Can Guitar Center Do Service Work In Jtv?

[chuskey]

I'm having an issue with my JTV69 where the signal is clipping when I play it really hard.  It's most noticeable on the 3rd and 4th strings.  I noticed it when using the VDI cable and it seemed like using the 1/4" it wasn't happening.  But I noticed that when the alternate tuning knob is enabled it's happening regardless of how the guitar is connected.

 

I've tried it into multiple sources (HD500, regular amp, Guitar Rig), and I have a JTV59 that doesn't do this.  So I've isolated it to a problem with the JTV69.

 

 

 So I dropped it off at the Guitar Center where I bought it, it's about 4 months old so should still be under warranty.  I thought to check on Line 6's site today and noticed that Guitar Center isn't listed as a service center in my area.  Their tech hasn't looked at it yet so they haven't contacted me one way or the other yet. 

 

I just don't want it to sit there for a few weeks to be told that they don't even do service work for JTV's.  

 

Anyway, that's a very long way to ask a short question:  Does anyone know if Guitar Center can actually work on JTV's or should I have just contacted Line 6 directly?

[phil_m]

Well, if they aren't listed as a service center, than, no, they won't be able to do service work associated with a warranty repair. If there's not a service center near you, than contacting Line 6 directly is the way to go about it.

[chuskey]

Thanks for the heads up.  I'll head back over there and pick it up.  There's a service center in my area, but a friend of mine just got his JTV worked on there and it took over a month for them to look at it and determine the pick up selector needed some contact cleaner...

 

I may open a support ticket with Line 6 first and see what they say. 

[cruisinon2]

Thanks for the heads up.  I'll head back over there and pick it up.  There's a service center in my area, but a friend of mine just got his JTV worked on there and it took over a month for them to look at it and determine the pick up selector needed some contact cleaner...

 

I may open a support ticket with Line 6 first and see what they say.

 

J

Thats ridiculous...nothing should ever sit for a month waiting for service. And for a 0.73 second blast of contact cleaner?!?!?! Was that even the problem, I hope? I wonder how long it would have sat there if it needed something really challenging, like a new set of strings.

[chuskey]

I agree!!  I have used this service center years ago when I had a problem with my Vetta floorboard.  From what I remember it took forever then too. 

 

Oh and on top of it taking forever for my friend to get his guitar back he said when he did it reeked of cigarette smoke.  I'm not excited about the prospect of them being my only option!

[cruisinon2]

I agree!!  I have used this service center years ago when I had a problem with my Vetta floorboard.  From what I remember it took forever then too. 

 

Oh and on top of it taking forever for my friend to get his guitar back he said when he did it reeked of cigarette smoke.  I'm not excited about the prospect of them being my only option!

I agree!!  I have used this service center years ago when I had a problem with my Vetta floorboard.  From what I remember it took forever then too. 

 

Oh and on top of it taking forever for my friend to get his guitar back he said when he did it reeked of cigarette smoke.  I'm not excited about the prospect of them being my only option!

About your problem...the fact that its happening only with alternate tunings sounds like a software issue, rather than hardware. I had a similar a problem with the acoustic models when using 1/2 step down tuning...open G string was out of control loud, but only in an altered tuning. Knocked level down in workbench, and all is good.

 

Also had issue with the acoutic model, position 3...if the tone knob was anywhere but on '10', I got a horrible distorted echo about 300ms after any note I played. Happened after I flashed 2.0 firmware the first time, but again only happened in alt. tuning. Reflashing firmware fixed it.

 

Only thing I can figure is that the alt tuning algorithms are doing a lot in a short amount of time...and sometimes it sh*ts the bed. Try reflashing the guitar and see what happens...might also want to lower the string volume, see if that helps.

[silverhead]

I think you should report that service Center to Line 6. Perhaps they will decertify it and find a replacement.

[chuskey]

About your problem...the fact that its happening only with alternate tunings sounds like a software issue, rather than hardware. I had a similar a problem with the acoustic models when using 1/2 step down tuning...open G string was out of control loud, but only in an altered tuning. Knocked level down in workbench, and all is good.

 

Also had issue with the acoutic model, position 3...if the tone knob was anywhere but on '10', I got a horrible distorted echo about 300ms after any note I played. Happened after I flashed 2.0 firmware the first time, but again only happened in alt. tuning. Reflashing firmware fixed it.

