Yamaha CPX 900 high action?

Discussion in 'Acoustic Heaven' started by Craig Williams, Aug 22, 2019.

  1. Craig Williams

    Craig Williams TDPRI Member

    Age:
    56
    Posts:
    50
    Joined:
    May 16, 2016
    Location:
    Thailand
    Bought a Yamaha CPX900 yesterday. Got it home and thought pretty easy to lower the action. I shaved the bottom of the saddle a bit. Tightened up the truss rod a bit and to me anyway still seems a bit high. Mind you I like a very low action on an acoustic similar to an electric. Played around with it all day and best I could get it. I can't take any more off the saddle or the strings will be going over the bridge wood. There is no noticeable belly bulge but I put a straight edge across the top of the guitar behind the bridge and it is not 100% flat. The bridge isn't tilted forward or anything like it is under strain. Looks flat on the top of the guitar. Just sort of raised slightly where the bridge sits. I guess you would fit a coin under each side of the straight edge at the edge of the guitar. I took it to a local luthier and he said this model guitar is not meant to have a 100% flat top and he thought the action was pretty normal. He put a light and mirror in the sound hole and said bracing was sound. I reckon there is about 3mm at the 12th fret on the low E string. The lowest I can get the action is with the truss rod tightened so the neck is slightly concave believe it or not. I have 11-50 strings on it. I tried 10's but weren't a lot different. Come to think of it I have only ever had one acoustic guitar with a super low action in the past, an early Japanese Takamine. Was like silk to play. Neck so straight. About 1mm strings off the frets all the way up the neck and no buzz etc.

    Am I being unrealistic. I know a better tone is probably achieved with a higher action but I wish I could lower it more. I have played around with the truss rod to lower as much as I can without buzzing and taken as much as I can off the saddle. I guess the Luthier should know however I am not 100% confident this guitar is meant to have a slight arch.

    What do you guys think? Been doing my own set ups for years, mostly electrics but this one has me stumped.
     

    Attached Files:

  2. rangercaster

    rangercaster Friend of Leo's

    Posts:
    4,894
    Joined:
    May 8, 2008
    Location:
    portland, or
    Maybe the nut is too high???
     
  3. Craig Williams

    Craig Williams TDPRI Member

    Age:
    56
    Posts:
    50
    Joined:
    May 16, 2016
    Location:
    Thailand
    No nut not too high mate. I think someone has actually shimmed the nut up a poofteenth. When I do lower the strings to the point it is starting to buzz it is buzzing up on the first 1 or 2 frets near the nut. The action near the nut is low. It starts to get higher as you go down the fret board. The neck is well set and straight, joint looks good
     
  4. boredguy6060

    boredguy6060 Friend of Leo's

    Posts:
    4,648
    Joined:
    Mar 28, 2012
    Location:
    Sou Cal
    Measure the bottom of the strings to the top of the guitar at the bridge, if it’s over 1/2 inch it may need a neck reset.
     
  5. rangercaster

    rangercaster Friend of Leo's

    Posts:
    4,894
    Joined:
    May 8, 2008
    Location:
    portland, or
    Yamaha quality control is the best in the biz ... But nobody is perfect ...
     
    boredguy6060 likes this.
  6. boredguy6060

    boredguy6060 Friend of Leo's

    Posts:
    4,648
    Joined:
    Mar 28, 2012
    Location:
    Sou Cal
    Is this a brand new guitar?
    I was under the impression that it was used.
    If it’s new then forget the reset suggestion, Yamaha is no t likely to pass one that needs a neck reset.
    I have two Yamaha’s one is brand new, the other is about 40 years old, both are near perfect in their construction.
    I’m sure they make mistakes, but I doubt they’d make one like setting they neck wrong.
     
  7. Nick Fanis

    Nick Fanis Poster Extraordinaire Ad Free Member

    Posts:
    5,000
    Joined:
    Mar 3, 2003
    Location:
    Athens-GREECE
    From your pictures it looks like the top has swelled around the bridge.
    Only way around it is to reset the neck but this will cost more than the guitar.
     
