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Rogers JR 149 repair

Well finding out I dont have a tension bar has really put a hold on finishing these speakers :eek:
The chances of finding the original items is pretty slim so I will have to come up with an engineering solution that may not be original but will work as a tension bar.
I am going to fit a 6mm x 20mm flat steel bar to the laminated top plate glued and screwed into the top plate, this bar will have a drilled and taped with a 6mm thread into it. This will give me a good anchor onto the top plate so I can tension up the base plate
I will dress the thread off the bar behind the Bass/ mid driver so it doesn't touch.
Once I get this fixed I can finish the wiring fit the grills and foam surrounds
I really want to listen to these speakers at their best and it will be through my Rogers A100 amplifier
Alan
 
What exactly is left in the cabs? The torsion bar is a single threaded (likely some obscure BA thread pattern) piece of metal that runs from a retainer on the top cap through the whole cab, through the bottom cap, where the tensioning nut resides, and then the crossover mount and alloy base is attached to it. The point I’m trying to make is I don’t understand how your speakers are in one piece if it is missing. What is holding the crossovers and alloy bases on?

I’ve certainly heard stories of people breaking the rod by over-tightening it (audiophiles just don’t understand torque IME!), but how has whoever broke yours compensated for its absense?
 
Tony
No tension rod the circuit boards were held in in place with a machine bolt from the bottom plate to the bottom cover with a wing nut holding it all together
Nothing holding the top plate to the bottom plate
Shocking really now that I know but I was naive enough not to have known what to look for when I bought them
Note
I have contacted the original owner to see if he still has the tension rods
Alan
 
I bet he snapped it. The stupid thing about "Linn tight" is that the Linn dealers could easily have made good theatre out of using torque wrenches to set some more sensible value unnecessarily accurately, without breaking anything.
 
There's no need to even to adjust the tension bar on the JR149s, unless perhaps the long bolt holding the crossover in place is over-tightened and/or is seized up and the whole rod turns, in which case a drop or two of lubricating oil would hopefully free it up.
 
I’ve taken a quick look in one of mine, since I had no memory of seeing a bar inside. There is one, and if it helps my calipers give a diameter of about 4.18mm (can’t think of a close imperial equivalent.) What’s more the bottom half is covered by a loose-fitting plastic sheath. To stop the B110 magnet touching it? I have no idea.
 
Visible here in mine:

14296085611_78095377b3_b.jpg


I assume the plastic coating is just a little mechanical damping. I stuck a drop or two of oil on the tensioning nuts as they were slightly oxidised and I wanted to make sure they weren’t seized-up and were both at the same tension. I just backed them off and then nipped them back up to roughly where they were. I was well aware this is a potential point of failure (I have read of others breaking the rods) so was *very* careful!
 
Thanks for the photographs guys
A 4mm tension rod seems very thin, no the wonder they get snapped with a bit of corrosion on the thread it would probably just sheer when you try to loosen it ? A little bit of copper slip or molycote 1000 on the threads would be a good protector against corrosion
Im going to stick with the 6mm threaded bar and dress the bar down to 4mm dia in the section of the B110, Ill fit some shrink tube to this section as well

Alan
 
Ok Progress on the tension bar, I know the purists will cringe this is a bodge but its the best I can do right now to get these speakers singing again:)
I cut 2 pieces of 100mm flat bar with five holes one central one for a threaded insert and 4 for 5/8 mounting screws.The plate was securely screwed into the base plate.
The 6mm threaded bar was dressed in the area of the B110 magnet down to 4 mm and covered in shrink tube.
The 6mm bar was screwed into the top plate and locked with a spring washer and lock nut
Where the threaded bar passed through the base plate it was sealed with blue tac and a large flat washer, spring washer and lock nut fitted to tension the top and bottom cap plates together, just hand tight
The crossover was refitted with 4 blobs of blue tac to reduce vibration.
The hole where the wires penetrate the bottom plate was sealed with Blue tac.
Now I am ready to refit the drivers and I have been told that the best gasket is a thin sausage of blue tac ?, anyone tried that?

some Pics

IMG_2083 by Alan Towell, on Flickr

IMG_2085 by Alan Towell, on Flickr

IMG_2089 by Alan Towell, on Flickr

IMG_2092 by Alan Towell, on Flickr

IMG_2087 by Alan Towell, on Flickr

IMG_2091 by Alan Towell, on Flickr

IMG_2096 by Alan Towell, on Flickr
 
Nicely done! Looks like they will be returned to correct function and the repairs will be invisible.

I take it you are missing the dual-threaded nut thing that holds the crossover and circular threaded washer to retain the alloy base. Here’s a pic if you are looking to fabricate some new ones:

8578371088_2db2fd81d4_b.jpg
 
All ends terminated with spade connectors so everything still removable
All gaskets made from strips of blue tac
Mesh grills fitted with double sided neoprene tape and stapled.
Foam surrounds held in place with velcro strip either side of the joint
All tested and working cant really try them in my own system due to the poxy speaker terminals on these speakers but I am going to try them out in a friends system tomorrow who has LS3/5As so I made a couple of JR149 terminal to XLR adapters to try them out

IMG_2106 by Alan Towell, on Flickr

IMG_2107 by Alan Towell, on Flickr

IMG_2163 by Alan Towell, on Flickr

IMG_2170 by Alan Towell, on Flickr
 
I second Tony’s comment. Looking good and well done to you. Hope they sound great after all that work.

I expect you will end up with them on stands for the best listening.

Congrats
 
Well I have just spent a very nice few hours this morning listening to these speakers and a absolutely mint (new :eek:) pair of Spendor LS3/5As in my friends system and WOW his system sounds superb its just a wall of delicate and beautiful sound his Spendors image amazingly, and his Denon PMA-850 vintage amp and tuner sound sweet as a nut, I could have listened all day long.
The good news is my JR149s sounded superb as well so I am very very pleased with them.
 
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