Large Advent possibly blown?

[Leo7504]

Help!!! I have a pair of 1972

Large Advents with the walnut cabinets that I bought new in 72. I have kept them all these years and a few years back reconed the woofers and restored them to the sweet classic sound that I remember so well from my youth. I really babied them and rarely turned the volume to halfway on my Harman Kardon 3375. I recently took a weeks vacation and when I returned I found that my son had a party and has apparently blown one of my speakers! The sound form the right speaker only emanates just barely from the tweeter and nothing comes from the bass. Please tell me that they can be fixed. Help!!!

[Pete B]

Help!!! I have a pair of 1972

Large Advents with the walnut cabinets that I bought new in 72. I have kept them all these years and a few years back reconed the woofers and restored them to the sweet classic sound that I remember so well from my youth. I really babied them and rarely turned the volume to halfway on my Harman Kardon 3375. I recently took a weeks vacation and when I returned I found that my son had a party and has apparently blown one of my speakers! The sound form the right speaker only emanates just barely from the tweeter and nothing comes from the bass. Please tell me that they can be fixed. Help!!!

Probably a good time now to recap them while you have them open.

Do you have a meter? Can you read the DC resistance of each driver

and report them here?

Also, are you certain that the receiver is all OK?

[Doug G.]

Yeah, what Pete said.

Switch the speakers around and see if the problem stays on the right channel or moves to the left.

If it stays on the right, the receiver is at fault. If it moves to the left, the speaker is at fault.

Oh, and they can ALWAYS be fixed :^)

Doug

[Leo7504]

Yes,

I did switch the wires from the right channel to the left and the right speaker continued to procuce a barely audible sound only from the tweeter with the volume halfway up. I am fairly certain the problem is with the speaker, the question is how to proceed from here to determine how extensive the problem is. I have replaced the foam surrounds a couple of years back and so I can remove the bass speaker if necessary, and I am desperately hoping I can salvage the speaker because I understand that a suitable replacement would involve swapping both bass speakers out unless I opt to buy another vintage set of Large advents to cannibalize a suitable replacement speaker. Any help that you could suggest would be appreciated.

Leo

[Doug G.]

OK, remove the woofer and look for any obvious damage like broken wires from the terminal strip to the cone.

If you have an ohmmeter, check the DC resistance. It should be around 4.5 ohms.

Lacking a meter, hook up a sound source directly to the woofer and see if it produces sound. The highs will not be there, of course and you will probably have to compare it to the good woofer to see if it is satisfactory.

The only thing in the crossover that has anything to do with the woofer is a 1.6uH inductor which should have about a 2 ohm DC resistance.

If the woofer is bad, they show up on eBay fairly frequently. You can use any masonite woofer since they never changed throughout the original Advent Loudspeaker production.

If the sound from the tweeter is barely audible, there is probably damage somewhere there too. We can tackle that after dealing with the woofer circuit.

Doug

[Leo7504]

OK, remove the woofer and look for any obvious damage like broken wires from the terminal strip to the cone.

If you have an ohmmeter, check the DC resistance. It should be around 4.5 ohms.

Lacking a meter, hook up a sound source directly to the woofer and see if it produces sound. The highs will not be there, of course and you will probably have to compare it to the good woofer to see if it is satisfactory.

The only thing in the crossover that has anything to do with the woofer is a 1.6uH inductor which should have about a 2 ohm DC resistance.

If the woofer is bad, they show up on eBay fairly frequently. You can use any masonite woofer since they never changed throughout the original Advent Loudspeaker production.

If the sound from the tweeter is barely audible, there is probably damage somewhere there too. We can tackle that after dealing with the woofer circuit.

Doug

[Leo7504]

Doug,

Eureka! There was no resistance in the woofer circuit and upon further inspection the fine wire from the lead to the woofer cone is broken. I have about one inch left on each side but not enough to make a connection. As you know this is a very fine flexible wire to facilitate the movement of the woofer. I will attempt to connect the circuit temporarily to see if the woofer produces sound. I guees the next question is how best to replace this wire or make a suitable repair. Where would I get a similar wire?

