Jump to content


Photo

G50 - Guitar Tone Slowly Sweeping Between Bright And Dark.


  • Please log in to reply
13 replies to this topic

#1 moff

moff

    Just Startin'

  • Members
  • Pip
  • 7 posts

Posted 02 June 2013 - 02:38 PM

I picked up a G50 over the winter to replace one of the XDS Plus systems I have had for some time.  They still work fine, but I grew tired of putting in a new 9V every night, so the fact that the G50 uses a pair of AAs was a plus, added to the fact that those two AAs last two or three nights.

 

Recently, I've noticed a very slow but pronounced tone "sweep", as though I have some kind of mod effect turned on.  The guitar gets very bright, then slowly gets dull, and then slowly bright again.  I have isolated the problem to somewhere in the G50 system, as the symptom does not appear when I use the XDS Plus in its place.  I'm wondering if it's perhaps a problem with the "cable length" adjustment circuitry, because the "sweep" seems to have the same effect on the guitar's tone as manually changing from a very short cable setting to a very long one.  It's as if that control is not stable, and is "sweeping" through all of the possibilities.  Admittedly, I have not tried setting the cable length to "off".

 

Additionally, I've found the XDS is noticably brighter overall.

 

Is this a known issue, and is there something I can do?


  • 0

#2 RonMarton

RonMarton

    Power User

  • Line 6 Expert
  • 1275 posts
  • LocationSydney, Australia.

Posted 02 June 2013 - 07:03 PM

That post is a brilliant and helpful description and analysis, moff !

 

"Is this a known issue, and is there something I can do? "

 

The Line 6 guys may know of it, ...but I (and countless others) can certainly testify to its extreme rarity.

 

Unfortunately, I'm reasonably sure it's caused by the sort of instability in your G50's circuitry that you already suspect, ...one that'll most likely require fixing on the workbench. (Line 6 do have a great history in terms of honouring their warranties.)

 

That route is accessed via either your local Line 6 dealer, or via the "Support" link (in the black area at the bottom of this page) and then "Repair Information" under the "Customer Service" heading of the page that will then be revealed.

 

To my mind there's only a very faint hope of a cure by another "...something I can do..."  :huh:  

 

In the unlikely event that the problem's been induced by a "volatile" corruption somewhere, depriving both of power (no batteries in the beltpack, no mains plug pack to the receiver) for about 48 hours might possibly force a system-clearing reset.

 

It pains me to say that I will be very pleasantly surprised if anyone can offer more hope than that.  :wacko: 


  • 0

#3 dboomer

dboomer

    Line 6 Staff

  • Moderator
  • 2521 posts

Posted 03 June 2013 - 08:40 AM

Hi moff

 

I've never experienced it or heard of it.  It's unlikely related to cable tone as that is a digital program.  Imagine that your digital calculator sometimes adds 2+2 and gets 5.

 

Have you tried it and found the problem with more than one guitar and more than one amp?  Are you using the factory power supply?  Can you send a wav file?



#4 moff

moff

    Just Startin'

  • Members
  • Pip
  • 7 posts

Posted 03 June 2013 - 06:04 PM

dboomer - No, I didn't try multiple guitars and amps, but I did swap out the G50 for my old XDS Plus and the problem went away, so the problem definitely follows the G50.  Now, the other thing is I'm using a Godlyke PowerAll, which is 9VDC, 2A, and it's only shared between the G50, a Cry Baby, a CS-3, and a Box of Rock, so I'm nowhere near underpowering the units.  Can custom-made T4A - 1/4" cables cause this?  Switchcraft and Neutrik ends, Radial cable.  I guess my next step might be to borrow a G50 and see if I can further narrow the diagnosis to the transmitter or receiver.  If it ends up being the receiver, can the cable tone be reset?  I suppose I could reflash the unit, but I'll have to borrow an XD-V75 so I can do that...  Failing that, does this mean it needs to go into the shop?


