Quiet Notes on Upgraded Bass

[BottomE]

Hi folks

Finally got round to upgrading a bass that has been lying around for ages.

Its a Korean Squier P Bass from around 1993 ish.

The upgrades were:

Fender US P Bass PuPs
Vintage Wiring with Old style Oil/Paper Capacitor (bought off of Ebay)
New Pots
New Jack
New Bridge
New Strings

Before gigging the bass last night i played it at home into my USB interface linked to Cubase through headphones and all sounded good. Great in fact, the bass seemed to have come alive with the upgrade and sounded lovely.

On the gig i found that there were 3 notes that seemed lower in the mix than all the others.

F#, F, E - the 3 lowest notes in "normal" tuning. The higher up on the fretboard i go on the bottom string the less of an issue this becomes until at about 6th fret, Bb, it is performing as you would expect.

So after the long winded preamble may i ask for some suggestions of things that might help to fix this issue?

2 things to add are that this was not an issue on this bass before the upgrade.
The venue was one that i had never played at before so was unfamiliar with the room.

Thank you

Jerry

[Prime_BASS]

Probably room reflections. If it sounds fine through headphones (where room reflections won't play a part) then I'm sure it must be fine.
Double check though through an amp somewhere else though.

Doesn't make sense to me that only selected notes are quiet on 1 string and it be because of upgrades, it'd be more logical for the whole length of string to be quiet.

Edited June 21, 2014 by Prime_BASS

[3below]

Duff string?, if you have the old one put it back on, see if problem disappears or remains.

[BassTractor]

Maybe I misunderstand the issue here, but my knee jerk reaction was that this sounds like a phasing issue that is worst on the low E, and is reduced for each step you move away from that frequency. I would expect such a phasing issue to come back one octave higher up though, but with less of a nullifying effect and more of a modulating effect on the sound.

[Lozz196]

[quote name='3below' timestamp='1403384681' post='2482335']
Duff string?, if you have the old one put it back on, see if problem disappears or remains.
[/quote]

Definitely a possibility. I`ve had a couple of sets of Rotosound Steel Rounds recently where the E has had a differentish sound to the rest, a bit like it`s already worn in, as opose to the shiny new twanginess of the others. Though as Prime Bass says, as it all seems ok through headphones it is also a good possiility of the acoustics of the room.

Another thing to look at is pickup height. I`ve found that if I get mine to all sound roughly the same at home levels, at a gig the E string seems to get lost compared to the others. Whereas set it so it`s louder than the others for home use, and all even out at gigs.

[BottomE]

Thanks guys. Just sat with it now in USB interface/Cubase etc and sounds great. Even watching the output meter as i strike the notes and there is no noticeable difference.

I think i will take it out to the next gig and see if it was something to do with the room. May also take a Compressor. Start the gig in by-pass mode and if the issue re-occurs see if adding some compression will boost the necessary frequencies.

Longer term it will be string heights and PuP adjustment. Failing that i have some expensive firewood.

[zero9]

The problem is more likely to be with the amp/cab, room and eq setup on the night, not the bass. If the bass sounds fine through headphones / cubase, the problem is elsewhere. I once plugged into someone else's rig during a rehearsal and had a similar problem, when my bass just disappeared on certain notes.

[BassTractor]

[quote name='BottomE' timestamp='1403465134' post='2482975']
I think i will take it out to the next gig and see if it was something to do with the room.
[/quote]

You can't change the room that much, but as you say you can change settings.
What you maybe also can change is the distance of the speakers to the closest significant objects and walls. It's not hard to calculate a probably good distance or compromise if the worst phasing is around the low E.

BTW, IMS it's always a good idea to create a minimum lag for reflected sound of 50 ms, as a longer lag seems discernable by the human ear and thus not as ruining to the perception of the sound itself.
If this is wrong, somebody should be able to rectify me.

[BottomE]

Thank you folks.

