View Full Version : HDR-HC9, A/V Remote Terminal, and LANC


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Bill Koehler
April 26th, 2008, 08:27 PM
In reading through the specifications for the HDR-HC9 camcorder, the following really stood out to me.

The LANC, Composite Video, S-Video, and Component Video connections are all obtained through a single 10 pin proprietary connector. So if you already have a LANC controller for an older camera, forget it. It has no hope of plugging in because of the change in connector.

But wait! It gets even better! If you do get and plug in Sony's special LANC controller for this camera, you now can't access the video outputs (composite, S-Video, and component) for monitoring your video!

Am I wrong? Am I misreading something here? Or is this camera screaming for a breakout cable that will give the user the ability to hook up their older LANC controller (I have a Manfrotto 523PRO) AND access to the video outputs? And does that cable already exist somewhere?

Dave Blackhurst
April 27th, 2008, 11:25 AM
First, the HC9 still has a dedicated LANC, look closer, it's in the front of the port bay on the left side under the LCD.

Second, I've hacked the 10pin A/V jack, and yes, what you're asking is possible, I'm just about done with the documentation for DIY'ers. And AFAIK, no one makes such a cable...

Bill Koehler
April 27th, 2008, 01:05 PM
Thanks for the info, Dave. I missed that on the HDR-HC9.

I was going partly by looking up the products (HC9, SR11, and SR12) on the B&H PhotoVideo website.
To go by the accessories B&H lists for those cameras, the SR11 & SR12 also have LANC, but you get it only through the A/V Remote Terminal.

So a break-out cable would be directly applicable to those cameras as well.

Dave Blackhurst
April 27th, 2008, 08:53 PM
Yep, that is correct, I originally hacked the A/V jack for the CX7, but it applies to several other cams, including the SR11/12

Bill Koehler
April 28th, 2008, 10:38 AM
Seems to me there should be a business opportunity here.
If you're selling, I'm buying.

I found your previous HDR-CX7/LANC discussion here:

http://www.dvinfo.net/conf/showthread.php?t=110755

One note: the Sony external microphone to AIS adapter has been discontinued. Or at least B&H lists it as such.

http://www.bhphotovideo.com/bnh/controller/home?O=Search&A=details&Q=&sku=479976&is=REG&addedTroughType=search

Is it just me or is Sony trying to make it hard to plug anything but their own stuff into their consumer cameras?

Christian de Godzinsky
June 3rd, 2008, 04:37 AM
Hi,

Does a 2,5 mm Lanc Jack to 10-pin AV-connector adapter exist - or not ?

I would like to puchase one immediately but cannot find such an adapter...

Does anybody know if such is - or will be - available?

I would like to use my SR12 with my nice tripod, that has a nice Lanc commander... There MUST be other people suffering from this same problem. I am NOT going to buy the small flimsy remote that Sony is promoting as an accessory!!!

Thank's in advance for any comments.

Christian

Bill Koehler
June 17th, 2008, 08:39 PM
The short answer, Christian, is no.

I agree completely with you. If Sony thinks for a moment that I'm going to replace my Manfrotto 523PRO with the sorry excuse for a LANC controller that they offer for the HDR-SR11, SR12, CX7, etc. then they have taken leave of their senses.

Indeed, bundling so many I/O's into one tiny connector like that I think was really counter- productive, and unnecessary. Even with adapters, typically you are going to have access to just one function. You have to make a choice - LANC, or Video output for monitoring, for example. It would have been far better to have multiple connectors, segregated by function:
a) LANC
b) SD Video I/O
c) HD Video I/O
d) 3.5 mm Stereo Audio Line-In (Stereo Microphone Input)
e) 3.5 mm Stereo Audio Line-Out (Headphone Jack Output)
f) FireWire

At least that's what I look for. Feel free to make up your own list.

Christian de Godzinsky
June 19th, 2008, 12:39 AM
Bill,

Your list is as almost copied from my HC-1 - it had just about everything on separate connectors...

We will probably never get such an adaptor from Sony, but neither have I found one froma ny other wendor (Hama)... SIGH!!!

Christian

Dave Blackhurst
June 19th, 2008, 04:06 AM
IF you're handy with a soldering iron, you can build your own at least to some extent - I've managed to reverse engineer SOME of the mysteries of the A/V jack. I'm trying to get time to revisit the thing and try a couple new twists so I've got EVERY secret unlocked before I "publish". I've got the LANC licked, and the s-vid outputs figured...