  • 0

#5 RonMarton

RonMarton

    Power User

  • Line 6 Expert
  • 1275 posts
  • LocationSydney, Australia.

Posted 03 June 2013 - 07:51 PM

In my opinion, moff, the key words from your first post remain

 

"Recently, I've noticed..." along with "I have isolated the problem to somewhere in the G50 system, as the symptom does not appear when I use the XDS Plus in its place." (My underlining.)

 

To my mind those words indicated from the outset that (as you so rightly replied) individual guitars and amplifiers can have no bearing on this matter. Now to the three other issues you've raised, in order:

  1. Power. As you also say, none of the four devices you're running from your PowerAll suck anything like half an amp ...and anyway, why would a power issue take so long to manifest itself ?
  2. There's simply no way that any adapter cable can cause any sort of "smooth" variation in sound, far less the weird sort you've described so clearly. "Splatting", "crackling", consistent "brightness" or "dullness" from an impedance mismatch, or total silence, ...definitely. Smooth sweeping variation of your tone, ...out of the question.
  3. As Don Boomer says, it's very unlikely to have a digital cause like "Cable Tone" ...and (as I indicated earlier) I think that, sadly, it's also fairly unlikely that any sort of "re-set" (even the one I suggested that you try) will clear the fault.   

  • 0

#6 dboomer

dboomer

    Line 6 Staff

  • Moderator
  • 2521 posts

Posted 04 June 2013 - 07:08 AM

Even though the problem is fixed when switching to XDS does not rule out an interaction with the guitar or amp (and everything else plugged into the signal line).  A better test would be to play music from an iPod into the transmitter and plug the receiver into a PA system and check again.  You should also use the factory power supply when testing.  We have not approves the Godlyke unit which means it may be fine but it may not.  You would need to measure it under load to find out.

 

To Ron's question about power issues.  So the seemingly strange thing about the power requirement is that everything may work fine for a while (during a performance) but then something as simple as one more LED turning on can push the system past the current requirement and as that LED turns on and off the system begging to behave again and then act funny.  That's why we went to great trouble to certify the power supply that we supply with the units.  They do not exhibit this behavior which I have witnessed with other brands.

 

The only way to "reset" cable tone would be to re-flash the units, but that is unlikely the source of your problem.  The problem is much more likely to involve analog parts of the system (guitar, radio, amp, etc).  It is also possible that you simply have a defective unit but it would be preferable that we do as much as possible to rule that out before sending jot for service unless you do not mind the time that will take.

 

The best course would be to try it as described into the PA and if there still a problem send me a wav file recorded directly from the output  If the problem is somehow digital there are usually timings that show up that relate to the digital circuitry.



#7 RonMarton

RonMarton

    Power User

  • Line 6 Expert
  • 1275 posts
  • LocationSydney, Australia.

Posted 04 June 2013 - 12:17 PM

Sorry folks...

 

I should have explained that my comments arose from me having worked with several multi-stomp-box users, who insist that hordes of their "tribe" swear by (not at) their Godlyke Power-All PA-9B (transformer-based) and PA-9D (switched mode) supplies.

 

Those two (relatively cheap) supplies would also be among the "cleanest" and best-regulated providers of "bulk" smooth, stable and ripple-free DC that I've seen.

 

None of which would negate any of Don B's (typically) excellent advice, ...in particular that a "known signal source" comparison, powered from the brilliantly compact and fuss-free "wall wart" that Line 6 supplied with your G50, is almost certainly the best way to eliminate the suspicion that your Godlyke supply has somehow started to induce this behaviour after months of successful operation. 


  • 0

#8 RonMarton

RonMarton

    Power User

  • Line 6 Expert
  • 1275 posts
  • LocationSydney, Australia.

Posted 04 June 2013 - 01:16 PM

Something that's just occurred to me may be a "Eureka !" moment, or may be of no consequence whatsoever...

