[penguinpages]

I have been super happy with the MTM speakers and Servo sub kits I build and purchased.  With the money saved, I was able to spring for the recommended upgrades (caps and tube connetors).

But now that I have used them a while, and now build a tube amp to drive them, I have twice now noted an issue that I need to see if others have /have seen and means to remediate it.

The tube connectors if I move the box around to see if it sounds different, or just with vibrations.. I have seen the tubes start to slide out.  Their is no locking mechanism to them. (see picture).

With a transistor amp, meh... not a huge deal.  With a tube amp, it can do major damage.

It would seem the ROI for the tube connector is now in question.  It may have better quality, but not if I burn out a >$2k worth of amp.

Picture attached is my "noticing" in passing the speaker where it was plugged in a few weeks.. but seems to have wiggled out.  Not totally, but not what I would call acceptable for $60 for the investment.

[corndog71]

That’s weird.  The ones I have are are very tight and have never drifted out like that. 

[BGA]

Mine do the same, as I walk up to turn my tube amp on I double check that they are in all the way, they have never been close to falling out but I usually push them back a couple mm each time.

[mlundy57]

Did you apply silicone adhesive to the outside of the tube connectors before inserting them?

If not, or if you did and they are still loose, disconnect the speaker and pull the tube connector out as much as you can. If it is a little loose, put some silicone adhesive around the base of the tubs connector and put it back in. If it is too loose for the silicone alone to tighten it up, wrap a piece of electrical tape around the shaft until it is slightly snug leaving a slight gap under the outer flange. Then apply the silicone and reinsert the tube connector.

Let the silicone cure completely before hooking the speaker back up.

[Shives]

Did you apply silicone adhesive to the outside of the tube connectors before inserting them?

If not, or if you did and they are still loose, disconnect the speaker and pull the tube connector out as much as you can. If it is a little loose, put some silicone adhesive around the base of the tubs connector and put it back in. If it is too loose for the silicone alone to tighten it up, wrap a piece of electrical tape around the shaft until it is slightly snug leaving a slight gap under the outer flange. Then apply the silicone and reinsert the tube connector.

Let the silicone cure completely before hooking the speaker back up.

I think he’s speaking of the metal male end into female end!!??  Also, to eliminate the thought of these ever moving, use two part epoxy. Hit glue can loose it’s grip, and silicone I feel opens a whole other can of worms. More so if you have anything one the cabinet that will react to silicone.


Yeah, I gotta agree.. let’s say out of the 10 I used, 5 were beyond loose. Very easy for them to work there way out. What I did to try and help that was swap around the parts I had before install. Trying to make the tightest fit. But, for sure! This is a thing.

Something that helped when assembly.. your crimp and solder. Make sure that they are just like instructions.

I was going to send an email over to Danny about this.. But I feel like all I do I bother.

[CurtisIIX]

Part of the appeal of the tube connector is low mass, so one shouldn't expect a locking mechanism on them.

Given the friction fit of the connector and the fact that the speakers are being moved around, it would be advisable to provide some strain relief. Your photos show a very short distance from where the two connectors split off from the outer jacket. Cutting back some of the two connector outer jacket may provide some strain relief. Adding a cable clip to the speaker or speaker stand is a method of strain relief as well.

Alternatively, the female tube connectors do accept normal banana connectors. You could replace the male connector with a locking banana. I use the tube connectors with Blue Jeans Cable locking banana.

[mlundy57]

I think he’s speaking of the metal male end into female end!!??  Also, to eliminate the thought of these ever moving, use two part epoxy. Hit glue can loose it’s grip, and silicone I feel opens a whole other can of worms. More so if you have anything one the cabinet that will react to silicone.


Yeah, I gotta agree.. let’s say out of the 10 I used, 5 were beyond loose. Very easy for them to work there way out. What I did to try and help that was swap around the parts I had before install. Trying to make the tightest fit. But, for sure! This is a thing.

Something that helped when assembly.. your crimp and solder. Make sure that they are just like instructions.

I was going to send an email over to Danny about this.. But I feel like all I do I bother.

OK I see that now.