Leo

[Leo7504]

I was able to find a braided copper wire at Radio Shack (desoldering wire) to make a temporary connection by making a simple slip loop at each end and inserting each broken end into the loop to make the connection. The bass speaker is now working but I did notice a bit of static which I attributed to the shoddy connection.

Do you have a suggestion on how to make a suitable repair? If I could find a suitable braided wire is it feasable to resolder at the cone and the terminal?

Thanks for your help.

Leo

[Doug G.]

Yeah, that tinselized wire they use for those leads is tricky to work with as far as soldering to it.

I have always just added fexible braid like you did and soldered it at the terminal strip and to the ends of the leads.

Try to tin the ends of the braid first and avoid the solder from completely wicking up the braid. Then get a blob of solder onto the end of the original lead (that's the tricky part - getting solder to stick to that wire) and then sweat solder the two together. Solder the other end of the braid to the terminals.

I wouldn't mess with the connections right at the cone or the rivets there, especially if those look good.

EDIT: I think I'm wrong about the tinselized deal. I think Advent just used braided wire for these leads. It's been awhile since I had a masonite woofer out and sometimes it seems, these days, my long term memory can be measured in microseconds :^)

Doug

[Leo7504]

Doug,

I was able to find a source for braded wire at www.speaker repair.com. This wire is a heavier guage than the original but works fine. After reattahing the new wire and completing repairs the test revealed nearly new sound but the speaker has a slight raspy echo which becomes inaudible at higher sound levels. I am wondering if this could be wear on the speaker cone?

The testing of the repaired speakers revealed a problem with the other speaker. It seems the tweeter was not working. I connected directly to the tweeter and was able to produce sound. Does this mean that there is a problem with the crossover? How would I troubleshoot that issue. Thanks for your help.

Leo

[Doug G.]

Well, there used to be a schematic of the original Advent Loudspeaker in the library on this site but I don't see it now, only one as part of a service bulletin and it isn't very good.

So, go to Pete's site to get a good one:

http://baselaudiolabs.googlepages.com/ADVENT_LA_XO.html

You will see that, depending on the tweeter switch position, different components are swtched into, or out of, the circuit.

Extended:

C1 and C2 are in circuit (in series with the tweeter) and L1 and R1 are not (they are bypassed by the switch).

You can see that it would have to be C1 or C2 not passing a signal if the tweeter doesn't work in "Extended." It could be the switch, of course, but I believe this would be a very rare situation of these fairly heavy duty switches to quit functioning.

Decrease:

C1, L1, and R1 are all in circuit, C2 is not. In my experience, R1 is the most likely component to fail here as the low resistance means fairly heavy current flow and likelyhood of overheating and opening. L1 would be the second most likely I guess.

Normal:

C1 and R1 are in circuit, L1 and C2 are not. L1 is bypassed by the switch. Here, R1 is, again most likely to be the bad component (open).

The first thing to do is see which switch positions produce which results and go from there.

The only other component here is the inductor (L2) in parallel with the tweeter. This would only cause silence from the tweeter if it were completely shorted and shunting the signal to ground.

Looking at Pete's schematic, I see some differences between his and the one I got from here a while ago. On mine, the positive terminal of the speaker goes directly to C1, the 16 ufd capacitor and then the cap. goes to the switch where L1 (L2 in Pete's) is wired. My hand-drawn one also agrees with the one that used to be in the library.

Doug

[Leo7504]

Well, there used to be a schematic of the original Advent Loudspeaker in the library on this site but I don't see it now, only one as part of a service bulletin and it isn't very good.

So, go to Pete's site to get a good one:

http://baselaudiolabs.googlepages.com/ADVENT_LA_XO.html

You will see that, depending on the tweeter switch position, different components are swtched into, or out of, the circuit.

