University 312 Triaxial

sachu888

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Hi all,
I am very lucky to get these drivers as a gift from a kind 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.
I am getting distortion if I increase the volume. There is one small tear on midrange, could this be a problem? I have no experience in speaker/drivers, any suggestion is welcome.
I will try to measure them next week? Kindly advise some suitable enclosure designs for them. I am also looking to replace old 4uf cap.
Few pics:









Regards
Sachin
 
Sachin,

Congrats on these new speakers. The tear shouldn't create much trouble. Take a slightly thicker (Kitchen roll is better) tissue paper and patch the tear using a flexible glue like fevibond and should nicely work. I would have preferred experimenting with a mini-DSP kind of setup to get the right balance.

I am sure it was designed to be housed in a simple vented box.

Regards
 
Thank you everyone. I think I have located the source of distortion. I feel the problem is Voice Coil rubbing. I have confirmed this by pushing driver cone inside. I can feel the little scratching noise while pushing driver cone manually. Can this be corrected without damaging the cone?There is only one driver having distortion on low frequencies, HF and mids are Crystal clear.

Regards
Sachin
 
@Anilva thanks for enclosure suggestion.I was reading on web and like you said,most people suggested big Bass Reflex cabs for them. Some people have used them successfully in Open baffle too. There is one suggested design for University 6201 driver, which was quite similar to my drivers High Efficiency Speaker Asylum

Regards
Sachin
 
These are excellent vintage speakers and well regarded. Look for cabinets suggested for them on the net. These are generally played with tube amps. They must kind of quite heavy. You are lucky to have them. Put them in a nice suggested cabinet and get hold of some nice tube amp.

They should not distort at high levels. May be you are feeding them too much. Check their sensitivity on the net.

Thanks Yogibear. I am considering big BR cabs posted in my earlier post. I have read very good reviews of these speakers on various forums. They used to be compete with Altec and EV of that time. Later Altec bought University. Here is an 1963 catalog University Speakers Circa 1963 | Preservation Sound
also here http://www.hifilit.com/University/1957-4.jpg Box plan for some drivers are here New Page 1
I am aware of their high sensitivity. I think they are close to 100db. I am playing them with my DIY Class A, 5W Amp Camp.

Regards
Sachin
 
If the voice coil is rubbing then the solution is to adjust the magnet structure little bit to remove the rubbing or remove the woofer cone and reseat it. Second option is messy and may be destructive. Loosening the magnet screws and adjusting is an easier option.

Cheers.
 
Thank you everyone. I think I have located the source of distortion. I feel the problem is Voice Coil rubbing. I have confirmed this by pushing driver cone inside. I can feel the little scratching noise while pushing driver cone manually. Can this be corrected without damaging the cone?There is only one driver having distortion on low frequencies, HF and mids are Crystal clear.

Regards
Sachin
Congrats Sachin. This looks like nice speakers. Do not repair the original cone with out confirming the issue. Usually Voice coil rubbing is rare. Please check visually flex wire coming out of cone. Normally they do slap on cone material and create distortion.
Regards.
 
Success!!
I sent those drivers to my friend and FM sann at Pune. He took them to another 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 the original place. He had to cut one ring/cover from the back side to access the pole piece.He is an elderly person and we all call him Kaka(Uncle)
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







Regards
Sachin
 
Last edited:
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
 
Congrats Sachin!

They are playing as clean as a whistle! :)
Very clean sound without a hint of distortion. Horn is giving good highs.
It is indeed a very skilled work acomplished.
The finish on these drivers is just exquisite and they have a very royale touch to them if I may say!

I have to complement these drivers that even if they are designed long long time back they have stood the test of time and they are playing with the kind of resolution and clarity to compete or even outperform some of the modern day drivers.

Cheers!
NJoy! :)
 
BTW what amp is the one showing in the foreground? It looks similar to an EL 34 pp Sophia integrated that I have an like very much, though mine has a wooden panel in front unlike yours
 
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