 

Only thing I can figure is that the alt tuning algorithms are doing a lot in a short amount of time...and sometimes it sh*ts the bed. Try reflashing the guitar and see what happens...might also want to lower the string volume, see if that helps.

Thanks for the advice.  

 

I've tried reflashing the firmware, as well as rolling back to version 1.9.  I still had the issue.  

 

When I connect via VDI I get the same issue in standard tuning.  When connected via 1/4" cable I don't get the issue in standard tuning.  I thought I was good to go but discovered last week that it happens in alt tuning mode even when connected via 1/4".  

 

My JTV59 doesn't do this.  I've really been enjoying playing this guitar so I'm bummed to be without it for a while :(

[chuskey]

I think you should report that service Center to Line 6. Perhaps they will decertify it and find a replacement.

I'll open up a support ticket and see what Line 6 has to say.  I'm sure they wouldn't be happy knowing that this company is representing them.  When I had my Vetta floorboard worked on all those years ago, and when my friend took his JTV there, they didn't really seem to be very familiar with Line 6 products anyway.  Not sure how they became a certified service center.  

[arislaf]

I think you should report that service Center to Line 6. Perhaps they will decertify it and find a replacement.

Wow, how can we do that? Our service in Greece (Nakas ) is also no good at all.

[silverhead]

Use the Contact Us link at the foot of this page.

[ajktsb]

Even though you only hear it in the alt tuninjgs, I'll bet it is there in the original tuning as well. I recently spent A LOT of time tracing the distortion in my JTV69. traced it directly to the piezos in strings 3 and 4. I opened up Workbench HD and lowered the volume down several DB on the 3rd string and just a little bit less on the 4th. Problem went totally away and the guitar still sounds fine even with the lowered string volume. Try it!

[chuskey]

Even though you only hear it in the alt tuninjgs, I'll bet it is there in the original tuning as well. I recently spent A LOT of time tracing the distortion in my JTV69. traced it directly to the piezos in strings 3 and 4. I opened up Workbench HD and lowered the volume down several DB on the 3rd string and just a little bit less on the 4th. Problem went totally away and the guitar still sounds fine even with the lowered string volume. Try it!

Thanks for the advice.  It's in the regular tuning when connected via VDI, but for some reason it's not prevalent when connected with 1/4".  

 

I had gone into Workbench and dropped the volume of the 3rd and 4th strings down to 20% to see if that would fix the problem but it was still there.  Just quieter.

 

I opened a support ticket with Line 6 yesterday and hope to hear something soon.  I opened up a support ticket a month ago about not being able to register this guitar to my account.  I never heard anything back.  I'm hoping they will respond to the ticket I opened yesterday.

[ColonelForbin]

Ask the Guitar Center where you took the gear, if they have an onsite third party repair company. That may be the case, and that company may be an "authorized L6" repair facility.

 

For example, the Guitar Center near me (on Halsted near Wrightwood, in Chicago) has an in-store repair facility - but it's not staffed by Guitar Center, it's actually a 'satellite' branch of Third Coast Guitar Repair.

[snhirsch]

All the discussion I've read about the Workbench level settings suggests that the gain adjustment occurs between the piezo pickups and the AD converter.  While that certainly would be a logical place to put it, does anyone know for sure if that's actually the case?  I'd certainly hope so, but it would be nice to hear confirmation from the Line 6 technical folks.  Hard to believe this would be considered proprietary information.

[stevekc]

 

 

All the discussion I've read about the Workbench level settings suggests that the gain adjustment occurs between the piezo pickups and the AD converter.  While that certainly would be a logical place to put it, does anyone know for sure if that's actually the case?  I'd certainly hope so, but it would be nice to hear confirmation from the Line 6 technical folks.  Hard to believe this would be considered proprietary information.

 

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

[chuskey]

I haven't been back to guitar center to pick up my guitar yet, but I went ahead and opened a ticket with Line 6 to get the communication started.  I sent them a sound clip and heard back from them today.

 

Basically that this is something they've heard before and is happening because I'm "playing too hard".  Even though my JTV59 doesn't do this.  Difference between a tremolo bridge and fixed bridge maybe?

 

They said I could send it in for diagnostics, but if they're just going to tell me nothing is wrong with it I'd rather skip the time without my guitar.   

