neck dive

[OldG]

Tried everything I could think of to cure the neck dive on my Tokai Jazz, including moving the buttons and weights... nothing worked for any length of time (the neck would creep downwards throughout the set).

I was at the point of adapting to play while supporting the neck, when my wife bought me a strap with a sheepskin type underside - this kinda locks the strap to the fabric of your shirt or whatever you wear to stop it slipping round. Works perfectly!

[mcnach]

[quote name='Evil Undead' post='1312578' date='Jul 22 2011, 12:02 PM']The most obvious solution to me would be to move the strap button to counter the dive - an inch or two towards your shoulder should do it.[/quote]


Unfortunately not nearly enough on a bass with this body shape.

These telecaster shaped basses look great, but neck dive is the price you pay for looking so cool.
I have the same issue with this:

Edited July 23, 2011 by mcnach

[mcnach]

[quote name='OldG' post='1313545' date='Jul 23 2011, 09:12 AM']Tried everything I could think of to cure the neck dive on my Tokai Jazz, including moving the buttons and weights... nothing worked for any length of time (the neck would creep downwards throughout the set).

I was at the point of adapting to play while supporting the neck, when my wife bought me a strap with a sheepskin type underside - this kinda locks the strap to the fabric of your shirt or whatever you wear to stop it slipping round. Works perfectly![/quote]


I tried that with a suede strap... but it just pulled my shirt and took it with it, rather than curing the neck dive.

[mart]

[quote name='Mod_Machine' post='1313420' date='Jul 23 2011, 12:14 AM']....
Also with regards to strap pin placement at the rear I can confirm that the further up the bass towards the shoulder it is moved the WORSE the neck dive becomes. There is a very good post somewhere on bass chat discussing the mathematics and science behind this, but ultimately the fact I've moved the strap pin down toward the jack socket and not returned it to it's original position is also an indication that in 'practice' the science behind that post is accurate.
...[/quote]
That fits with my understanding of it. But I'd love to read that post you mention that discusses the science behind it - if you could try and track it down, I'd be very grateful.

[quote name='Mod_Machine' post='1313421' date='Jul 23 2011, 12:15 AM']For example what about creating a cavity at the rear of the bass loaded with weights to weigh down that side?[/quote]
I'd be wary of doing anything that added weight. So how about simply putting a cavity in the top horn, to lighten that end, and hopefully shift the centre of gravity towards the bridge?

[Mod_Machine]

Some pretty cool ideas.
I'll try and locate the thread over the next couple of days and hotline it.
I read it a while ago and remember thinking at the time thank god I don't have a bass that suffers from neck dive so did save a linkstraight to it even though now SO relevant!

[synaesthesia]

The tele shape will not balance with a strap if you have a 34" scale neck and you can place you neck buttons anywhere, I've tested it quite extensively. I have a lefty tele bass I made, it is one of my main studio basses and most of the time I play with it seated. For normal balance, you need some wood hovering around the 12 or 13th fret to mount one strap pin and the other can be at the back or slightly higher. For a tele shape, as far strap pins go, as the yanks will say 'ferget about it.'

However, for stage strapped use, I added about 250g - 400g ( I can't remember - weighed it but did it mostly by feel ) of lead shot to my strap at the body end. You get these from scuba diving shops and its about 5 quid for 1kg soft bag. You can open it up and take out what you do not need. You can seal the bag once you have determined how much lead shot you need. The dive weight is sealed and encased in a soft Hard drive case or phone case, you can get these for £1. and this is stitched or attached to the back end of the strap. My strap is a Slapstrap and has enough velcro to firmly fix this weight bag.

It adds a bit of weight to the proceedings but sometimes only this bass will do what I want to, from amongst the stable of better balanced basses. The weighted strap works for me. See low res iPhone pics.

Edited July 23, 2011 by synaesthesia

[mart]

[quote name='synaesthesia' post='1314284' date='Jul 23 2011, 10:10 PM']... For normal balance, you need some wood hovering around the 12 or 13th fret to mount one strap pin and the other can be at the back or slightly higher. For a tele shape, as far strap pins go, as the yanks will say 'ferget about it.'
...[/quote]
That fits with my impression. When I checked the centre of gravity for all my basses, they were all in quite similar places, whether the bass balanced well or appallingly. From that I concluded that the problem is largely down to the length (or lack of it!) of the top horn. (Since the bottom buttons on my basses all happen to be at the centre bottom, and the top buttons are all on the top horn, so their positioning is limited by the length of the horn).

