A question about the T2 SE

[INVASCdigger]

Hello,

I'm strongly considering buying a T2 SE (or a Fisher f75 SE Ltd) and would like to know if the T2 has proportional volume. What I mean by that is...the deeper the target, the softer, or quieter the response through the headphones. I like having the ability to use that feature because it tells me, audibly, if I'm dealing with a deep target. Many detectors have the volume digitally increased so that the target sounds about the same, whether it is 1" deep or 10" deep. Thanks for any information that you can give.

 

[woodchiphustler]

I use the boost process setting and it will let you know by the sound it generates what is shallow and deep. Whines on shallow targets. Can't miss.

 

[Dave J.]

T2 has proportional volume.

There are a few people who want a weak signal to bang as solid as a strong one. Several lower cost El Paso products offer that, but I am solidly in the proportional audio camp and argued successfully for it in our least expensive metal detector, the BH Junior. Which by the way is a "real" metal detector performance-wise, doing very well what it's supposed to do within its limitations.

Proportional audio is what allows you to crank the sensitivity up and listen for good hits through the background noise. There are other advantages to proportional audio which happen to be in the realm of "trade secret" but for now I'll simply point out that there are reasons beyond the obvious why an engineer might prefer proportional audio despite its greater difficulty in implementation.

Although I'm certifiably of fogey age, I have pretty good hearing, fairly hot up to 13 kHz. Hmmm....... come to think of it, come Monday I really oughta see if there's some way I can listen direct to a T2 searchcoil! Meanwhile, what with aircraft and artillery in last century's wars and 110 db rock & roll on headphones thereafter, there are lots of folks younger than me who can't even hear a 3 kHz piezo alarm (for example an electronic alarm clock). For those customers, being able to bang out marginal targets and put up either with loss of sensitivity or with huge amounts of background false hits may in fact be the best setup.

There is a compromise between those two worlds, and it's designing proportional audio such that gain can be cranked up ridiculously high so you can run pretty deep into the noise. The weakest possible signal may difficult to hear, but a signal only a little bit stronger than that may hit pretty solid. Since most customers don't grasp the fact that the purpose of the sensitivity control is to crank it down, not to crank it up, offering the customer control over response on fringe targets is a two-edged sword. The people who like to listen to weak signals through lots of noise love it, and the other customers complain here and elsewhere about electrical interference and chatter which to a neophyte user may be hard to distinguish from a defective machine.

--Dave J.

 

[TerraDigger]

Here's a post from one of the most knowledgeable members regarding T2 tones:

How Tones Work On The T2
I think I am slowly putting it all together. Don't have all the answers yet, but I'm getting there.

At first glance when you are choosing a "# of Tones" mode to use, you may think that you are just selecting how many tones you'll hear for the tone id. You can choose between 1, 2, 3, 4, and dP tones. But what you are really selecting along with the above is how you want the audio mode to process the signal response for the audio side of the detector. And along with that, two modes also change the way the visual id processes the signal.

If you go back to the manual you will find that you can choose between several audio signal processes: Continuous, sampled, or some combination of both.

The 1, 1+, and dP audio modes use a continuous signal process for the audio. You get to hear the entire signal from leading edge, peak, to falling edge of the signal. There is no internal threshold that limits how much of the signal you hear so you get to hear everything that the target might produce. Your sweep speed combined with the signal strength and target position under your coil is the only limiting factors as to how much information the audio can convey.

The 2+ mode uses a split sampling process. Continuous for the high tone side, but a combination of continuous and sampled for the low tone iron side. One aspect of 'Sampled' means that there is an internal threshold that has to be reached in order for a signal to produce a audio response. This gives you a nice long audio look at the non-ferrous signals, but helps to keeps the ferrous responses short. This in combination with the Biaxial coil is what makes this mode so good in the iron.

The 3 and 4 tone modes also use a combination of continuous and sampled signal processing. It works just like the 2+ ferrous response mentioned above, except it affects the entire discriminatory range.

The 3b mode also uses a combination of continuous and sampled signal processing but with a tighter threshold on the sampled side that requires a more stable peak signal response.

The Visual ID side only uses a sampled signal process. It works on a different sampling process than that of the audio modes and is the same for all audio modes but one. When you chose the 3b audio mode, you are also selecting to use a Visual ID mode that uses a tighter sampling process for the visual id. This is probably the least independent mode you can select and I tend to think that the same sampling process is used for both the audio and visual id modes.

