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thorneven

Low E string piezo pickup - volume way too low

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I have a JTV-59 probably JUST out of warranty.  As the subject says, the maximum volume of the low E string piezo pickup is significantly lower than all the other piezo pickups.  I looked in the Workbench and all the volumes are the same and at the max.  Obviously I need to balance the volumes, but I'm thinking I first need to replace the low E piezo.  Is there somewhere I can order one and is the replacement procedure relatively easy for a guy who does his own guitar work?  I would hope the procedure is pop the old one out, drop the new one in.

 

And once that's done, is there an easy way to balance the piezo pickups without having to do it blindly in Workbench and then connect the guitar to an amp to see how close I got?  In other words can I adjust and test volume balance while connected to the Workbench?

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I believe the peizo's are soldered in so if you're comfortable with soldering shouldn't be too bad. As for balancing the volume just plug your guitar into the amp while you adjust the levels in workbench.

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I assume the piezo elements are inside each string saddle.  A Google search turned up no place where I can buy individual saddles for a JTV59. I assume the saddles can be easily replaced.  Hopefully Line6 personnel will chime in.

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This is odd.  My JTV-69 has started showing the same symptoms over the past few weeks.  I thought it was my imagination at first, but it's now about half the volume of the A string.  These strike me as being very cheap and chintzy transducers. 

 

The transducers ARE the saddles! 

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Makes me a bit angry that the piezo problem wasn't fixed with the JTVs. It's definitely something they should have looked at and fix, and it's an obvious solution: ground wire for ground instead of piezo's contact of saddle for ground.

 

We all rest our hands around that area a lot especially for palm muting or anything like that, so our sweat and all will go in between the piezo and saddle eventually cutting off the grounding.

 

Another thing that would help is not having that opening at all, like the graphtech piezo system.

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I'm wondering what material the transducers are made from.  If they will take solder, one solution would be to run a piece of 30g wirewrap wire to the element as a discrete ground.  Anyone tried this?

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Hmm, I see that each piezo has its own wire (of course). I wonder what the wiring looks like.  Anyone have any pictures of the piezo wiring?

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here's nother interesting post from stevekc

 

 

1392396982_9222147_P1020031.JPG

Above is a JTV-69

Actually each Piezo saddle signal feeds a fixed gain op amp that feeds an AKM5386 Stereo A/D There are three U2,U3,U5 - to cover all 6 strings.

http://www.akm.com/akm/en/file/datasheet/AK5386VT.pdf

There is no "adjustable Gain" block in the AKM5386

 

The Variax String Gain is accomplished post A/D inside the Freescale DSPB56725F DSP

 

(trivia : The Mag PUs use a separate AK4556 Stereo CODEC (U6) - (for A/D for the VDI interface) and D/A for the 1/4" out  

http://www.akm.com/akm/en/file/datasheet/AK4556VT.pdf

 

http://line6.com/support/topic/5702-can-guitar-center-do-service-work-in-jtv/?do=findComment&comment=40004

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The low-E transducer on my 69 went from weak to stone dead during band rehearsal yesterday...  I'm hoping that Full Compass can ship these in a reasonably short amount of time.  Is there any other source in the US, just in case?

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I would think that if you pay for it, Full Compass would ship it overnight.  Worth a phone call to ask.

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The gain is adjusted via DSP but it's still pre-modeling, so sting volume will still effect the sounds of the modeling, at least they did in pre HD firmware, don't know about the HD firmware now.

 

One of the best ways to tell is to turn down the string volume in the sitar and listen if the drone effect goes away when the volume is low.

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I would think that if you pay for it, Full Compass would ship it overnight.  Worth a phone call to ask.

 

I will call them tomorrow, but their website says this is a non-stock item.  That means they'll first have to get it from Line6.  I'm hoping for the best.

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I hooked up my JTV59 to Workbench HD and an amp, adjusted the piezo pickup volumes trying to get unity gain (same volume on all strings) and then played out last night.  What I found is that it is useless to adjust the individual volumes, trying to get unity gain, for 2 reasons... 1) When I adjust volumes for one model, the "unity gain" adjustments don't hold for other models.  2) The tone difference resulting from the pickup selector on one setting versus another (which actually is selecting different models but a bridge pickup setting versus a neck pickup setting) affects the volume of each string. For example, if I balance the volumes while on a clean, trebly acoustic setting, when I change the pickup selector so that I have a bassier tone, the bassier sound causes the low e string to be much louder.  So ideally I would want to adjust the piezo volumes for each model and pickup combination.  Oh well.