Extended:

C1 and C2 are in circuit (in series with the tweeter) and L1 and R1 are not (they are bypassed by the switch).

You can see that it would have to be C1 or C2 not passing a signal if the tweeter doesn't work in "Extended." It could be the switch, of course, but I believe this would be a very rare situation of these fairly heavy duty switches to quit functioning.

Decrease:

C1, L1, and R1 are all in circuit, C2 is not. In my experience, R1 is the most likely component to fail here as the low resistance means fairly heavy current flow and likelyhood of overheating and opening. L1 would be the second most likely I guess.

Normal:

C1 and R1 are in circuit, L1 and C2 are not. L1 is bypassed by the switch. Here, R1 is, again most likely to be the bad component (open).

The first thing to do is see which switch positions produce which results and go from there.

The only other component here is the inductor (L2) in parallel with the tweeter. This would only cause silence from the tweeter if it were completely shorted and shunting the signal to ground.

Looking at Pete's schematic, I see some differences between his and the one I got from here a while ago. On mine, the positive terminal of the speaker goes directly to C1, the 16 ufd capacitor and then the cap. goes to the switch where L1 (L2 in Pete's) is wired. My hand-drawn one also agrees with the one that used to be in the library.

Doug

[Leo7504]

Doug,

The tweeter does not make any sound in either of the three switch positions. I see that C1 is in circuit in all three switch positions. Does that make C1 a likely culprit.

What is the easiest way to access the crossover. Should I remove the baas speaker and the insulation or is there another way to access the crossover.

[Pete B]

Well, there used to be a schematic of the original Advent Loudspeaker in the library on this site but I don't see it now, only one as part of a service bulletin and it isn't very good.

So, go to Pete's site to get a good one:

http://baselaudiolabs.googlepages.com/ADVENT_LA_XO.html

You will see that, depending on the tweeter switch position, different components are swtched into, or out of, the circuit.

Extended:

C1 and C2 are in circuit (in series with the tweeter) and L1 and R1 are not (they are bypassed by the switch).

You can see that it would have to be C1 or C2 not passing a signal if the tweeter doesn't work in "Extended." It could be the switch, of course, but I believe this would be a very rare situation of these fairly heavy duty switches to quit functioning.

Decrease:

C1, L1, and R1 are all in circuit, C2 is not. In my experience, R1 is the most likely component to fail here as the low resistance means fairly heavy current flow and likelyhood of overheating and opening. L1 would be the second most likely I guess.

Normal:

C1 and R1 are in circuit, L1 and C2 are not. L1 is bypassed by the switch. Here, R1 is, again most likely to be the bad component (open).

The first thing to do is see which switch positions produce which results and go from there.

The only other component here is the inductor (L2) in parallel with the tweeter. This would only cause silence from the tweeter if it were completely shorted and shunting the signal to ground.

Looking at Pete's schematic, I see some differences between his and the one I got from here a while ago. On mine, the positive terminal of the speaker goes directly to C1, the 16 ufd capacitor and then the cap. goes to the switch where L1 (L2 in Pete's) is wired. My hand-drawn one also agrees with the one that used to be in the library.

Doug

You had me worried there for a minute Doug!

My circuit is funtionally the same since the order does not matter in a series circuit.

However, it is not physically the same, since you can see in the picture that the first

16uF cap comes right off the + terminal as you point out.

This doesn't bother me much however, I suppose that I should change it if people

rebuild directly from the diagram.

I probably did it because it laid out cleaner in the schematic.

[Pete B]

Doug,

The tweeter does not make any sound in either of the three switch positions. I see that C1 is in circuit in all three switch positions. Does that make C1 a likely culprit.

What is the easiest way to access the crossover. Should I remove the baas speaker and the insulation or is there another way to access the crossover.

Yes remove the woofer and damping.

Disconnect and measure the DC resistance of the tweeter.

Or use a 1.5V battery directly on the tweeter and see if you

get a click. Just tap it for a few seconds.

