Hum and noise

[Mlazarus]

Hey all, so today i tested my markbass 15 and peavy max 100 10inch with the series 1 and DS-5. To my upsetting surprise, Just noise and hum.
I also used my stereo to mono cable. Same thing--noise. I turned the gain on the amps to 1, same problem. I know it's not the amps, because they BOTH can't be bad. Then i remember the TONEPOT procedure. That helped a little, but not quiet. The worst thing is that when i moved my body at different angles, the amps would get quiet or loud. When i walk closer to the amp, the nose would be very loud! I din't have this problem last week at a gig though. Perhaps not plugging into a strip would help.

I also read that the series 1 upgrades are worth it. Quieter than the original sound, but expensive. I wonder that it will cost shipping, parts and labor.

[lbpesq]

If I understand correctly, you aren’t getting any actual signal, no bass notes, just ‘noise and hum’.   If that’s the case, lack of the upgrade isn’t your problem.  Have you tried the 1/4” jack with a standard instrument cable?   Even if your bass is in need of the upgrade, you should still be able to get a good strong signal.   FWIW, I have ‘76 and ‘77 Series guitars that didn’t need the upgrade.

Bill, tgo

[Mlazarus]

Oh Sorry NO! I still get powerful volume and notes. Clean and clear. I just have the noisyness and hum. So what is my 'Hum cancelling Dummy" middle pickup doing??!

[edwardofhuncote]

Has this noise/hum just started recently, or has it been there since you got the bass?

[Mlazarus]

I noticed it tonight. Let's say there wasn't any noise before. What would that mean?

[edwardofhuncote]

It sounds environmental to me. You may have to adjust for RF noise at various places in your area of the world. Where I am, there isn't much, so I seldom ever have to fiddle with the trimpots to cancel any hum. Your situation is likely different.

The only other thing I can think of is shielding, or rather a lack of it. A few days ago you were musing over the idea of moving the pickup selector switch. If you do that, make sure to cover that hole back up. (with something that rejects bad juju)

Jimmy J will be awake in a little bit, and probably will have much better advice. I just have a bad case of workmares tonight. Hang in there. We'll get that axe sorted out.

*here's a link to the subforum for troubleshooting btw- https://club.alembic.com/index.php?board=160.0

[Mlazarus]

I made adjustments with the middle tone pots. They were cranked to the max before. Still some noise so i have to keep the gain on the amp really low.

NOW: as you know each pickup selection has its own power level i noticed. So when i hade the selector to both= loud front pick up only(with same volume settings really lower. Maybe i should use a volume pedal.

[JimmyJ]

Understand that the preamps in our Series basses can put out a very hot signal - close to line level and enough to drive a power amp directly - if the trimpots are set that way.  A description of those back panel trimpots can be found here:
https://club.alembic.com/index.php?topic=273.0

Also note that unlike passive instruments the tone and character of the sound does not change as you turn the output volume down - either using the trimpots or your front panel volume controls.  So you can set up the output gain of your instrument to work best with the gear you normally use.

Because you say you are only able to have the amp set on "1" it sounds like you are driving that input too hard. So you might start by trying to find a more compatible bass output level that will make more sense to your amp's input.  You can easily experiment with that using the pickup volume knobs. Turn on the neck pickup only and turn that pickup's volume knob down to where the amp would more normally be set so the volume coming out of the speaker seems about right.  (Not an exact science.) Then try adding the bridge pickup and find a similar level.

Getting that output level down to where your amps are operating in a more "normal" range might already improve your "signal to noise" ratio.

The idea of the rear panel "gain" trimpots is so you can set the overall output level and the balance of the two pickups so that when running in mono you get the blend you like.  I tend to run that blend with a bit more gain on the bridge pickup but the neck pickup has more low-end energy so they compliment each other in a way.  That blend balance is totally up to you.

Once you've found a better level to send into your amps the next step would be to turn up the front panel pickup volume pots and use the rear panel gain pots to achieve the same results.  The goal is to get the "mono" balance of the two pickups sounding the way you like it when you have the front panel volume controls all the way up.  That gives you the ability to fine-tune on the fly using the volume knobs, but you will always have your "mix" available as a starting point.

All that just to describe output level.  Sheesh, I'm long-winded.  Now give me a few minute to compose another post about hum...

[JimmyJ]

OK so ... the reason our basses have such a gigantic wide-open sound is because they've got these big hand-made single-coil pickups.  The problem with a big single-coil pickup is that it doesn't only hear the string vibrating in its magnetic field, it also hears any electrical interference being broadcast by various nearby equipment, or even just unshielded AC cables.

So Alembic founder Ron Wickersham (Mica's dad) devised an amazing way to deal with this issue by having the two pickups share one hum-bucking coil.  That's the black piece between your pickups.  This coil is essentially the same winding as a pickup but it has no magnet.  The result is that it does NOT hear the string vibrating in front of it but does hear all the electrical hash being transmitted by nearby equipment.  (Neon signs are among the worst offenders - essentially high voltage buzz transmitters.)

