• TalkBass has been independent since 1998. Add your voice.
    Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
    Join free Log in
    Want zero display ads or expanded classifieds tools? Compare plans.

Need help with "reverse dead spots"...

J

JasonNL

Aug 23, 2008
116
35
The Hague, The Netherlands
#1
For as long as I can remember I have been suffering from something I call "reverse dead spots". I call it this way because instead of having a couple frets that are dead, I have a couple of frets, or notes to be precise - because they move around with different tunings, that clearly put out more volume than others at the same settings.

As we speak, I have my bass (Ibanez GSR190 from the pack) plugged in and tuned a half step down and at this time the 7th, 8th, 9th(but less than 7 and 8), 19th, 20th and 21st(but less than 19 and 20) fret (on the E-String) clearly produce a note that is of higher volume than all the others on the fretboard. IIRC this also happens on my Fender Classic 50s P, but I can't check this right now because it's been at the shop since last Saturday. It's also not amp-specific because I also had the same problem on my previous amp, which had a 1x15. My current cab is a 4x12.

I've thought a lot about this and tried a lot of different things to make it go away, but it just doesn't seem to help enough if I just mess around with the knobs on my amp.

I have a couple of things noted down that could be the/a cause of the problem:
-The size of the speakers combined with my location, because I am only sitting about 2meters/6-7ft. away from them.
-The EQ, because it's only on the B, C and C# and it's octaves on the E string, and upon further investigation also the high B, C and C# on the A String, maybe I need to do something specific with the knobs on my amp.
-The pick ups, maybe they're just crappy.
-The lack of a compressor, maybe I just need one of those.

I'm also pretty sure that it's NOT my playing, because if I slide to one of the trouble-notes from a regular sounding note, there is a noticeable increase in volume.

I hope someone can help me with this because it's really freaking me out, it's not that it's so bad that I can't play properly, it's just really annoying.

If you need anymore info on my rig/setup, don't hesitate to ask if you think it can help solve the problem.

Also, I wanted to do search but didn't know what to look for because I don't know what the 'official' term for this kind of problem is. I also hope this is in the right section, if not, I would like to ask a mod to move it to the proper section.

Thanks, Jason.
 
#3
Well, I've only tried my current Marshall half-stack in 1 room, but with my previous amp, an Ashdown MAG300 C115 combo, I also experienced the same problem in a different room in the same house as I currently live in, but also in the house where I used to live. I can't remember if it also happened when I tried it at the store and played it at my school.
 
#6
It sounds like a resonance issue to me. It could be due to the room(s), the cabinets, both seperately, or an interaction of the two. "Standing wave" just means a resonance issue - where the geometry is such that at some frequencies the reflected sound wave is in phase with the direct sound wave and amplifies the overall volume, and at other frequencies the reflected and direct sound waves are out of phase with each other and tend to attenuate the overall volume.
 
#7
a "reverse" dead spot is known as a wolf tone.

For the heck of it, plug the bass into a tuner. Play those notes and see how they read. For instance, I have a bass where the D, played on the D string, very quickly reads as an A.

These overtones actually amplify the note too.
 
#9
Rick Auricchio said:
Try playing in another room, with another amp, to see if it's wolf tones in the bass itself.

If it's not the instrument, then it's almost surely your room. Try moving your amp/cabinet to the center of the room and see what happens.
Click to expand...

that's why I mentioned the tuner. This will take amp, speaker, speaker placement, room et al.....out of the mix. ...so to speak.
 
#11
i think its a combo of instrument resonance and cab resonance. the string may just be vibrating perfectly for you PU config. into the cab. combine that with the room boundaries and you have a killer B. (or something like that)

ive seen this on a few P basses that have passed through my hands.
 
#12
Turn some knobs. IME, this has always been an EQ problem, and is especially aggravated by boosting frequencies. I struggle with some active bass because of this; it has contributed to my preference for passive basses. I used to work with a soundman who's low end eq ALWAYS made my D (open 2nd OR 5th fret 3rd) ridiculously loud.

