Headphone Issues? Try Gray Ghost NDTs!

[Erik in NJ]

I have heard that many headphones don't work correctly with the CTX. I'm assuming that this is a stereo/mono issue and you can use an adaptor from Radio Shack--can anyone confirm that this is the issue? So it's not, as some have said, Minelab forcing you to use their headphones. The Gray Ghost NDTs not only have a replaceable cord (a must have really), but a mode switch that switches between mono and stereo. One setting works when the phones are plugged into the CTX and I noticed that the stereo setting works with the wireless unit. Since the headphone jack is now a module on the CTX I'm assuming that Minelab will provide various modules such as 1/4" Stereo, 1/4" Mono, 1/8" Stereo/Mono....they can also make one with a switch for both settings.

If you're looking for Gray Ghost NDT headphones (have had a pair for over 10 years now and they are still going strong) try forum sponsor Detector Depot. Gray Ghost NDTs have been my headphones of choice for a while now and I'm even happier now that they have that mode switch on them.

 

[Digger]

I'm assuming that this is a stereo/mono issue

Actually, it is not a Stereo/Mono issue. The problem with many headphones is that they do not allow the sleeve lead to provide proper signaling to the CTX 3030. I'd encourage you to read previous posts regarding this matter, as well as the Frequently Asked question section of the CTX Classroom. The CTX 3030 sleeve lead signalling requirements. Stereo/Mono schematics, the Wireless compatibility and many other audio related issues have been discussed quite thoroughly, with a multitude of solutions available. HH Randy

 

[Erik in NJ]

I did read it and I could not find a straight answer in the classroom FAQ or here.

It is a stereo/mono issue. The Koss headphones they supply are actually STEREO headphones (I'm measuring 112 ohms across each channel) leading me to believe that the machine is outputing a stereo signal (currently with the same signal on both channels). Most metal detecting headphones are mono--some with a stereo plug on the end and a switch like the Gray Ghost to compensate for where the sleeve contact is on different machines. Stereo/Mono adapters typically locate the sleeve contact so it falls in the groove between the ring & sleeve so that both are in contact with it.

When you say "signaling to the CTX" this is confusing to the layman as there is no signal being sent from the headphones to the machine per se--the machine "sees" an impedance on each channel and in this case if one of those channels has an infinite impedance (open circuit) the machines speaker acts as the second channel. The jumper fix is not a good idea IMHO because it forces the two impedance sources (speakers) in series, doubling the impedance and yielding 1/2 the volume that a set of stereo headphones would provide.

I thought the switch on the Gray Ghost NDT headphones compensated for the issue, but I was wrong, as the headphones do work, BUT I didn't realize that the speaker was ALSO still on . Now I see why Minelab added the headphone module...when enough users got frustrated with the new headphone jack, they could easily market a second module the works with our old mono headphones. An even better solution would have been a software setting to automatically switch the output signal from stereo to mono.

Please add something to the classroom discussing the stereo output on the machine and the drawbacks of the "jumper fix"....people rewiring their headphones not only voids the warranty but is just plain a bad idea. The stereo/mono adapter is also a bad idea. People are going to need to buy stereo versions of their favorite metal detecting headphones for a proper solution.

 

[Digger]

I am well aware that the GGNDT compensation network does not allow for the speaker to be disconnected. As I said in my previous response, this matter has been discussed quite thoroughly.

Here are links to Minelab's website, as found on the CTX 3030 Classroom forum, discussing the various audio options, ....

http://www.minelab.com/__files/f/93182/KBA_21-1-CTX-3030-Audio-Options.pdf
http://www.minelab.com/usa/treasure-talk/ctx-3030-audio-options

 

[Erik in NJ]

As I said in my previous response, this matter has been discussed quite thoroughly.

That may be, but I have yet to see any discussion on parallel vs. series wiring of speakers and its affect on volume and any salient discussion of the fact that the CTX has a Stereo output and why. I think it's OK to engage in further discussions so that everyone including those who are just getting machines are clear on this point and why the "jumper" fix is not the right thing to do for a number of reasons. Bottom line is, regardless of how much this has been discussed in the past, I still see a lot of confusion on this topic with users and dealers alike.

The parallel vs. series issue is a big one for resistance (impedance):

Series: x + y

Parallel: 1 / ( 1 / x + 1 / y)

I am well aware that the GGNDT compensation network does not allow for the speaker to be disconnected

In the title of the reply to my original post I was correcting my initial incorrect statement that the switch on the Gray Ghost NDTs allow these headphones to be used with the CTX.

 

[Ray-Mo.]

They are out of warranty so not an issue but would not matter as no solder or wires cut.They also still work fine on my other machines....

 

[amberjack]

interesting discussion about this headphone problem, my only concern is that minelab did not disclose that after market headphones do not work on the ctx therefore giving me and other buyers a choice and then this choice then made the buyer responsible for their actions, but as this was not disclosed this then became a problem solvable buy the spending of a further set of pro golds which even then can not be wired with a limiting switch.

i also agree that it has not been sufficiently rectified to my satisfaction am now on my 3rd adaptor as they protrude out of the detector to far.

AJ

 

[Ralph Sun Ray]

AJ,

The new Sun Ray Pro Gold headphones - CTX 3030 compatible version - are wired to the Limiter than same as they always were. However, the CTX like other Minelabs (as well as other detector brand models, that have their own limiter or adjustable volume circuits are not affected much, if any, by the headphone limiter. This has always been the case and is not unique to the CTX. We did find that if the wireless module is being used with the headphone limiter switched on, that the audio was somewhat skewed, therefore the reason for our statement on the limiter. As for target volume control the limiter had little if any effect. When plugged directly into the CTX jack (no module used) there was no audio skewing when the limiter was switched on but the target volume was unaffected the same as it has always been on the above mentioned models. Hope this helps.

Ralph (Sun Ray)

 

[amberjack]

great thanks Ralph for clearing that one up are these out to the dealers yet the CTX phones?

AJ

 

[Ralph Sun Ray]

Yes, some of the sponsoring dealers either have them in stock or will in a few days as many have been shipped out last week.

Ralph (Sun Ray)

 

[Erik in NJ]

That's interesting...thanks for the input Ray. Is there a switch on the Pro Golds like on the Gray Ghost NDTs?? I was curious why they put a stereo plug on the end of the Gray Ghosts, but the switch selects 2 segments 2 ways to work with various detectors. I'm assuming there's a stereo plug on the end of the Pro Golds too, but unless there's a selector switch or they are stereo or there's some smart switching in the headphones I don't yet understand why they would have a stereo plug as opposed to a mono 2-segment which would have worked without the jumper on the CTX. Still trying to grasp the whole headphone thing--it's a bit confusing.