The audio I/O is a bit more problematic, and interacts with other inputs on the camera... From the service manual diagrams, Sony has all the different I/O ports (AIShoe, A/V jack, mic and headphone jacks) linked to some degree and re-configurable depending on what is plugged in where... the LANC interface was relatively easy to suss out... it's mapping all the other functions that's turned out to be a PITA...

Dan Miyahira
June 25th, 2008, 01:10 PM
Hi I've been following this thread for sometime and may have found something of interest. I have been in contact with a company that makes these adapters.

Go here: http://www.digi-dat.de/produkte/index_eng.html#AVR_LANC

They have had some problems with production but I was told that they would be ready for shipping sometime this week. Cost is in Euros but they accept Paypal.

They are sold in pairs (for stereo video)- EUR 150 ($223 US)


Shipping is as follows:

Standard postal service as maxi letter (no insurance, no tracking, shipping 10-14 days): EUR 9 ($14 US)

Postal service as maxi letter express service (no insurance,no tracking, shipping 6-10 days): EUR 14.50 ($22.55 US)

Postal service international package (includes insurance, tracking only within Europe, shipping 10-12 days): EUR 33. ($51.31 US)

Postal service international package premium service (includes insurance, tracking only within Europe, shipping 6-10 days): EUR 49. (76.19 US)

UPS worldwide expedited (includes insurance, tracking worldwide, shipping 2-3 days): EUR 102. ($158.60 US)

Hope this helps

Dave Blackhurst
June 25th, 2008, 06:53 PM
That's a lot of lettuce for a plug, a bit of cable, a couple jacks and a resistor...

Dan Miyahira
June 25th, 2008, 07:34 PM
That's a lot of lettuce for a plug, a bit of cable, a couple jacks and a resistor...

About $248 worth. I flipped when I converted it (is the US dollar that weak?) But you get 2 so roughly $124 a piece.

Still, for those who "have to have it now", at least there is something available. I think I can wait for you to "publish" when you are ready. I just need Lanc + video out. Shouldn't be too hard. Just have to find a reliable way to remove all of that glue on the plug without melting everything.

Bill Koehler
June 25th, 2008, 11:38 PM
That's a lot of lettuce for a plug, a bit of cable, a couple jacks and a resistor...

I think I'll wait...for another solution.

Dave Blackhurst
June 26th, 2008, 12:48 AM
About $248 worth. I flipped when I converted it (is the US dollar that weak?) But you get 2 so roughly $124 a piece.

Still, for those who "have to have it now", at least there is something available. I think I can wait for you to "publish" when you are ready. I just need Lanc + video out. Shouldn't be too hard. Just have to find a reliable way to remove all of that glue on the plug without melting everything.

Hair dryer or heat gun - careful not to overheat, but all that stuff is just hot glue... It's almost more of a pain dissecting the outer plastic molding... but I go through that in detail in the instructions, trying to be thorough so it is a no-brainer... getting closer...

Christian de Godzinsky
June 26th, 2008, 01:48 AM
Hi,

Yes, that price is r i d i c u l o u s !!! I have made up my mind and found a DIY solution.

I bought the Sony RM-AV2 remote (ONLY 64 euro!). First I thought that I just take the cable and put at its end an 2,5mm jack. I decided to keep the remote (you never know weh you some day might need it), but instead I installed the 2,5mm jack INSIDE the remote!!! I will post pics of this mod if it is of any interest.

Christian

Rob Taylor
July 14th, 2008, 09:06 AM
I am interested in seeing you pictures of how you put a 2.5mm jack in the Sony Lanc remote. Rob

Tom O'Brien
July 14th, 2008, 10:48 AM
I found I website the sells the 10-pin with a "special" cable

http://www.xtremerecall.com/Products/Accessories_Helmet_Cam.htm#10pin_Adapter

Rob Taylor
July 14th, 2008, 02:11 PM
Hi Tom,

I saw that over the weekend, but is it wired for Audio and Video. What I want to do is cut the cable from the Sony controller that has a 10 pin connector on it and wire in a 2.5 mm for a standard lanc connection. I know you need to add a resistor between two wires, just not sure which two. That's why I would like to see the pictures of 2.5mm jack being added to the Sony controller.

I have all the parts, just not sure how to assemble it.

