Aria Pro II Cat Bass truss rod problems - kill or cure (but how?)

Alex Masters

Alex Masters

Aug 3, 2017
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#1
Hi,

I've dragged my old Aria Pro II cat bass out from the back of a cupboard, and have been fixing it up for my son to play.

Having completed a rewire and replacement of the pots, overhall of the active circuits etc, I now have it working and sounding suprisingly decent. The active tone controls are effective and the basic tone is quite rich and beefy - result!. It's never worked or sounded as it should for as long as I had it, so I'm pleased with that.

The next problem, which is potentially a show stopper, is that the neck is bowed, and the truss rod can't pull it straight. I've added a drum washer to the nut, and it is working, sort of, in that I can crank the truss rod and get some back bow with the strings off. The truss rod seems to be single action.

Problem is that as soon as the guitar is strung up, the neck just wants to curl up and you end up with about 1mm of relief anf the action is way too high even with the saddles slammed.

I've tried to reset the neck by clamping to a straight edge and using blocks to bend it with a radiator as a heat source. It did seem to straighten up a bit, but the strings will still pull it into a bow when under tension. The truss rod has a lot of tension but it isn't sufficient to hold the neck straight, so I don't think it is having much effet when adjusted to the max. I think the anchor may have compressed and / or the tension available isn't enough to hold the neck even when it's set straight or with a slight backbow

What are my options?

a) try the heating / pressure method to try to straighten the neck again. If the truss rod isn't engaged or working this won't fix it.
b) I could heat and peel the fretboard, straighten the neck as much as possible, fit a new single action truss rod, and reassemble, or repair the existing one
c) do 'b' fit a new double acting truss rod - would this work?
d) do 'b' (or a) and add some graphite rods to support the truss rod

This has to be a DIY job - the bass isn't worth anything other than some sentimental attachment (had it for 25 years). I appreciate it might be impossible or attempt to fix might break it permanently, but it isn't really properly usable as-is.

What are your thoughts?

Regards,
Alex
 
#2
is there any chance that shimming the neck pocket will allow you to set the action low enough to make it playable? It doesn't sound like it will, but it's a simple thing to try (or at least consider and dismiss) before embarking on any truss-rod-related fixes.
 
#3
I did try adding a playing card to the rear of the neck pocket, and it gave an acceptable action on the upper frets but the relief is still excessive. I could probably live with it but I think the neck will always be unstable without addressing the truss rod issue.

Thanks for the input - will give that a try though!
 
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#4
A shim isn't going to help a weak neck. You'll just wind up with a curled neck that's shimmed. Try your surgery, you have nothing to lose. As a last resort, that neck appears to be fender compatible, and Rondo has some necks that appear to be of good quality (tight straight grain with little to no run out) and reasonable cost (~$70) Here's a replacement Aria Pro II neck even cheaper than the Rondo.
Aria Pro II CAT Bass Neck | Duane's Vintage Guitars

EDIT: That Aria neck is NOT Fender compatible. it's a 22 fret neck; Fenders are 20 fret necks. The Aria is also a little thinner in width at the pocket.
 
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#5
sissy kathy said:
A shim isn't going to help a weak neck. You'll just wind up with a curled neck that's shimmed. Try your surgery, you have nothing to lose. As a last resort, that neck appears to be fender compatible, and Rondo has some necks that appear to be of good quality (tight straight grain with little to no run out) and reasonable cost (~$70) Here's a replacement Aria Pro II neck even cheaper than the Rondo.
Aria Pro II CAT Bass Neck | Duane's Vintage Guitars

EDIT: That Aria neck is NOT Fender compatible. it's a 22 fret neck; Fenders are 20 fret necks. The Aria is also a little thinner in width at the pocket.
Click to expand...

Thanks for that. I agree - shimming isn't going to deal with the bow. I think the anchor must have compressed - it appears that the truss rod isn't broken, but it's just not working.

I think I'll attempt a repair. If it goes horribly wrong then that Aria neck might be a fall back. If it has a simple single truss rod does it need to be replaced like for like?. Is the routing of the channel flat or have a curve? I'm wondering if a double acting truss rod could be used instead of the single acting truss rod.

I'll clamp and heat the neck and finger board to get them as flat as possible before reassembling. I'm going to try to avoid removing the frets and see how it comes out.
 
