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Choosing transducer: 3 in 1 or 2 in 1?


No, this has nothing to do with PCs, engineoils, porn or Kindereggs, which is what Google will tell you if you start googling these new Lowrance and Simrad transducers.

In this article we will focus on these two transducers, what they do, what units they are compatible with and for what applications we recommend them. 

Let us start with the tech, what are these ducers?

They are both ducers for scanning sonar, ie they use high frequencies and narrow coneangles to produce a photo-like image of what is under the surface. Scanning sonar for recreational fishing typically consists of sonar looking down (DownScan) and/ or sonar looking to both sides of the boat (SideScan). Lowrance and Simrad use the term StructureScan for both.

In the image below I`m trying to show you how the difference in coneangles (and -shape) of 2D, DownScan and SideScan effects what you are looking at.
Difference in coneangles

Here are a few screenshots showing what to expect:

The first one is the classic 2D-view. We see the fish as arches (as long as the boat is moving) and bottom-structure drawn as a line on the screen. From the size, shape and color of the arches we can guess how far from the ducer the fish are, and in some cases even what size they are. From looking at how the bottom-structure is drawn, we can guess bottom-composition (soft or hard).
The classic - 2D.
Switching to DownScan, we leave the more or less perfect circle of the 2D-cone and venture into a cone so oval it is more like a strobe. The frequency also increases, leaving us a much more detailed, but also very different look.

A wreck on DownScan
With DownScan you can look at a brushpile, and see if there is fish in the brushpile. The fish will not show as the classic arches, but look more like small dots. In the image above you are looking at the same shipwreck as in the first image in this article (the one with the coneangles). You can easily make out the railing on top of the deck and you see the top of the ships hut at the back. The same wreck in 2D:
The same wreck in 2D - with two different coneangles.

On the left side of the screen you see 200 kHz with its rather narrow coneangle of 11 degrees (measured at -3 db), while the right side of the screen is 50 kHz with a whopping 45 degrees coneangle. (You can read the full spec of the P66 from Airmar HERE.) This screenshot clearly shows you how a narrow versus wide coneangle affects how your sonar reads and draws the bottom line. With 200 kHz the wreck clearly rizes from the bottom, while the wide coneangle of the 50 kHz makes it disappear in the bottom line. On 50 kHz we can only see a faint hint of the wreck since the bottom line thickens slightly where the wreck is, due to the wrecks harder return of the acoustic signal than the surrounding (softer) bottom. (These screenshots are from an article on wreckhunting, you can read the full article HERE.)

Moving on to SideScan, and thereby moving from sonar looking DOWN to sonar looking SIDEWAYS as well. We will start with an image showing 2D and SideScan:
Some fish on 2D - lots of fish on SideScan.
On the 2D we see some fish, but with the wide perspective of SideScan we see a lot more. On both sides of the boat there are large shoals of baitfish (green circles) and even one larger fish. In the middle of the SideScan-image you see a white line, this is effectively the course of the boat since we are looking approximately 89-90 degrees out to each side of the boat. You see the watercoloumn (and fish) and then the bottom (rather dull in this image).

The first image in this article (the one with coneangles) was made from a sonarlog of SideScan. The same wreck as seen there and with DownScan, looks like this on SideScan:
Here it comes - a sunken shrimptrawler
The same shrimptrawler but zoomed in.

To summarize, scanning sonar is a great tool when looking for both structure and fish, and supplements our 2D-sonar well. But in order to make the most of this tech, we need to take care when setting up the ducer, and learn the basics of how it works so we can decipher the image and use the information for our needs.

And with those facts fresh in our memory, it is time to look at these two transducers and what they will do for us.

Active Imaging 3 in 1 (SKU/ part 000-14489-001)

The number 3 in the name relates to 2D, DownScan and SideScan. This is the do-it-all transducer for users who like simplicity. 2D uses the same ceramic element we know from older transducer-models like 83/200HDI and TotalScan to produce 83 or 200 kHz fixed frequency or medium or high chirp. The medium chirp uses 60-100 kHz while high chirp uses 160-240 kHz. Coneangles for 2D are 21 degrees for 200kHz and 52 degrees for 83kHz.
000-14489-001 Active Imaging 3 in 1 transducer
In addition the the 2D-element there are elements for SideScan and DownScan. The SideScan-elements produce 455 or 800 kHz while DownScan is 455 kHz.

The connector on the 3 in 1 is the black xSonic connector often called "9 pin". It is only available with this connector, and you can not use any adapter on it. You can use the extension-cable for StructureScan if the original cable is to short for your boat.

You might have heard of another "do it all"-transducer called TotalScan. TotalScan is basically an older version of AI 3 in 1. The 2D in TotalScan and AI 3 in 1 is exactly the same, the downscan is more or less the same but the SideScan from 3 in 1 is a big improvement over TotalScan.

The following models are fully compatible:

  • Lowrance HDS Live
  • Lowrance HDS Carbon 
  • Lowrance Elite Ti2
  • Lowrance Elite FS
  • Simrad NSS Evo3
  • Simrad GO XSE/ XSR

Active Imaging 2 in 1 (SKU/ part 000-14490-001)

The number 2 in the name relates to the transducer having two sets of ceramic elements. One set for SideScan and one set for DownScan. There is no 2D-element in AI 2 in 1, so you need a separate transducer for 2D. The SideScan-elements produce 455 or 800 kHz while DownScan is 455 kHz.

The connector on the AI 2 in 1 is the black xSonic connector often called "9 pin". It is only available with this connector, and you can not use any adapter on it. You can use the extension-cable for StructureScan if the original cable is to short for your boat.

