Hi all,
I am very lucky to get these drivers as a gift from a member at lencoheaven. I received them couple of days back. They are big and heavy. Packing was superb. I am listening to these drivers since I received them. I liked them very much especially midrange. They are playing very well in low volumes with my DIY Class A 5W Amp Camp Amp.
Does any one know TS parameters for them? I am looking to build beautiful enclosures for them. Kindly suggest some suitable designs for them. I am also looking to replace old 4uf cap. Any good capacitor suggestion?
Few pics:
I am getting distortion if I increase the volume.I have verified coil rubbing or alignment problem in both the speakers. The Cone is making rubbing noise when pushed by hand.Can I DIY coil alignment, repair or replacement without damaging the cone and other parts of driver? I have searched on web and it seems there are no reconing kits available for University drivers.
Regards
Sachin
I am very lucky to get these drivers as a gift from a member at lencoheaven. I received them couple of days back. They are big and heavy. Packing was superb. I am listening to these drivers since I received them. I liked them very much especially midrange. They are playing very well in low volumes with my DIY Class A 5W Amp Camp Amp.
Does any one know TS parameters for them? I am looking to build beautiful enclosures for them. Kindly suggest some suitable designs for them. I am also looking to replace old 4uf cap. Any good capacitor suggestion?
Few pics:
I am getting distortion if I increase the volume.I have verified coil rubbing or alignment problem in both the speakers. The Cone is making rubbing noise when pushed by hand.Can I DIY coil alignment, repair or replacement without damaging the cone and other parts of driver? I have searched on web and it seems there are no reconing kits available for University drivers.
Regards
Sachin
Pushing the cone by hand is not very precise and can "throw out" the alignment an give the impression of rubbing. As for the apparent rubbing when it plays music, have you tried rotating the drivers to see if it goes away? It may be sagging in the spider. Maybe that "presence" control is a bit worn out or dirty as well?
With drivers of that age, it's often better to measure the parameters yourself. You can download the free version of ARTA and use the LIMP module to do so. You only need to build the impedance testing jig, which is quite easy.
Cool drivers, hope you sort things out and can enjoy them!
With drivers of that age, it's often better to measure the parameters yourself. You can download the free version of ARTA and use the LIMP module to do so. You only need to build the impedance testing jig, which is quite easy.
Cool drivers, hope you sort things out and can enjoy them!
I did rotate them 180 degree, and played 2-3 days in same position. It did not solve the issue. Cone movement seems to be very stiff and its hardly moving. I have tried to clean voice coil, since there is no need to cut dust cap. I tried to clean it with very thin plastic strip by rotating inside voice coil gap. I could not rotate it fully 360 degree as It was getting stucked somewhere. I am attaching pics for reference.
Do you think Brilliance control can cause distortion?
Regards
Sachin
Do you think Brilliance control can cause distortion?
Regards
Sachin
The impossibility to go all the way around the VC with the thin strip might be indicative of something amiss.
I think VC alignment might have gone bad in shipping. I could only move thin strip in 3/4th part of circle inside VC gap.
Regards
Sachin
Regards
Sachin
I might have a 312 in a slimline R-J cabinet. Looking at my old 6201 data, Qts ~0.67, fs ~51Hz. (Qes~0.94) Some old drivers have their spider dry, raising fs and qes. I've seen a Lafayette SK58 and University UCX-22 with fs>100Hz. (in the SK58 case, the chamois had also dried) IIRC, a 312 should have a beautiful dark but clear midrange. with the cone facing up, put your little finger through the largest of the basket openings and feel the spider - it should still be soft and compliant.
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A sagging spider should let you move the strip all the way around, with a bit more resistance where it rubs. Shifted motor assembly? Is that even possible the way this thing is put together?
I have checked the spider and it feels soft enough. It has a beautiful midrange,but distortion starts as soon as low fq comes.
Regards
Sachin
Regards
Sachin
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do you see the cone move much at all on bass passages? - they're not great in that regard when working right - I had one in an Eliptoflex which probably was tuned around 60Hz.
There are numerous tricks for fixing misaligned voice coils if you google for it. One that I recall offhand is sticking paper shims in the gap to align the coil, and soaking the spider with acetone. Might take some pushing and prodding.
I would try mounting it on a baffle board, with the jammed side of the VC down, and try pushing on the magnet assembly a bit to see if that makes a difference.
Obviously you're not going to find a recone kit for a driver that hasn't been made in more than 50 years. That said, a good speaker repair guy could probably fix it.
I would try mounting it on a baffle board, with the jammed side of the VC down, and try pushing on the magnet assembly a bit to see if that makes a difference.
Obviously you're not going to find a recone kit for a driver that hasn't been made in more than 50 years. That said, a good speaker repair guy could probably fix it.
I should have read your post better - are the surrounds compliant? my 6201 is in good shape but UCX22 whose spider is soft for some reason has its surround very hard and stiff pushing fs to around 120Hz. If the surrounds are compliant, then you can try to do what GregB suggests - maybe unequal torquing of the mounting screws might set it loose or film in the gap - if that will fit. Maybe Planet10 has some hints.
Also, it's possible something fell (or crawled 😱) into the gap, seeing as there isn't a dustcap to keep stuff out.
Success!!
I sent those drivers to my friend at another city. He took them to a common friends who has a great knowledge and skill. He has found out the problem and rectified it. Actually the problem was with pole piece shifted from original place. He had to cut one ring/cover from the back side to access the pole piece.
I am posting few pics for better understanding.
After removing the dust cap. You can see the coil gap is not even.
Back side
After removing the tweeter
Alnico magnet
He has repaired one driver. Another one will be done tomorrow. I requested him to take few pics out could be helpful for other members. He send me few recordings. They are sounding superb.
Regards
Sachin
I sent those drivers to my friend at another city. He took them to a common friends who has a great knowledge and skill. He has found out the problem and rectified it. Actually the problem was with pole piece shifted from original place. He had to cut one ring/cover from the back side to access the pole piece.
I am posting few pics for better understanding.
After removing the dust cap. You can see the coil gap is not even.
Back side
After removing the tweeter
Alnico magnet
He has repaired one driver. Another one will be done tomorrow. I requested him to take few pics out could be helpful for other members. He send me few recordings. They are sounding superb.
Regards
Sachin
I am posting step by step pics sent by my friend. These could be helpful for other members.
Back cap opened
Put it on lathe
Regards
Sachin
Back cap opened
Put it on lathe
Regards
Sachin
Great save!! I knew it could be done. Glad you found the a friend with the skills to do it.
Thanks for the cool repair pics. Looks like the HF motor is basically a big weight on the end of a lever. Presumably it torqued the pole piece out of whack during shipment. It's almost hard to imagine it wouldn't.
My father used to have one of those drivers in a big trapezoidal corner reflex cabinet, until my mother banished it to the basement.
Thanks for the cool repair pics. Looks like the HF motor is basically a big weight on the end of a lever. Presumably it torqued the pole piece out of whack during shipment. It's almost hard to imagine it wouldn't.
My father used to have one of those drivers in a big trapezoidal corner reflex cabinet, until my mother banished it to the basement.
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