LMII speakon problem

pbass2 · #1 08-05-2010, 11:30 AM

Anybody have the speakon jack on a LMII go bad?
I used it at a rehearsal yesterday (powering two cabs, so, using both the speakon and the regular speaker out) and all was fine.
Fired it up today and it seems either the speakon jack has fritzed out or my speakon cable has suddenly gone bad. I get a crackly, intermittent signal. The regular speaker out however seems fine.
I have no time to go get a new speakon cable today to test it, but I have a gig tonight. I can do the gig with just one cab and use the regular output jack, but fear I'm courting disaster . . . ..

DaveLS · #2 08-05-2010, 11:37 AM

Crack open the speakon cable and inspect. It's extremely easy to fix those. Only need a small screwdriver and no soldering! I'd bet 100 to 1 it's the cable and not the head.

KJung · #3 08-05-2010, 11:37 AM

The MB stuff, like many other heads, use those Nuetrik dual mode speakon cables. If you are using an 'off brand' speakon cable, you can have intermittent connection issues. This could be your issue.

If you do have a real Neutrik speakon, then my guess is it is a bad cable versus a bad output jack.

One thing to do is try your 1/4 cable in the dual mode speakon as a test. If that works, then you most likely have a cable issue.

pbass2 · #4 08-05-2010, 11:37 AM

Duh---I forgot I can plug a 1/4" speaker cable into the speakon jack--that seems to work fine so it must just be my speakon cable. Phew . . .

JimmyM · #5 08-05-2010, 11:38 AM

funny but i've seen a couple posts recently saying how those jacks have been failing when using it with a speakon. their solution was just to use it as a 1/4" jack and it works again.

pbass2 · #6 08-05-2010, 11:42 AM

Quote:

Originally Posted by JimmyM

funny but i've seen a couple posts recently saying how those jacks have been failing when using it with a speakon. their solution was just to use it as a 1/4" jack and it works again.

Interesting---certainly doesn't breed confidence! I will get another speakon cable soon and test it. I guess for tonight I will just go for it and hope it's not just the tip of some kinda iceberg . . .

I got this sucker used for I think 400 bucks---no warranty, etc. etc.

KJung · #7 08-05-2010, 11:44 AM

Quote:

Originally Posted by pbass2

Duh---I forgot I can plug a 1/4" speaker cable into the speakon jack--that seems to work fine so it must just be my speakon cable. Phew . . .

Cool. 99 time out of 100, it is the cable.

pbass2 · #8 08-05-2010, 11:53 AM

Quote:

Originally Posted by DaveLS

Crack open the speakon cable and inspect. It's extremely easy to fix those. Only need a small screwdriver and no soldering! I'd bet 100 to 1 it's the cable and not the head.

This one is a Neutrik Speakon NL4FC (with the blue grippy part).
Please enlighten me--how the heck do I open it up?! Seems pretty musician-proof

The blue part I would expect to unscrew but no go . .

Ah, never mind--I was just being too timid with how hard I was cranking it--a pair of pliers cracked it open.
Connections LOOK good--I'll tighten everything up and see. If still bad then a new cable will reveal it was the cable or the amp after all . . .

pbass2 · #9 08-05-2010, 01:53 PM

Well, I ran out and bought a new cable--a Speakon to 1/4".
Plugged into the Speakon out of the LMII and the 1/4" into the 1/4" in of my Dr. Bass cab(which has both Speakon and 1/4"). Works fine. That certainly suggests my other (Speakon-to-Speakon) cable is bad.

But then I discovered this: I then tried plugging the 1/4" end of my new cable into both the 1/4" out and the Speakon out of the LMII (and therefore, the Speakon end of the cable into the Speakon in of the cab) and voila---no sound! Is this normal? Is a Speakon-to-1/4" cable a uni-directional cable?

JimmyM · #10 08-05-2010, 02:08 PM

Quote:

Originally Posted by pbass2

Well, I ran out and bought a new cable--a Speakon to 1/4".
Plugged into the Speakon out of the LMII and the 1/4" into the 1/4" in of my Dr. Bass cab(which has both Speakon and 1/4"). Works fine. That certainly suggests my other (Speakon-to-Speakon) cable is bad.

