Avoid Lumberg jacks like the plague!

jeffwhitfield

jeffwhitfield

Well-known member
Ok, so I've been working on a batch of Parentheses Fuzz pedals and ordered some Lumberg style jacks to use in them. After about the 5th one I started to notice a problem: the jacks would fail after a number of times of plugging and unplugging. After a close inspection, I found that the problem is due to a rather serious design flaw. Looking at the part of the jack where the tip is attached, you'll see there's a channel open. The problem with this is that when there's tension added, the tip pushes up on this channel and causes the edges to bend up. Eventually, the edges will start to crack and, when that happens, the jack will fail and won't hold any tension anymore. Noticed this on every jack I installed so...ended up throwing them all out and got a batch of Neutrik style open jacks. Way more sturdy and will hold up over the life of the pedal.

It's a shame really cause the Lumberg jacks take up a lot less space and are actually quite useful for times when a tight fit is needed. But that design flaw makes them total deal breakers. So, yeah, avoid them like the plague! :P

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I don't really care for them myself. Some people love them for sure. Saw once where someone recommended to squeeze the metal part that makes contact with the tip down a bit to make them work at their best. Never felt like I could get the modification correct and decided just to use jacks that don't need to be modified in the first place.
 
jeffwhitfield said:
Ok, so I've been working on a batch of Parentheses Fuzz pedals and ordered some Lumberg style jacks to use in them. After about the 5th one I started to notice a problem: the jacks would fail after a number of times of plugging and unplugging. After a close inspection, I found that the problem is due to a rather serious design flaw. Looking at the part of the jack where the tip is attached, you'll see there's a channel open. The problem with this is that when there's tension added, the tip pushes up on this channel and causes the edges to bend up. Eventually, the edges will start to crack and, when that happens, the jack will fail and won't hold any tension anymore. Noticed this on every jack I installed so...ended up throwing them all out and got a batch of Neutrik style open jacks. Way more sturdy and will hold up over the life of the pedal.

It's a shame really cause the Lumberg jacks take up a lot less space and are actually quite useful for times when a tight fit is needed. But that design flaw makes them total deal breakers. So, yeah, avoid them like the plague! :p

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You say Lumberg "Style" jacks, were they actually Lumberg or a knock off?
 
Between this and that the solder lugs feel designed to accidentally short to enclosures I've never liked em despite getting the appeal
 
All KLBM sockets that I have or have used have an unusually shaped contact tip. It is quite difficult to push the plug in because the tip does not want to move to the side, like it's "too much open". I just take the pliers and bend (squeeze) the contact tip slightly . No more cracking channel walls.

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Barry said:
You say Lumberg "Style" jacks, were they actually Lumberg or a knock off?
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I was wondering the exact same thing. I have some cheap knock offs that have the same stamp on the metal and everything, but they're basically pot metal, they feel like garbage. I've been using Lumberg KBL jacks exclusively for years in a ridiculous number (right around 1000) of builds, I've never had an issue with them failing like this.
 
vigilante398 said:
I was wondering the exact same thing. I have some cheap knock offs that have the same stamp on the metal and everything, but they're basically pot metal, they feel like garbage. I've been using Lumberg KBL jacks exclusively for years in a ridiculous number (right around 1000) of builds, I've never had an issue with them failing like this.
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That’s likely the issue. I suppose that unless they’re official Lumberg jacks then they’re not worth using.
 
jeffwhitfield said:
That’s likely the issue. I suppose that unless they’re official Lumberg jacks then they’re not worth using.
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Where did you get them? My knock-offs came direct from the manufacturer in China so I got a screaming deal on them, but they're unusably bad. I tried to buy Lumbergs direct to get a price break since I do reasonable quantity, but they require a $10k minimum order :confused:
 
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