So the two "hum balance control" trimpots on the rear panel allow you to mostly cancel the interference that the pickups are hearing.  The official description of how to tweak these is here:
https://club.alembic.com/index.php?topic=269.0

Because these coils are not exactly in the same position and not "stacked" like standard humbucker pickups, they can sometimes hear interference at a slightly different "time" or phase.  So the cancellation of this noise was not always perfect.  I've been playing these basses since the mid-70s so I recall having to deal with this "un-rejected" hum and noise in various locations.  Certain clubs and even one Hollywood recording studio I found to be very problematic.  In those situations I'd gotten used to rotating the bass to find the quietest position and trying to stay pointed that direction whenever the music got quiet. 

In recent years our chief Wizard Ron devised a modification which can be done to our instruments to further reject noise.  But it is an arduous (and costly) job which must be done to the instrument onsite at Alembic HQ.  As you can imagine there's quite a backlog of service requests for this mod.

So again, before you jump into trying to get work done on your bass, get those output levels under control, go through the hum balance procedure, find the quietest direction to point the headstock, etc...  See if you can get the BIG BASS sound, the hum and the noise all under control.

Oh and here is a good description of the front panel "Q-switches" so you understand what they do:
https://club.alembic.com/index.php?topic=271.0

Keep the questions coming and you'll soon be explaining this all to the next new owner!

Jimmy J

[hammer]

I’m not going to go over what Jimmy has told you because his responses are quite clear as to the process you need to follow in order to minimize hum. I do want want to let you know that while it takes some tweaking in order to get things really quiet, on most older Series basses, in most situations, adjusting output levels and going through the hum canceling procedure is sufficient to minimize hum to a point where it’s not very noticeable. I have four series basses and the electronics upgrade was absolutely necessary on only one of them. That took a good deal of time and cost a good amount (price varies depending on the bass but can run from somewhere in the neighborhood of of $1,000 to close to $2,000) but the instrument is now perfectly quiet in all situations. The process is however labor intensive and Ron is the guy who does it so you would need to be okay with not having your bass in your possession for at least several months depending on the current backlog. The situation with my other series basses varies a lot depending on the bass. Two are quiet in just about all situations and neither needed an upgrade. The other, in one or two environments, has been a bit noisy but adjusting the hum canceling and being careful about my positioning has been all I’ve needed to do.

[s_wood]

May I suggests a couple of easy tests to determine whether the problem is environmental?  First, while standing slowly rotate 360 degrees and listen for whether the noise level changes as you do so. RF noise can be directional - there was one particular bar I used to play in where I had to stand at a precise 45 degree angle facing stage left to find a quiet place. Second, try moving your rig somewhere else; a different room or building. If you hear a big difference that strongly suggests that the noise is environmental.

[gtrguy]

Sounds like something broke or failed or a bad cable or battery to me...

[Mlazarus]

Amazing!! thank you for the thorough input JIMMY J and rest. It's funny, because TODAY, as i was testing the 82' series 1 i noticed when i stand up, turn in one direction, the noise and hum would stop! That seems "environmental"? Then i would experiment turning the pot controllers in the back, but making arbitrary adjustments, guessing and experimenting. Mica's method helped. I will remember the procedures. I can't forget keeping the selection switch on "OFF" before connecting to the DS-5 is important too. I forgot to do that and what happened was the amp's signal spiked seemingly causing the noise and hum to come back. Not sure about that, but i see it's so interesting to learn that this type of bass is NOT a "Plug and Play" instrument like all the other basses in the music world. Definitely set apart from the rest. It's worth the time to learn.

Here is an example; I let another bass player play it at a big club Two weeks ago, he played for a few songs. Later complained the power was so much he had to change to a bigger amp and keep the gain to 1(not to mention the truss rod plate and selector switch prevented him from performing his usual circus slapping. His underlying conclusion about the bass: HE DOESN'T LIKE IT!! lmao!! Stopped playing the bass. That was fine with me, i just wanted to hear how it sounded from watching that's all. LOL.

Hammer, can you give me the info i need to do the upgrade by Ron? I need to know the price as well. I may do this upgrade since my Series 1 is a noisy one. Thanks again people.

[Mlazarus]

gtrguy, i don't think my problem is cables and batteries. I have new energizers installed.

[StephenR]

Michael,

I asked Mica once about having  the electronics upgrade done on my 78 Series bass. If I remember correctly all she could give me as far as a price estimate was a high and low range. Every instrument is slightly different so they won’t know the exact price until it is in the shop and can be evaluated. Some basses need new pickups that are better matched etc. so the price can vary quite a bit but it will not be cheap. Best to call Mica and have her advise you about the process, price, and Ron’s availability to do the work. It is a small company, they generally are available to answer phone calls between 11AM-4PM PST. Great to hear how much you are enjoying your bass!