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I called Full Compass Systems yesterday and ordered a couple of transducers.  To save time, they suggested a drop ship directly to me from Line6.  Full Compass could not have been more helpful and responsive, but the real test is how Line6 handles it on their end. 

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So I have now begun experiencing the low E phenomenon. I also have discovered that it is definitely happening at the piezo transducer. It was sometimes low and sometimes normal. One time when it was low, I hit my whammy bar (JTV69) and it popped up to normal volume. So, I have a question. I seem to remember someone mentioning that, I think it was Graphtech, had replacement saddles that worked and were a lot better. Is that true and if it is, is it a relatively easy job to replace the saddle? I am going to make sure the saddle is clean but an thinking about replacing them with better piezos,, if there is such a thing.

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So I have now begun experiencing the low E phenomenon. I also have discovered that it is definitely happening at the piezo transducer. It was sometimes low and sometimes normal. One time when it was low, I hit my whammy bar (JTV69) and it popped up to normal volume. So, I have a question. I seem to remember someone mentioning that, I think it was Graphtech, had replacement saddles that worked and were a lot better. Is that true and if it is, is it a relatively easy job to replace the saddle? I am going to make sure the saddle is clean but an thinking about replacing them with better piezos,, if there is such a thing.

 

I believe it's not so easy on the JTV models. Since James Tyler decided to have his whacky little bridge design, the graphtechs don't sit in the bridge very well.

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Thank you. Yeah, I'm hoping it just needs a good cleaning. Or at least a loose connection I can fix. I just saw a post from the guy in this thread who ordered a Line 6 saddle from Compass in September and still hasn't received it!!!!!!!!!!!!!!!!!!!!!!!

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Still waiting...  It's 20+ days and counting.  Full Compass indicates that Line6 is chronically slow to ship parts.  Supposedly they were (finally) shipped at the beginning of last week.  If the carrier is UPS I might have them by next Wednesday or so. 

 

Damn good thing I had my Roland GC-1 / GR55 as a backup for tonight's gig.  This is really poor form in my opinion.

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Can you let us know if and when you get them? It looks like I'm gonna need to get one too. I might as well get two I guess. Also, can someone explain to me just what's going on physically that creates this phenomenon? Is it a bad connection?. Possible piezo damage? Wear and tear due to Whammy bar usage? It seems to be a relatively common occurance. Seems odd that it seems to occur mostly on the E string.

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They rolled in this past Monday.  Singularly unimpressive performance on Line6's part.  I won't have time to pull the guitar apart until this weekend.  Hopefully this will cure the numb low-E string. 

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.....Also, can someone explain to me just what's going on physically that creates this phenomenon? Is it a bad connection?. Possible piezo damage? Wear and tear due to Whammy bar usage? It seems to be a relatively common occurance. Seems odd that it seems to occur mostly on the E string.

On my first Variax 300, I had a problem with my B-string piezo going dead on hot humid outdoor gigs. On my JTV-59 I had my A-string piezo go silent when I was playing in humid conditions in it's first year 2011 -- when I would bring it inside to air conditioned and reduced humidity, it would magically work fine.... The 59 bridge had a corrosion issue that L6 did a slight redesign and change of hardware vendor to the Korean factory -- this was one of their early QC problems they had to deal with. They sent me a replacement bridge, and it has not corroded or had a loss of signal on it's piezos, since then. My 69S bought in October 2012 has never had the issue.

 

My opinion is that the piezo design has a single wire lead -- the "hot" or signal lead is soldered to the little printed circuit (pc) board under the bridge. The ground return to complete the circuit is achieved with the metal case of the piezo being in contact with the grounded bridge. When my 59 bridge corroded, that ground contact became less conductive -- resistance would build up, and the signal would fade away to nothing when it was very humid...

 

One thing I noticed while replacing the bridge was that there are 2 solder pads per piezo element on the bridge pc board -- one for hot and on for ground. The piezo lead is soldered to the hot signal pad, and nothing to the ground pad. If I used a hand held hair dryer, I could coax the piezo back to operation by drying out the humidity from it, but it was a big hassle to do & rather embarassing to boot in the middle of a job. I actually had to do it when we had an outside gig at dusk, and dew settled in... not cool. No problems and no corrosion since replacing the bridge.