So yes, an unbalanced bass basically needs a longer horn. Which makes me think an unbalanced bass needs a cross bar like those old Roland guitar synths:



Most of us would shy away from bolting a plank of wood from top horn to headstock, which was what led me to try attaching a string from the top horn (or somewhere on the strap) to the headstock, to try and pull the anchor point some way towards the headstock.

Edited July 24, 2011 by mart

[molan]

How about one of these:



Or these:



Love this product shot, lol:



Sorry - forgot product links:

[url="http://www.fretbase.com/blog/2010/06/the-heads-up-strap/"]http://www.fretbase.com/blog/2010/06/the-heads-up-strap/[/url]
[url="http://www.neckheavy.com/index.html"]http://www.neckheavy.com/index.html[/url]

Edited July 24, 2011 by molan

[essexbasscat]

[quote name='molan' post='1315092' date='Jul 24 2011, 08:36 PM']How about one of these:



Or these:



Love this product shot, lol:



Sorry - forgot product links:

[url="http://www.fretbase.com/blog/2010/06/the-heads-up-strap/"]http://www.fretbase.com/blog/2010/06/the-heads-up-strap/[/url]
[url="http://www.neckheavy.com/index.html"]http://www.neckheavy.com/index.html[/url][/quote]


Thanks for that B, very handy to know

[Mod_Machine]

The bass is a short scale (well same scale as the EB0 which is 30.5! I stole the bridge from that donor also as its quite heavy weight and the only good thing about the eb0 is that the intonation can be set pretty tight and stay there!)

I have recetified the dive quite a bit (certainly doesnt fall as 'low' as the BEFORE shot above!) and this has eased the weight on my neck hand trying to keep it up a little and thus reducing chance of cramp.

Ive done this by moving the strap pin at the bridge end down about 1/4 inch. This on its own didnt make much difference so i looked at what gibson were doing with their SGs as they suffer similar neck dive issues. This led me to forget about using the horn strap pin and fit a strap retaining pin at the rear of the neck plate using a longer reatianing screw.

Has helped massively. Dont know the science as its moving it further away from the 12th fret location but is alos placing the strap pin within the basses central line, or something!??

Although now actually playable a small weight like shown above very well may eradicate all neck dive now. Only draw back is the slightly lowered bridge end strap pin means the top of the bass has an inclination to roll forward, away from my stomach, when im not playing...but at least it doesnt flip.

[Ou7shined]

I'm just going to briefly stick my neb into this fascinating discussion and bugger off again (I don't want to have the same argument with the same people )

I'm from the "rear strap button being raised" camp. My proof? ...

note the strap button


note the playing angle


Cheers over and out.

[Mod_Machine]

I have a similar playing angle in my avatar photo but havent moved the strap pin?!!?

[BigRedX]

In which case you should get less neck dive if you move the strap pin further up so that it's attached to the body where the tangent to the curve of the body is 90° to the ground.

[mart]

[quote name='BigRedX' post='1315824' date='Jul 25 2011, 03:27 PM']In which case you should get less neck dive if you move the strap pin further up so that it's attached to the body where the tangent to the curve of the body is 90° to the ground.[/quote]
You mean 90° to the ground when the bass is held at the angle you want, right?
Can you explain why that should help, or is it just based on years of experience?

[BigRedX]

Exactly.

It's basic geometry. It the strap button is too low down (typically at the mid point of the body) and the bass is generally unbalanced anyway then it will tend to pull up causing neck dive. Moving the strap button higher up will stop this tendency for body to pull up and the neck to drop down.

[Mod_Machine]

But in real terms this is the absolute opposite of what happens.

Im assuming becasue of the weight distribution - eg the cavities for all the electrics on an aready light body mean that if the pin is moved up the centre of gravity is moved and due to the lack of the weight pulling it down at the base of the body the head stock takes over as the heaviest point and gravity then really starts to pull the thing down.

I really need to find that thread on the scince behind it all. Ultimately though i have three holes in the end of my bass at the moment - and guess which one causes greatest neck dive....

the one that is highest up.

