Strange Harmonics from my Fretless

[adamg67]

I'm hoping someone can help me get one of my basses sorted, I fear that is cursed and will end up being sold for parts!

I won't go through the whole story, just the latest chapter. It's an Overwater by Tanglewood that has been fretlessed, and there's no reason it shouldn't be a loverly bass. The problem is it has some weird harmonics that come in as you get past the 5th fret (well, ex-fret line) on the D string and get stronger as you go up. They're also there high up the A string and on the G string, not exactly the same on all 3 but close enough that it seems to be related to the pitch of the note and not which string or where on the fretboard you are.

I've stuck a quick clip on soundcloud that illustrates it fairly well especially at the end: [url="https://soundcloud.com/adamgx/fretless/s-MjM1Y"]https://soundcloud.c...retless/s-MjM1Y[/url]

Things I've tried so far:[list]
[*]Adjusting string height and neck relief, no difference no matter what I tried.
[*]Checking theres nothing loose anywhere, doesn't seem to be.
[*]Dropping the pickups as far as possible (though it happening in different places on different strings didn't point towards them, but just in case), no difference.
[*]Changing strings, had flats and now has a set of tapewounds on, no difference
[*]Taking out the shims that were tweaking the neck angle (don't like them in anyway, I think I'll tweak the bridge saddles instead of putting them back in), you guessed it, no difference.
[/list]
So I've run out of things to try from my own experience, but that's not much.

Any ideas for other things to try? Preferably ones that might help work out what's going on

Edited June 26, 2016 by adamg67

[paul_5]

Have you checked that the strings aren't touching the fingerboard (right at the end) and giving you automatic 'pinch harmonics'?

It can happen if there's a slight bow in the neck and your action's set very low.

Edited June 26, 2016 by paul_5

[adamg67]

[quote name='paul_5' timestamp='1466971296' post='3080167']
Have you checked that the strings aren't touching the fingerboard (right at the end) and giving you automatic 'pinch harmonics'?

It can happen if there's a slight bow in the neck and your action's set very low.
[/quote]

Yeah, I've had it with plenty of relief in the neck and the action very high and it does exactly the same thing.

[Manton Customs]

As it's been defretted it's most likely that the board needs dressing, there's probably a bump in there somewhere. Basically the fretless equivalent of needing fretwork! To check: first slacken the strings, then set relief to zero (flat neck) then check the board with a straight edge a long the string paths. My bet would be one of the filled fret slots is proud.

Edited June 26, 2016 by Manton Customs

[HowieBass]

[quote name='Manton Customs' timestamp='1466974077' post='3080201']
As it's been defretted it's most likely that the board needs dressing, there's probably a bump in there somewhere. Basically the fretless equivalent of needing fretwork! To check: first slacken the strings, then set relief to zero (flat neck) then check the board with a straight edge a long the string paths. My bet would be one of the filled fret slots is proud.
[/quote]

I think this seems quite likely and that unwanted sizzle you're getting is the string making more contact with the fingerboard than it should.

[adamg67]

[quote name='Manton Customs' timestamp='1466974077' post='3080201']
As it's been defretted it's most likely that the board needs dressing, there's probably a bump in there somewhere. Basically the fretless equivalent of needing fretwork! To check: first slacken the strings, then set relief to zero (flat neck) then check the board with a straight edge a long the string paths. My bet would be one of the filled fret slots is proud.
[/quote]

That was my first thought, and I wish it was that, but it doesn't seem so. I'll recheck it when I get chance, but I can't find anything. I made sure the guy who refretted it paid special attention to the fretboard, as it did have bump in it before, but I now get the harmonics a long way either side of where that was, and right down to the end of the fretboard.

[MoonBassAlpha]

It sounds a bit like the truss rod is vibrating in sympathy at certain notes. Might be worth tightening the truss rod so the board is [i]more[/i] flat.You can raise the saddles a bit to stop the buzzing. I had just this on a Rickenbacker 2 weeks ago, it turned out the truss rod on the treble side was very slightly loose, so I nipped it up almost imperceptibly, and the weird noise was gone.

[adamg67]

[quote name='MoonBassAlpha' timestamp='1467029180' post='3080547']
It sounds a bit like the truss rod is vibrating in sympathy at certain notes. Might be worth tightening the truss rod so the board is [i]more[/i] flat.You can raise the saddles a bit to stop the buzzing. I had just this on a Rickenbacker 2 weeks ago, it turned out the truss rod on the treble side was very slightly loose, so I nipped it up almost imperceptibly, and the weird noise was gone.
[/quote]

I was wondering if it could be something like that, one thing I've just rememberd and should have mentioned already is that it's easily most noticeable if I put my ear to the back of the neck, it does feel like the neck is resonating. I'll tweak up the truss rod (carefully!) and see how that sounds.