 

If you sweat when you play, like most people do, it could be that you might have some salts or moisture getting into and adding resistance into the contact area between the metal case of the piezo element and the bridge. That is it is on you low E string might make a certain amount of sense, as that would be the most likely side of the bridge to rest your hand for palm muting, etc. -- it is for me. I don't have an easy answer for how to get that fixed other than unsoldering it and getting any corrosion out of the bridge piece and off of the piezo. I at one time toyed with the idea of soldering a ground lead on the piezo metal case and then to the unused ground solder pad on the bridge pc board, but have not done it, as I have had 3 hot humid summers of use with my 59 since I replaced the bridge, and 2 summers with my 69S and not had it happen....

 

I made use of the forum when it was happening to me, and really only found 1 other guy with the same problem, so I don't believe it is a widespread issue. If you are with in warranty you should probably work with Line 6 with a trouble ticket. The fact that it works sometimes but not others indicates to me that it's a contact issue. If a piezo just fails, it would not be in and out, it would just be dead, period....

 

My 2 cents.

Dave

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Excellent advice davidb7170 !

 

All matches up with my own Variax Piezo failure experiences, you have documented the issues  / problems very well  

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If the casing of the transducer will take solder, I'm planning to use some 30g Kynar wire to implement a real ground connection.

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Be careful - heating a piezo saddle can cause damage 

 

many use electrically conductive adhesive instead

8331S-15G.jpg

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I was planning on using a heat-sink, but that's certainly a good alternative.  I'll practice on the bad transducer and see if it's even possible.

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Thank you for all the info and  because of it, I have a fix that so far has worked for about 30 minutes. I mess with electronics in my job and the fact that the piezo's housing acts as the contact for ground gave me an idea. I loosened my E sting enough so I could get the string off of the piezo and sprayed some electronics cleaner into it using the thin red straw that came with it (like what WD-40 has). Worked immediately. I just used Radio Shacks version of this (Precision Electronics Cleaner catalog #64-4345) and it left no residue. It looked like it would at first (sprayed everywhere!) but it eventually dissipated. There's something called Deoxit that I used to use at work a long time ago. It claims to improve the connectivity of contacts. I remember loving the stuff but I don't remember what residue, if any, it leaves.  

 

Unfortunately I had JUST placed an order for the piezo replacement and by the time I called today it was too late; it had already shipped. They must have ordered a few extra when they placed snhisch's order with Line 6.

 

Sorry snhisch. They put mine in the mail less than 24 hours after I ordered it. I can only assume it is thanks to your efforts. So, although I may not need it, thank you.

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Full Compass told me that they had ordered a bunch for stock at around the time I placed my order.  I'm glad you were spared the long wait, but I doubt I had anything to do with it. :-)

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I'm pleased to say that my problem with the bottom E string was poor grounding.  This morning I removed the bridge/tremolo assembly from the JTV-69 and had a very close look.  The transducers are just breathtakingly chintzy.  They're stamped out of sheet-metal with the piezo element potted in epoxy.  There's a single wire connected to a small PCB on the lower part of the assembly and ground return is strictly through a very iffy sequence of mechanical contacts: transducer --> bridge piece casting --> adjustment screws --> plate --> lower assembly.  The good news is that you can, indeed, solder ground wires to the transducer and I'll describe the process as best I can.

 

The signal wire emerges from the potting compound at one end of the transducer body.  At the other, there is a small "tab" that's an artifact of the stamping process.  Trick is to take a Dremel grinder with a dental-sized grinding bit and remove a very small amount of the epoxy that lies immediately on the inside of the tab.  Surface tension causes the epoxy to climb up the tab while it's setting and this is all you want to remove - perhaps 1/32".  If done carefully you don't get anywhere near the element.  With the transducer clamped lightly in a metal-jawed hobby vise to draw off heat, put a tiny dab of flux on the inside of the tab and tin it with high-grade electronic solder.  I used a temperature-controlled solder station, but any small iron should be fine if you work quickly.  Then, strip the end of a piece of Kynar 30g wirewrap wire, tin it and carefully tack it to the inside face of the tab.  If you have removed enough epoxy, it's possible to bend it around the tab to help hold it in place while you apply heat.  After the joint cools, trim any projecting length of wire with a pair of diagonal cutters and carefully file off any solder buildup on the outside of the transducer body.  If you don't get all of it, you will have trouble getting it back into the bridge piece.  The ground wire can be dressed across the bottom of the potted area and routed out the back of the bridge piece alongside the signal lead (plenty of room).  This process is not rocket science, but it isn't a whole lot of fun either, particularly with 63-year-old eyes :-).  Definitely do NOT try this unless you have at least intermediate bench skills - this isn't a good candidate for "My first electronic repair" (I've been doing this stuff for more years than I like to think about...)  As others have observed, there are six ground pads on the PCB all ready to receive these wires.

