Suggestions: Tweeter has very low audio output, almost none

[Guddu]

Dear Forum Members,
I am looking for some pointers to rectify some issues with my MA Bronze bookshelf.
Tweet volume output has gone to about none, mid woofer works okay.
No physical damage.
I did open up and connected a small satellite speaker after crossover and same issue. If I connect it directly bypassing crossover then it works.
Don’t know which of the components are causing this, any pointers will be great help.
I have encircled the tweeter’s crossover here.

Thanks

 

[Guddu]

 

[JSmith]

Tweet volume output has gone to approximately 20%

First thing to check is the speaker connections on both speakers and amp, especially the dual binding post jumpers (assuming you are not bi-wiring). The jumpers may just need a clean. Are you using bare wire?

If that is all ok... closely inspect the cross-over connections and other components. I suppose the next step is to test the capacitors and if out of spec, you could replace the cross-over capacitors, if you're keen. It's also possible the low output tweeter may somehow have been damaged. If that is the case, then hopefully you can source a new replacement tweeter directly from Monitor Audio.


JSmith

 

[Rivet Head]

I can't fix your problem, but I can tell you that I was able to order a replacement tweeter directly from Monitor Audio for a very reasonable price when I had a similar issue. You didn't mention how old your speakers are.

 

[Guddu]

First thing to check is the speaker connections on both speakers and amp, especially the dual binding post jumpers (assuming you are not bi-wiring). The jumpers may just need a clean. Are you using bare wire?

If that is all ok... closely inspect the cross-over connections and other components. I suppose the next step is to test the capacitors and if out of spec, you could replace the cross-over capacitors, if you're keen. It's also possible the low output tweeter may somehow have been damaged. If that is the case, then hopefully you can source a new replacement tweeter directly from Monitor Audio.


JSmith

Thanks for quick response.
I am using banana plugs, jumpers and clean and properly placed.
I have connected tweeter with direct wires and it works fine. It doesn’t work when signal comes through crossever.

I am going to get multimeter tomorrow, just to see if I can test components.

 

[Guddu]

I can't fix your problem, but I can tell you that I was able to order a replacement tweeter directly from Monitor Audio for a very reasonable price when I had a similar issue. You didn't mention how old your speakers are.

Thanks for the response.
I bought these 3 months back, don’t know how old are these but no physical damages, looks beautiful and were sounding good when worked earlier.
I don’t think tweeter if bad, I tested it directly.
I believe something is wrong in crossover part.

 

[JSmith]

don’t know how old are these

Since they're 2nd hand, could be 20+ years as the bronze line came out in 2000.

I am going to get multimeter tomorrow, just to see if I can test components.

JSmith

 

[wwenze]

I once had this happen and the culprit was faulty capacitor. Hope your multimeter can read capacitance.

Add: That speaker was also a Monitor Audio. Hmm...

 

[solderdude]

A: Is it the same on both speakers ?
B: Bronze.. which exact model ?
C: Have you played around with the location ?
D: You could increase the treble a few dB by shorting the 3.9ohm resistor BUT the filter will be tuned differently when you do (XO point will shift)
E: Have you tried EQ ?

 

[mhardy6647]

The problem could be with the tweeter itself.
Do you have two of the loudspeakers? If so, the most straightforward way to troubleshoot would be to physically swap tweeters between the "good" loudspeaker and the "bad" loudspeaker and see if the low output follows the tweeter.
You can certainly take some measurements, @guddu, but if you want to measure components in the XO, you'll need to disconnect each one and measure it in isolation, or it will be very difficult to impossible to interpret the results. Also, bear in mind that the only "figure of merit", so to speak, you'll be able to easily measure for the tweeter is its DC resistance, which may not tell you too much.

Oh -- are you completely certain that the issue lies in the loudspeaker and not in the source or the amplifier?

EDIT: jumpers, eh? Why not replace them with a pair of other wires or cables (for test purposes)? Could be a broken, or even intermittent, connection someplace(?).

 

[DVDdoug]

I'm having trouble visualizing a schematic in my head... And I'm guessing the yellow wire goes to the woofer? (The inductor appears to be in series.)

Are there 4 terminals on the back for bi-amping./bi-wiring? If so, is one or both jumpers missing?

It's most-likely a bad connection but the solder connections I can see look OK. Capacitors, resistors, and inductors almost never fail, and when a resistor or inductor fails it's usually because it's literally burned-up and black. Is that a black inductor (coil) under the red capacitor and resistor? Hopefully, it's not black because it's burned... I really wouldn't expect that to happen... And I assume the other speaker looks the same, but they could both be burned with only one completely burned-out. Does it smell burned?

A shorted coil in the tweeter section could "short out" the tweeter with little or no effect on the woofer. (And that's not good for the amplifier.)

A shorted inductor is difficult to measure because they have low DC resistance and they normally measure "almost shorted".

Otherwise,, if it is a component the red non-polarized electrolytic capacitor is the most likely suspect. If your meter doesn't have a capacitance function you can't measure capacitance, but it should measure infinite resistance after it charges-up. Either way, need to take it out of the circuit (make sure at-least one end isn't connected to anything except your meter). I'm assuming you have a soldering iron?

Or, if you remove that capacitor you can put it series with the tweeter (with nothing else) and if it's OK, it should work as a high-pass filter and the high-frequencies should be at-least as loud as with the full-crossover. If you get nothing (and the tweeter is working when directly connected, the capacitor is bad.

I assume that yellow component is a capacitor but I don't know what the markings mean and I can't tell exactly how it's wired... I'm kinda'-thinking it's in the woofer circuit.

