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Post by Deleted on Dec 10, 2013 2:59:04 GMT -5
It is about this Yamaha APX-500. Yesterday i removed all shims from the bridge saddle in order to lower the string height. It all went well. But today, i plugged in and noticed (something that i had some signs about since when i first got it), that the sound out of low E and A was too weak. So weak that the built-in tuner hardly could sense the note. Same thing plugged. D,G,B,high E all were sounding loud. A and low E, very weak. In the previous state, with the shims in, i didn't have those problems. Now the pickup in this guitar is built-in with the saddle. I cannot see why the removal of some shims and lowering the height could have such an impact. Any ideas? Is the pup damaged is some way? Why does it work fine with the shims installed? The guitar looks like this one : The piezo pickup is bound to the saddle as shown here : Another schematic here :
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Post by ux4484 on Dec 10, 2013 3:34:36 GMT -5
I would guess there is a gap under the saddle now that the shims corrected. Try putting one or two back in. Piezo is all about contact.
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Post by Deleted on Dec 10, 2013 4:30:15 GMT -5
I would guess there is a gap under the saddle now that the shims corrected. Try putting one or two back in. Piezo is all about contact. I think you are very right : www.acousticguitarforum.com/forums/showthread.php?t=298045 those guys also suggest that something may have changed regarding pressure between the saddle and the saddle pocket, where the piezo resides. Thing is, with the shims the guitar sounded good, but the action height was quite high. Is there any way to correct this without extra shimming ? Maybe the saddle base is not 100% flat? Hmm maybe if i shimmed only this portion of the saddle, covering low E, A ? Since D->high E all sound loud?
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Post by Deleted on Dec 10, 2013 7:27:23 GMT -5
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Post by Deleted on Dec 10, 2013 13:33:40 GMT -5
You won't believe how easy the fix was. Just added a very small shim of paper, covering just low E and A strings. I fit this beneath the UST housing, between the UST housing and the saddle pocket. So i guess it was some small factory defect. By observing the way the UST was soldered to its housing but also its wire, it was rather visible that the solder created quite an anomaly to the flat surface of the housing bottom. I guess some more careful soldering would do this better. Now the price i paid was 0.1mm in action height in low E : 1.8mm->1.9mm which is no problem at all.
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Post by 4real on Dec 10, 2013 17:32:17 GMT -5
Well yes, but in fact a piezo is really all about PRESSURE ~ The low strings are under less tension, pressure. Sure you need contact, but touching it is not enough. Generally what goes wrong is that there is not enough pressure over the saddle if this is lowered too much. Electrics need a good downward pressure, the break angle, over the bridge too ~ On My guitar, the bridge is 'slotted' to the pins as this provides an improved break angle and pressure and is generally the way to address such problems ~ There is still a fair bit of height in the saddle however to provide good downward pressure and still a low action ~ Another reason action liftsis that a fla top guitar's top is under significant upward pressure from the strings, causign teh top to deform or 'hump' so the entire bridge area increases in height. I used a more radical soluton and found it to be really successful on my guitar ~ the JLD bridge doctor attaches to the underside of the bridge and is like a truss rod for the top, canterlevering it to the end block. The result is also a slightly improved bass response and sustain and loudness, though I am sure this will vary from guitar to guitar. It's relatively simple, if you are good with tools and such but it may well not fit inside all guitars, many EA's are a bit shallow to fit, some bridges could be too small to adequately drill through and it does take a bit to ensure that it is done well. For me the end result was a perfectly flat top (it had not moved much), stronger and does not change with altered tensions when chaning tuning. Theyare standard in high end Breedlove guitars... Obviously, if the top has risen, action and intonation can be affected ~ I chose to try this to bring it back to spec, rather than mess with filing away at the saddle or reducing pressure. The bridge is already 'slotted' ~ Obviously lighter strings will also adversely affect the pressure on the bridge and so the piezos ~
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Post by Double Yoi on Dec 10, 2013 20:13:11 GMT -5
4Real, Does that device under the bridge change the sound quality of the guitar? Seems to me it would act a damper on the guitars top leading to less vibration and less volume.
