Acoustic Electric Bass Pickup Issue?

Sojourner · #1 12-01-2010, 05:07 PM

I've got a cheapo Dean acoustic electric fretless to knock around. Does the job acoustically, but plugged in is another story. When I got it all of the strings but the E were nice and loud, where the E string wasn't as loud and had a distinct lack of low end.

Well I decided maybe the under saddle pickup was misaligned, possibly causing this. So I took the strings off and pulled out the saddle and the alignment of the pickup looked okay, but I decided to pull it out and reseat it anyway. Basically flipped it a little from its original position since it's just essentially a braided copper wire...didn't figure it would make a difference...and put it back in. Well it did make a difference...now the G string is really loud and the other 3 strings are much quieter, if not worse than the E string originally was. I tried to check out the Dean forums for suggestions, but you've got to register to even see them and approval of new accounts takes up to 3 days. Really need to use the bass this weekend for a little one-off Christmas song gig.

Any thoughts?

Martin89 · #2 12-01-2010, 09:05 PM

I'd say mic the soundhole for this weekend, wish I could help more...

Sojourner · #3 12-02-2010, 07:42 AM

Quote:

Originally Posted by Martin89

I'd say mic the soundhole for this weekend, wish I could help more...

Unfortunately, in the venue we'll be in that's not a great option. I fiddled with it some more and got it back to where just the E string was not outputting much. So then I shimmed under that string beneath the saddle and sensor and it seems to have boosted the output a bit closer to the rest. Probably manageable now. If I have time I may put a bit more shim under it to see if I can even it up more.

Any other tips are still greatly appreciated, though.

mccartneyman · #4 12-02-2010, 09:08 AM

Outboard graphic EQ boosted in the 110 or 250 Hz range should help the E. I've found that more than few acoustic basses have a weak E.

JTE · #5 12-02-2010, 09:28 AM

I went nuts this summer trying to fix a customer's ABG with the same issue (it happened to be a Dean, but the issue is related to the way they're made so it's not specifically Dean, but any ABG built in the same off-shore factory). That one had a weak string when it came in. And as we worked on it, the problem shifted from string to string. The way the under-saddle piezo pickup works is that it reacts to pressure to create the electric current. For it to work right, the bottom of the saddle and the top of the slot routing have to be perfectly flat in relation to the pickup. And the saddle can't bind in the slot, but not be so loose that it leans. There's a lot of minute variations involved that really require a pretty precise machining, and that's not a hallmark of the inexpensive factories. The saddle slot on the bass I was working on was noticeably wider than the piezo element, so that exacerbated our problem.

What we wound up doing was putting some sandpaper on a piece of glass to get a very flat surface, and buffing the bottom of the saddle. The slot routing seemed very very clean so we only buffed it a tiny bit and blew out all the dust and rubbing compound. That helped, but it was still uneven so we wound up with a trial-and-error positioning of the piezo element, using a little tape to hold it in place. Once we found a location that gave us relatively equal response we out one drop of white glue on the element to keep it in that location (but allowing for future easy removal).

John

Sojourner · #6 12-02-2010, 09:28 AM

Quote:

Originally Posted by mccartneyman

Outboard graphic EQ boosted in the 110 or 250 Hz range should help the E. I've found that more than few acoustic basses have a weak E.

Hmm...I've got a spare 31 band lying around. Maybe I'll give that a shot, too. Thanks.

T-Bird · #7 12-02-2010, 09:50 AM

Hi.

The "under the saddle" piezos are a major PITA to adjust for an even tone/volume.

WHAT A RELIEF, I was just beginning to type a lenghty response, but fortunately I refreshed first and JTE saved me

.

What he said, is basically how I do it as well. It takes a lot of time, but since it's Your time, not the techs, it's reasonably free.

Regards
Sam

Sojourner · #8 12-02-2010, 10:09 AM

Just saw JTE posted about the same time I did, too, so I'd missed that. I did notice that the saddle was leaning toward the neck a bit, so it seems the routing is a little on the loose side on mine. However, holding it upright while tightening the strings back seemed to keep it fairly straight. I'm thinking some extra shimming on the E might help, but if not I'll probably try the EQ route for this weekend and some other fiddling around for the long term.

iiipopes · #9 12-02-2010, 10:13 AM

Not only could the construction be suspect, but on cheap basses it is common to see regular guitar pickups in them, so the strings don't line up over the piezo crystals.

Sojourner · #10 12-02-2010, 10:30 AM

Quote:

Originally Posted by iiipopes

Not only could the construction be suspect, but on cheap basses it is common to see regular guitar pickups in them, so the strings don't line up over the piezo crystals.

Crystals? It just looks like a braided copper wire with a plastic sleeve over it in there...is there something else I should be looking for to align properly?