I own 1979 Altec Lansing Model 15 loudspeakers and rebuilt the crossovers. Now I have a extremely low volume. Can you please recommend the next course to take to resolve it?
The story:
I replaced the caps w/ Solen and rewired it. Upon reassembling the speakers the sound is now very quiet.
I rechecked my assembly hookup to my hand drawing of the factory x-over schematic. (The schematic and crossover photo posted below) Note that the woofer runs full range and the crossover only affects the horn.
When I hook the speaker wire direct to the binding posts it produces an almost un-hearable volume. When I touch the speaker leads direct to the woofer I hear the same until I remove one of the x-over leads, then the woofer sounds normal, of course I can test the horn. So the problem is with the x-over.
Let me clarify. The xover only operates the horn, but if it is in the system because it isn't bi-wired. The woofer sound is very muted. If I remove at least one x-over lead from the binding post the woofer sounds fine, but of course there is no way to test the horn.
To do another test it I took one x-over to a friends, hooked up another woofer and another tweeter and a vintage amp it it worked fine. I bring it home and hook it in the Altec Model-15 speakers/ Carver Receiver 900 and it doen't work again.
I'm using a Carver receiver that worked before the x-over rebuild that powered the M-15 w/o issue. The Carver has no problem driving other speakers, only the Altecs. Furthermore, using the M-15 if I turn the volume up the protection circuit clicks in until I turn it back down, like there is a short somewhere, yet the x-over worked w/ other components at my friends.
It's crazy. Bad caps, bad pots, etc? What should I test?
Any suggestions? (I've have built many crossovers and have rebuilt many others and have never experienced this, but there is a first time for everything.) A simple project has become a little more complicated.
Attached:
x-over drawing
x-over rebuild photo (I since redid it in its entirety from scratch but using thinner Kimber Kable instead of the 14 ga. Audioquest as in the photo.
Regards,
Mike
The story:
I replaced the caps w/ Solen and rewired it. Upon reassembling the speakers the sound is now very quiet.
I rechecked my assembly hookup to my hand drawing of the factory x-over schematic. (The schematic and crossover photo posted below) Note that the woofer runs full range and the crossover only affects the horn.
When I hook the speaker wire direct to the binding posts it produces an almost un-hearable volume. When I touch the speaker leads direct to the woofer I hear the same until I remove one of the x-over leads, then the woofer sounds normal, of course I can test the horn. So the problem is with the x-over.
Let me clarify. The xover only operates the horn, but if it is in the system because it isn't bi-wired. The woofer sound is very muted. If I remove at least one x-over lead from the binding post the woofer sounds fine, but of course there is no way to test the horn.
To do another test it I took one x-over to a friends, hooked up another woofer and another tweeter and a vintage amp it it worked fine. I bring it home and hook it in the Altec Model-15 speakers/ Carver Receiver 900 and it doen't work again.
I'm using a Carver receiver that worked before the x-over rebuild that powered the M-15 w/o issue. The Carver has no problem driving other speakers, only the Altecs. Furthermore, using the M-15 if I turn the volume up the protection circuit clicks in until I turn it back down, like there is a short somewhere, yet the x-over worked w/ other components at my friends.
It's crazy. Bad caps, bad pots, etc? What should I test?
Any suggestions? (I've have built many crossovers and have rebuilt many others and have never experienced this, but there is a first time for everything.) A simple project has become a little more complicated.
Attached:
x-over drawing
x-over rebuild photo (I since redid it in its entirety from scratch but using thinner Kimber Kable instead of the 14 ga. Audioquest as in the photo.
Regards,
Mike
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I'm not quite sure I understand, so I'll ask a few questions:
- If you connect the amp directly to the woofer, what do you get?
- If you connect the amp to the horn via a cap (say 8uF and keep the volume low) what do you get?
- Can you isolate or bypass any sections of the new crossover with jumper leads to test it?
Pano,
If I hook the amp direct to the woofer while it is connected to the speaker binding posts shared by the x-over and horn it plays very quite. If I remove at least one lead from the binding post connection to the woofer, and then connect the amp to the woofer it plays normal volume.
The xover is laid out nicely to isolate, but do I need to desolder, or can I just use jumpers as in the case of using 8uf cap and horn?