 

After doing all six pickups, I reassembled the guitar and discovered to my delight that not only was the low E issue gone, but everything sounded better.  I've been thinking there was a slow, steady degradation in the sound of the modeling and that seems to have been exactly the case. 

 

I'm glad that Line6 is saving themselves perhaps all of $5 in production costs by not using pickups with hard-wired ground return, but after this experience I can say authoritatively it was a poor decision.  Hopefully this is an area where Yamaha can help.

 

Another observation:  If I was responsible for the design of that bridge and tailpiece assembly, I sure as heck wouldn't put my name on it.  Let's leave it at that.

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I've had my new JTV59 for just a couple of days and it has this problem with low volume from the low E.  I think that the theory of palm muting focusing on the low E saddle has merit and that dirt, dead skin and somewhat corrosive sweat may be the culprit.  I also know that some piezo pickups can have less sensitivity than others and this contributes to poor string balance.

 

Here's the work-around which I had a good result with:

 

- I took a can of de-oxit and sprayed some into a shot glass.  I pushed the red, straw-like, nozzle through a paper towel, placed the paper towel over the shot glass and very gently sprayed about 1/2 a thimble worth of de-oxit into the shot glass.

 

-I then used a "whip tip" from StewMac guitar supply (wooden toothpick would also work) and drew some de-oxit out of the shot glass.

 

-I then placed a couple of VERY small drops of de-oxit directly onto the bridge saddle.  FIRST, I loosened the E string and moved it to the side.  I put a couple paper towels on the guitar body to surround the bridge to avoid getting de-oxit on the body.

 

-I wiped the saddle clean with paper towel and then reapplied de-oxit, let it soak in for a minute and wiped clean again.

 

-I repeated these steps several times and then tested the guitar.  There was a very noticeable improvement.  At that point I adjusted string balance in workbench so that the other 5 strings were set to 65% or 60%. 

 

It is now one day later (my birthday) and my fix seems to have held up well.  I think the low E string is even louder than last night when I tried this fix.  Perhaps the de-oxit took a little time to fully dissolve the oxidation, or perhaps my very dry basement dissolved whatever moisture built up on or under the saddle while the guitar sat in warehouses and delivery trucks in this cold season.  I un-boxed the guitar when it was still cold, so when it was exposed to my warm, dry basement, some condensation may have formed near the saddle.  Whatever the reason, I'm just very relieved that the low E is working much better.

 

Hope this helps. 

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If this is any help.... I had what sounds to be the same problem with my JTV69. The D string was much quieter than the rest, nothing had changed, one day it was ok the next not. I'd not been near workbench for some time but connected up anyway to check the string levels. All ok.

 

So, after reading this and another thread, I cleaned the saddle with a small amount of contact cleaner and an old toothbrush.

I did also reflash the firmware but I'm sure it was the cleaning that did the trick.

 

I always clean my guitars down after playing/gigging but I have added 'nut sauce' to the saddles (a really small amount) but obviously this has contributed to the problem.

 

It wasn't immediate but after a few minutes gently cleaning, the D string came back to life.

 

Touch wood, all is good with it at the moment.

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Just bought a real nice used JTV 69. The piezos made noise / and had low volume issues when I used thw whammy bar.

 

Sprayed contact cleaner into a little clean cat food can/ used a q-tip to wick some down into the saddles.

 

Works perfect now.They get dirty and need to be cleaned. This JTV I bought had sat a very long time.

 

Really enjoying this guitar and I have many

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Yes, relying on conductivity between dissimilar metals is not a great approach.  I solved it permanently by installing dedicated ground returns on all six pickup elements.

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