Rob

Tom O'Brien
July 14th, 2008, 07:41 PM
I don't know anything about a resistor, but ...
I have rm-vd1 and rm-av2 lanc controllers for my different sony camcorders.

I cut the cable for the rm-av2, found 4 wires( red, white, black and shield).
I cut the male end off an lanc extension cable.

I hooked the tip to the white wire
center to the red
base to the shield wire.

Now the rm-av2 has both an 10-pin connector and the 3 segment male connector.

Now it controls the old camcorder and the new one.

next step is to get an 10-pin connector and add it to the older rm-vd1 lanc controller.

Rob Taylor
July 14th, 2008, 08:10 PM
Hi Tom,

Thanks for the info. From what I've found out is if you cut the cable on the RM-AV2 and you want to put on a 2.5mm jack on the end, so you can make a conversion cable, you need to put a resister between 2 of the 4 wires on the RM-AV2 cable.

Apparently this tells the video camera there is a LANC being pluged in. The RM-AV2 has the resistor between the two wires on the RM-AV2 circuit board.

I am trying to find out more detail information before I start cutting too much up.

Thanks, Rob

Tom O'Brien
July 18th, 2008, 07:02 AM
From reading different post, it looks like the one of the pins on the a/v jack is "magically".
Some of the pins are inputs, some are outputs , some are both... and it looks like the pin the goes to the "B" connection of the RM-AV2 is the controller. I am guessing, by changing the voltage/signal going to this pin, the function of the other pins change.


One thing that surprised me, the lanc controller rm-av2 works with my sony hdr-sr1!

Rob Taylor
July 18th, 2008, 10:42 AM
From what I have found out, there are 4 wires in the RM-AV2 cable. You need to connect a 100k ohm resistor between the blue wire and the ground. That will configure the port for LANC control.

Rob

Tom O'Brien
July 18th, 2008, 12:57 PM
the 100k resistor did the trick!!!!!!

My old Rm-VD1 now works using the a/v connector.

Just hooked up to video. It works too!

LANC and Video Out.... just like the cable Sony should have made!
Works with the HDR-SR1 and the HDR-SR11!!!!!!!!

Thanks for the help.

Rob Taylor
July 18th, 2008, 01:36 PM
Just to let you know, I got the 100k ohm resistor info from the guys at Studio 1 Productions. They are getting ready to come with a Lanc adapter cable. The tech there said, they are having a hard time getting the 10 pin connector and so far have been making them (special order item) by cutting the cable off of the RM-AV2 and wiring a 2.5mm jack with the resistor.

He said the 10 pin AV cables don't have the wires going to the pins for the LANC. So it was either cut the cable off the RM-AV2 or go to China to have special cables made. For now they are just going to hand make them with the RM-AV2 cable, until they see what the demand is for them.

Rob

Tom O'Brien
July 26th, 2008, 09:18 AM
Attached is a picture of what works for me.
Lanc and video out

I think this picture is right.

Rob Taylor
July 30th, 2008, 09:34 AM
Tom, thanks for the photo.

I was just on the Studio 1 Productions website ( http://www.studio1productions.com ) and saw they now have an adapter cable for the LANC connections that convert 2.5 mm to a 10 pin 'D" connecter. The cable is a little expensive, but they do have an explanation of why it is $69.

I did build my own, it ran me about $50, but that does not include any labor cost.

Here is what I did. I bought a RM-AV2 for $39.95 + $8.75 for shipping. I then bought the 100k ohm resistors and a couple of 2.5 mm female jacks, a few more dollars. I had a hard time finding a 2.5 mm jack that has a large enough plastic casing on it so you can put the resistor inside. It cost me $51.13 including tax and shipping, but no labor cost.
So I guess with Studio 1 charging $69 for one is not too bad.

Rob

Rob Taylor
July 31st, 2008, 11:50 AM
I made a mistake on the price of the Lanc Adapter cable from Studio 1 Productions, it is $59.00

Rob

Tom O'Brien
July 31st, 2008, 12:09 PM
I'm glad to someone selling them (10-pin to "normal" lanc) ...

I want a cable that has both lanc and video out.

Rob Taylor
July 31st, 2008, 12:22 PM
Tom, according to Studio 1, they are looking into other global sources (ie. China) to have a custom cable made so they can offer both LANC and Video out.

For now they do have the Lanc adapter. I made my own, for one camera and just ordered one for another camera.