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Post by 4real on Dec 10, 2013 21:32:03 GMT -5
You can read and see the installation on my guitar where I weighed up this decision here ~ guitarnuts2.proboards.com/thread/6883/godin-seagull-maritime-modifications?page=2It is an interesting thing and results mightvary from guitar to guitarand not all guitars are suitable candidates and searching youtube found some very bad installations... They are very affordable in the permanent install model from stew-mac where you can get reviews there ~ www.stewmac.com/shop/Tools/Special_tools_for_Bridges/JLD_Bridge_Doctor.html?read=reviews#reviewsThis can help explain the principle behind it ~ www.jldguitar.net/louder/problems.htmlThere are numerous benefits I thought so was willing to give it a go. My fairly new and high quality guitar was barely lifting, but impressed with breedloves sound from new and to ensure the top never moves, was willing to give it a try ~ You'd think that would be the result hanging this thing off the bridge and connecting it through string pressure to the end of the guitar it would ahve a significant dampening effect. However, you can feel the sides vibrate a bit which activates the top from the sides as well as the bridge a bit. It was a bit "tighter" in sound and perhaps stronger bass and midrange but did not lower the highs on my gutiar. It took out the very slight 'hump' easily and is unlikely any will be had (and can be adjusted if need be) in hte future. It returned the top to flat and so to the action which of course was rising with it a little. structurally stronger, the bridge is now bolted and not just glued and the top is prevented from climatic and pressure variations, preventing the risks of warped tops and cracking, etc The tuning is more stable and altered tunings easier because the changes in string presure does not detune other strings. It is a subtle change in sound, it is not dramatically louder but there is a bit more volume and certainly a bit more sustain, the dynamics and such seem a little more 'even' perhaps. Breedloves are designed for this system with a very light braced top since the pressure is off, my Seagull is also light braced and solid wood and worked well. The results are likely to vary from guitar to guitar. However, most tops deform under such pressures over time and with that the action will rise. It's ok but there is only so much one can shave the saddle and as you do, you lower the bridge and break over angle and as you do, you have less bridge hieght and so less 'leverage' on the top to cret the vibrations ~ this too will 'alter the sound and playability' but not necessarily in a good ay! This device is extremely light, made of spruce, you wouldn't want to force the top or you could break it. In fact, it is designed to break before the top would if you try and force it. If the hump is bad, it might need conditioning and slow adjustment over weeks. Withmind the problem was tiny, but showed that it could get worse so was keen to stop it before any damage would happen and to try this out. I was not so keen to drill a hole in the guitar and did a lot of careful measurements to see if and how it would fit. In particular that the bridge is big enough to make a neat hole and the body deep enough to clear the back braces, the end block is strong and flat and none of the electronics would be hit (tail endpin jack), etc, that the bridgeplate underneath would be big enough before the x-brace on the widest setting on the JLD(for the leaverage)and strong enough ... bought a new drill bits and such to ensure that things would cut cleanly, careful measurements and taping and protecting the guitar from potential accidents. Be sure that there is enough room forthe end pins when it and string balls under the bridge and the JLD device. I used a smaller dril to cut all the way through for the thread part, after using a brad point drill for the head and inlay to cover it and a same size ordinary drill to make the countrsink for the machine screw. I used a hand drill for accuracy and prevent damage over a power tool. ... So intuitively and superficially you'd think that it would be disasterous to have such a thing connected to the top and I did think long and hard and sought as much info as I could and weighed up the principles before trying it. The non-permanent version has problems and a lot more expensive. You just wont get tht important 'break angle' and the brass pins are heavy and the JLD will be off centre. The single hole in the bridge is the only permanent mod so was prepared to risk it. I was surpised it did not ahve more of an effect, it's kind of subtle really. The guitar overall is perhaps a bit more 'even' if that makes sense, that's what I notice most as a player anyway. This is perhaps what the PR is about the 'aging' like effect. Breedlove players tend to suggest they have a kind of 'church like' sound, what ever that means and the JLD device plays a major role in their high end models. Structurally it must be significantly stronger in the long run. The thing is, it's about the only device that will actually do something about the cause of such problems (lifting top) and from my experience after this, more positives and no real negatives where as, the alternative to leave the top 'humping' and getting worse and shaving the saddle and making the bridge lower only offers negative returns. My epiphone acoustic has a very low saddle and action (and use 10's on it) and is a laminated top. The top has remained flat and is much stronger built. The neck is bolt on so have been able to shim it slightly. It is a very old (40+ years) gutiar and built strong. It is a lovely guitar to play but would have to slot the back of the bridge to get a beter breakover I suspect. It does not have a piezo system in it and if I were to, likely use a K&K or similar to the top itself rather than s saddle piezo. It would be less of a candidate for the JDL I suspect, less room on the bridge but doable, but does not need it. I wouldn't do it 'just' for teh percieved sound benefits, as I say, it is subtle. But no, strangely, from my experience, the JDL did not have a dampening or detrimental or significant change to the sound of the guitar, it's volume or response. A little less 'explosive' in the dynamics perhaps (ie more 'even' or compressed through the entire range) a bit more sustain and more even midrange. It was honestly something of a surprise. If I were to design an acoustic from scratch, I suspect for my purposes, I'd incorporate such a device into the design and make a far more lighter braced top like breedloves do since the pressure is off. It wont fix things like action though if the problem is not the top having moved of course, but this is often the cause and what alternatives are there?
