MM Sterling LUKE Conflict w/Nextone Special amplifier

[Bill_Old Guitarist]

I have a new, very impressive and loved Sterling LUKE. The guitar played (transmitted pickup signal) to a new Boss Nextone Special. LUKE played successfully with two previously owned Egnater Rebel 30 and a new Fender Mustang GTX 100. My PRS SE 245 successfully plays now with the newly marketed Nextone Special. I am wondering if the active boost may result in my sad problem. But, I'm also wondering about a statement made by a guitar tech friend; he suggested that LUKE ostensibly incorporates a rather unusual negative polarity output design. LUKE cannot transmit, via Mogami or Live Elite cables using tip and one ring connectors, any signal that results in any sound. I'm totally.stumped. Any theories you might propose are welcomed sincerely. BTW, I've tested the electrical outlets and the very few surge protectors throughout my house. No spikes, sags, or potential amperage issues can account for LUKE'S silence. Thanks in advance for your help.

 

[beej]

I'm sorry, I don't understand the problem. What is the issue with the amp exactly?

If you're saying you don't get any output with certain cables, I would test the cables for continuity- make sure the tips and rings are properly connected. I'm not an expert on the Sterling line, but there's no reason that one cable would be different than another, unless you have a short or an open circuit.

 

[Bill_Old Guitarist]

Thanks for the response. Both cables work well with my PRS SE 245. The Nextone amp processes the pickups signal from the PRS SE 245. The LUKE, however, under various test conditions recommended by a tech at Sweetwater, cannot produce any sounds when connected to the Nextone Special. I can only conclude that the problem unfortunately is with the LUKE. The tech sent two adapters in an attempt to change the polarity of the LUKE or to change the polarity when inputted directly into the amp. Still no music. Two hypotheses: (1) I have been told that MM guitars, and by extension Sterling guitars, output from a negative polarity to the cables; AND, (2) perhaps the active boost from the LUKE creates the problem. Thoughts?
'

 

[beej]

I'm afraid that doesn't make any sense to me. The buffer circuit electrically isolates the guitar electronics from what comes after- there's no magic here. And the boost just increases the overall volume that the buffer puts out. (This is no different from plugging your guitar into a clean boost pedal- set it with no boost and you're buffered, or increase the boost and increase the volume ...)

What do you mean by a "negative polarity"? There isn't really a polarity per se- the signal is alternating current and the voltage swings from positive to negative and back, as with all audio signals. What exactly did the tech send you to "change the polarity"?

My best guess here is that the cables aren't making good contact with the output jack in your Luke. Do you have some other cables you can try? (There isn't anything magic about cables either, but not all plugs are the same size, maybe that's the issue.)

 

[Bill_Old Guitarist]

Thanks again for the rapid response. Both cables worked on an Egnater Rebel 30 and a Fender Mustang GTX. The same cables currently work when connecting my PRS SE 245 to the Nextone Special.

I believe the Sweetwater tech just doesn't have sufficient knowledge or experience to help. His recommendations seemed random. I also think he did not want me to return the guitar; it's only.a month since I purchased it. Yet, he did send me cable extensions. He might have tried to evaluate whether the problem was, as you wrote, in the cable plugs. No success with three types of cable extensions. I had already considered that the cables might be the problem and had tried cable extensions on my own and used yet a third top of the line but shorter cable.

I was earlier in life a software engineer--emphasis on engineering the software process. But, I have a unique and rare problem, and after considering all potential causes and isolating all electrical hypotheses, all I come with is this: one guitar, using the same cables connects with the Nextone Special and produces great and various tones and the LUKE remains silent.
I'm frustratingly stumped. I truly look forward to you response.

 

[tbonesullivan]

Negative polarity? Like it is putting the signal on the ground or something like that? That doesn't make any sense, and in that case it wouldn't work with ANY amp, if I understand that correctly.

If anything this sounds like the old "Active preamps don't play well with wireless systems / etc" thing. A lot of fancy electronic modellers and such use stereo input jacks, which is not uncommon, however many of them also decide to put a muting circuit or something on the "ring" area contact. I believe that the design of the LK100 may also do the same thing, using continuity to ground to tell the preamp when to turn on, or something like that. This could be interfering with the ability of the preamp to know it is plugged in, so the guitar never turns on, and you get no signal.

 

[DrKev]

(1) I have been told that MM guitars, and by extension Sterling guitars, output from a negative polarity to the cables; AND, (2) perhaps the active boost from the LUKE creates the problem. Thoughts?
'

(1) That's just nonsense talk that can't make any difference. (2) like Beej said doesn't make any difference.

When trouble shooting annoying issues like this it is super important to check all the stupidly obvious stuff that we think is so obvious it can't possibly be that. (Every single professional tech or luthier gets tripped by this kind of thing once in a while, nobody on earth is immune to it). First put a brand new alkaline battery in there. Then verify that there is ANY output form the Luke, TODAY, using a MONO cable (i.e. just TS, not TRS) that you know with certainty works TODAY, into any other device, e.g. a tuner pedal, or into a USB interface, headphone amp, mixing desk, present today. (Don't rely on past knowledge of it worked last week with X or Y). If there is output, the problem is not with the instrument, probably a cable issue like Beej mentioned.

If the problem is with the guitar, then plug a cable into the guitar, does the problem change change when the active boost is engaged or not? Then use a multimeter from the tip of the cable to various parts of circuit. This really is the kind of thing that should be bread and butter work for any guitar tech worth their salt and they should able to diagnose pretty quickly. If they can't, time to find a new tech.

Also, do contact Sterling by Music Man customer service. They may be able to offer troubleshooting assistance that Sweetwater can't.

 

[Bill_Old Guitarist]

Negative polarity? Like it is putting the signal on the ground or something like that? That doesn't make any sense, and in that case it wouldn't work with ANY amp, if I understand that correctly.