[snhirsch]

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

 

Interesting.  Does it have enough S/N ratio to be massively conservative in gain matching - to the point where even the heaviest pickers cannot run out of headroom?  This is one of the issues that gives me pause when thinking about the GraphTech bridges.  I suppose one could get in there and twiddle the feeback around the input op-amps if required.

[chuskey]

Well I got my problem sorted out.  The fix was a bit of a duh moment, and I'm almost embarrassed that it took me as long as it did to figure out how to correct it.  

 

What I had to do is change the global string volume settings from the edit menu.  I searched the forums and heard people talking about how this acts as a type of pre gain.  Lowering it by 5-6db did the trick. 

 

I didn't even know that setting was there.  I don't use workbench all that much, probably because I can't connect through my HD500 and have get out a separate interface, and just never noticed that setting in the edit menu.  

 

I had been adjusting the the string volume on the patch, but that didn't do anything to help the problem.  

 

As to why the signal was so hot and clipping I couldn't say.  My JTV-59 never had that issue.

 

So all is well again thankfully!

[cruisinon2]

Well I got my problem sorted out.  The fix was a bit of a duh moment, and I'm almost embarrassed that it took me as long as it did to figure out how to correct it.  

 

What I had to do is change the global string volume settings from the edit menu.  I searched the forums and heard people talking about how this acts as a type of pre gain.  Lowering it by 5-6db did the trick. 

 

I didn't even know that setting was there.  I don't use workbench all that much, probably because I can't connect through my HD500 and have get out a separate interface, and just never noticed that setting in the edit menu.  

 

I had been adjusting the the string volume on the patch, but that didn't do anything to help the problem.  

 

As to why the signal was so hot and clipping I couldn't say.  My JTV-59 never had that issue.

 

So all is well again thankfully!

 

It seems that there is considerable variation with piezo output...it's also odd that along with the 2.0 update, the default global string volumes are not all at 0db. I toggled back and forth between 1.9 and 2.0 a few times, just testing things out...each time I reflashed 2.0, the volumes werwe set at  0db, -3.1db, 0db, -6.0db, 0db, -6.0 (low E to high E). I've got them all set at -6db now, plus some individually tweaked models.

[toasterdude]

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

You seem to know quite a bit about JTV guts. I have a whacky question for you, if you know the answer. Lets say I was building a guitar and didn't want model selector and alt tune knobs on it. If the knobs are physically not there, can I still select model and tuning via VDI?

[toasterdude]

Well I got my problem sorted out.  The fix was a bit of a duh moment, and I'm almost embarrassed that it took me as long as it did to figure out how to correct it.  

 

What I had to do is change the global string volume settings from the edit menu.  I searched the forums and heard people talking about how this acts as a type of pre gain.  Lowering it by 5-6db did the trick. 

 

I didn't even know that setting was there.  I don't use workbench all that much, probably because I can't connect through my HD500 and have get out a separate interface, and just never noticed that setting in the edit menu.  

 

I had been adjusting the the string volume on the patch, but that didn't do anything to help the problem.  

 

As to why the signal was so hot and clipping I couldn't say.  My JTV-59 never had that issue.

 

So all is well again thankfully!

Hmmm in another thread someone asked about tapping off the ghost system and if a buffer was required. Maybe the fact that the models seem 6db hot, would allow just tapping off and the possible signal loss could be handled by lowering by less than 5-6db in worbench?

[stevekc]

 

 

You seem to know quite a bit about JTV guts. I have a whacky question for you, if you know the answer. Lets say I was building a guitar and didn't want model selector and alt tune knobs on it. If the knobs are physically not there, can I still select model and tuning via VDI?

 

Yes 

[stevekc]

 

Hmmm in another thread someone asked about tapping off the ghost system and if a buffer was required. Maybe the fact that the models seem 6db hot, would allow just tapping off and the possible signal loss could be handled by lowering by less than 5-6db in worbench?

 

 

If it were me, and swapping out the LR BAggs Piezo saddles for higher output Graphtech - it all depends on the player.

If you are steve vai and use a very light swept pick attack - or if you can actually play a guitar with a full floating floyd rose during your most aggressive solos and not suffer the "boing-boing"of the bridge bouncing on every note  - then you might be OK and not have to resort to the measure explained below:  

 

In my case I have a very aggressive right hand, based on growing up playing non tremolo Gibsons with P90's and Acoustic Guitars with heavy strings. My right hand can deliver a tremendous amount of dynamic range.