I have that same issue sometimes especially if I didn't unwind the positive and negative wires enough to leave plenty of slack in the two wires. If there is not enough slack, and one wire is a little shorter that the other, the longer wire has a tendency to pull the shorter one out.

You can try removing more of the outer insulation (6-12") then untwisting the wires to see if that reduces the pulling force on the male studs enough to prevent the pulling out.

What Curits said. we were typing at the same time.

[Chewbacca]

Dang... That's far from ideal. You go from the best binding post to most likely the worst binding post with those pulled out even a little. With them pulled out you're only passing the signal through the extremely thin (by design) copper tube.

Has me second guessing swapping my amp side to tube connectors... may just stick with spades and upgrade the posts to cardas all copper or something, even though they're over double the price, and less performance. But no way they're coming out.

Honestly, these things need some sort of retention. Something like a vacuum tube retainer/spring. Slide the male in, pull back on a spring steel retainer/spring that clips around the male post (shielded with a piece of plastic or something of the sort)... hmmm, may come up with something for mine so I don't need to always be worrying about it.

[Chewbacca]

Took a few minutes to quickly show what I was thinking off the cuff:





Not a pretty model, nor to scale, nor the correct spring length, but I think it gets the idea across. Basically a plastic retainer that has the same ID as the OD of the tube connector, then some sort of spring tension that pulls it tight to the female connector inside of the cabinet. Obviously would need some sort of eyehook or the like on the cabinet for the springs to attach to.

aka I'm a little bored at work

[Shives]

That’s a cool idea if they could be.. plastic, composite or brass? Brass could work. Don’t want metal around the wires, or EMI could play a factor.

Took a few minutes to quickly show what I was thinking of off the cuff:





Not a pretty model, nor to scale, nor the correct spring length, but I think it gets the idea across. Basically a plastic retainer that has the same ID as the OD of the tube connector, then some sort of spring tension that pulls it tight to the female connector inside of the cabinet. Obviously would need some sort of eyehook or the like on the cabinet for the springs to attach to.

aka I'm a little bored at work

No man that’s cool! So, if you can use a cup that’s tilted in and down, that works.. Sadly I did not look closely at that photo! 

Absolutely remove some out that outer jacket. Like a good 6-12 inches. You can use a piece of heat shrink where you cut the jacket off to make it look like a professional style cable.. or clean. 😁
Good eye on the Jacket!

I have noticed some of the male ends have like almost a step under the plating or ridges. I think it was when I did not see as much of those they were in the looser side. Again, mine got a little better after swapping things, and then crimping and soldering the wire in place.

Some are stuck in like glue. Some are loose. Just something noticed. Guess like chewy come up with a cool solution if it’s bad. The jacket route will help for sure a bit.

[penguinpages]

I am not trying to start flame fest here, or be negative.  What GR-Research has done is allow me within a reasonable price to get Fabulous speakers.   I am just a fan of call out issues as others may have it and as such, maybe have a fix / or can get manufacture to make a change

REsponse to suggestions in above threads
1) Glue: Silicon.. is non-conductive. So if that gets on box finish.. it can create issues (of small concern). If it gets on tube. it inhibits electrical flow.. which is signal.
2) Glue of other type such as epoxy.  Uh.. I do move them. Test with other amps. If it is not mechnaical it is probelmatic.. I see glue as DOA IMAO
3) Mechhanical C ring + Spring idea and diagram.  Ok.. seems a bit more complex then I was hoping but .. it works.  My concern then is that those items are ferrous metals which is not great. And you would obviously have to create one for each wire as contact across would short. 

I will have to come up with mechanical means.  I have strink tape / tubes on those connectors (just not shown in that picture) so I think I may have to devise means to hold onto the main wire where it is shielded before it splits.   Maybe this (for $60 +2 more ) could be added to the tube kit.

[Chewbacca]

3) Mechhanical C ring + Spring idea and diagram.  Ok.. seems a bit more complex then I was hoping but .. it works.  My concern then is that those items are ferrous metals which is not great. And you would obviously have to create one for each wire as contact across would short. 

The C ring you should be able to find in teflon/polyethylene/UHMW or similar plastic. The springs may be another story... Probably could if you order a few thousand from alibaba lol.