#6
Well you're going to have the neck apart so a double acting rod could be installed, but double acting rods are generally thicker than a single rod so you may need to route out the channel for it to fit. Yes the channel has a bow to it. From the fretboard side it is deeper in the middle than on the ends. I'll be surprised if you manage to save the board; I'll be amazed if you manage to save the frets too.
 
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#7
EpicSoundtracks said:
is there any chance that shimming the neck pocket will allow you to set the action low enough to make it playable? It doesn't sound like it will, but it's a simple thing to try (or at least consider and dismiss) before embarking on any truss-rod-related fixes.
Click to expand...
No amount of shim will fix a bowed neck. The graphite stiffening bars may be the only workable option, though you could try heat pressing the neck into a significant back bow.
 
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#8
Heat pressing is less invasive than most of the other methods. However, a hot water radiator won't generate enough heat to allow you to bend wood permanently. A steam radiator might if it's maxed out on a cold day. Even at that, a heavy metal plate (or maybe a cast iron griddle) would be necessary to heat the neck evenly.

Even heating is one of the keys to getting this right. In the shop, we use silicone heat blankets. The blankets connect to a controller that regulates the heat. These blankets will cause the guitar to ignite if care is not exercised. You never leave a guitar when you're heating it. Not for a phone call, a baby crying, nothing. Have your beverage handy when you start.

Decades ago we used heat lamps. Then we used halogen. It doesn't matter what you use, if you aren't getting the wood over well over 200°F it's not going to bend and take a set permanently.
 
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#9
202dy said:
Heat pressing is less invasive than most of the other methods. However, a hot water radiator won't generate enough heat to allow you to bend wood permanently. A steam radiator might if it's maxed out on a cold day. Even at that, a heavy metal plate (or maybe a cast iron griddle) would be necessary to heat the neck evenly.

Even heating is one of the keys to getting this right. In the shop, we use silicone heat blankets. The blankets connect to a controller that regulates the heat. These blankets will cause the guitar to ignite if care is not exercised. You never leave a guitar when you're heating it. Not for a phone call, a baby crying, nothing. Have your beverage handy when you start.

Decades ago we used heat lamps. Then we used halogen. It doesn't matter what you use, if you aren't getting the wood over well over 200°F it's not going to bend and take a set permanently.
Click to expand...

That's bad news. I can't really generate that kind of heat at home for any length of time, or in a controlled way. If heat is being used, is it actually causing the wood to take on a set to a new position, or is the glue melting and then cooling so that the fingerboard is acting as a brace?. If I separate the fingerboard, would I need to apply a similar amount of heat to the neck?. Also, how long does the heat need to be applied for? I could heat the neck in a relatively controlled, uniform way with a heat gun but not for long.

Sorry to ask detailed questions - I haven't found something consistent that describes the method as a 'how-to'.

Thanks,
Alex
 
#10
Alex Masters said:
That's bad news. I can't really generate that kind of heat at home for any length of time, or in a controlled way. If heat is being used, is it actually causing the wood to take on a set to a new position, or is the glue melting and then cooling so that the fingerboard is acting as a brace?. If I separate the fingerboard, would I need to apply a similar amount of heat to the neck?. Also, how long does the heat need to be applied for? I could heat the neck in a relatively controlled, uniform way with a heat gun but not for long.

Sorry to ask detailed questions - I haven't found something consistent that describes the method as a 'how-to'.

Thanks,
Alex
Click to expand...
Yes you can. Use a heating pad, the sort you would use for a sore back, or an electric blanket; whats more they don't generate an amount of heat that makes igniting the neck a possibility. You can clamp the neck into a back bow and apply heat for a week or so, then allow the neck to cool to room temp before unclamping. This thread may be of some interest to you.
Rescuing a badly-twisted 1964 Jazz Bass neck
 
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#11
sissy kathy said:
Yes you can. Use a heating pad, the sort you would use for a sore back, or an electric blanket; whats more they don't generate an amount of heat that makes igniting the neck a possibility. You can clamp the neck into a back bow and apply heat for a week or so, then allow the neck to cool to room temp before unclamping. This thread may be of some interest to you.
Rescuing a badly-twisted 1964 Jazz Bass neck
Click to expand...

Thank you for that - very interesting. I didn't think that sort of heating pad normally got hot enough to work - they normally have a thermal cut-out or a timer. I'll have a look at that.