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Post by Deleted on Dec 11, 2013 2:30:39 GMT -5
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Post by 4real on Dec 11, 2013 14:57:30 GMT -5
String 'tension' I was using in a broader sense ~ compliance or elasticity plays a factor in the perception of string tension ~ liutaiomottola.com/myth/perception.htmI'm not the only or first to use things like 'tension' in the venacular ~ Lower strings also vibrate at a slower frequency which can effect things somewhat. The acoustic guitar top also works through a cantilever of the bridge as one lever against the top as the other, transforming vibrations into flexs of the top. Obviously lowering the bridge will affect the strength at which these vibrations will be transmitted and thus heard. This is less of a factor for the electric guitar. However, the 'tailpiece' is adjustable to adjust this 'compliance' through the downward pressure on the bridge saddles. Longtitudinal tension (the tension sepeced on a packet of strings) is one thing, but the breakover onto the bridge or nut provides for translating this string pressure down onto the saddle. Consider no breakover, just the string tension and 'contact' ~ in fact, adjust the guitar to produce that and see what happens. There will be litle to no downward pressure, regardless of the string tension. This angle can be greatly affected by the diameter of the string, the lower the breakover often the more effect this has, lower strings are obviously significantly bigger. There is a lot to be said for ratios. Regardless, the piezos are pressure sensitive, sufficient pressure is required for the crystals to respond to the tiny changes of the vibrations through the string. To little and the response will be far less. Even without the piezo side of things, in order for the top to move, the bridge has to have some height as a general rule, otherwise the 'string tension' will be pulling along the top, not up on the top producing flex and volume. Interestingly, the perhaps expected dampening of something like the JDL exploits some of these principles to. It takes most of the longditudial raw string tension and directs it through a cantilever back to the endblock. By doing this, it actually frees the top from this tension allowing it to vibrate freer. A lot can be achieved through the use of breakover angle and downward pressure to affect and solve problems with the guitar. Some players in the 70's used to wrap the strings over the gibson style tailpiece (string it backwards) to get a very shallow breakover and more elasticity while others, such as tele players, covert string thru designs that have a sharp breakover compared to the string thru bridge counterparts and a less 'solid' tone. Strats have a very strong breakover, but comparisons are tricky due to the differences one can create with the spring tension of the tremolo. Your ibanez example sems to have a very shallow breakover and little adjustment available in the tail compared to something like an LP which can have massive adjustment so perhaps not a good example ~ does that make it 'good' is up to the player. Similar effects are also just as evident at the nut and head end, the angle of the headstock or string trees on a fender provide for the necessary downward pressure over the nut. In sufficient pressure can create something of a a sitar effect or less 'solid' note at either end of the string, this pressure is independent of the individual string 'tension' but as it is translated into downward pressure by the break angle over it. This calculator was devised to try and calculate it if wnating to work out figures and numbers, but regardless of the 'numbers' the principles are the same. liutaiomottola.com/formulae/downforce.htmI'm not sure if any of this relates to the problems you are having, there are no pictures as usual of the actual problem at hand to even suggest it, though these aspects are the common problems associated with piezos and acoustic setups and playability. Obviously, lowering string gauges also lowers the overall tension and what is being translated down to the bridge and a tninner gauge may well affect the break over. The JDL is one method of flattenign the tp if this has caused action to rise, but one could route down the entire bridge as an alternative, but that is less satisfactory. Back-slotting behind the bridge to allow for a strong downward force on the bridge generally does the trick. Be aware that if teh bottom of the bridge is not flat, the bridge saddle may crack (this happened to me last year ~ doh!). Doing this provides for nore room for the strings to have an adequate break angle and so downward pressure on the bridge and piezos. ^ this pic shows the 'breakover' on my guitar greatly afforded by 'backslotting' with the strings on, below illustrates them from above with the strings off. I used foil to ground the strings when this pic was taken. The first pic shows the way I disguised the JDL's screw into the bridge. By ensureing tht the top is and remains flat, I can use the bridge as originally set up with a fairly low action without sacrificing the lever action of a higher saddle. The alternative would have been to take a bit off it proportionately to it's height losing volume and sustin and changing the feel of the guitar in the process, as well as a continued 'lift' of the top over time and so, more shaving to be required and eventually collapse around the soundhole and likely damage or cracking that would be virtually irreversable. ^ this is a pic of the JDL installed in my guitar. I did all the electronics mods before doing this as it makes access in there a lot harder once installed.