Rob

Riku Naskali
August 16th, 2008, 07:06 AM
Hey,

First, thanks for the pin-outs. However, I'm having some trouble getting my adapter to work.

I've followed the pin-outs carefully and according to my multi-meter everything should be working. I soldered a 2.5mm lanc stereo jack directly to my 10-pin connector with the resistor between pins 7 and 8. I didn't use the Sony cable, I hacked apart the 10-pin connector from Chinese cable, but it shouldn't make any difference

Can anyone confirm that the picture is indeed correct?

Dave Blackhurst
August 16th, 2008, 02:08 PM
I suspect there's an error in the diagram posted... the LANC connections are correct, BUT the resistor is not in the right spot... I'll say this much, pin 8 is usually not connected according to my reverse engineering...

I've been trying to finish up detailed (AND TESTED) plans for this hack for some time (a computer crash and rebuild didn't help!). I got some flak on another forum for wanting to charge a few $ for the CORRECT information with good, "can't screw it up if you tried" step by step instructions... interesting to see that the diagram posted isn't quite correct, but hey, it's CLOSE <wink>!

You should have no trouble using the cheap Chinese cable end, works fine once you get things on the right pins!

Tom O'Brien
August 17th, 2008, 10:02 AM
If you look at the "normal" 3 segment lanc connector, the tip is the "serial lanc", the center is somewhere around 5 vdc and the base is ground. For me, the 5vdc was missing (on pin 4) until pin 7 was connected thru a resistor to ground. When pin 7 voltage was pulled down to about 1.4 vdc, then the 5 vdc "appeared" on the center segment (pin 4).


I think pin 3 and pin 8 are each some type of ground.


It worked for me.

Dave Blackhurst
August 17th, 2008, 02:24 PM
I think pin 3 and pin 8 are each some type of ground.




<wink> Normally 8 is N/C (not connected), it depends on the model or the specific accessory... I've had the chance to review about a couple dozen different configurations, and there can be minor changes that result in some quirky-ness...

Rob Taylor
August 17th, 2008, 08:17 PM
Tom,

That pinout you posted with your picture worked perfectly for me too.

Rob

Dan Caputi
August 21st, 2008, 09:40 AM
My treck through cyberspace on a mission to solve a similar problem has lead me to this discussion... (thank you ALL for the information thus far!)

I was wondering if I could buy a Y adapter like this:

............................../-- Composite Video male (RCA)
AV/Remote female --<
..............................\-- AV/Remote male (10-pin mini 'D') - OR - LANC male


At paltalk.com we have a collection of HandyCams we use for video webcasting.
So I bought this great VCT-80AV tripod with the remote handle, but it plugs into the AV jack (How stupid is that? These handycams all have a seperate LANC jack too!) - I need the AV outputs to feed into the capture device on the PC.

Sadly, I think my best solution is to return the tripod.

- Dan C.

Tom O'Brien
August 21st, 2008, 11:33 AM
what makes this hard is every cable you buy for the sony 10-pin connector seems to use different pins. For example, the lanc controller rm-av2 from sony only has 4 wires in its cable. (uses pins 2,4,7,8) There is no spare wires for video.

If everyone used a cable with 10 wires (1 for each pin), then all this would be easy.

I bought a cable online for video/audio out and found the separate lanc did not work on my HDR-SR1 with the 10-pin cable plugged in. I didn't have that problem with the cable from sony (10-pin connector).

If you really like the vct-80av (av meaning 10-pin connector) tripod, you could modify it. I added the "old" (2.5mm with 3 segments:tip, center, base) male lanc connector to my rm-av2. I can now plug it into the 10-pin or the "old" lanc socket.

Dave Blackhurst
August 21st, 2008, 02:16 PM
Dan -
You can't buy it, but it's possible to hack the one you've got (or buy one of the older Sony tripods that uses the miniplug LANC).

As Tom points out, there's a number of slightly different cable configurations - I've documented MOST of the variables... and am close to making it available in an easy to follow format. It's several pages.

Tom - if it was an aftermarket (not Sony OEM) cable it probably shorted the LANC connection inadvertently - the Chinese cables ARE NOT WIRED CORRECTLY!!!! While they "sort of" work, they cause some odd camera (mal)functions. Fortunately they are cheap and yield a wonderfully usable 10pin plug for you to hack into the system with!