Guess which one causes lowest. the one furthest down!

Logically if you think about it, if the neck is the heaviest part of the bass which is what is causing the neck dive and you move the retaining pin higher up the bass (meaning less load on the strap itself and therefore less load to pull the neck back up) moving the pin up is very unlikely to erradicate the problem - but actually make it worse.

Sorry for the lady bird book of science approach but its the only way i can put it into words - the strap placement on the picture in the one above is already at around the 12th fret - not the 15th (as mine is) which should already be balancing the bass out quite well. The photo by ou7shined just shows the bass being played and could therefore just be being held up but as it has the longer 'horn' section shouldnt be suffering from neck dive in the first place.

Where the lack of a longer horn section is causing the problem surely its actual load on the rear of the strap that will pull the neck up, therefore moving the strap to lowest point means that all of the load of the bass is on the strap! this is as apposed to thinking that the weight of the bass below the strap pin will 'pull' the neck up through the strap, when in fact that would be one of the lighter parts of the bass all of the weightless cavities with electrics in are actually there!

[mart]

[quote name='BigRedX' post='1315873' date='Jul 25 2011, 03:57 PM']It's basic geometry. It the strap button is too low down (typically at the mid point of the body) and the bass is generally unbalanced anyway then it will tend to pull up causing neck dive. Moving the strap button higher up will stop this tendency for body to pull up and the neck to drop down.[/quote]
Hmm, still can't quite follow this. I was looking for an explanation of why the bass body would tend to pull up with the strap button lower down, because it doesn't fit with my understanding. And with Mod_Machine's experience, by the look of it:

[quote name='Mod_Machine' post='1315928' date='Jul 25 2011, 04:36 PM']But in real terms this is the absolute opposite of what happens.

....

I really need to find that thread on the scince behind it all. Ultimately though i have three holes in the end of my bass at the moment - and guess which one causes greatest neck dive....

the one that is highest up.

Guess which one causes lowest. the one furthest down!
....[/quote]
I wonder if this is the thread on the science of it that you are thinking of:
[url="http://basschat.co.uk/index.php?showtopic=119946"]http://basschat.co.uk/index.php?showtopic=119946[/url]
It has an eerily familiar selection of people posting so I can see why ou7shined doesn't want to go through this whole argument all over again. Personally, I hope it's not that thread that you're thinking of, cos I'd love to read some more serious physics input into this problem.

But I'm very much with Mod_Machine on this one. And when I searched back I found that the conclusions I'd reached from thinking about the physics fits exactly with what a guy named Golem said on the Warwick forum ages ago. What makes his opinion more interesting is that he's not afraid of drilling holes in new basses so has actually put into practice what I've merely theorized about. His main input is here and in some of the later posts:
[url="http://forum.warwick.de/10-warwick-bass/7267-neck-dive-2.html#post122682"]http://forum.warwick.de/10-warwick-bass/72...html#post122682[/url]

Of course, the optimal position for the bottom button does depend on the rest of the bass, so just because one bass works fine with a high strap button doesn't mean another will. But I don't believe you can take a bass which neck-dives when its button is on the centre-line and make it better balanced by moving the button a little higher up. When you move it up you'd first see an increase in neck-dive. Only when you'd moved it so far round the top edge that it was vertically above the original centre-line position would you start to reduce neck-dive at all.

But when I talk about an "increase" in neck-dive, that brings out another problem: this stuff is very hard to measure objectively. When I removed a tuning peg to test whether Ultralites would make any difference for me, I'd say there was no difference to the balance. But of course I'd be wrong: there must be some difference, just not enough for me to notice. And that difference in perception is, I guess, why we'll still be discussing neck-dive when the cows come home!

[LawrenceH]

Well adding more weight to the bridge end of the body will definitely work, it's just a question of how much weight you have to add. The further you get that weight out from the centre of gravity around which the bass is pivoting, the less you will need cos it'll have more leverage. A good place to start might be to hang kitchen weights from the bridge strap pin and see just how much you need to bring it up to an acceptable position.

