Thought I would post a little on my latest distraction. I'm a sucker for buying cheap stuff and testing/modifying/restoring. Always looking for the next cheap thing to be improved. Bought a lot of cars and fixed them up too, I usually end up paying more for less + the extra work I put in, but I guess that's what they call a hobby 😉
Anyway, I found these nearby on FB marketplace, and first dismissed the idea of buying them, because I have a garage full of stuff already. Then I was reading about them a bit, and they seemed to get some decent reviews, and many seemed to have kept them for many years, so I reconsidered. I never owned a pair of coaxials either, so I kind of wanted to try a pair.
Payed abt 30EUR, and at first glace they were in decent shape. Had been sitting in a storage as part of an estate that was being cleared out now.
It did turn out that the glue for the baffle had partially let go, but I did not notice it at first glace.
I listened to them a bit when I got them to the garage, and everything was working, no blown tweeters etc, and I did think they had some nice sonic qualities. For some reason it seems I like the sound of poly-cones.. I got the idea I could use them as front speakers for the TV, since they sounded pretty nice on vocals.
When I removed the terminals/XO, I found there was no damping material at all inside, and no wonder, since the lower part of the enclosure was just an empty box to make them 'floorstanders'. The upper part was decently braced and had a lot of stuffing, so it seemed like a decently put together speaker.
XO seems to be a 2nd order using cheap parts, electrolytic caps and cored inductor for the woofer. I did not touch that though, since I thought they sounded ok.
The driver basket is made of thin stamped sheet metal, so nothing fancy there.
I have limited space for TV speakers, so I decided to remove the empty box at the bottom to make them smaller. I re-glued the baffle and glued some extra small pieces of wood to strengthen the connection to the box, cut a new hole for the terminals/XO, painted the baffle and plastics white. Used some vinyl wrapping to finish the cabinets. I also added some basotect to the bottom, and the rear panel behind the driver. I cut down the grilles to fit, but I prefer the look with the grilles off.
I found they are a bit big to fit as TV front speakers (should have measured first!), so now I'm not sure what to do with them. I will post measurements if I do more with them.
Anyway, I found these nearby on FB marketplace, and first dismissed the idea of buying them, because I have a garage full of stuff already. Then I was reading about them a bit, and they seemed to get some decent reviews, and many seemed to have kept them for many years, so I reconsidered. I never owned a pair of coaxials either, so I kind of wanted to try a pair.
Payed abt 30EUR, and at first glace they were in decent shape. Had been sitting in a storage as part of an estate that was being cleared out now.
It did turn out that the glue for the baffle had partially let go, but I did not notice it at first glace.
I listened to them a bit when I got them to the garage, and everything was working, no blown tweeters etc, and I did think they had some nice sonic qualities. For some reason it seems I like the sound of poly-cones.. I got the idea I could use them as front speakers for the TV, since they sounded pretty nice on vocals.
When I removed the terminals/XO, I found there was no damping material at all inside, and no wonder, since the lower part of the enclosure was just an empty box to make them 'floorstanders'. The upper part was decently braced and had a lot of stuffing, so it seemed like a decently put together speaker.
XO seems to be a 2nd order using cheap parts, electrolytic caps and cored inductor for the woofer. I did not touch that though, since I thought they sounded ok.
The driver basket is made of thin stamped sheet metal, so nothing fancy there.
I have limited space for TV speakers, so I decided to remove the empty box at the bottom to make them smaller. I re-glued the baffle and glued some extra small pieces of wood to strengthen the connection to the box, cut a new hole for the terminals/XO, painted the baffle and plastics white. Used some vinyl wrapping to finish the cabinets. I also added some basotect to the bottom, and the rear panel behind the driver. I cut down the grilles to fit, but I prefer the look with the grilles off.
I found they are a bit big to fit as TV front speakers (should have measured first!), so now I'm not sure what to do with them. I will post measurements if I do more with them.
I was listening to these at home while I was writing the above, and some more after that. I found there was something irritating with the treble, and it gave me fatigue with a headache after a couple of hours of 'passive' listening. Because of this, I took them back to the workshop, and figured I should measure them and see what could be done.
So, I measured the usual FR of the complete speaker, and found it a bit wobbly, so I thought some tuning on the XO could improve it.
I took the FRD's and ZMA's and did some quick sims in xsim, but it proved a bit hard to get the tweeter to behave, and I started thinking that they could not have been that far off at KEF from the start, so I just ran a FR of the other speaker, and that one was a lot better in the tweeter department, so I ran some distortion measurements on that tweeter, and then on the problematic tweeter. Distortion was significantly higher on the wobbly one. I tried some sine sweeps on the faulty tweeter, and could hear some buzzing/rubbing. I was able to remove the tweeter and open it up. I did not see any obvious problems, the buzzing would vary depending on how I was pressing on the tweeter housing, so I figured the VC was not centered in the gap, or possibly some debris in the gap. Cleaning it made no difference, and when looking closely I could see the VC was slightly tilted, and thought the surround had 'sagged' from age. However, when pushing the dome and looking in a magnifying glass, I could see that the the glue for the surround had partly come loose from the VC, so I took some glue on a piece of thin wire and tried to re-glue it. It's now fixed in a parallel position while drying, will see if it works better tomorrow. I don't think it's worth buying spare parts, but if I can repair it with glue, I'm happy.
BTW, the suck-out above 10k is there on both tweeters, so I'm guessing that is some kind of cavity resonance from how it's mounted, or possibly caused by the pole piece that is just a bare flat metal surface behind the dome. Maybe I will try some damping if the tweeter is ok.
So, I measured the usual FR of the complete speaker, and found it a bit wobbly, so I thought some tuning on the XO could improve it.
I took the FRD's and ZMA's and did some quick sims in xsim, but it proved a bit hard to get the tweeter to behave, and I started thinking that they could not have been that far off at KEF from the start, so I just ran a FR of the other speaker, and that one was a lot better in the tweeter department, so I ran some distortion measurements on that tweeter, and then on the problematic tweeter. Distortion was significantly higher on the wobbly one. I tried some sine sweeps on the faulty tweeter, and could hear some buzzing/rubbing. I was able to remove the tweeter and open it up. I did not see any obvious problems, the buzzing would vary depending on how I was pressing on the tweeter housing, so I figured the VC was not centered in the gap, or possibly some debris in the gap. Cleaning it made no difference, and when looking closely I could see the VC was slightly tilted, and thought the surround had 'sagged' from age. However, when pushing the dome and looking in a magnifying glass, I could see that the the glue for the surround had partly come loose from the VC, so I took some glue on a piece of thin wire and tried to re-glue it. It's now fixed in a parallel position while drying, will see if it works better tomorrow. I don't think it's worth buying spare parts, but if I can repair it with glue, I'm happy.
BTW, the suck-out above 10k is there on both tweeters, so I'm guessing that is some kind of cavity resonance from how it's mounted, or possibly caused by the pole piece that is just a bare flat metal surface behind the dome. Maybe I will try some damping if the tweeter is ok.
The glue fixed the tweeter, so I was lucky! The ferrofluid I used was a bit thick, so the tweeter lost some from 2k and down, but it's below XO, so it did not affect frequency response much. Good enough, and with abt 1ohm extra in series with the tweeter circuit, they sound better balanced overall. They had a bit too much treble for my ears wit the stock tuning.
Paired with a sub I think they would make a pretty good budget system.
Paired with a sub I think they would make a pretty good budget system.