The AI 2 in 1 should be combined with a separate transducer for 2D. If that transducer has the older blue connector (called 7-pin, but keep in mind it often has far less pins) you must use an adapter in order to connect it to the blue port on HDS Live. The partnumber for the "7-to-9-pin adaptor" is 000-13313-001. This way you are free to mount/ place your AI 2 in 1 without having to worry of on-plane performance, as the 2D-transducer can be mounted low and the 2 in 1 higher, or you can use a shoot-though 2D. In most cases you can also mount the 2D on one side of the transom and the AI 2 in 1 on the other, thus avoiding issues with the 2D being in the way for the SideScan-signal and creating a shadow on SideScan.
My own setup - Structurescan on one side and 2D on the other.

The AI 2 in 1 looks the same as the AI 3 in 1, and they use the same metal mounting-bracket.

You might have heard of other similar transducers called LSS-1 or LSS-2. LSS-2 is basically an older version of 2 in 1. The DownScan is more or less the same but the SideScan from AI 2 in 1 is a big improvement over LSS-2.

The following models are fully compatible:
  • Lowrance HDS Live
  • Lowrance HDS Carbon 
  • Simrad NSS Evo3


So what is right for you?

As a rule of thumb our recommendation for the best performance possible is AI 2 in 1 and a separate transducer for 2D. But there are exceptions and those are:
  • With Lowrance HDS Carbon/ Live or Simrad NSS Evo3 you can run a AI 3 in 1 in combination with a separate transducer for 2D. That way you can use the separate 2D in situations where the 2D from AI 3 in 1 is less then ideal (on plane on a bassboat or out in really deep water where you want an Airmar transducer), and the 2D from the AI 3 in 1 when that 2D is ideal. (like idling or drifting in 0-150 feet of water). Thus, the problems related to the size of the AI 3 in 1 is less of an issue AND you will typically get much better 2D than an average shoot-through transducer will provide.
  • If you intend to use FishReveal a lot, you want your source for 2D and your source for DownScan as close together as possible, especially from a vertical viewpoint. They will not get much closer than in a AI 3 in 1.
  • On small boats or for portable kits where one might prioritize simplicity of setup over functionality of the equipment.
  • Under a TM (trollingmotor) if you want SideScan up front.
  • If you plan on having only one HDS Live and want LiveSight for that HDS, you want the Ai 3 in 1 and not the AI 2 in 1 to avoid running out of ports for transducers on your HDS Live.

Hooking it up.

All sizes of HDS Live has two ports for sonar at the back, one black and one blue, BUT they are both of the 9-pin type. 3 in 1 and 2 in 1 both go to the black port (number 5 in the photo below). A second 2D-transducer would go to the blue port (number 4 in the photo below).
Ports on HDS Live 9 (the 7 has only one ethernetport but is otherwise the same)
AI 3 in 1 or AI 2 in 1 are to be connected using the black port. The blue port is for the LiveSight-transducer or a separate 2D-transducer.

All sizes of HDS Carbon has two ports for sonar at the back, one black and one blue. Here we have the same configuration as on older models, where the black port is xSonic (can take up to 9-pins) and the blue is the older style connector (can take up to 7-pins).
Ports on HDS 7 Carbon, the 9/12/16 have one additional ethernetport but are otherwise the same. 
In the photo above the third connector from the left is the blue 7-pin connector and the fourth is the black xSonic 9-pin connector. As for HDS Live, 3 in 1 and 2 in 1 are to be connected using the black port.

As for Elite Ti2 and Elite FS, those units only has one port for transducers, the black xSonic 9-pin. 

Just to avoid confusion, this is what the blue port looks like on older units versus HDS Live:
New (top) versus old (bottom) blue connector.

What about LiveSight?

LiveSight (part 000-14458-001) will connect to HDS Live using the blue port for transducers (Channel 1), and to HDS Carbon or Elite FS using a module (part 000-14899-001) and ethernet (the yellow port). So if you plan on having only one HDS Live and LiveSight, you probably want the AI 3 in 1 and not the AI 2 in 1 to avoid running out of ports for transducers on your HDS Live.
LiveSight - yet to be released.

What about ActiveTarget?

ActiveTarget is the latest offering from Lowrance, providing high-resolution real time sonar, as opposed to LiveSight which is low-resolution real time sonar. The ActiveTarget transdcuer connects to a module (regardless of unit used), and the module connects to your unit using an ethernetcable (the yellow port on your HDS or Elite FS).
ActiveTarget module and transducer.


Looking for info on other transducers?

Lowrance and Simrad also offers other transducers with scanning elements. TotalScan is the older version of AI 3 in 1, LSS-2 is the older version of AI 2 in 1. And then you have HDI with 2D and DownScan and off course StructureScan 3D. All of these options are older than the two transducers described in this article, but if you are interested in more information on these options you might find THIS article helpful.

We have also made an overview of which transducers fits the different Lowrance-models. READ THIS article if you are looking for such info.

EDIT 15.02.19
Feedback is appreciated, including feedback on errors or things that should be clarified: For Elite Ti (The previous generation of Elite Ti2) there was an option in the US where you could buy the unit bundled with LSS-2, a separate 2D-transducer and a Y-cable that made it possible to use both these transducers with the Elite Ti. As for now, no such option is available for Elite Ti2.

EDIT 22.10.19
The Y-cable mentioned above is now available in the US as a bundle with AI 2 in 1.

EDIT 11.01.21
Added information on ActiveTarget and Elite FS.

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