The neck was warped by being left resting against a radiator (thanks Mum!) so I guess that temperatures don't need to be very high, but might need to be applied over a long time period. I think the anchor may have compressed the wood as the truss rod has been over-tightened. I can tap the truss rod thread back towards the headstock, so the anchor isn't in a 'fixed position'. maybe the anchor is bent, or pulling through the wood. In that case I don't think it would exert enough force to keep the neck straight, but if it isn't bowed beforehand then maybe it would be enough to keep the neck straight against the force of the strings.

I'm going to measure the bow with a straight edge and take a view as to how to proceed.
 
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#12
  1. Halogen lamps.
  2. Babysitting.
  3. Turning neck like bar-be-que.
  4. Clamp into back bow.
  5. Cool.
Basic outline.

Not a fan of low temp solutions. The reason is that white glue releases at 175°F and yellow glue at 225°F. Even if yellow glue does not release at the lower temp it can get gummy. It hardens when it cools but why fool around? And you still have to babysit, but with low temp it takes longer.

Once the neck has cooled it can be attached to the body and a complete set up done.

By the way, sometimes it takes a couple of tries even when you know what you're doing. Each piece of wood is different so each session is trial and error. When you have a dozen or two under your belt you start to get a feel for it.
 
#13
Thanks for the guide. A couple of questions, if I may. How much back bow should I put in while heating it? how long does it need to be heated for if using a higher heat (say 200f)?.

should the neck be set straight for the heat treatment process, or bend past straight to allow for spring-back once pressure is removed?. I guess you set the block at the point of greatest non-straightness, or in the middle if it's not uniform- I'll check that with my notched straight edge.
 
#14
202dy said:
By the way, sometimes it takes a couple of tries even when you know what you're doing. Each piece of wood is different so each session is trial and error. When you have a dozen or two under your belt you start to get a feel for it.
Click to expand...

Loosen the truss rod. When it reaches temp, block, clamp, and bend. Let it cool. Not right? Refer to the above.

It may seem glib, but it is all about the method. There are no measurements. Even if there were they would still be dependent on the neck.

Disclaimer: This is advanced repair work. If you have to hunt through kitchen drawers to find a screwdriver, call changing a tire working on a car, or think a tool is someone who yells "Freebird" during load out, please out take your instrument to a pro.
 
#16
202dy said:
Loosen the truss rod. When it reaches temp, block, clamp, and bend. Let it cool. Not right? Refer to the above.

It may seem glib, but it is all about the method. There are no measurements. Even if there were they would still be dependent on the neck.

Disclaimer: This is advanced repair work. If you have to hunt through kitchen drawers to find a screwdriver, call changing a tire working on a car, or think a tool is someone who yells "Freebird" during load out, please out take your instrument to a pro.
Click to expand...

I'm pretty handy, and any new task is an opportunity to acquire new skills (and more importantly, new tools :D). Your point is well made though.. no point in paying for single use tools if someone can do it for me for less. I've had a chat with a local luthier and he's going to give it a go clamping with heat for a week and see if that's enough to reset the wood to something like a neutral position and give the truss rod a better chance of holding that position against string tension. He says the truss rod is working, and has a bit more adjustment to go so we'll see how that goes.

More drastic surgery is still an option of that doesn't work out.. all bets are off at that point, LOL!.
 
#17
Heat for a week? More like heat for an hour or two.

Leaving a cheap resistance heat source like an electric blanket or heating pad on in one's shop (or house!) for a week is courting disaster. Not to mention a close relationship with the local VFD.
 
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#18
Sorry, I wasn't clear.. He wanted to block and clamp it for three or for days and manipulate the truss rod to see if there was more that could be done with that before trying heat, and that would be short term if needed. The russ rod is definately working and can be tighened further, so there may be some hopewith this approach.

He said that he used heat when making guitars but hadn't needed to use it to fix necks before, and has done loads like mine.In fact he had a Squire which was similar to, but worse than mine and it was fine and stable.

Fingers crossed for the easy / cheap fix..

Regards,
Alex
 
#19
Clamping the neck before adjusting works a lot of the time.

If he has done loads like yours, then he should know that it is unnecessary to leave the neck clamped for three or four days to see if it will stay. It will either work or it won't. Sometimes it takes several tries (not days!) to get it to do so.
 
#20
I guess you were right - I just got a text today saying that the truss is working, the neck is straight and it's ready to collect. I'm pretty pleased with that outcome, for sure. I'll ask him in detail what he did, but seeing as I only delivered it yesterday, I'm guessing he set the neck straight and tweaked the rod to hold it.

Thank you everyone for your input and the education!.

Alex
 
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