A couple of weeks ago I visited a guy who had placed this ad on the net selling a pair of older Sony speakers quite cheap. Now Sony isn't exactly the most respected speaker company in the world but I knew they made some quality series in the 70/80's so I wrote and asked about a model number - SS-G5 he replied and I told him I would buy them as I've read good things about that model series.
Anyway came to his house and bought them without hesitation - on the way out I mentioned my interest in vintage hifi and he offered me another pair of speakers currently connected to his stereo.Turns out it was a pair of B&W DM14
got em for a very reasonable price as he was on the verge on dragging both speaker pairs to the local dump - pretty shocking but I guess it proves that for some people this is just old worthless junk.
Safe at home base I connected the b&w's and immediately noticed the sound was wrong- within a few seconds I concluded one tweeter had significant weaker output compared to the other. My first guess was that the crossoveer had a worn out capacitor so i swapped the tweeters - the error followed the tweeter so the tweeter had to be the source of the problem. Took out the diaphram and inspected it but it looked fine and both had the same resistance when measured. I then remembered an old thread http://audiokarma.org/forums/showthread.php?t=48842 and it would seem these speakers had the same problem with the resin-coating on the tweeter domes.
Holding the diaphragm up against a bright light source I could see that a good part of the original coating was missing from the dome of the bad tweeter - on the good one most of it was still attached. In the thread i mentioned my fellow AK'er used french polish to coat the dome I didn't have that or any product like it - also I was worried I might overdo the coating if the shellac wasn't thinned enough and thereby adding too much weight to the dome.
Instead I tried to use diluted glue the same white stuff that many of us uses to glue new foam surrounds. Now before I started coating the dome I wanted to remove any old resin as it was probaly in a decomposed state. Did it by pouring a bit of alcohol on the dome... that worked fine. Afterward I diluted the glue with water until it looked like milk and started to coat the dome with several thin layers. I used a small soft painters brush and coated both the back and front of the dome - I let it dry between each new coating.After a couple of coating I held the diaphram up against a light source to check for missed spots - the coating should be thick enough to block out bright light(compare it to the other dome) but as soon you reach that stage stop adding new coatings.
All in all I gave it around 5 coatings on each side of the dome - the number of coatings depends of how diluted the glue is. Put the tweeter back in the cabinet and succes it played just as good as the other tweeter perhaps with a tiny bit more output.
Even though the other tweeter played fine I wanted to give it the same treatment as the original resin just isn't as it once were anymore. Finally after both tweeters had been coated the speakers sang beautifully := no difference in tweeter output.
Quite a remarkable speaker the DM14... now these aren't bass monsters but the sound they bring forward is crisp and well rounded - vocals are very well defined.
A final comment about the old B&w tweeters - I suspect many of these resin covered dome models (DM14, DM7 maybe others) in many cases may not live up to their potential due to the reasons stated above. B&W owners own it to themselves to check the tweeters.
Now... the Sony's
Plugged em in and like with the B&W's i noticed some was wrong... yep one dead tweeter. Also the other tweeter had been replaced with an unoriginal part...
Took out the dead tweeter to measure and sure enough - no continuity. Took a look at the thin wire right at the terminals a found the cause it was was burnt through but it looked like it could be soldered. Using a bit of extra wire I soldered the remaining coilwire to the terminal and again success
regarding the unoriginal tweeter i'd like to replace it with an original but it seems these parts are rarely up for sale. These are heavy and well built speakers in the JBL vein and while I initially thought they were a bit recessed in the upper bass/low midrange they do make a solid presentation of the music but I need to test em for a while before I pass any judgement. Maybe some stands will make a difference?
And now the final score...
A couple of days later I went to a car booth sale didn't expect to find anything as my "speaker fortune" surely was used up but lo and behold a pair of old PA cabinets with no woofers. Normally I wouldn't even take a closer look but there were these large horns sticking out at the top end of the cabinets and they looked pretty old and sturdy and of course my curiosity was piqued. First thing I noticed was the backside it said altec on the speaker terminal plate I then took a closer look at the horns and it said H-811B horn on the topside. The price tag was too low to not take a chance but these things were so large they couldn't fit in the car so I paid for them and agreed to collect later.
To make a long story short - when I finally got them home it turns out the drivers were Altec 806-8A both are functional but i'm not sure the diaphragms are in the best state. I'm currently thinking about a diy procect - maybe a 2-way with active crossover - something in the vein of the speakers seen on this webpage http://members.myactv.net/~je2a3/speakers2.htm
I'd like to hear more about these drivers...also are they even suitable for hifi use?
