Author Topic: 1979 Series I noise (Read 1616 times)

FC Bass · « **Reply #15 on:** May 03, 2015, 06:25:51 AM »

And Jimmy: I am enjoying the heck out of it, this baby is hard to put down.
Extremely inspirational and I'm sure it's going to make me a better bass player. :-)

FC Bass · « **Reply #16 on:** May 03, 2015, 06:32:56 AM »

Working on my post number count :-)

Mica: For refurbishing the DS-5: I found RAL 5024 to be closest, would that be the right color?

(Message edited by fc_spoiler on May 03, 2015)

mtjam · « **Reply #17 on:** May 03, 2015, 07:55:22 AM »

Your Series sounds great! Can't wait to hear more from you rockin' out live with it! Enjoy!

bob2 · « **Reply #18 on:** May 03, 2015, 06:59:43 PM »

flip, I don't know if your instrument has had The Upgrade, but here is the FAQ thread, just in case you have not seen it yet:
http://club.alembic.com/Images/16271/16310.html?1107541986

FC Bass · « **Reply #19 on:** May 04, 2015, 07:09:29 AM »

Thanx both!

No upgrade on this bass (I've asked Mica before purchase) only downgrades...

First thing I removed (before both recordings) was a ground wire that was attached to the bridge and ground lug of the 5 pin output (not even soldered, wire was twisted around bridge/lug...)
Also the powersupply had some poorly done mods...

terryc · « **Reply #20 on:** May 05, 2015, 12:45:46 AM »

In the 17 years I have owned my MK Signature I have never heard any erroneous noise coming from my bass at all, okay if I put directly close to an EM source(a TV) it certainly buzzes but under all the conditions I have played under I have never heard EM interference, those humcancellers really are the biz!

Enzo · « **Reply #21 on:** May 06, 2015, 07:20:38 AM »

Very interesting thread Flip, thanks for uploading those samples, they kind of match what I was hearing on my SII, at least from what I can judge thru my computer speakers.
My bass is now at the factory waiting to be tested by Ron, hopefully he can reduce the hum working on the same set of pickups or maybe even find part of the problem in the accessories (DS5 and cable).
Looks like it will be getting also a full respray! I bought some Yoga DVDs to help with the waiting.

FC Bass · « **Reply #22 on:** May 09, 2015, 12:53:09 PM »

OK, done some more detective work...
Looks like one of the signals is out of phase... (is that even possible?)

I've recorded the bass and treble out direct into a Roland VS recorder, each pickup on a seperate track with all controls (and Q) at 100%

24 MB wav file download

00:00 Sound as is

00:28 Phase reverse on bridge pickup channel

00:57 Phase reverse on bridge pickup channel, neck pickup gradually turned down

01:23 Phase reverse on bridge pickup channel, bridge pickup gradually turned down

01:50 Phase reverse on bridge pickup channel with chorus and reverb on treble channel, for fun :-)

Did you see my mails Mica?

(Message edited by fc_spoiler on May 09, 2015)

FC Bass · « **Reply #23 on:** May 09, 2015, 01:08:19 PM »

Also found that one of the flatpacks legs was bend and most likely shorting out to the leg next to it:

FC Bass · « **Reply #24 on:** May 09, 2015, 04:16:49 PM »

Looks like one of these fellas is installed backwards, could that be the reason for the signal being out of phase?

FC Bass · « **Reply #25 on:** May 10, 2015, 01:26:44 PM »

Note the reversed phase setting is also much quieter...

JimmyJ · « **Reply #26 on:** May 10, 2015, 02:02:08 PM »

Hey Flip,

Yeah, I like the last version with the effects. Ha!

OK, a couple things regarding your questions about the components mounted on the board... Last one first: Pay no attention to the printing on the FET, that does not indicate which pins are which. If it were installed incorrectly you would have no signal whatsoever coming from the bridge pickup.