But then I discovered this: I then tried plugging the 1/4" end of my new cable into both the 1/4" out and the Speakon out of the LMII (and therefore, the Speakon end of the cable into the Speakon in of the cab) and voila---no sound! Is this normal? Is a Speakon-to-1/4" cable a uni-directional cable?

not that i know of. it's possible that the speakon end of your cab is wired differently, though.

this just keeps getting more and more bizarre. sounds like you better sell everything and start over

pbass2 · #11 08-05-2010, 02:20 PM

Quote:

Originally Posted by JimmyM

not that i know of. it's possible that the speakon end of your cab is wired differently, though.

this just keeps getting more and more bizarre. sounds like you better sell everything and start over

Yeah, or the Speakon jack on that cab is toasted.
You're right, I'll just sell it all!

ga_edwards · #12 08-05-2010, 03:22 PM

Quote:

Originally Posted by pbass2

But then I discovered this: I then tried plugging the 1/4" end of my new cable into both the 1/4" out and the Speakon out of the LMII (and therefore, the Speakon end of the cable into the Speakon in of the cab) and voila---no sound! Is this normal? Is a Speakon-to-1/4" cable a uni-directional cable?

Not sure. I have LMII and a MB cab and use a speakon to speakon cable to connect them. The cable only works one way round. I've had to label it so I know which end goes in where.

wcriley · #13 08-05-2010, 03:24 PM

pbass2 · #14 08-05-2010, 03:53 PM

Quote:

Originally Posted by ga_edwards

Not sure. I have LMII and a MB cab and use a speakon to speakon cable to connect them. The cable only works one way round. I've had to label it so I know which end goes in where.

Just when I thought I had it figured out! Craziness. My other matching cab isn't here but tonight I will see if the same phenomenon happens with it. If it DOESN'T, then it must mean the Speakon output on the LMII (which accepts 1/4") can't go 1/4" OUT to Speakon IN on the cab. Seems nutty.

Jim C · #15 08-05-2010, 04:12 PM

Here's the deal:
Some LMII's have this flakey Speakon connector; doesn't matter if the brand of jack is Neutrik or not, it can be intermittent and not always able to wiggle it on and off.
Plugging a 1/4" jack into the center has worked for me (and others I've talked to) without fail.
Based on what others have posted about repairs costs and MB heads, I'm going to leave this thing alone and run it until it dies, upon which time I'll give it to some repair shop for spares and switch brands to company that will provide me reasonable repair costs (board swaps) and with a schematic.

A great sounding amp that I will not own again.

pbass2 · #16 08-06-2010, 09:06 AM

While it certainly sounds like the LMII jack can be an issue, in my case at least (for now) it seems to be the cab. Markbass told me this:

"Speakon connectors have 4 pole +1/-1/+2/-2, the female speakon on the head rear panel is standard wiring +1/-1, and as it works when you plug the speakon to the head I assume your speaker cable is standard wired (please check inside the speakon of the speaker cable connector), otherwise as when you plug the speakon to the cab it doesn’t work it is possible that cabinet female speakon is different wired (probably +2/-2)."

My (Speakon-to-1/4") cable is standard as I checked it out, so I have to assume it's how the Dr. Bass cab is wired. I might open that up to see, but I may just run with also and just use regular cables and get on with things!
Funny though--if I didn't have that cable go bad I never woulda become so "enlightened"

KJung · #17 08-06-2010, 09:18 AM

Quote:

Originally Posted by pbass2

While it certainly sounds like the LMII jack can be an issue, in my case at least (for now) it seems to be the cab. Markbass told me this:

"Speakon connectors have 4 pole +1/-1/+2/-2, the female speakon on the head rear panel is standard wiring +1/-1, and as it works when you plug the speakon to the head I assume your speaker cable is standard wired (please check inside the speakon of the speaker cable connector), otherwise as when you plug the speakon to the cab it doesn’t work it is possible that cabinet female speakon is different wired (probably +2/-2)."

My (Speakon-to-1/4") cable is standard as I checked it out, so I have to assume it's how the Dr. Bass cab is wired. I might open that up to see, but I may just run with also and just use regular cables and get on with things!
Funny though--if I didn't have that cable go bad I never woulda become so "enlightened"

+1 There is nothing 'proprietary' or special about the Markbass Speakon outs... industry standard Neutrik combo jacks.