[MoonBassAlpha]

Let us know the outcome either way.
Sometimes if you rap your knuckle on the back of the neck you can hear the rod vibrate.
I've a couple of basses with carbon fibre reinforcing that make the neck very stiff. At various times I've found that I've had to loosen the truss right off to get the right relief, and the whole thing has subsequently buzzed like a ***********r, so I've had to compromise on either action, string gauge or relief.

[adamg67]

I had another go at this last night, with no joy. I tightened the truss rod up so the fretboard was actually slightly bowed, with the truss rod really feeling nice and tight to turn, with no improvement. Then I gradually eased it off until I had plenty of relief in the neck and could feel the lack of tension, again no change. I had the action high the whole time to make sure it's not the fretboard, but it is definitely related to the frequency of the note rather than position on the fretboard.

I'm wondering if it's to do with the neck joint & pocket? Anyone ever seen that?

Just as an experiment I might take the neck off and pad it with something so it's a nice tight fit at each side, and maybe try something between the neck and the body.

Thanks for the help anyway.

[MoonBassAlpha]

How about a slightly loose tuner peg? It's surprising how much buzz they can contribute. Sometimes you do get a frequency dependant resonance, but some do it all the time on pretty much any note. I'm borrowing an EUB at the mo with a very loose tuner peg (it has had a whack at some point) I've wrapped a hair scrunchie round that peg and the next one as a temporary cure.

[adamg67]

[quote name='MoonBassAlpha' timestamp='1467202789' post='3081869']
How about a slightly loose tuner peg? It's surprising how much buzz they can contribute. Sometimes you do get a frequency dependant resonance, but some do it all the time on pretty much any note. I'm borrowing an EUB at the mo with a very loose tuner peg (it has had a whack at some point) I've wrapped a hair scrunchie round that peg and the next one as a temporary cure.
[/quote]

Worth a try, especially as padding out the neck pocket made no difference at all - nothing seems to! Given the way it behaves, I'm worried that there's some part of the truss rod mechanism that's touching the inside of the neck, no matter how much tension there is. I'll check the tuners, and if that doesn't work I'll need a second opinion.

[Twincam]

I'm sorry I'm just not getting what you hear and I'm a bugger for hearing noises!.

Ok I don't think anything is coming through. Truss rattle, tuning peg rattle will not come through an amp but you will still hear it untill the amp is fairly loud!

I've had one of these basses albeit fretted and I honestly can't hear any thing odd even at the end. Like I say I'm a bugger for picking up on these types of noises.

Have you tried playing it really loud?
Also some basses do have a certain resonance to them. Just like dead spots I suppose.

Oh are the strings correctly seated?

[Andyjr1515]

I think I can hear what you are describing on the clip, although not totally sure. What I can hear is a reasonable level of resonance that you would hear on, say, a good acoustic 6string.

Is it that what you are describing and hearing? Basically a harmonic at the same pitch as the note being played?

If you play the bass acoustically, do you still hear it?

[adamg67]

[quote name='Andyjr1515' timestamp='1467266897' post='3082315']
I think I can hear what you are describing on the clip, although not totally sure. What I can hear is a reasonable level of resonance that you would hear on, say, a good acoustic 6string.

Is it that what you are describing and hearing? Basically a harmonic at the same pitch as the note being played?

If you play the bass acoustically, do you still hear it?
[/quote]

That's it, yeah, and it's a lot more noticeable when playing acoustically - I should dig my mic out and try recording it that way. It probably seems more obvious to me in the soundcloud clip because I know what it sounds like. It's also more obvious compared to much lower notes than I've got in the clip, if you're playing and you run up to a high D it really sticks out.

I think it'll need to go to someone who knows what they're doing, I'm just loathe to spend more money on it.

[adamg67]

[quote name='Twincam' timestamp='1467241966' post='3082269']
I'm sorry I'm just not getting what you hear and I'm a bugger for hearing noises!.

Ok I don't think anything is coming through. Truss rattle, tuning peg rattle will not come through an amp but you will still hear it untill the amp is fairly loud!

I've had one of these basses albeit fretted and I honestly can't hear any thing odd even at the end. Like I say I'm a bugger for picking up on these types of noises.

Have you tried playing it really loud?
Also some basses do have a certain resonance to them. Just like dead spots I suppose.

Oh are the strings correctly seated?
[/quote]

It is a good point that it's not so obvious through the amp, so maybe for band work it would be fine, I do think it does still come trhough a bit though. I might have a play with headphones on and figure out how bad it is. It's definitely not anything loose, I've checked everything now, and the strings are seated nicely both ends.