[Ou7shined]

[quote name='mart' post='1316050' date='Jul 25 2011, 06:21 PM']....I wonder if this is the thread on the science of it that you are thinking of:
[url="http://basschat.co.uk/index.php?showtopic=119946"]http://basschat.co.uk/index.php?showtopic=119946[/url]
It has an eerily familiar selection of people posting so I can see why ou7shined doesn't want to go through this whole argument all over again. Personally, I hope it's not that thread that you're thinking of, cos I'd love to read some more serious physics input into this problem.....[/quote]
Yep that was the one.
I couldn't add much more to a debate where one persons theory wins over practice and photographic evidence, hence the respectful distance.
Hey, I'll keep making basses the way I do (with no neck dive ) and you guys keep keep debating about it.

If there was a guy out there that knows how to produce a physics model that demonstrates this then we'd have it done and dusted in no time.

[quote name='Mod_Machine' post='1315814' date='Jul 25 2011, 03:18 PM']I have a similar playing angle in my avatar photo but havent moved the strap pin?!!?[/quote]
To me those angles aren't even mildly similar. One is clearly way under 45° the other is clearly over. Might just be me though. As I said I'm happy with what I do.

Edited July 25, 2011 by Ou7shined

[mart]

Ah, the old discrepancy between theory and practice. The cause of many a good argument. Sometimes it's a shortfall in the theory (a failure to consider all the relevant issues), and sometimes it's an anomaly in the practice (some quirk in the experiment that makes it an unrepresentative case). But most often it's simply a misunderstanding - the theory and practice are not addressing the same issue, and I think that's what's going on here.

What your Pingray clearly shows is that a bass can have a high strap button and no neck-dive. I totally agree with this and have never claimed otherwise. Many basses (including Ps, Js and MMs) are well-balanced, and could have the button in many different places and still not neck-dive. There would be a difference in the balance, but in most cases it wouldn't be discernible.

What I am saying (and what I've always been saying) is that if you have a bass that is NOT well-balanced, then moving the strap button up will (nearly always) make it worse rather than better. This is exactly what Mod_Machine has found, after following the advice on that other thread.

Most of us don't dare to move buttons about, so can't actually compare the effect of different positions on the same bass. But M_M has done exactly this, and his experience backs up what I claimed exactly - practice perfectly matching the theory. If, on the other hand, you can show me a bass that neck-dives when its bottom button is on the centre line or below, and which balances well when the bottom button is higher up, then you'll have evidence that contradicts the theory. For example, did Pingray neck-dive when it had the button on the centre-line?

Yes, obviously you should keep making basses the way you do, and if you stick to the classic shapes then you probably won't get any neck-dive even with a high button. But those of us who, for one reason or another, go for other shapes that are prone to neck-dive, will want to keep discussing different ways of solving the problem. And most of us will want to know whether a change will actually make things better or worse before we start drilling or gluing or spending any money.

[Monckyman]

How about a 6" nail through the strap and into the shoulder?

[goingdownslow]

Passing the strap under my belt keeps my shortscale EB3s where I want them.

Edited July 28, 2011 by goingdownslow

[LawrenceH]

All this stuff about the load being more on the strap if you move it further down is incorrect, and the science behind what's actually involved is very simple. It's about the centre of mass around a pivot point. In this case the pivot point is on the strap, at the point where the load is balanced equally. Assuming the strap is free to travel along the pivot point, the point of equal loading is dependent on the anchor points of the strap relative to the object being suspended.

To make it clear which way this works, consider the extreme cases of a bass with an infinitely small distance between anchor points - ie suspended from the bridge end alone or from the horn alone. Pretty obviously, a bass suspended from the bridge alone has the worst neck dive possible (pointing at the floor). So Ou7hined is basically correct, apart from a few special cases with unusual body contours. But, if the horn strap pin isn't sufficiently neck-wards, even suspending from that alone will still leave the centre of mass too far up the neck. In those cases altering the bridge strap pin won't help much either way.

Having said all that...this simple model makes the assumption that the strap is free to slide around the pivot point. In actual fact, there is considerable friction between the strap and the player's body, plus the player's body gets in the way of the instrument preventing it hanging freely and probably takes some of the weight. If less of the weight is taken by the player's body eg because you alter the strap position so that the guitar hangs at a different front-back angle, then it will improve neck dive, potentially even if that move takes the pin the other way to normal.