Anyway came to his house and bought them without hesitation - on the way out I mentioned my interest in vintage hifi and he offered me another pair of speakers currently connected to his stereo.Turns out it was a pair of B&W DM14
got em for a very reasonable price as he was on the verge on dragging both speaker pairs to the local dump - pretty shocking but I guess it proves that for some people this is just old worthless junk.Safe at home base I connected the b&w's and immediately noticed the sound was wrong- within a few seconds I concluded one tweeter had significant weaker output compared to the other. My first guess was that the crossoveer had a worn out capacitor so i swapped the tweeters - the error followed the tweeter so the tweeter had to be the source of the problem. Took out the diaphram and inspected it but it looked fine and both had the same resistance when measured. I then remembered an old thread http://audiokarma.org/forums/showthread.php?t=48842 and it would seem these speakers had the same problem with the resin-coating on the tweeter domes.
Holding the diaphragm up against a bright light source I could see that a good part of the original coating was missing from the dome of the bad tweeter - on the good one most of it was still attached. In the thread i mentioned my fellow AK'er used french polish to coat the dome I didn't have that or any product like it - also I was worried I might overdo the coating if the shellac wasn't thinned enough and thereby adding too much weight to the dome.
Instead I tried to use diluted glue the same white stuff that many of us uses to glue new foam surrounds. Now before I started coating the dome I wanted to remove any old resin as it was probaly in a decomposed state. Did it by pouring a bit of alcohol on the dome... that worked fine. Afterward I diluted the glue with water until it looked like milk and started to coat the dome with several thin layers. I used a small soft painters brush and coated both the back and front of the dome - I let it dry between each new coating.After a couple of coating I held the diaphram up against a light source to check for missed spots - the coating should be thick enough to block out bright light(compare it to the other dome) but as soon you reach that stage stop adding new coatings.
All in all I gave it around 5 coatings on each side of the dome - the number of coatings depends of how diluted the glue is. Put the tweeter back in the cabinet and succes it played just as good as the other tweeter perhaps with a tiny bit more output.
Even though the other tweeter played fine I wanted to give it the same treatment as the original resin just isn't as it once were anymore. Finally after both tweeters had been coated the speakers sang beautifully := no difference in tweeter output.
Quite a remarkable speaker the DM14... now these aren't bass monsters but the sound they bring forward is crisp and well rounded - vocals are very well defined.
A final comment about the old B&w tweeters - I suspect many of these resin covered dome models (DM14, DM7 maybe others) in many cases may not live up to their potential due to the reasons stated above. B&W owners own it to themselves to check the tweeters.
Now... the Sony's
Plugged em in and like with the B&W's i noticed some was wrong... yep one dead tweeter. Also the other tweeter had been replaced with an unoriginal part...
Took out the dead tweeter to measure and sure enough - no continuity. Took a look at the thin wire right at the terminals a found the cause it was was burnt through but it looked like it could be soldered. Using a bit of extra wire I soldered the remaining coilwire to the terminal and again success
regarding the unoriginal tweeter i'd like to replace it with an original but it seems these parts are rarely up for sale. These are heavy and well built speakers in the JBL vein and while I initially thought they were a bit recessed in the upper bass/low midrange they do make a solid presentation of the music but I need to test em for a while before I pass any judgement. Maybe some stands will make a difference? And now the final score...
A couple of days later I went to a car booth sale didn't expect to find anything as my "speaker fortune" surely was used up but lo and behold a pair of old PA cabinets with no woofers. Normally I wouldn't even take a closer look but there were these large horns sticking out at the top end of the cabinets and they looked pretty old and sturdy and of course my curiosity was piqued. First thing I noticed was the backside it said altec on the speaker terminal plate I then took a closer look at the horns and it said H-811B horn on the topside. The price tag was too low to not take a chance but these things were so large they couldn't fit in the car so I paid for them and agreed to collect later.
To make a long story short - when I finally got them home it turns out the drivers were Altec 806-8A both are functional but i'm not sure the diaphragms are in the best state. I'm currently thinking about a diy procect - maybe a 2-way with active crossover - something in the vein of the speakers seen on this webpage http://members.myactv.net/~je2a3/speakers2.htm
I'd like to hear more about these drivers...also are they even suitable for hifi use?
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