  8. Craig Williams

    Craig Williams TDPRI Member

    Age:
    56
    Posts:
    50
    Joined:
    May 16, 2016
    Location:
    Thailand
    Yeah there is nothing wrong with the set of the neck. Solid as a rock. And the guitar would be about 10 years old. I guess back to my original question is the string height I discussed normal for an acoustic player? Is it unreasonable to expect a super low action on an acoustic?
     
  9. Craig Williams

    Craig Williams TDPRI Member

    Age:
    56
    Posts:
    50
    Joined:
    May 16, 2016
    Location:
    Thailand
    Oh well I have learnt a bit about acoustic guitars last few days...

    Apparently the more high end the guitar the higher the action usually is. An acoustic guitar can either be built for sound or playability. The higher the action the better the sound and high end guitars are built for sound. Better sounding high end guitars are also built lighter than cheaper guitars and in some cases are less durable. It's a trade off between strength and sound.

    The lower the bone / plastic saddle on the bridge is, the duller your sound will be. This because the saddle sitting in the slot actually vibrates from leverage from the strings. The higher the saddle the more leverage and the more clear, loud and defined the sound will be. I took my saddle down to where the strings were just barely off the bridge wood. Very low. I actually thought I must have got some dud or copy strings as the sound was so dull. Replaced the saddle with a higher one and a completely different guitar.

    Don't adjust truss rod more than an 1/8th of a turn at a time. Then re tension strings, play it a bit or preferably leave over night to recheck adjustments. Don't be too hasty to make further adjustments even after just adding new strings. They take a while to settle in.

    Most flat top guitars are not made perfectly flat and will have a slight radius under the bridge.

    If the above not correct please correct me :)

    After playing around with everything over the past two days finally have a passable result.
    Bottom E string 2.5mm off the 12th fret. Playing open chords nice and smooth but action still seems high to me playing up the neck. it's certainly not a low action but at least playable.
     
    Last edited: Aug 23, 2019
  10. Slowpoke

    Slowpoke Tele-Afflicted

    Age:
    81
    Posts:
    1,132
    Joined:
    Dec 3, 2011
    Location:
    Mandurah. West Australia
    Hi Craig, after looking at your photos and reading your entry I'm thinking your soundboard has too much of a hump at the bridge area. So you need remove the strings and hold the guitar halfway up/down the neck so the body of the guitar is not touching anything. Now with fingertips only (no nails) tap the front soundboard at various parts around the bridge area corresponding with the strengtheners that are glued on the inside of the soundboard and listen for a vibration. If there is a vibration you'll need to re-glue that strengthener because that having come loose has allowed the soundboard to form into a hump around the bridge area Having worked on a few Yamaha Acoustics and found that to be the reason for the hump. It will be a bit of a fiddly job re-glueing the strengthener, getting the glue into the right place and clamping it.
    If I get stumped on any repair jobs I always visit Randy Schartigers videos on You Tube he's a pretty knowledgeably guy and explains thing in laymans terms that are easy to understand. You can find him doing a Yamaha guitar at this URL.. S

     
  11. Craig Williams

    Craig Williams TDPRI Member

    Age:
    56
    Posts:
    50
    Joined:
    May 16, 2016
    Location:
    Thailand
    Yeah did what you said mate. No rattles that I could detect. I did take it to a Luthier yesterday and he had a pretty good look under the sound board with a inspection light and mirror, even tried to slip paper under the braces. He was adamant that these CPX series of guitars are meant to be like that. I don't know if I mentioned it but I am in Thailand and the Luthier Thai. he has been trained but......hmmmm. With the naked eye you wouldn't even notice a hump but putting the straight edge across it tells the story. It is just raised as you said like a hump immediately and evenly around the bridge. It's not sort of dipping in the front of the bridge and raised at the back as some older guitars do. Mind you I feel there must be something wrong. You should be able to have a saddle on in at least 1/8" above the bridge and be about in the right area. Had another play around with it today. The neck is dead straight and the bottom E string 2.5mm off the 12th fret. How does that sound? Best I could get it yesterday about 3mm. Is there any rule of thumb to this measurement what it should be? Anyway, playing nicely and no buzz or rattles but I wish I could lower it even more a bit. I don't think I have ever played an acoustic apart from the Takamine I had that was too my liking. Particularly Matons and Martins. Matons in particular seem to have what I would call a very high action.