 (evidence here)

http://www.vguitarforums.com/smf/index.php?topic=82.0

 

I would study the fixed gain opamp input section on the Variax  DSP Board , and swap out 6 SMT Gain set feedback resistors for different values to lower the input gain right at the input - because once the signal is clipping and distorting - lowering the gain down stream post A/D in the DSP is a futile effort that is never going to tame transient spikes or make the signals  clean again..

http://www.radio-electronics.com/info/circuits/opamp_basics/operational-amplifier-gain.php

http://youtu.be/i1TDtNwoJiA

 

But remember swapping to Graphtech piezo saddles with higher output signal also means higher susceptibility to adjacent string crosstalk   - this really clobbers DSP generated alt tunings - so higher piezo saddle output signal is often not a good thing  

[snhirsch]

Yes.  That was exactly the point I was trying to make in an earlier post.  In a perfect world, Line 6 would have designed things such that the pre-AD gain could be software controlled.  If the current setup has monster amounts of headroom, it may be physically impossible to overrun the converter.  But I pick harder than hades myself and wouldn't take that bet.  Piezo transducers can put out some serious peaks.

 

Do they still teach analog circuitry in an EE cirriculum?  Sometimes I worry that analog design is a vanishing skill set.

[stevekc]

 

 

 

Do they still teach analog circuitry in an EE cirriculum?  Sometimes I worry that analog design is a vanishing skill set.

 

Tell me a bout it! ;)

 

I'm willing to share more Variax circuit tips  - but I want to avoid getting in hot water with Line6 / Yamaha  - but physics and electronics is my day gig and most of the circuits for A/D>D/A and piezo preamps are already out there  - just a google image search away.  

[toasterdude]

Tell me a bout it! ;)

 

I'm willing to share more Variax circuit tips  - but I want to avoid getting in hot water with Line6 / Yamaha  - but physics and electronics is my day gig and most of the circuits for A/D>D/A and piezo preamps are already out there  - just a google image search away.  

Wait a second. You know all this cool info on the JTVs. . . .AND . . . have a variax with bigsby? damn. . . .

[snhirsch]

I can't see where discussing perfectly visible aspects of the Line 6 internals even remotely compromises intellectual property.  It's not as if anyone's sitting here trying to reverse engineer the firmware. 

[snhirsch]

You are Elantric?  Yow.  Quite a background... 

[Charlie_Watt]

Higher gain piezos does not mean more crosstalk.  It means hotter signal, yes but if you reduce the gain, the crosstalk is reduced also.  Crosstalk is much more a function of the mechanical design.  (I do this for a living too but for Hard Disk Drives)  I have used piezo elements for measuring acceleration disturbances.  I would feel comfortable modifying the input gain stage if I had to.  I would first put a scope on the analog signals going into the A/D and see what they look like when I strum hard.  If they are clipping there or exceeding the input parameters for the A/D, then the gain is too high and there is no way adjusting the string volume in Workbench will fix that.  I have no idea how much headroom Line 6 designed into this circuit.  That is always a Signal / Noise and resolution tradeoff.

[toasterdude]

Higher gain piezos does not mean more crosstalk. It means hotter signal, yes but if you reduce the gain, the crosstalk is reduced also. Crosstalk is much more a function of the mechanical design. (I do this for a living too but for Hard Disk Drives) I have used piezo elements for measuring acceleration disturbances. I would feel comfortable modifying the input gain stage if I had to. I would first put a scope on the analog signals going into the A/D and see what they look like when I strum hard. If they are clipping there or exceeding the input parameters for the A/D, then the gain is too high and there is no way adjusting the string volume in Workbench will fix that. I have no idea how much headroom Line 6 designed into this circuit. That is always a Signal / Noise and resolution tradeoff.

On the graphtec site they have verbage about their piezos compressing so as not to produce clipping. I will have to investigate to see if that is only with ghost system in addition to piezos.

[Charlie_Watt]

The piezos themselves will not do any compressing.  They respond to acceleration input (from the string vibration)

[toasterdude]

Yes 

 

Hmmm. . .what about no volume  or tones pots? lol Pickup selector? Ma make a cool lap steel f  can work all of that out.