[Leo7504]

Pete,

The DC resistance on the tweeter is 4 ohms. I can reproduce sound by connecting the speaker directly to the tweeter.

Leo

[Pete B]

Pete,

The DC resistance on the tweeter is 4 ohms. I can reproduce sound by connecting the speaker directly to the tweeter.

Leo

OK that's good.

1972 means that you probably have the small round red inductors in the crossover,

can you check this?

Next, if you measure the two leads that would connect to the tweeter with it still

disconnected the resistance should be about 2 ohms if you have the round red inductors.

It probably measures closer to zero indicating that the inductors were overloaded and

shorted.

You probably also have 2 16 uF caps in the crossover?

The entire crossover has probably been over stressed and you should replace the

two caps, and red inductor, might want to do the resistor just because it has been

stressed.

[Leo7504]

OK that's good.

1972 means that you probably have the small round red inductors in the crossover,

can you check this?

Next, if you measure the two leads that would connect to the tweeter with it still

disconnected the resistance should be about 2 ohms if you have the round red inductors.

It probably measures closer to zero indicating that the inductors were overloaded and

shorted.

You probably also have 2 16 uF caps in the crossover?

The entire crossover has probably been over stressed and you should replace the

two caps, and red inductor, might want to do the resistor just because it has been

stressed.

[Leo7504]

Pete,

OK I see the two 16 UF caps, one connected to the tweeter one to the bass, neither is measuring any resistance. I don't see a red inductor. connected to the 16 uf cap on the tweeter side is a vanilla colored box that says 3 ohm 10% 5W. Also on the crossover plate are two round cilinder shaped objects about the size of a watch battery, one is yellow one is brownish red. Aldo connected to the crossover plate and in line witht he bass speaker is a black coil looking device. I am attaching a picture.

I am happy to replace all of these items but where do I get them?

Leo

[Pete B]

Pete,

OK I see the two 16 UF caps, one connected to the tweeter one to the bass, neither is measuring any resistance. I don't see a red inductor. connected to the 16 uf cap on the tweeter side is a vanilla colored box that says 3 ohm 10% 5W. Also on the crossover plate are two round cilinder shaped objects about the size of a watch battery, one is yellow one is brownish red. Aldo connected to the crossover plate and in line witht he bass speaker is a black coil looking device. I am attaching a picture.

I am happy to replace all of these items but where do I get them?

Leo

OK, well they were not very consistent in the production of these crossovers.

What I called the red inductor is the natural steel colored inductor to the right

of the 3 ohm resistor in the top right of your picture. It is wound with magnet

wire follow them and measure across it should read around 2 ohms, but not

close to zero. You can see that something black is oozing out of it.

I suggest that you get poly film caps, these Bennics are the only 16uFs that

I know of. They are a bit expensive; let me know if you want a less expensive solution:

http://www.madisound.com/catalog/product_i...products_id=133

If you find the extended position to be too bright you might want to replace C2

with an 8 uF instead.

Here's a .75 mH to replace the natural steel one (L3):

http://www.madisound.com/catalog/product_i...products_id=489

Here's a 3 ohm resistor for R1:

http://www.madisound.com/catalog/product_i...products_id=208

The other inductor is probably fine, but if you want to replace it here is a .2 mH:

http://www.madisound.com/catalog/product_i...products_id=478

These air core inductors are better than the originals. Hook up their leads and glue

them down as far away from each other as possible, to minimize coupling.

No need to replace the woofer inductor unless you want to go air core. Here's a

good air core if so but is really not required:

http://www.madisound.com/catalog/product_i...products_id=891

Let me know if you want a less expensive solution.

[Leo7504]

OK, well they were not very consistent in the production of these crossovers.

What I called the red inductor is the natural steel colored inductor to the right

of the 3 ohm resistor in the top right of your picture. It is wound with magnet

wire follow them and measure across it should read around 2 ohms, but not

close to zero. You can see that something black is oozing out of it.