 

Does your use of the Godlyke (I must confess to not liking that name) mean that your G50 receiver sits at your feet as a consequence of it being powered by one of that supply's included 9 volt "stompbox daisy chain" outlets, moff ?

 

If so, all sorts of strange behaviour may possibly be induced by

  1. Radiation from nearby stompbox devices and/or
  2. Diminution and/or reflection of RF from your beltpack to your G50 receiver and/or
  3. The random capacitive effects of various materials in the floor. 

The receiver's probably best located at or above the height at which its companion belt-pack is worn, but its dual-diversity whip antennae do allow considerable latitude in this regard.

 

Very few players have any problems at all with it sitting atop their integrated amp/speaker enclosures, or atop or alongside separate amp "head" units.


  • 0

#9 moff

moff

    Just Startin'

  • Members
  • Pip
  • 7 posts

Posted 06 June 2013 - 05:43 PM

First, let me thank you guys for you excellent advice.

 

Just refer to the power adapter as a "Powerall" :)

 

The same issue was present intermittently at the house gig I had all winter, so unless this venue has something in common with the house gig venue, I don't think it's environmental.

 

Yes, the G50 receiver is generally on the floor with the rest of my pedals, so I can keep the overall signal chain cable length as short as possible.

 

I tried it again at setup before the gig on Tuesday night.  The first thing I did was turn off the cable tone altogether, and at first, it didn't seem to change, then after five minutes or so, it did, and appeared to be triggered by my position onstage, which may indicate environmental interference or proximity to my amp as I moved back, or to the pedalboard as I moved forward.  I changed the channel and changed the transmitter batteries (which were indicated at "2 bars" on the receiver).  Then a very high-pitched whine - almost feedback-like - appeared, that didn't seem to be affected by anything but the guitar's volume.  At that point, I replaced the custom transmitter cable with the (far too short) stock cable, and all symptoms disappeared.

 

Because three things were changed at or about the same time (battery, channel, and cable), I can't say for sure which "fixed" the issue, or if it's indeed fixed.  It worked fine all night though.  I'm going to guess the cable might have been the problem, but maybe that's just coincidence?  The custom cables are made with Radial guitar cable (sure, it's not Mogami or Canare, but still decent cable) with Neutrk/Switchcraft ends (longer than the stock cable because I use multiple guitars in a night and keep the pack on my belt), and wired as in the published L6 documentation.  As I write this, I'm reminded that, when running my hand down the cable to grab the plug, you can hear a "rubbing" noise.  Maybe I'll try some George L instead...


  • 0

#10 RonMarton

RonMarton

    Power User

  • Line 6 Expert
  • 1275 posts
  • LocationSydney, Australia.

Posted 06 June 2013 - 07:54 PM

Just what we all absolutely adore, an intermittent fault !

But bear with us, moff, it looks like we may be (at last) making progress...

I am now almost certain that the black alchemy that is "RF interference" lies at the heart of your problem, rather than any fault in your G50 system.

As I indicated earlier, there's almost certainly no way that connecting cables can, of themselves, actually cause this type of problem, however, if I'm right, they'll have almost definitely added to the "witchcraft like" variability you've experienced.

I'll now try to explain (as clearly as I can) the theory that's behind both my earlier question and my current "Aha !". (Be warned: this could get messy.)

The key words are "Yes, the G50 receiver is generally on the floor with the rest of my pedals..." and also your saying that (it) "...appeared to be triggered by my position onstage, which may indicate environmental interference or proximity to my amp as I moved back, or to the pedalboard as I moved forward."

 

Well spotted and well described.

 

Now, in 99.99% of cases, there will be no problems whatsoever with a Line 6 Relay receiver operating in (or on) a device-populated, floor-sitting pedalboard exactly as you have done.

 

(Congratulations! You are the lucky one in ten thousand to have been chosen for this special prize, ...without so much as a single "click here".)