    By the way, I have seen a few videos on repairing humps with damp rags, steam etc. The Piezo system on my yamaha is fairly intricate and a lot of electronics inside the body. I am guessing steam etc wouldn't be a good idea on a guitar with a pick up?

    Man they are hard on guitars here! 90% second hand guitars I have seen here, expensive ones too USA Fenders etc look like they have been sitting out in the weather 10 years. Dings and bangs, stickers all over them. Very poor country here but people don't seem to look after their stuff as you would expect. Climate very hard on guitars too. Spend half their life in humidity to air conditioning. Very extreme. Thanks for your help again :)
     
    Last edited: Aug 23, 2019
  12. dreamingtele

    dreamingtele Friend of Leo's

    Posts:
    2,449
    Joined:
    Jun 16, 2010
    Location:
    Melbourne, Australia
    My Cort L300VF is like that, solid adi top, solid hog back.. I put 12's on it and it did put tension on the top like yours..

    [​IMG]

    The top would be like that under tension.. but I got a decent action.. around that 3mm (0.11 inch).. I'm buzzing a bit but only because the frets werent level 14th fret onwards.. To me its very low.. I have a heavy hand and I like a higher than usual action, and heavier strings to drive the top harder..

    My second Cort L450CL, an All mahogany acoustic solid top and solid back, was also set up that way, but Mahogany is a harder wood, and I got it new, so it's bulging a bit with 12"s.. here's my lowest action when I shaved the saddle..
    I know it could go even lower, but that would mean a new nut, fret levelling and bridge saddle, a trip to a guitar tech which is a bit expensive..

    [​IMG]
     
  13. Craig Williams

    Craig Williams TDPRI Member

    Age:
    56
    Posts:
    50
    Joined:
    May 16, 2016
    Location:
    Thailand
    Slowpoke, what about reducing the height of the actual Ebony bridge? I have seen videos of guys removing the bridge and shaving under but seems to me may be easier to shave or sand 1mm off the top? Then no need to remove the bridge, which looks a bit tricky.

    Then again I am not sure if I have the slot depth to take 1mm off. Then I would need to have the slot deepened and I don't feel confident to do it myself as you previously mentioned.

    I live in Thailand and only have one Luthier available and not 100% certain about his work. Heard good and bad reports. If I was back home I'd take it to a reputable shop and let them deal with it.

    Have you ever removed a bridge? Seems to be the key is heating up the top of the bridge. Seen guys using an iron heated up on a hotplate. I would have imagined this would burn the wood? Maybe a normal steam iron (without steam) would do the trick? Then slowly carefully work a thin steel under to remove. Have you every done this?

    Man have a look at this guy shaving the top of an expensive Martin with a belt sander lol. Shakin like a dog crapping razorblades haha. Probably lucky the owner wasn't there watching haha
     
    Last edited: Aug 25, 2019
  14. Freeman Keller

    Freeman Keller Tele-Afflicted

    Age:
    74
    Posts:
    1,627
    Joined:
    Aug 22, 2018
    Location:
    Washington
    Craig, I am late to this party but if you have't already shaved the bridge, don't. That is an absolute last resort "fix" and it isn't really a fix because when you do it right you'll just have to put a new bridge on it. Lets review a couple of things

    - first, the belly in the lower bout that you show in your first pictures is normal and desirable. That indicated that your guitar is well humidified. It was built with a little dome in the top - that makes the wood stronger and allows it to move a bit without cracking. As guitars age they may get a little more of a belly but most of the time it is OK. Since you live in a high humidity area you might experience more of a belly than those in a dry climate but unless glue seams have come loose on braces you should be fine.