The challenge of the 10 pin A/V jack is that it has a plethora of possibilities... LANC, SVid, Video out, Audio out, Audio IN... Sony stuffed a bunch of possibilities into those 10 little pins (one of which apparently isn't even used), and most of it is parralleled in the AiShoe... (and on cameras that HAVE a LANC jack, that too), meaning that things plugged in one place interact with things plugged in other places!!!!

I'm about 99% certain on the LANC hack, and about 99% certain on being able to hack the 10pin for SVid and regular video with the LANC active... the audio has been a bit more interesting... since I've had requests for a mic in on cameras that don't have it!

Riku Naskali
August 21st, 2008, 04:16 PM
Well,

I have at least four 10-pin connectors without any cables, I hacked them apart from the Chinese cables. Not easy, but doable. So no problems there :-) And I can always get more of them.

I got some suggestions from elsewhere, I'll try them out asap and then post my results. I'm thinking of installing a BNC connector instead of regular rca since most "pro" stuff uses BNC anyway.

Tom O'Brien
August 22nd, 2008, 01:43 PM
Dan Caputi : "So I bought this great VCT-80AV tripod with the remote handle, but it plugs into the AV jack"

I have been thinking about buying one of those?

Could you post a picture of the lanc controller?
I have one of the older sony tripods and can't find a closeup of the vct-80av lanc controller.

Dan Caputi
August 23rd, 2008, 10:06 PM
(Thanks everyone here for all this great info. I'd really be high and dry without you guys!)

The plot thickens! ...
Our resident news reporter and his producer took the tripod "on the road". So I guess that means we're going to keep it - and now I suppose the simplest solution will be to either add a video in jack to the handle or replace the AV/R connector with a 2.5 mm LANC plug. I can't believe they don't already make an adapter for this!

And because I no longer have possession of the tripod, I can't post a pic for you Tom.
But alas! - a google image search turned up this nice Taiwanese web page:
Sony Style - Sony ?????? - ??????A / V R??? - VCT-80AV (http://www.sonystyle.com.tw/is-bin/INTERSHOP.enfinity/WFS/Sony-SonyStyle-Site/zh_TW/-/TWD/ViewProductDetail-Start;pgid=1HZOSYWDl55SR0gv2DoLhiJ40000y_DcF9CJ;sid=5eG-V8FGse2WXInux_QPXMBMg2437afJbFs=?ProductUUID=dnwKAQuxg8cAAAEY8t4J3KGf&CatalogCategoryID=Sk8KAQux_UkAAAESLrIMeAPy)

I don't think you need to understand the captions to get the idea.

- Dan C.

Bill Koehler
August 24th, 2008, 08:14 PM
For those who prefer English, Here's the SonyStyle USA link:

VCT-80AV | Tripod VCT-80AV | Sony | SonyStyle USA (http://www.sonystyle.com/webapp/wcs/stores/servlet/ProductDisplay?catalogId=10551&storeId=10151&langId=-1&productId=8198552921665286323)

Tom O'Brien
August 27th, 2008, 05:06 PM
Attached is a picture of a cable made by Extreme Recall.

10-pin av connector
to
LANC (2.5mm female connector), video out, audio (left and right).

Christian de Godzinsky
August 28th, 2008, 04:48 AM
Attached is a picture of a cable made by Extreme Recall.

10-pin av connector
to
LANC (2.5mm female connector), video out, audio (left and right).

Extreme Recall ??? Is that you (DIY) or a company that really sells these adaptors?

Christian

Tom O'Brien
August 28th, 2008, 08:44 AM
Extreme Recall is in Reno Nevada and have been making helmet cams for several years.

I ordered the (special cable made for me) cable from them.

Riku Naskali
September 1st, 2008, 04:11 AM
Wel, I've tried two configurations and still no dice...

First I tried the schematic posted here, a resistor between pins 7 and 8, and all the other signals from 2,3 and 4.

Today I tried using pin 8 as a ground (connected to my lanc jack's sleeve) with the resistor still in place. Nothing...

Maybe I should remove the resistor next.. And start measuring my contacts with the adapter connected to camera.. Or try putting the resistor between pins 3 and 7 and using 8 as a ground on my lanc...

I'd be happy to pay something for Dave's instructions, but I'm in a hurry getting it up and running...

Riku Naskali
September 1st, 2008, 06:48 AM
Success! I don't know what I've done wrong earlier, but now it works perfectly.