Should I test caps and inductors? I'm willing to buy a cheap $50 cap/inductor meter, as it would be a wise investment for me.
Could I have applied to much heat in soldering w/ my small 15 watt (?) iron to have damaged the Solen caps, pots, or inductors?
If I hook the amp direct to the woofer while it is connected to the speaker binding posts shared by the x-over and horn it plays very quite. If I remove at least one lead from the binding post connection to the woofer, and then connect the amp to the woofer it plays normal volume.
The xover is laid out nicely to isolate, but do I need to desolder, or can I just use jumpers as in the case of using 8uf cap and horn?
Should I test caps and inductors? I'm willing to buy a cheap $50 cap/inductor meter, as it would be a wise investment for me.
Could I have applied to much heat in soldering w/ my small 15 watt (?) iron to have damaged the Solen caps, pots, or inductors?
I doubt you hurt the inductors or the pots, maybe the caps. But even if the caps were shorted, it should not cause a short from + to -. If connecting the crossover causes a big drop in woofer volume then you are right to suspect a short.
You may have to look hard and start unsoldering some stuff.
Double and triple check your wiring (yes, again) then start unsoldering the parallel elements one at a time. That would be the pots and the 1.2mH inductor. That's the way to start.
You may have to look hard and start unsoldering some stuff.
Double and triple check your wiring (yes, again) then start unsoldering the parallel elements one at a time. That would be the pots and the 1.2mH inductor. That's the way to start.
OK. I actually rebuilt the xovers 2x. After finding the problem I rebuilt them w/ the same components, but replaced the 14 ga wire w/ small gauge to make sure my solder joints were clean. At that time I pulled the woofer wires from the binding posts instead of off the xover post. I know the circuit is laided out correctly.
Tomorrow I will begin you all suggestions. First jumping across the MF pot and then by disconnecting one end of the 1.2mH inductor coil. I will get back with you with my findings. I wish I had a meter to measure capacitance to test that 3uf cap.
Tomorrow I will begin you all suggestions. First jumping across the MF pot and then by disconnecting one end of the 1.2mH inductor coil. I will get back with you with my findings. I wish I had a meter to measure capacitance to test that 3uf cap.
I found the problem.
I found the problem, at least on the one speaker I tested, but the other is probably the same. Thankfully its not the caps.
The cup that the binding posts are mounted on is conductive. (see attached photo of cup) It doesn't feel like metal, but if it is painted cast aluminum it is conductive through the paint and a poor design. This is why the x-over worked with just the x-over and speakers when testing with my friend, and didn't work when installed in the speakers at home.
I replaced the cheap factory push-spring speaker wire posts for beefy gold plated brass posts that bite the cup firmly. (see attached photo) I was so concerned with x-over issues I didn't notice the cups. Now I will need to coat the through-bolt and use some type of insulator on the front and back of the cup. What is funny is that the factory speaker pot metal wire posts didn't use insulators either, but the posts I installed dug in and make a good contact. When I tested resistance with my $10 cheapo MM on the post cup I get a small reading on the cups surface, and the same reading from + post to - post. Crazy isn't it.
Has anyone experienced this? I've read where the glue used to adhere caps in some vintage amps becomes conductive over time.
I found the problem, at least on the one speaker I tested, but the other is probably the same. Thankfully its not the caps.
The cup that the binding posts are mounted on is conductive. (see attached photo of cup) It doesn't feel like metal, but if it is painted cast aluminum it is conductive through the paint and a poor design. This is why the x-over worked with just the x-over and speakers when testing with my friend, and didn't work when installed in the speakers at home.
I replaced the cheap factory push-spring speaker wire posts for beefy gold plated brass posts that bite the cup firmly. (see attached photo) I was so concerned with x-over issues I didn't notice the cups. Now I will need to coat the through-bolt and use some type of insulator on the front and back of the cup. What is funny is that the factory speaker pot metal wire posts didn't use insulators either, but the posts I installed dug in and make a good contact. When I tested resistance with my $10 cheapo MM on the post cup I get a small reading on the cups surface, and the same reading from + post to - post. Crazy isn't it.
Has anyone experienced this? I've read where the glue used to adhere caps in some vintage amps becomes conductive over time.
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Well, it was a short. - Status
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