I don’t think tweeter if bad, I tested it directly.

Hopefully, at low-power. I trust you but, sometimes you might have a bad-intermittent connection, like a small break in the voice coil or a break in the wiring to the voice coil. Then sometimes when you apply enough voltage, the voltage might "break-through" and it starts working (temporarily).

 

[Guddu]

A: Is it the same on both speakers ?
B: Bronze.. which exact model ?
C: Have you played around with the location ?
D: You could increase the treble a few dB by shorting the 3.9ohm resistor BUT the filter will be tuned differently when you do (XO point will shift)
E: Have you tried EQ ?

No, only one speaker has issue.
I swapped the tweeter to verify, and issue moved to the other speaker. So don’t think it’s tweeter.
I will invest some time over weekend to test components.
Thank you

 

[Guddu]

The problem could be with the tweeter itself.
Do you have two of the loudspeakers? If so, the most straightforward way to troubleshoot would be to physically swap tweeters between the "good" loudspeaker and the "bad" loudspeaker and see if the low output follows the tweeter.
You can certainly take some measurements, @guddu, but if you want to measure components in the XO, you'll need to disconnect each one and measure it in isolation, or it will be very difficult to impossible to interpret the results. Also, bear in mind that the only "figure of merit", so to speak, you'll be able to easily measure for the tweeter is its DC resistance, which may not tell you too much.

Oh -- are you completely certain that the issue lies in the loudspeaker and not in the source or the amplifier?

EDIT: jumpers, eh? Why not replace them with a pair of other wires or cables (for test purposes)? Could be a broken, or even intermittent, connection someplace(?).

I swapped the tweeter to verify, and issue moved to the other speaker. So don’t think it’s tweeter.
Checked source, DAC and amp already.
Jumpers are intact, but tried replacing as well.
Probably test further over the weekend.
Thank you for suggestions

 

[Chrispy]

Seems isolated to the xover....does MA offer a replacement crossover? Might be easiest way to go....

 

[Guddu]

I'm having trouble visualizing a schematic in my head... And I'm guessing the yellow wire goes to the woofer? (The inductor appears to be in series.)

Are there 4 terminals on the back for bi-amping./bi-wiring? If so, is one or both jumpers missing?

It's most-likely a bad connection but the solder connections I can see look OK. Capacitors, resistors, and inductors almost never fail, and when a resistor or inductor fails it's usually because it's literally burned-up and black. Is that a black inductor (coil) under the red capacitor and resistor? Hopefully, it's not black because it's burned... I really wouldn't expect that to happen... And I assume the other speaker looks the same, but they could both be burned with only one completely burned-out. Does it smell burned?

A shorted coil in the tweeter section could "short out" the tweeter with little or no effect on the woofer. (And that's not good for the amplifier.)

A shorted inductor is difficult to measure because they have low DC resistance and they normally measure "almost shorted".

Otherwise,, if it is a component the red non-polarized electrolytic capacitor is the most likely suspect. If your meter doesn't have a capacitance function you can't measure capacitance, but it should measure infinite resistance after it charges-up. Either way, need to take it out of the circuit (make sure at-least one end isn't connected to anything except your meter). I'm assuming you have a soldering iron?

Or, if you remove that capacitor you can put it series with the tweeter (with nothing else) and if it's OK, it should work as a high-pass filter and the high-frequencies should be at-least as loud as with the full-crossover. If you get nothing (and the tweeter is working when directly connected, the capacitor is bad.

I assume that yellow component is a capacitor but I don't know what the markings mean and I can't tell exactly how it's wired... I'm kinda'-thinking it's in the woofer circuit.


Hopefully, at low-power. I trust you but, sometimes you might have a bad-intermittent connection, like a small break in the voice coil or a break in the wiring to the voice coil. Then sometimes when you apply enough voltage, the voltage might "break-through" and it starts working (temporarily).

I swapped the tweeter to verify, and issue moved to the other speaker. So don’t think it’s tweeter.
Will try testing over the weekend.
Thank you for suggestions

 

[Guddu]

Seems isolated to the xover....does MA offer a replacement crossover? Might be easiest way to go....

These are probably 20+ yrs old, don’t think I could get the same parts but surely going to try.

 

[Zek]

I swapped the tweeter to verify, and issue moved to the other speaker. So don’t think it’s tweeter.

Does that mean when you replaced the tweeters the problem shifted to the other speaker box?
Then that tweeter is broken.

 

[mhardy6647]

J

I swapped the tweeter to verify, and issue moved to the other speaker. So don’t think it’s tweeter.

Am I misundersanding this, or did you make a mistake in your text?
As written, this makes it look like the problem is the tweeter.

 

[solderdude]

Most likely either the resistor or capacitor.
Perhaps swap these around ?
Those resistors can have a nasty habit of increasing the value.
Capacitors can have the nasty habit of lowering capacitance or increasing ESR. The XO frequency may move upwards when the capacitance gets lower.
By swapping the capacitor and resistor individually you could probably find out what part is faulty without measurements.

On the other hand it would be safe to simply replace the 4.7uF cap for a film type (will be much bigger) and simply replace the 3.9ohm resistors in both speakers anyway.

At least, when swapping the tweeter did not change the treble level in the faulty speaker.

 

[Guddu]

Does that mean when you replaced the tweeters the problem shifted to the other speaker box?
Then that tweeter is broken.

Ahh, my mistake. I meant to say it made no change to that speaker and tweeter works fine on other speaker.