Just random brain storms again... Could always go with a plastic Z-Clip with slots on the speaker side, and open ended slots on the tube connector side. You'll be fairly limited to what sizes you can find, but you can always put a spacer behind the female tube connector, or just base how far you put the wire inside the female tube connector to match the offset of the bracket. Again, just random thoughts

[Beerbellydad]

Took a few minutes to quickly show what I was thinking of off the cuff:





Not a pretty model, nor to scale, nor the correct spring length, but I think it gets the idea across. Basically a plastic retainer that has the same ID as the OD of the tube connector, then some sort of spring tension that pulls it tight to the female connector inside of the cabinet. Obviously would need some sort of eyehook or the like on the cabinet for the springs to attach to.

aka I'm a little bored at work

It's a garder belt for your speaker cables. I like it 

[Shives]

I think two things are being spoken about here.

1 the fact the male end of the gold tube connection, and the play in the female portion.

2. The fact the the body of the female side of the tube connections come out of wood or plastic they are drilled into.

So, answers to 1. are the springs, and other items mentioned. Stress reliever of the jacket. Making sure of your crimp and install factors.

Answers for 2. Are the glues/epoxy. Rather silicone. The tube connectors as a whole I don’t think should be pulled from speaker to speaker. I don’t know how you would un-crimp and re-crimp for other speakers. Yes, using the Male side for others sure. Those just go into the female.

So I hope that divides the conversation, hopefully the ways to fix it will also not get confused.

[penguinpages]

Now that.. is what I am looking for.  elegant but functional.  Yes.. Made of plastic. It slides so easily changed, yet can lock (tighten screws).  And it would be able to have fixed depth to back of connector.  My only concern is that it would mean stripping back shrink tube to give it the 1/8" thickness of the plastic material behind the connector.

well.. this is when you need a friend with plastic 3D printer.  Whomever is posting diagrams.. if your doing it in sketchup.. maybe post the file and see if we can get someone else to convert to 3D printer format and then someone can make and we can purchase.

I am in for a pair

[penguinpages]

Your correct in clarification:

1 the fact the male end of the gold tube connection, and the play in the female portion. 

2. The fact the the body of the female side of the tube connections come out of wood or plastic they are drilled into.

Item 1 is issue...  I need it to NOT pop out and fry my tube amp.

Item 2 is just "did you not follow instructions and drill right size hole and use proper glue to adhere it when seating it into box.

[Chewbacca]

Now that.. is what I am looking for.  elegant but functional.  Yes.. Made of plastic. It slides so easily changed, yet can lock (tighten screws).  And it would be able to have fixed depth to back of connector.  My only concern is that it would mean stripping back shrink tube to give it the 1/8" thickness of the plastic material behind the connector.

well.. this is when you need a friend with plastic 3D printer.  Whomever is posting diagrams.. if your doing it in sketchup.. maybe post the file and see if we can get someone else to convert to 3D printer format and then someone can make and we can purchase.

I am in for a pair

I modeled these up in SolidWorks. Unfortunately I don't have a tube connector in my possession, so I can't accurately model the bracket. I would also need to know your exact spacing from female to female on the back of your speaker.

I can convert to any 3D file type: .igs, .stp, .sldprt, etc.

Obviously anyone can model this up easily if they have a 3D program and a tube connector on their person.

OR, send me some dims, and  I can get you the 3D file and a PDF to verify dimensions no problem!

[Chewbacca]

How about this instead:



Just fill in the blanks, and I'll adjust the model accordingly

I can make it back into a Z bracket if you'd like. But this is a bit simpler and cleaner IMO.

[Shives]

Your correct in clarification:

Item 1 is issue...  I need it to NOT pop out and fry my tube amp.

Item 2 is just "did you not follow instructions and drill right size hole and use proper glue to adhere it when seating it into box.

Ha ha ha ha. No no… I’m fine my female sides are in place really good. It’s the male end that can be an issues.

The locking bit might be cool.

[Jaytor]

I think a plate or z-clip like that is a great idea. We'd have to standardize on spacing between the two female tube connectors, but that's not too big an issue going forward.

I've also had issues with my tube connectors creeping out and this looks like a good solution.