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Post by Deleted on Dec 12, 2013 2:46:34 GMT -5
I'm not sure if any of this relates to the problems you are having, there are no pictures as usual of the actual problem at hand to even suggest it, I guess i was explicit in guitarnuts2.proboards.com/post/71889/thread that the problem was easily solved. Also i tried to find technical info about this specific piezo UST and post as much as i found. Problem was solved with a miniature paper shim, and that is all the interested reader should find in this thread. The thread got bloated for no reason.
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Post by 4real on Dec 12, 2013 3:03:35 GMT -5
Well, you asked for "ideas" and said you didn't see why you wre having problems ~ then I replied to a direct question ~
It's a forum, there are others in it. Reading is optional ~ but I did not see anywhere in this thread that the problem was solved, I figured that you'd have worked that out before even getting to posing at all, let alone multiple threads ~ bloating out the forum with the same 'problem' to be fixed by a piece of paper!
Reading things is entirely optional, I see no reason in anything I wrote that you should take offence at or that I need to be regretful for. In fact, it raised a bunch of things that I need to question of myself and other questions that I am looking for for my own understanding. You need to accept that threads go where they will and be a bit more civil about it. My intentions were only to be of assistance to you and the wider community, what's your problem with that? I happen as you know, to be working very much with acoustic and acoustic electrics nor for a few years, it's an interest and have some knowledge. If you don't appreciate it, others might.
Your opinion of 'bloating' might well be of interest and raise questions for others...it has for me and not found for instance a good explanation for the reason for bronze strings, only knowing from experience that there is a significant difference and yet, failing to understand why or find anything directly to that question.
As to the importance of 'pressure' it is important that this understand in regards to piezos or even the set up of guitars of any type and that is not just 'contact' that matters, but the pressure on that contact. Paper shims provide the contact for pressure to be applied, but hey, I did not see till this last snark that you ahve solved the question at all, for all the threads apparently all about the same project!!
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Post by ux4484 on Dec 12, 2013 6:59:59 GMT -5
You two can continue with your lovers spat after I'm done: If it was a window in which air was leaking from one side, and the pressure was even from the top of the sash, it would be because of lack of contact from the bottom of the sash to the frame. No amount of pressure can fix it. The gap HAS to be filled. Hence my comment, hence shim being installed with the same amount of pressure applied, the problem was fixed. There was no change in pressure applied, any lack of pressure was from said gap... Contact was the issue. Do I like being told I'm wrong like an errant school child? No, because I wasn't wrong... I let it go, because that's just how 4Real is sometimes... and his contribution here outweighs his (very likely oblivious) slights.
4real: We've ALL seen the MANY posts on the miraculous JDL device. A full run down is not required each time. A link to a post is all that's required, and... It's kind of overboard for a thread that was already dead.
GD: You DID only need one post to address all three issues on this.
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Post by Deleted on Dec 12, 2013 8:13:28 GMT -5
You two can continue with your lovers spat after I'm done: I think there is no such thing as "You two" here, or at least no such thing that includes me. GD: You DID only need one post to address all three issues on this. If you mean the 3 separate threads, you might be right, but it was different concerns. One was about strings, the second about action/relief setup, and the third about the piezo problem. I guess if i had mixed all 3 concerns into one thread, it would be even more harder for the casual reader to find the useful info (i.e. the solution which you posted for low E/A). But its OK either way.
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