[Andyjr1515]

[quote name='adamg67' timestamp='1467272422' post='3082347']
That's it, yeah, and it's a lot more noticeable when playing acoustically - I should dig my mic out and try recording it that way. It probably seems more obvious to me in the soundcloud clip because I know what it sounds like. It's also more obvious compared to much lower notes than I've got in the clip, if you're playing and you run up to a high D it really sticks out.

I think it'll need to go to someone who knows what they're doing, I'm just loathe to spend more money on it.
[/quote]


Two things - diametrically opposed - occur to me in my random musings:[list]
[*]If it is purely acoustic and is indeed resonances through the whole body and neck (which acoustic builders like me would give their back teeth for) and doesn't really come through when fully amplified, I wouldn't worry about it because 'it is a good thing'. Indeed, the same characteristics will be actually enhancing the tone through the amp.
[/list][list]
[*]The other thought is totally opposite. If it is not the body, then something else is resonating. On 6-string guitars, I quite often get this from the nut to tuner stretch of the string. In fact, I pop a buffer - in the shape of a velcro cable tie - on some of my guitars to stop it happening:
[/list]


Same thing sometimes happens with jazz tail stocks where there is a length of string between the stop tail and the bridge, and also the springs in a Stratocaster tremolo chamber are notorious for doing the same thing.

Is there a long run from the nut to the tuners or do you have a string tree?

Edited June 30, 2016 by Andyjr1515

[Andyjr1515]

I'm interested in this because of the revelation I gained when building my first acoustic steel-string relating to the black magic of 'tap tuning' a top when you are carving the braces.

I've just been doing some checks on my fretted and fretless solid bass guitars. Here I have been listening to the harmonics produced on ONLY the other three strings when I play D. My method was a sharp pluck at each fret of the D string and immediately mute [i]with two fingers to avoid creating a harmonic on the D, [/i]and then listening for a harmonic ringing out from the E, A or G by muting each one in turn until the harmonic, where I can hear one, abruptly stops. Some REALLY interesting results:[list]
[*]Up to the 5th fret on D, almost no harmonics induced in the other three stings
[*]5th Fret; strong harmonics on both basses, E on f/less and G on fretted
[*]6th Fret; no harmonics on either bass
[*]7th Fret; harmonic on A string on both basses
[*]8th; harmonic on G on fretless; no harmonic on fretted
[*]9th; A on fretless; E on fretted
[*]10th; E on fretless; no harmonic on fretted
[*]11th; A on both
[*]12th; G on both
[/list]
Worth trying the simple test to see if it is simply the other open strings vibrating at a harmonic frequency.

If it is the above, it is probably simply the mark of a good bass. It is the body vibration that sets the strings ringing at the various harmonics. Usually the better the 'tone wood' the more it happens. For electric basses and guitars, this effect is rarely strong enough to come through the pickups and hence the one side of the 'tone wood makes no difference' argument. On an acoustic it is fundamental and critical to the tone and clarity.

So in summary, if it is this, don't worry on three counts:[list]
[*]It means your bass is made out of decent wood
[*]The audience aren't going to hear it
[*]When you are playing a riff rather than fretting individual notes, the open string is rarely open long enough for this to be heard even if it could be
[/list]
It's a long shot but I'd be really interested in the results of your further checks....

Edited June 30, 2016 by Andyjr1515

[Twincam]

My old aria ive just bought if I pluck the g and totally mute all the strings even the full length the bass. The bass still rings out must be the truss rod? But it really does sing. The pickups are unsophisticated (how I like them) and wouldn't pick up such nuances

[adamg67]

Very interesting. I'll have a play again this weekend, and especially see how it sounds at volume.

If it resonated across the whole range it might be fine, I think the problem for me is how much the tone changes in specific places - but again, the real test is whether that comes out at stage volume or when recording I suppose. I can try cutting the highs as well, I'm aiming for a really low thumpy DB tone anyway.

I'll check out the strings above the nut as well, and check out the open strings, although I play floating thumb and with a flat left hand so usually I'm ok keeping the rest of the strings muted.

Thanks everyone for the advice and suggestions.

[Ghost_Bass]

Obvious question, sorry to ask, but you've tried different strings? Maybe that brand/gauge may resonate more with the bass whilst a diferent set may be silent.

[juliusmonk]

This is a good point - I once had a strange resonance on a low B and it ended up being the string.

[adamg67]

[quote name='Ghost_Bass' timestamp='1467373499' post='3083179']
Obvious question, sorry to ask, but you've tried different strings? Maybe that brand/gauge may resonate more with the bass whilst a diferent set may be silent.
[/quote]

Yeah, I changed from a set of Overwater round wounds and D'Addario tape wounds and the effect was about the same.

I didn't get chance to have a play with it last weekend, but will do have another when I can get up the enthusiasm