Mono switched jack to speakon jack help

[homedoc]

First time poster. I am hoping someone can help me with an issue I have with my Kustom Profile One speakers. I would like to change the 1/4" speaker inputs to a speakon jack. The existing jack is pcb mounted and it appears to be a Neutrik NMJ4HCD2. I would like to put the speakon connectors on for the safety and security aspects. I have included two photos to show the top and bottom of the pcb. If this is possible can someone please list the steps. Thanks for your assistance!

[Chuck H]

I don't know what a Speakon jack is... But I suppose it's one on those stress disconnect type things. I wouldn't reccommend theor use for speaker cabs. Trying to save a jack short is more likely to cause you to run the amp into an open load. But anyway...

You would probably need to remove the PCB and hardwire direct to the jack. Mounting the jack in the exsiting hole and floating that capacitor on the solder connections. Just look at the connections OR mount the new jack on a Rat Shack perf board and jumper the connections the same as it's done on the existing board. Draw a diagram of how it's hooked up now. What goes to + and what goes to - and where the cap is connected. That way you have a diagram to reference. Be careful with removal of the PCB and cap so that you can put it back the way it was should things get too difficult. You'll need a desoldering tool. A simple bulb sucker should be fine.

[homedoc]

Chuck H, thanks for the reply. A speakon jack is used to prevent the speaker cable from being pulled out of the cabinet jack and causing the mixer to short out and require repairs. The PCB has a green electronic part on it. I was wondering if the PCB is required to make the speaker work and if removing the PCB would disable it from working. The existing jack appears to have two pins soldered in the front and two pins in the back. Then two black and two white speaker wires are soldered directly to the PCB as shown in the photo. I am sure it is probably an easy swapout for experienced techs. I am hoping someone has already done this mod and could let me know it is possible to do and which Neutrik speakon jack I would require to make it work since the existing jack has the PCB. Thanks for your assistance!

[Steve Conner]

A Speakon jack is a kind of twist-lock speaker connector. Very popular in Europe, much better than 1/4" jacks in my not-so-humble opinion.

Now, from that board, I can see the following:

The two black wires are connected together directly to the ring (negative) terminal of the jack.

One white wire is connected directly to the tip of the jack. The other is connected via the green component on the board. (I'm guessing these speakers have piezo horn tweeters and the green thing is a resistor to tone the treble down a little?)

Anyway... Speakons have four lugs labelled 1-, 1+, 2-, 2+. And, 2- and 2+ are only used in bi-wired installations. Here's what I'd do:

Unsolder the jack from the circuit board, run a short wire from 1- to where the jack ring contact was, and another short wire from 1+ to where the jack tip was. Wrap in electrical tape and stuff back inside the cabinet.

(My reason for doing this is that the circuit board gives somewhere to mount the resistor, and it saves you having to remember which white wire had the resistor.)

Or, you could leave the jack in place to give you a choice of jack or Speakon, and a way of mounting the PCB.

Either way you need to drill a bigger hole.

[homedoc]

Steve, Thank you for taking the time to give such great detail on how to do this. Speakon has a combo jack that allows the user to have both the speakon and 1/4" jack in one receptacle. That would allow for versatility just in case something went bad with the speakon cable. I would like to install that type of jack. I mostly understand what you are telling me in your reply. The thing I don't understand is the four pins on the existing jack. It appears that the two front soldered pins on the existing jack are negative and the two rear soldered pins are positive. I looked at the PCB and the two white wires, as you said, do appear to each connect to one end of the green resistor. The speakers do have horn tweeters. Once I desolder the four pins and remove the existing jack I understand I need to a short wire from 1+ to where the jack tip was and a short wire from 1- to where the jack ring was. If I understand correctly, the 1- will be one of the empty front holes and the 1+ will be one of the empty rear holes. How do I know which hole is 1+ and which hole is 1-? Do I need to run any short wires from the other two empty holes left by the removal of the jack or does the PCB have them connected already? I have included photos of the front and rear of the speakon combo jack. I believe the speakon connector requires a 15/16" hole to mount it. Thanks again!

[J M Fahey]

Steve's idea of somehow keeping the board is excellent.
Yes, both pins closer to the panel are negative, both further ones are positive, +1 goes to former positive (tip), -1 goes to former negative, (ring), I *guess* the jack contacts are so wired in the combination jack; +2 and -2 go unused for now.
Speakons are 1356728 times better than *any* jack/plug , mainly for not shorting when plugging/unplugging, and for having about 50 times more contact surface, not to mention the twisting, locking.
Youmust certainly have Piezo horns (nothing against that), and the green thingie must be a 10 to 50 ohm resistor in series with them, because they are excellent capacitors to ground and most amps don't like that.

[Steve Conner]

As far as the existing jack goes, the ring terminal is the one nearest the panel the jack is mounted in: on the left in your first picture. The tip terminal is on the right.

As you can see from the PCB, the jack has two terminals at each end, but they are connected in parallel. You only need to use two of the four holes: one of the left-hand ones and one of the right-hand ones. The left-hand goes to 1-, the right-hand goes to 1+.

2- and 2+ are unused.

Edit: I'm glad JM agrees with me that speakons are better

[homedoc]

JM, thanks for helping clarify the 1+ and 1- issue. Yes, I believe the speakons are superior in every way. I use this small PA mainly at small "mom and pop" type bars and coffee houses and at family gatherings. Inevitably one of the small children go and step on one of the speaker cables or pull on them. I have been wanting to do this mod for awhile and now I believe I can tackle doing it. Thans for your great help.

[homedoc]

Steve, You and JM have totally clarified the procedure to do this mod and have removed any apprehension I had about doing it. Speakons are fantastic for many reasons. It is a shame speakon is not the universal standard for all speaker connections. Maybe one day it will be. I guess it would cost the speaker manufacturers a few more dollars per unit and that is the bottom line. One more question: What is the proper gauge of wire I should use to make the connection from the PCB to the new speakon connectors? Now I have to figure out the best way to secure the PCB and enlarge the mounting hole to 15/16" to accomodate the speakon. Thanks again

[homedoc]

I forgot to ask a very important question in my initial post: My original speaker input jack is a PCB mounted switched jack. Will a combo speakon/1/4" jack work because it is a "switched" jack? I really don't know how a switched jack works. Thanks!

[J M Fahey]

The original jak is "switched" because it was manufactured that way, *but* the little PCB shorts both sides of the switch, killing that needless (in this application) feature.
Don't worry, Steve's suggestion about keeping the PCB was , in part, meant to help you avoiding confusions about which jack contacts actually use.

[homedoc]

JM, once again, thank you for stepping up to straighten me out.