This problem always affected my playing - I end up backing off on these notes, digging in on those notes. I used to get distracted enough by the volume of the note that I sometimes forgot to play the RIGHT note. That's what I tell people the problem was, anyway.
 
#14
I had this problem with one of my sixes. I was given two sets of Trace Elliot strings when Trace was still a going concern. I put them on and the bass became almost unplayable. Just about every other note was horrible. The trace strings came off and a new set from Carvin went on. Never has that problem again. I still have a pack of those strings unopened.

I would suggest you try changing your strings to a different make. Carvin's strings are very reasonably priced. I forget who actually makes them but it is a well known manufacturer.

Paul
 
#15
Thanks for all the replies so far, I think we're getting close to a solution.

Today I picked up my P Bass from the shop (sounded and played absolutely great with the new strings and bridge) and tried it through my amp at home. Same problem happened on the same notes.

I don't think it's the strings because on both of my basses I recently switched to DR Hi-Beams 50-70-90-110, and prior to those my Ibanez was equipped with DR Hi-Beams 45-65-85-105 and my Fender was equipped with Fender Super Bass 7250ML's 45-65-80-100, and with those strings both basses also had the same issue with the wolf tones, though I do think that it's a little more prominent on the Ibanez (both now and then). Maybe that has to do with the kinds of woods used in both basses.

I think the resonance is probably the problem, partially due to the room(s). Would adjusting the EQ help counter it? If yes, would one of those 31(!)-band EQ's rpsands mentioned help out and where should I look for one? I don't think I can 'fix' it with just the treble, mid, bass and tone shape knobs on my VBA400 because I suspect it's somewhere in between those, maybe(or probably) in the low-mid section.

I did try it through just the tuner as well, and even though I noticed some overtones, they didn't seem all that prominent, but this could be because of my tuner, which isn't really chromatic, just for tuning your bass and guitar. It's a Korg GA-40.
 
#17
JackANSI said:
Could it be that your neck has a bit of a curve to it, and the strings are actually getting closer (height-wise) to the pickups the closer you fret to them?
Click to expand...

This shouldn't be the problem, because both of my basses are set up properly (at least they ought to be, I paid good money for it). The strings do get a little closer to the pick up when I slide down the fretboard, but it doesn't become really noticeable until I pass the 12th fret or so, and even then it's only a very small difference. Still, by that logic the notes would get louder gradually on each string as I slide down the fretboard, but this isn't the case, it only happens on the specific notes I mentioned in the first post and the notes/frets after those seem to have a regular volume.
 
#18
Technically, what you're hearing could be boundary conditions in the room. With the amp against walls, floors, and ceilings you will get a boost in certain note frequencies.

Room modes are where standing-wave problems arise. The dimensions of the room cause loud and soft bass depending on where you listen. A standard 8-foot ceiling, for example, affects 71Hz, 142Hz, etc. That's why expensive studios are designed with high ceilings and no parallel walls.

Have you moved the amp to the center of the room? Then walk around and hear the difference.

EQ can be used to compensate for boundaries and room modes, but be advised that you'll need different settings when you move the amp around among rooms and stages. And amplifier EQ is often not tight enough to fix a wolf tone---most EQ bands are fairly wide, so they'll take out several notes. Your wolf tone might be tamed, but nearby notes are now weak.

Compression doesn't help (before you ask). Why? Because the room is doing the "amplification" for your wolf tones. Compression just keeps your playing level more constant---it can't compensate for the room.
 
#19
Currently, I can't move the half-stack and play it because it's 11:35 PM in The Hague and my dad and neighbors would go crazy, but I do hear a difference when I stand 3ft. from my amp as opposed to 6ft. when I play it, so I think I get what you're trying to point out.

I also figured that I would need to adjust the EQ everywhere I go, but I see this as an advantage as it allows me to balance out my tone wherever I am, and I usually write down my 'at home settings' for other effects as well, as those can also sound different through different amps and such when I go over to friends and bring along some stuff.

Would the 31-band EQ rpsands mentioned help me out, or is this overkill? If it isn't, what brands make them? If it is, what else would be a good thing to check out and by which brand?
 

Latest posts

Top Bottom
Back