I have thoughts that the dP mode also changes the visual id sampling process just by the amazing way the audio can sound so good, yet not give a visual.

So...what does this mean? Well to me, it means that I do more than just select how many tones I hear when I select an audio mode. It means I'm selecting how much or how little of the signal information I want the machine to put into my ears. Better machine control for the site, and better control of the information I'm feeding my ears and eyes. All resulting in better dig/no dig decision making.
Thats where I'm at right now.
Mike Hillis

 

[INVASCdigger]

T2 has proportional volume.



Although I'm certifiably of fogey age, I have pretty good hearing, fairly hot up to 13 kHz. Hmmm....... come to think of it, come Monday I really oughta see if there's some way I can listen direct to a T2 searchcoil! Meanwhile, what with aircraft and artillery in last century's wars and 110 db rock & roll on headphones thereafter, there are lots of folks younger than me who can't even hear a 3 kHz piezo alarm (for example an electronic alarm clock). For those customers, being able to bang out marginal targets and put up either with loss of sensitivity or with huge amounts of background false hits may in fact be the best setup.

There is a compromise between those two worlds, and it's designing proportional audio such that gain can be cranked up ridiculously high so you can run pretty deep into the noise. The weakest possible signal may difficult to hear, but a signal only a little bit stronger than that may hit pretty solid. Since most customers don't grasp the fact that the purpose of the sensitivity control is to crank it down, not to crank it up, offering the customer control over response on fringe targets is a two-edged sword. The people who like to listen to weak signals through lots of noise love it, and the other customers complain here and elsewhere about electrical interference and chatter which to a neophyte user may be hard to distinguish from a defective machine.

--Dave J.

Hi Dave,

I'm of certifiable "old fogey" age, too (mid 60s & a Vietnam Vet that has heard his share of high decibel helicopter noise & other loud sounds) and I still love to get out and swing a detector whenever I can. Are you the lead engineer for the Fisher f75 & Teknetics T2? If so, we couldn't be getting better "inside" information from anyone else on this forum! I want to thank you for the in-depth reply to my question about proportional volume. I'm really glad to know that the T2 has it. Now, I'd like to ask your opinion for which detector might suit me best between the T2 Limited Edition or the f75 Special Limited Edition. Most of my detecting will be for Civil War relics in Northern Virginia, which has very bad mineralized ground in many places, but I also like to hunt for coins around old homesites and old parks. The fact that the F75 is priced a couple hundred dollars more than T2 implies perhaps more flexibility and .... maybe a little more depth???? I'd appreciate your thoughts. Many thanks!

 

[INVASCdigger]

Here's a post from one of the most knowledgeable members regarding T2 tones:

How Tones Work On The T2
I think I am slowly putting it all together. Don't have all the answers yet, but I'm getting there.

At first glance when you are choosing a "# of Tones" mode to use, you may think that you are just selecting how many tones you'll hear for the tone id. You can choose between 1, 2, 3, 4, and dP tones. But what you are really selecting along with the above is how you want the audio mode to process the signal response for the audio side of the detector. And along with that, two modes also change the way the visual id processes the signal.

If you go back to the manual you will find that you can choose between several audio signal processes: Continuous, sampled, or some combination of both.

The 1, 1+, and dP audio modes use a continuous signal process for the audio. You get to hear the entire signal from leading edge, peak, to falling edge of the signal. There is no internal threshold that limits how much of the signal you hear so you get to hear everything that the target might produce. Your sweep speed combined with the signal strength and target position under your coil is the only limiting factors as to how much information the audio can convey.

The 2+ mode uses a split sampling process. Continuous for the high tone side, but a combination of continuous and sampled for the low tone iron side. One aspect of 'Sampled' means that there is an internal threshold that has to be reached in order for a signal to produce a audio response. This gives you a nice long audio look at the non-ferrous signals, but helps to keeps the ferrous responses short. This in combination with the Biaxial coil is what makes this mode so good in the iron.

The 3 and 4 tone modes also use a combination of continuous and sampled signal processing. It works just like the 2+ ferrous response mentioned above, except it affects the entire discriminatory range.

The 3b mode also uses a combination of continuous and sampled signal processing but with a tighter threshold on the sampled side that requires a more stable peak signal response.