    - what is probably happening is the normal rotation of the entire top and neck block under string tension. Your guitar was built with a certain geometry but over time that has changed. Nothing is "broken", there has been no "failure", but the geometry has changed. The easiest way to test this is to lay a 24 inch straight edge on the frets in between the 4th and 5th strings and look at where the end is relative to the bridge. Ideal geometry will have the straight edge just touching or maybe a hair above the top of the bridge (not saddle). On most guitars that means the fret plane is about 3/8 off the top of the guitar. With that kind of geometry you will end up with about 1/8 on an inch of saddle sticking out of the bridge and nice playable action.

    Here is an ideal neck geometry, maybe a hair overset but this is what you want to see

    IMG_5618.JPG

    If I took that measurement with string tension the end of the straight edge might be on the top of the saddle - you don't want it any lower.

    This guitar has an extremely bad neck angle - most of the time the end of the straight edge won't be this low,

    IMG_5237.JPG

    Unfortunately the repair is not trivial (or inexpensive) but the correct thing to do is remove the neck, adjust the joint to change the angle and reinstall it. The procedure is called "resetting the neck" and most old guitars will either have had it done (or need it done). It is not an operation for a do it yourself person, a little searching will find lots of threads about what is involved.

    One thing that can further complicate doing a reset on your guitar is that at least at one time Yamaha used a glue on their neck joints that doesn't come apart easily - many people think is was epoxy. I have reset quite a few guitars but when it came time to do my 1969 FG-150 the neck simply would not come off - I had to do it by another method. I was successful and now the action is perfect and the old guitar plays wonderfully.

    I don't know if the CPX900 has that problem or not. If it does your repair tech may be able to council you on the best approach. I will say that under those circumstances, ie you simply can't do the proper repair, then shaving the bridge might be a viable alternative.

    Shaving the bridge has several ramifications. First, the bridge and saddle are so high for a good reason - a 3/8 bridge plus 1/8 saddle gives a nice lever to actuate the top movement - as you lower that lever you get less energy into the top. The guitar will not be as loud or responsive. Further the typical bridge has a slot about 1/4 inch deep (it doesn't go all the way thru to the top) so about 2/3 of the saddle is in the bridge. That is relatively strong - if you make that slot less deep you run the risk of the saddle tipping forward and eventually splitting the bridge. If you have an UST the situation is even worse.

    The correct fix for that, if you do decide to shave the bridge, is to route the saddle slot deeper. Again, that is not trivial - you will be trying to line up a 3/32 router bit perfectly in that angled slot without making it any wider. I have a special jig for doing this (there are other reasons to route a saddle slot with the bridge on a guitar

    IMG_3725.JPG

    Last, and far from least, if you do shave your bridge and sometime in the future someone decides to fix it correctly by resetting the neck, then the bridge will be far too low and will need replacement. Removing the old bridge involves applying heat and working a pallet knife between the bridge and top, then fabricating a new one with the proper footprint, scale and pin spacing. Again, not impossible but not trivial.

    If your tech is any good he/she will be able to help you measure everything on your guitar and decide the best plan of action. I can provide more information and some links if you would like.
     
