with this, try this simple experiment first: Swap the two pickup connectors so the bridge pickup is plugged into the connector near the center of the board and the neck pickup is plugged into the connector near the edge.  The bass's front panel controls and p/u selector switch will also be switched when you do this - but observe what happens to the output levels of the two individual channels.  Is the neck pickup now much louder than the bridge pickup?  Or do they still seem to be around the same level as before?

When you have the chance to try that, let us know the results.


Jimmy J

[JimmyJ]

Also, I've been reading online a bit and seen where audio folks will sometimes get a batch of these chips and "audition" them to find which ones have the best signal to noise specs.  Apparently they vary.  I don't know if that's standard practice or not and I don't know if Alembic actually goes through this "cherry picking" process either.  It may be a pointless exercise for the way our preamp boards are using these components. 

So again, we're getting caught up here in some extremely small details and losing focus on what we're trying to help you troubleshoot.  Try the above experiment when you get the chance.

Jimmy J

[StephenR]

Michael, it sounds like you have already decided to have the electronics upgrade done. If that is the case it would be best to just leave the existing electronics as they are. You will be paying for Ron's expertise, nobody else can diagnose your electronics and make any necessary upgrades and repairs better than Ron will be able to. I second Jimmy's suggestion to swap the pickup leads, it doesn't require removing/changing components and should give you a much better idea about why the pickup volumes are different. Meanwhile it does not sound like the disparity in pickup volume makes it impossible to play the bass so stop worrying so much and try to enjoy it. The Series basses have volume and gain controls, if the pickups don't sound balanced I change either the gain or the relative volume to even it out, for now I suggest you do the same. 

[Mlazarus]

That's why in the previous messages i stated -- I would want direction from Alembic and sure Ron would cover everything about the upgrade.  I'm not this panicking kid that wants to experiment. To old. It's just an interesting topic to learn about what makes these instruments work the way they do. And by chance IF Mica or Ron said that 5534 can be replaced and it will make a difference (with their own chip), i have a hunch they would make the changes at their shop.

[Mlazarus]

Jimmy, thanks for your observations. There must be alot of people who worry. This is not my 1st Alembic. They are very stable pieces of work.

[Mlazarus]

StephenR, your right too. The bass sounds great. Althought the gains are MAXED in yhe back, these is always the Bass anp volume and gain to make up.