ICE 55 Gain Question

[PFUNK]

I have a question for owners of this unit. I recently purchased a gently used ICE 55 online for a great price and have had a few chances to get on the ice with it. Really like it so far but have noticed that when I switch from the wide beam to the narrow beam I have to turn my gain up to see my jig. I would think it would be the opposite, as the narrow beam should give better detail and need less gain. This has been the case in all water depths from 10 to 35 feet. It really isn't a big deal, as I am able to get a distinct single line to display for my jig on both the wide and narrow beams, but I am confused as to why the gain needs to be higher on the narrow beam, even in deeper water. Is this normal? In case it matters, I do NOT have the support cable attached.

[Ishikawa]

Chances are your jig is on the outside of the cone angle and the higher gain is able to pick it up better.

[PFUNK]

Chances are your jig is on the outside of the cone angle and the higher gain is able to pick it up better.

Even if I let the jig sit still so it hangs straight down I still need higher gain on the narrow beam. Not sure how it would be on the edge of the cone if it's hanging straight down in the same hole that the transducer is in, especially in 30+ feet of water???

[ND4LIFE]

I have to do the same with my ICE-55. I have been running the narrow cone more often and find I'm in the 30's for gain while I would normally be in the 20's when set to wide. I've also noticed less interference in the first few feet when using the narrow cone vs wide.

[PFUNK]

Good to know. Just wanted to see if this was "normal" or not. It seemed backwards to me but like I said, it doesn't really bother me.

[eyedr]

Are you using the support cable on the transducer it came with? If so, quit using it. It is a pain and it can tip your transducer enough to get your jig out of the cone.

[fishwater]

The higher gain setting on the 9 degree is because the ice55 is not truly a dual beam. It relies on the secondary harmonic of the single piezo element which is not as strong as the primary.

[lakeshoremunster]

make sure to have your noise level lower that way you wont have to use so much gain

[toddb]

Fishwater ??? Explain please... Seems like far out technology for a flasher.

Cone angle is based on frequency and this is a dual frequency transducer 240/455kHz (9/19degree). Probably 2 elements if I had to guess... Wavelength differences between frequencies and sound field variations probably have more to do with the gain level than anything

[PFUNK]

I'd like to hear an explanation of this as well. I remember reading a review of the ice 55 written by a big marcum supporter in which he stated he "suspected" the gain issues on the ice 55 were due to it using a single crystal and picking up secondary signals as the "wide beam". I have never actually found that to be true,, but was rather just his guess.

[fisherman-andy]

I have one of the very 1st year model Ice 55, my unit is about 3-4yrs old I think. And yes on the narrow beam I have always have to turn up the gain 30+. This may not hold true for some of the Ice 35/45 models I am not sure.

Each year I play around with the settings of the display models at retail stores I believe Humminbird has tweaked the units over the years to be better. Makes want to send my 1st year unit in to see if it can be tweaked to current specifications?

[toddb]

Higher frequencies do not have the penetrating power of the lower frequencies and this could be part of the equation

[PFUNK]

Higher frequencies do not have the penetrating power of the lower frequencies and this could be part of the equation

This could be true but considering it happens in all different depths I am doubting it.

[jBohmer]

Higher frequencies do not have the penetrating power of the lower frequencies and this could be part of the equation

I think you my have this backwards Toddb. X-rays are High frequency which is why you can see your bones through your skin on an X-ray print. On the other end of the spectrum, your favorite am radio station is a relatively low frequency. I could pick up local Twin Cities stations radio stations at night sometimes while driving through Texas or Kansas when the weather is just right. This because the am frequency does not penetrate the atmosphere well and can bounce back to earth and be picked up in random places around the world. If you are listening to am radio at night and you think that you may be listening to a Japanese radio station you may be correct. I believe the phenomon is "atmospheric bounce"

Class dismissed.

[PFUNK]

I think you my have this backwards Toddb. X-rays are High frequency which is why you can see your bones through your skin on an X-ray print. On the other end of the spectrum, your favorite am radio station is a relatively low frequency. I could pick up local Twin Cities stations radio stations at night sometimes while driving through Texas or Kansas when the weather is just right. This because the am frequency does not penetrate the atmosphere well and can bounce back to earth and be picked up in random places around the world. If you are listening to am radio at night and you think that you may be listening to a Japanese radio station you may be correct. I believe the phenomon is "atmospheric bounce"

Class dismissed.

No i think he has it right. Lower frequency penetrates better than higher frequency but does not have the ability to show as great of detail. I believe this is due to water absorbing higher energy waves better than it absorbs low energy waves.

[jBohmer]

Fair enough, I very well could be wrong. I must do some more research to satisfy my curiosity.

[fishwater]

Fishwater ??? Explain please... Seems like far out technology for a flasher.

Cone angle is based on frequency and this is a dual frequency transducer 240/455kHz (9/19degree). Probably 2 elements if I had to guess... Wavelength differences between frequencies and sound field variations probably have more to do with the gain level than anything

Yeah, I'm not sure. I was just going off what I had heard from an avid marcum guy. That and the physical size of the ducer and proximity of the frequencies specified.

Every Hbird ice unit I've used had the gain shift favoring wide beam. I believe I've got a shredded ice55 ducer I can dissect, I'll see if I can get it apart cleanly.

Airmar puts out a neat informational handout on their transducers, look up Airmar Theory of Operations. Lots of neat sonar info and good diagrams that explain the potential ways the piezo elements can be implemented for dual beam operation.

[toddb]

They possibly do use a single element and harmonics to produce different frequencies, just doesnt seem like the best way. The stuff we use in the industry I work in are all single frequency transducers in which the frequency is dependent more on crystal thickness than anything. Multiple frequencies are undesirable and produce spurious results. Usually systems are optimized to make one frequency work well. Lots of variables involved in the physics of this and it works well enough to be used as claimed. Maybe it isn't too difficult to get a different frequency out of the ducer due to the lower desired frequncies. Sounds like the wider cone is the optimum for this transducer which would mean the 240khz frequency is probably what the crystal thickness is based on. I believe it is possible to get the 455 using harmonics but I dont believe it would work the other way. May have to do a little research...

[toddb]

J

Class back in session...

We need to figure this one out, I need to know for my peace of mind!

[toddb]

http://en.m.wikipedia.org/wiki/Acoustic_resonance

[McGurk]

Who's ready for a half hour headache? via Matt Johnson Outdoors and Vexilar. Talks about ducers, crystals, gain, cones, and angles. Applies to all ice ducers, though.

[fishwater]

We need to figure this one out, I need to know for my peace mind!

The transducer only has two pins going into the head unit, so it has only a single element. As you mention, the 240khz is likely the primary frequency of the transducer design. There is a slight discussion specifically about the ice 55 ducer on the xumba Hbird forum mentioning that it's driven by distinct frequencies independently depending on the setting selected.

[jBohmer]

This starting to get good now. This is my kind of discussion.

[PFUNK]

Yup... interesting stuff. Keep it coming.

[toddb]

I am thinking the setting for each frequency allows for changing the pulse width applied to the crystal. Shorter pulse width= higher frequency. This along with the proper damping will produce the desired broadband frequency response from the crystal.