The schematic is exactly like Tom's first one, 3 as a ground and the resistor between pins 7 and 8. And the device is Lanc Shepherd, camera CX-6.

Paul Stone
March 30th, 2009, 06:49 PM
New member here. Posting my first message.
I have enjoyed reading your posts on the development of an adapter to enable you to continue to use you standard LanC remotes with the new Sony AV/R connector.

I have learned a few things.
Sony has three remote tripods.

VCT 50AV List price $80 at B&H $56
VCT 80AV List Price $180 at B&H $122
VCT-1170RM List $499 at B&H $315

I called Sony and asked them for the part number for the remote handle on all three of these tripods. The 50 AV and the 80AV both take the exact same remote handle. The price of the replacement part is $116.95 (yes, that is $36.95 more than the 50AV tripod itself). The remote on the 1170 RM Looks identical to the others; however, it has the old style LanC connector (2.5mm stereo). The remote for the VCT-1170RM costs $161.95.

I own the VCT80AV. The zoom control with this remote is very nice. It is continiusly variable and offers a lot of control, none of the instant on and off stuff I got with their clip on, 2 speed remotes. I liked it well enough that I ordered two of the 50AV tripods just for the remotes. (These tripods have a lot of plastic including the gear on the center column. The proper thing to do with these tripods is to harvest the remote and toss the rest, although I may remove the 'non-removable' fluid head and adapt it for use on another tripod.) The remote is the entire handle and can be used on almost any tripod. The handle is 10mm in dia. and fits my Davis and Sanborn FL12 fluid head just fine (had to make a spacer).

I plan to take one of the remotes and patch in a standard 2.5mm stereo connector for use on my Sony HDR-FX1. The others will be used on my HDR-SR11's (I only have two).

The VCT 50AV costs $10 less than the adaptor cable from Extreme Recall.

I found a pinout diagram here: The SONY LANC protocol (http://www.boehmel.de/lanc.htm)
It differes slightly from the pictures published here.

My question: Has anyone spliced in a standard 2.5mm Stereo connector on one of the remotes for the VCT 80AV or the VCT 50AV? If so, how did it work?

Thanks,

Paul

Dave Blackhurst
March 30th, 2009, 10:36 PM
Hi Paul -

Sounds to me like the "AV" remotes have an improved zoom function over the old 2 speed standard Sony arrangement (I've got several Sony remotes with that approach).

You should be able to splice in a 2.5mm and it should work fine (I'd suggest making it a "two headed snake" - that way it should work with both cameras as needed). AFAIK, while a LANC using the A/V jack requires the dropping resistor to signal the A/V port to expect the LANC information, I believe that connecting the tip/ring/sleeve in the correct order should allow an AV series to be backwards compatible with the 2.5mm jack/plug.

The German LANC diagrams look right, although the sleeve (ground) can also connect to the pin BETWEEN the two LANC pins (pin 3). He's got it showing pin 8, which can be either ground or no connection, so it may vary from one Sony product to another. My reverse engineering has it on pin 3.

Paul Stone
March 30th, 2009, 11:15 PM
Thanks Dave,

I have already ordered the 2.5mm stereo connectors (actually two) both the plug and the jack. I plan to cut the wire on the remote and attach the plug to the end with the remote and the jack to the end with the Sony mini-D 10 pin connector. This will allow me to use it with either style camcorder.

I read earlier today that the LanC technology was developed to start and stop multiple cameras at the same time (helps with sychronization in post production).

Has anyone heard of a wireless system to do this? I have a multi camera shoot coming up on late May.

Connecting a single remote, using only the record button, to a splitter and then connecting to two camcorders could be interesting.

Thanks,

Paul

Dave Blackhurst
March 31st, 2009, 12:55 AM
Minor flaw, the AV version of the LANC controller requires a dropping/signal resistor between two of the pins, and I'd suspect the resistor is at the controller end of the cable... meaning if you cut the cable, you wouldn't be able to use it with the A/V end again. There is a slim chance they put the resistor in the molded plug, but I doubt it. When you open the cable, I'd carefully remove the outer sheath (the thin black that keeps the wires bundled inside together). If there are more than 3 wires, the 2.5mm will come up short on conductors.

You might be able to put the resistor inside the jack side of the 2.5mm, I was fiddling with making the whole adapter in a single compact molded assembly, so that probably would work.