Likewise for the bent leg of the flatpack opamp in post 1705. While you certainly don't want those to touch each other - if they were shorting then your hum balance circuit would not be functional at all.

The only possible fault you have discovered is the way the replacement pickup was soldered to the board (in post 1688). It looks like it was done professionally - as in, proper use of a wire-tie for strain-relief. And the way the board is laid out it would actually be a difficult mistake to make as the shield peels off first and the center wire connects logically 1/4 further. But since that pickup is obviously the only part that is non-original, this is the only logical fault that could be present. Follow my logic?

If you can confirm that this pickup is wired incorrectly, then you'd have something you could fix to bring it back to spec. (Can you take a better photo for us of just that spot? With better lighting? That might help us figure it out.)

Now a word about phase or polarity... When comparing one pickup to the other you will find that there is no exact in-phase. You can usually hear some change in the low end but the two pickups will never completely cancel each other out if thrown out-of-phase. That's because the pickups hear the string at different physical locations so the waveform is in different phases already. I think some guitars have out-of-phase as a switch choice right on the axe, no?

So this is part of the beauty of the Series stereo output - you can experiment with separate tone controls, effects, and phase of the individual pickups externally. You may decide you like it when the pickups are out-of-phase for soloing and in-phase for playing bass lines. Anything goes. The only right is the one you like the most.

Enjoy!
Jimmy J

FC Bass · « **Reply #27 on:** May 10, 2015, 04:05:13 PM »

Follow the logic totally, thanx! :-)

I think there's a way to see what the polarity of a pickup is, With a multimeter you should read either + or - when you put a signal through the pickup?

The signal (inner) wire was definately attached to the same strip where the other shielded wires were connected, so if the phase can't be reversed in the circuit the pickups must be out of phase I guess...
I just got in contact with the original owner, according to him it always had noise related problems and the pickup was replaced soon after he got it (old pickup was dead)
He got the bass in 1984 and it has been serviced many times.

Btw: When I got the bass I noticed was a ground wire attached to the bridge, in the cavity it was attached to the ground lug of the xlr output...

Here are some better pics:

(Click pics for full size version)

FC Bass · « **Reply #28 on:** May 11, 2015, 01:45:38 PM »

Also some positive notes :-)

This bass is absolutely stunning, plays like a dream and looks like she?s left the mothership yesterday.
There are only some dings in two spots, the rest looks brand new/showroom shine.
The side of the fingerboard is also under the finish, haven?t seen that on an Alembic before?
Frets, inlays and fingerboard also looks brand new, she has either seen very little action or must have been refinished. (Haven?t asked the original owner yet, but I doubt it was refinished)
Weight was a surprise for me, I was expecting a heavy monster but she is about the same weight as my 5 string basses. :-) (thanx for that also JJ! Like the low B a lot!) :-)

I also noted how well you can hear the effect of the chambered body when played unplugged, I?m pretty sure that also adds to the ?hugeness? of the amplified sound.

When the ?phase? problem is solved, I can move over to the next phase. :-)
I plan on upgrading the electronics to Series II, I do miss the master volume control a bit?
The pickup selector will stay in place, so it will be a classic 70?s/early 80?s SII layout. :-)

Here?s a recording I did with all controls at 100% (also the pickup gains (!)), each pickup on separate tracks.
Bridge pickup channel with phase reversed and chorus + reverb, no eq/etc on both tracks (just the direct signal from the DS5)
Tune is Jason Newsteds ?My friend of misery?: 15 Mb download

I love this bass! :-)

mica · « **Reply #29 on:** May 11, 2015, 02:35:17 PM »

Just hold a compass above the pickup to see if north is up or down - then see if the other pickup matches. There are both types of pickups out there, and since you've got them from 2 different vintages, it's certainly a possibility.

I sent you a reply a moment ago. I was out sick most of last week and didn't open my emails all weekend. Gotta love those little 7-year old disease vectors.