  15. Craig Williams

    Craig Williams TDPRI Member

    Age:
    56
    Posts:
    50
    Joined:
    May 16, 2016
    Location:
    Thailand
    Hi. Thanks for the lengthy reply and no I didn't shave the bridge. I have done 100 set ups on all sorts of electric guitars but have never had much interest in acoustics. I have learnt so much last couple of weeks just from these pages. How the saddle / bridge vibrates the top of the sound board and how critical the height of the saddle is to the sound quality. Learnt much of that on this guitar shaving saddles down too low, then replacing with new and starting again. I have the guitar about perfect now with around 2mm off the 12th fret which everyone seems to think is a low action for an acoustic. I normally play electrics and one guy told me to persevere with the higher action of the acoustic and in no time I won't notice it and that is exactly what has happened. I have really bonded with this guitar now and after saddle replacement and adjustment, tweaking the truss rod I am happy with the result. Really nice guitar.

    Have launched into a couple of other projects as well. One was fitting a Piezo pick up to a later model S.Yairi. The actual installation / cutting out the body etc was easy. I didn't realise I would need to deepen the slot of the bridge to accomodate Piezo and saddle and that was a whole adventure on it's own. I did manage to do it and a reasonable job too using only a drill (series of holes at the same depth), very fine thin chisel and a few other bits and pieces. I am in remote Thailand and really had no choice. I never really found what I would call a good craftsman Luthier in Australia let lone here in Thailand. Always seems to me better off being careful and doing it yourself. After a lot of mucking around the S.Yairi is fine now and have started on a 90's Aria FET-02. Beautiful little Japanese solid top. New Piezo also for that, ancient factory Fishman DED. Anyway, thanks again for your advice. Took on board your info about neck angles with a steel rule and will be grabbing a metre long steel rule today.
     
  16. Freeman Keller

    Freeman Keller Tele-Afflicted

    Age:
    74
    Posts:
    1,627
    Joined:
    Aug 22, 2018
    Location:
    Washington
    Couple of quickies. Most of the time there is enough depth in a saddle slot to fit a piezo type UST by simply removing that much from the bottom of the saddle. I measure it, usually somewhere around 0.050 (i'm in the US, forgive me for thinking in inches) and I simply sand that much off the bottom of the saddle providing the action was acceptable before. Fishman cautions about the depth of the slot when installing their saddles.

    https://www.fishman.com/support/install-guides/

    Second, to measure neck angle you need a straightedge that is just a hair shorter than the scale length - it needs to sit on the frets but not the nut and just come close to the bridge. A meter stick will be too long, 24 inches is perfect. Mine are cheap aluminum 36 inch rules from a hardware store that I cut off at 24 inches.

    2mm is reasonable low action for an acoustic. My usual goal for a finger style player is about 0.060 (1.5mm) on the high E and going up to about 0.090 (2.3mm) on the low E. For people with a heavy attack I might go a bit higher. Those are very close to the same values I use for an electric, but one big difference is the gauge of the strings (0.012 or 0.013 on the acoustic, 0.010 on the electric) which of course gives significantly more tension.

    I did a rather long thread about how I approach a setup on every guitar - classical, acoustic, electric, bass, whatever - its always the same. I might have different target values but the method of getting there is the same. It always starts with measuring that neck angle - its its not OK there is no point in going ahead

    https://www.tdpri.com/threads/basic-setup.952636/
     
  17. Craig Williams

    Craig Williams TDPRI Member

    Age:
    56
    Posts:
    50
    Joined:
    May 16, 2016
    Location:
    Thailand
    On another note I am about to replace the pick up on an older Aria solid top acoustic. I will post this in the correct area but do you know much about this?

    Have a 90's Japanese Aria solid top. Has a factory Fishman which is not only electrically dead but plastic trim etc falling to bits so replacing with a Chinese Fishman Presys which by all accounts are pretty good.

    The original Piezo pick up strip is wafer thin and as far as I know still in good condition and original to the guitar. It has the small jack on it to plug into the pre amp which most of them do. I would rather leave the original Piezo in as it is very thin and there will be no need for saddle adjustments etc. Is this ok? I believe under saddle Piezo strips are made differently now a days. Should it work the same with the modern preamp?
     
IMPORTANT: Treat everyone here with respect, no matter how difficult!
No sex, drug, political, religion or hate discussion permitted here.


  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.