If anything this sounds like the old "Active preamps don't play well with wireless systems / etc" thing. A lot of fancy electronic modellers and such use stereo input jacks, which is not uncommon, however many of them also decide to put a muting circuit or something on the "ring" area contact. I believe that the design of the LK100 may also do the same thing, using continuity to ground to tell the preamp when to turn on, or something like that. This could be interfering with the ability of the preamp to know it is plugged in, so the guitar never turns on, and you get no signal.

Great response! So I should purchase a stereo cable? Or, perhaps I should plug into the Return effects loop? I will try the latter. and report my results. Thanks!

 

[DrKev]

If anything this sounds like the old "Active preamps don't play well with wireless systems / etc" thing. A lot of fancy electronic modellers and such use stereo input jacks, which is not uncommon, however many of them also decide to put a muting circuit or something on the "ring" area contact. I believe that the design of the LK100 may also do the same thing, using continuity to ground to tell the preamp when to turn on, or something like that. This could be interfering with the ability of the preamp to know it is plugged in, so the guitar never turns on, and you get no signal.

The negative output thing is bandied around on the iterwebs as to why wireless units have a problem with actives but it's wrong.

Instruments with active electronics usually use a TRS socket on the instrument. The ring contact is connected to the negative side of the battery. Until a cable is plugged in, the circuit is open and the battery is not fully connected and will not drain. When a standard TS cable is plugged in, the negative side of the battery on the ring contact of the socket, is connected to ground through the sleeve of the cable jack, closing the circuit and connecting the battery correctly. That's why we say unplug when not playing the guitar so as to not run the battery down.

Some wireless systems don't like that voltage on the ring and/or try to do the same trick themselves, which can cause problems. But that's NOT the situation here, so just use a good old fashioned TS/mono cable for now to ensure the guitar does what it's supposed to and all should be well.

 

[Bill_Old Guitarist]

The negative output thing is bandied around on the iterwebs as to why wireless units have a problem with actives but it's wrong.

Instruments with active electronics usually use a TRS socket on the instrument. The ring contact is connected to the negative side of the battery. Until a cable is plugged in, the circuit is open and the battery is not fully connected and will not drain. When a standard TS cable is plugged in, the negative side of the battery on the ring contact of the socket, is connected to ground through the sleeve of the cable jack, closing the circuit and connecting the battery correctly. That's why we say unplug when not playing the guitar so as to not run the battery down.

Some wireless systems don't like that voltage on the ring and/or try to do the same trick themselves, which can cause problems. But that's NOT the situation here, so just use a good old fashioned TS/mono cable for now to ensure the guitar does what it's supposed to and all should be well.

Your kind responses have helped greatly. I plugged each cable into an old Class D amplifier I had forgotten I had. With the old amp in the ON position, I plugged each cable into, first the LUKE and, second, into the amp. The guitar caused a grating noise each time I pushed just the Tip into the first position of the output depressor. Then I pushed the cable "plug" completely into position. No sound. Next, I moved among the pickup selector's five positions. Finally some sound. I conjecture that the pickup selector's ground was problematic or that the pickup selector itself could not establish contact appropriately. I am ordering a can of nonliquid compressed air to clean the pup's contacts. Then I will follow at least two ground wires to determine if they are soldered as designed and attached appropriately.

Perhaps Occam's Razor applies here. Thanks for helping in my situation which appeared quite complex and inexplicable. I'm not sure I'm following the right path; but, your guidance will certainly result in restoring my LUKE to making music again. I am off to collect compressed air. I will report my progress. Thank you all for helping a 73 y.o. guitarist to once again see some light at the end of the metaphorical tunnel. Ciao!

 

[Iperfungus]

Another common issue that affects guitars with active circuits is related to batteries inside the battery holder.
It happens that 9V batteries from different manufacturers can show some small differences in size..but this small difference could be enough to make battery move inside the holder and loose contact = NO SOUND, because the active circuit is off.
To solve this put a small and folded piece of paper among battery bottom and the holder's cover/clip, to help battery staying in place withou moving.
This helped me to fix such kind of issue with my Luke III.

 

[Bill_Old Guitarist]

Your kind responses have helped greatly. I plugged each cable into an old Class D amplifier I had forgotten I had. With the old amp in the ON position, I plugged each cable into, first the LUKE and, second, into the amp. The guitar caused a grating noise each time I pushed just the Tip into the first position of the output depressor. Then I pushed the cable "plug" completely into position. No sound. Next, I moved among the pickup selector's five positions. Finally some sound. I conjecture that the pickup selector's ground was problematic or that the pickup selector itself could not establish contact appropriately. I am ordering a can of nonliquid compressed air to clean the pup's contacts. Then I will follow at least two ground wires to determine if they are soldered as designed and attached appropriately.

Perhaps Occam's Razor applies here. Thanks for helping in my situation which appeared quite complex and inexplicable. I'm not sure I'm following the right path; but, your guidance will certainly result in restoring my LUKE to making music again. I am off to collect compressed air. I will report my progress. Thank you all for helping a 73 y.o. guitarist to once again see some light at the end of the metaphorical tunnel. Ciao!

Another common issue that affects guitars with active circuits is related to batteries inside the battery holder.
It happens that 9V batteries from different manufacturers can show some small differences in size..but this small difference could be enough to make battery move inside the holder and loose contact = NO SOUND, because the active circuit is off.
To solve this put a small and folded piece of paper among battery bottom and the holder's cover/clip, to help battery staying in place withou moving.
This helped me to fix such kind of issue with my Luke III.

Will do. I'll notify you of the result tomorrow. Thanks for the very helpful post. BTW, in all my years, I have never owned guitar with active circuits.