The Visual ID side only uses a sampled signal process. It works on a different sampling process than that of the audio modes and is the same for all audio modes but one. When you chose the 3b audio mode, you are also selecting to use a Visual ID mode that uses a tighter sampling process for the visual id. This is probably the least independent mode you can select and I tend to think that the same sampling process is used for both the audio and visual id modes.

I have thoughts that the dP mode also changes the visual id sampling process just by the amazing way the audio can sound so good, yet not give a visual.

So...what does this mean? Well to me, it means that I do more than just select how many tones I hear when I select an audio mode. It means I'm selecting how much or how little of the signal information I want the machine to put into my ears. Better machine control for the site, and better control of the information I'm feeding my ears and eyes. All resulting in better dig/no dig decision making.
Thats where I'm at right now.
Mike Hillis

Thank you for the great information, TerraDigger!

 

[INVASCdigger]

I use the boost process setting and it will let you know by the sound it generates what is shallow and deep. Whines on shallow targets. Can't miss.

Thanks for your input!

 

[Dave J.]

T2 has proportional volume.



Although I'm certifiably of fogey age, I have pretty good hearing, fairly hot up to 13 kHz. Hmmm....... come to think of it, come Monday I really oughta see if there's some way I can listen direct to a T2 searchcoil! Meanwhile, what with aircraft and artillery in last century's wars and 110 db rock & roll on headphones thereafter, there are lots of folks younger than me who can't even hear a 3 kHz piezo alarm (for example an electronic alarm clock). For those customers, being able to bang out marginal targets and put up either with loss of sensitivity or with huge amounts of background false hits may in fact be the best setup.

There is a compromise between those two worlds, and it's designing proportional audio such that gain can be cranked up ridiculously high so you can run pretty deep into the noise. The weakest possible signal may difficult to hear, but a signal only a little bit stronger than that may hit pretty solid. Since most customers don't grasp the fact that the purpose of the sensitivity control is to crank it down, not to crank it up, offering the customer control over response on fringe targets is a two-edged sword. The people who like to listen to weak signals through lots of noise love it, and the other customers complain here and elsewhere about electrical interference and chatter which to a neophyte user may be hard to distinguish from a defective machine.

--Dave J.

Hi Dave,

I'm of certifiable "old fogey" age, too (mid 60s & a Vietnam Vet that has heard his share of high decibel helicopter noise & other loud sounds) and I still love to get out and swing a detector whenever I can. Are you the lead engineer for the Fisher f75 & Teknetics T2? If so, we couldn't be getting better "inside" information from anyone else on this forum! I want to thank you for the in-depth reply to my question about proportional volume. I'm really glad to know that the T2 has it. Now, I'd like to ask your opinion for which detector might suit me best between the T2 Limited Edition or the f75 Special Limited Edition. Most of my detecting will be for Civil War relics in Northern Virginia, which has very bad mineralized ground in many places, but I also like to hunt for coins around old homesites and old parks. The fact that the F75 is priced a couple hundred dollars more than T2 implies perhaps more flexibility and .... maybe a little more depth???? I'd appreciate your thoughts. Many thanks!

The T2 and F75 basic performance is virtually identical. The F75 might beat the T2 by a tiny smidgin in an air test, but the ground tends to erase those kinds of differences. The T2 user interface and feature set is aimed a little more at gold prospecting and relic hunting, whereas the F75 has features that aim it more at high end coinshooting. The F75 also has concentric coils available for it, whereas the T2 does not.

Between the two, I prefer the straightforward simplicity of the T2, but that's just a personal preference. How strong that personal preference is, was manifested in the GB/G2 where I was allowed to go nearly berserk in the quest for simplicity. ......But if you only knew how much complexity hidden in software it took to achieve that external simplicity!

Some people like a lot of features to fiddle with to get the max out of their machine. If you're that kind of person, you may find the F75 more to your liking than the T2.

--Dave J.

 

[Digger70pa]

Dave J. Has designed the CZ's too. They are GREAT.

 

[Old Virginia]

Dave is a rock star to detectorists.

 

[Justin E]

Maybe he could give his fan club,us, a hint as to what he's going to come out with next.

 

[Old Virginia]

Dave was a recent guest on The Relic Roundup internet radio show. He indicated that he thought the trend for future machines would be very "F75" and "T2" like - lighter, highly sensitive units. It was a great show. I believe you can access it in their archives.