I suggest that you get poly film caps, these Bennics are the only 16uFs that

I know of. They are a bit expensive; let me know if you want a less expensive solution:

http://www.madisound.com/catalog/product_i...products_id=133

If you find the extended position to be too bright you might want to replace C2

with an 8 uF instead.

Here's a .75 mH to replace the natural steel one (L3):

http://www.madisound.com/catalog/product_i...products_id=489

Here's a 3 ohm resistor for R1:

http://www.madisound.com/catalog/product_i...products_id=208

The other inductor is probably fine, but if you want to replace it here is a .2 mH:

http://www.madisound.com/catalog/product_i...products_id=478

These air core inductors are better than the originals. Hook up their leads and glue

them down as far away from each other as possible, to minimize coupling.

No need to replace the woofer inductor unless you want to go air core. Here's a

good air core if so but is really not required:

http://www.madisound.com/catalog/product_i...products_id=891

Let me know if you want a less expensive solution.

[JKent]

Hi

Interesting thread.

I hate to muddy the waters here, but I have a pair of OLAs that I have been meaning to get to. In this thread http://www.classicspeakerpages.net/IP.Boar...?showtopic=4919 Pete, you recommended some ways to improve the OLA but if keeping it "stock" you recommended going with the latest revision (Rev 2) of the xo. Wouldn't that be a good idea for Leo, since he has the earlier xo?

Kent

[Doug G.]

There seems to be very basic problem with this crossover and that is that C2 is missing! Somebody's been in there before.

C2 should be connected to that center terminal on the switch where it looks like something was soldered before and the other end to the yellow wire that goes to the tweeter (where the rust-colored inductor and 3 ohm resistor are already connected).

I'd be willing to bet that the 3 ohm resistor is open too because you have no sound in extended. Normally in this position, the resistor is bypassed by C2 but, since C2 is missing, the signal would go through R1 and produce sound. Since there is no sound, R1 must be open.

The big black cylindrical thing mounted on the back panel is the 1.6 uH inductor for the woofer, not a capacitor.

As Pete pointed out, the natural steel (now rusty) inductor is the one in parallel with the tweeter.

The yellow disc inductor is the one in series with the tweeter, C1, and R1 in Decreased mode.

Capacitors, when measured with a VOM or digital meter, will intially show a short and then the resistance will increase until a very high value. The larger the capacitance value, the longer it takes for the resistance to increase because the capacitor is charging during this period of time.

A 16uF capacitor will take a moderate amount of time to charge and so you should be able to see it happening on the meter. If it's a digital meter, you will initlially see the display show some numbers on it and then these numbers will increase until the display goes blank, indicating that the reading has gone above the range of that meter setting. This would indicate a probably good capaitor. If the numbers stay on the meter and it doesn't overrange, the cap. is shorted. If numbers never appear on the display, the cap. is open.

Of course, to get an accurate reading as to whether the cap. is really good or not, as far as value, requires a real capacitance meter but the ohmmeter method at least tells you if the cap. is shorted or open.

I should also say that open capacitors are relatively rare.

So, check all of the components and get a new C2 in there.

Doug

[Doug G.]

Hey Kent, nice of you to join in. Yes, I would recommend going with an 8 uF cap. for C2 also. The tweeter then doesn't have to work as hard producing the lower midrange and probably reduces distortion.

Doug

[Pete B]

Hi

Interesting thread.

I hate to muddy the waters here, but I have a pair of OLAs that I have been meaning to get to. In this thread http://www.classicspeakerpages.net/IP.Boar...?showtopic=4919 Pete, you recommended some ways to improve the OLA but if keeping it "stock" you recommended going with the latest revision (Rev 2) of the xo. Wouldn't that be a good idea for Leo, since he has the earlier xo?

Kent

I did mention the 8 uF as an option, OK I can explain more if he wants

exactly Rev. 2. but it seemed like he just wanted a repair.

Yes Rev. 2 would be my choice, but if he likes them as is, he can do Rev 1.