BassTractor i lost you halfway through the post but get the gist. I was setup in a corner and due to space limitations my cab was almost pressed against 2 walls - 1 behind and 1 to the side. Didn't really have time to fiddle with the EQ properly because the set was bang bang bang one after the other and i had difficulty reaching the head with space limitations.

Got loads of EQ options on amp and a Sadowsky outboard preamp and MultiComp compressor. Might actually force me to use them.

Usually i use a Jazz Bass with Audere PreAmp straight into my amp and have got used to being able to do EQ from the bass and leaving the amp pretty well flat.

In addition, this is the first time i have played on the right hand side (looking at the band) for about 5 years and truth be told the whole band sounded a bit weird to me. Of course as the bass player i was the only one who noticed

Come to the conclusion that there were so many variables at this gig that maybe i shouldn't use it as a benchmark.

[BassTractor]

[quote name='BottomE' timestamp='1403552484' post='2483878']
BassTractor i lost you halfway through the post
[/quote]


I don't blame you, mate. I had a terrible time trying to word both my posts, was painfully aware that I didn't get the clarity I was after, and was hoping that someone would chime in with better wording.


Seeing that I lost you, please allow me to try and word this slower and possibly simpler.
Mind you, I mean no disrespect! It's just that we all are different, and there are also other possible readers besides you - readers with all kinds of knowledge levels as to the physics of sound.


It's about the speed at which sound travels and the consequences for the impact that a reflected sound has on the original sound. When a speaker is close to significant reflecting objects, then reflected sound added to the direct sound (this is mostly the same as amplitude modulation) will boost the sound at certain frequencies, nullify it at other frequencies and modify the overtone spectrum of yet other frequencies.

Most typical example is when the reflected sound comes in and gets blended with the direct sound, but is exactly one half cycle late, so the positive amplitude from one source coincides with the negative amplitude of the other source. In this case they'd potentially nullify each other.

When the time difference between direct sound and reflected sound gets bigger than a certain threshold (I think it's 50 ms, but may be wrong), the human ear starts recognising it as reflected sound, and this is some way reduces our experience of the modulation going on.
I don't remember this stuff more exactly right now, but one should keep in mind that the attack phase of any tone is crucial for our evaluation of the tone, and therefore also the lag time that the reflected sound has is crucial, unless it is more than the threshold I mentioned.

Anyway, since we know the speed of sound and we know the frequency of the first harmonic of every tone, we can quickly calculate crudely which distance to reflecting obejcts will likely have an effect on which tones we play on the bass.

Since you said the nullifying was worst on the E and got gradually less bad on higher and higher notes (if this is ideed what you meant - I'm still not 100% sure I understood correctly), my immediate reaction was that this seemed like a typical case of reflected sound nullifying the direct sound.


That does not mean however that this is the definite answer.
It's merely one of the causes of certain frequencies being weak and others strong. Standing waves (closely related, but not identical), absorption and sympathic oscillation (probably the wrong term, but it's all I could come up with) are some of the others.

[3below]

50 ms at 330 m/s (speed of sound approx figure) gives 16.5 m distance. Given the sound has to travel to the reflecting surface and back gives 8.25 m distance from reflecting surface. How helpful this calculation is is debatable.....Just ensure the cab is less than 8.25 m from any reflecting surface

[HowieBass]

Here's the Wikipedia page for room modes, the way sound of certain low frequencies can either boom or be diminished http://en.wikipedia.org/wiki/Room_modes

If you have to play the same venue try positioning the speaker cab differently, say at an angle to all of the walls in order to create longer sound travel paths so reflected soundwaves do not bounce directly back at the cab.

[BottomE]

[quote name='BassTractor' timestamp='1403644529' post='2484955']
I don't blame you, mate. I had a terrible time trying to word both my posts, was painfully aware that I didn't get the clarity I was after, and was hoping that someone would chime in with better wording.
[/quote]

Thank you for taking the time to articulate a splendid reply. I understand what you are saying and it does sound like a possible explanation which i hope turns out to be the case.

[BassTractor]

Thanks for your kindness.