 

Although higher positioning of the receiver is always recommended, (for "accidental stomp" reasons, as much as for obtaining a better line of sight from the beltpack to aid reception) Line 6's data stream is nearly always robust enough to cope with nearly any configuration.

 

So I'm suggesting that the problem is not related to your beltpack's RF, but rather one caused by the induction into your system of "junk" radiated from another floor-bound device, or even a weirdly unique combination and correlation of such radiated "junk" from several (or all) of them.

 

(Effects pedal LFOs and BFOs are prime suspects.)

 

In terms of radiated RF, your (I'm guessing, superbly fit, ...in common with all Line 6 users) body acts as a large capacitor, conspiring to create a gigantic "tuned circuit" when it's fine form acts in concert with any (or every) nearby connecting cable. Each of those cables also has the innate ability to act as a reflector and/or an inductor and/or an antenna when placed in that kind of RF "circuit".


Hence the unpredictability. (The opportunity offered for stray radiation to enter your G50 receiver via the plastic components of its housing may also be a factor.)


Now for (what I'm hoping will be) "the cure"...


I'm presuming that you run something like a 5m (or 15ft) jack cable from the last device in your pedal-board's "daisy chain" to your amp input.

 

What I'm now suggesting you try is to

  • Relocate the receiver to sit behind you, on top of your amp or amp head, with just a short additional lead being now required to connect from its output to your amp's input,

  • Effectively "reverse" your long lead to now take your G50 receiver's output down to the input of your pedal rig ...and

  • Then use Line 6's supplied wall-wart from a power board behind your amp, as the new location would otherwise force a longer cable to clutter your performance space, should you stay with your former powering arrangement.

The thing about all radiation (be it RF "junk", sound, or light) is that it follows the Inverse Square Law. Double the distance and you don't receive half, you receive a quarter - the "inverse square" of 2.

Conversely, bring your source of radiated "junk" four times nearer ...and you'll swamp your circuitry with sixteen times as much of it.

Fingers crossed...


  • 0

#11 dboomer

dboomer

    Line 6 Staff

  • Moderator
  • 2521 posts

Posted 06 June 2013 - 07:59 PM

" I'm going to guess the cable might have been the problem, but maybe that's just coincidence"

No ... That Is far more likely the cause of the problem. Something about the cable isn't right

#12 dboomer

dboomer

    Line 6 Staff

  • Moderator
  • 2521 posts

Posted 06 June 2013 - 08:01 PM

I should add that changing the battery and the cable would only affect dropouts but remember the string of 1s and 0s are not affected by battery power of channel. It either works to it doesn't.

#13 moff

moff

    Just Startin'

  • Members
  • Pip
  • 7 posts

Posted 14 June 2013 - 08:17 PM

OK.  I'm posting this rather sheepishly...

 

I dug out my old Radio Shack multimeter and measured the pinouts of stock cable, and found that the custom cables were wired backwards, ie: the braided sheild of the cable was connected to the "hot" on the TA4, and centre wire went to the TA4's "ground" (I don't know a more plain way to describe it than that).  No wonder there was interference when I ran my hand down the outside.  I rewired them to match the stock cable (including the jumped ground that's not shown in the pinout diagram) and now everything's fine, interference-wise.  I haven't seen the tone sweep since changing batteries and channels, so can't confirm what stopped that.


  • 0

#14 RonMarton

RonMarton

    Power User

  • Line 6 Expert
  • 1275 posts
  • LocationSydney, Australia.

Posted 14 June 2013 - 08:47 PM

OK. I'm posting this rather sheepishly...

Crikey, (traditional Australian sheep-farming expletive) Moff !

Do you honestly believe that other experienced operators have never made similar sorts of mistakes ?

In any case, every single one of us initially assumed that the wiring of those adapters was correct, a salutary experience that goes to the heart of the customary military analysis that's applied to the word "assume", being

Assume: making an "a##" out of "u" and "me".


  • 0




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users