Audio drop from needle.

[mylesera]

Hello all,

First post here. I have a Numark turntable with a Ortofon OMB Pro S stylus. After playing records for about 2 hours yesterday the sound on a record (Suffragette City - Bowie) suddenly dropped. Sound still coming from both speaker except the backup vocals were very faint. Sort of as if half the stereo had dropped out, although still signal from right and left speakers audible. I switched out the cartridge needle assembly from my other deck to determine is it was the mixer / amp. It played perfectly with the other needle, so it seems the original cartridge /needle is faulty. Any ideas as to repair or is this something that folks are aware of as an issue that needs replacement rather than repair. Hope this makes sense. Thanks!
Grant

 

[TLS Guy]

Hello all,

First post here. I have a Numark turntable with a Ortofon OMB Pro S stylus. After playing records for about 2 hours yesterday the sound on a record (Suffragette City - Bowie) suddenly dropped. Sound still coming from both speaker except the backup vocals were very faint. Sort of as if half the stereo had dropped out, although still signal from right and left speakers audible. I switched out the cartridge needle assembly from my other deck to determine is it was the mixer / amp. It played perfectly with the other needle, so it seems the original cartridge /needle is faulty. Any ideas as to repair or is this something that folks are aware of as an issue that needs replacement rather than repair. Hope this makes sense. Thanks!
Grant

You can't repair it, so you need a new one. That is a strange fault. I do not know anything about the Numark turntable line. I went on their website and they look like absolute junk. If the turntable is in any way ferrous then it will demagnetize the moving magnets and ruin the cartridge.

 

[Eppie]

Hello all,

First post here. I have a Numark turntable with a Ortofon OMB Pro S stylus. After playing records for about 2 hours yesterday the sound on a record (Suffragette City - Bowie) suddenly dropped. Sound still coming from both speaker except the backup vocals were very faint. Sort of as if half the stereo had dropped out, although still signal from right and left speakers audible. I switched out the cartridge needle assembly from my other deck to determine is it was the mixer / amp. It played perfectly with the other needle, so it seems the original cartridge /needle is faulty. Any ideas as to repair or is this something that folks are aware of as an issue that needs replacement rather than repair. Hope this makes sense. Thanks!
Grant

If it works fine with the other stylus (needle) then the cartridge is fine. Did you try putting the original stylus back on, just in case? This may sound silly, but what you describe sounds like a ball of dust got caught in the stylus. Inspect the original stylus for any dirt or dust using a strong magnifying glass or jeweler's loop. If you don't have a stylus cleaning brush, use a very soft fine artist paint brush so that you do not damage the cantilever (what the diamond tip is mounted to). Most styluses have moving magnets so the odds of the stylus being defective is small unless it got damaged in manufacturing or during installation.

 

[TLS Guy]

If it works fine with the other stylus (needle) then the cartridge is fine. Did you try putting the original stylus back on, just in case? This may sound silly, but what you describe sounds like a ball of dust got caught in the stylus. Inspect the original stylus for any dirt or dust using a strong magnifying glass or jeweler's loop. If you don't have a stylus cleaning brush, use a very soft fine artist paint brush so that you do not damage the cantilever (what the diamond tip is mounted to). Most styluses have moving magnets so the odds of the stylus being defective is small unless it got damaged in manufacturing or during installation.

If that turntable is ferrous then it could easily demagnetize the small magnets in the stylus assembly. I would have thought a dust collection on the stylus would be obvious.

 

[Eppie]

If that turntable is ferrous then it could easily demagnetize the small magnets in the stylus assembly. I would have thought a dust collection on the stylus would be obvious.

Well, you never know. Sometimes the obvious slips by people. I would be surprised if the base is anything besides plastic. Most of the images I found looked to have plastic bases although some of the DJ turntables might have a metal plinth.

 

[DaisyBerry]

im having a similar issue

 

[lovinthehd]

Sounds like you need a replacement stylus assembly....

 

[TLS Guy]

im having a similar issue

What exactly is your issue? What is your turntable and cartridge? What is your turntable connected to? When did the problem start, and over what period of time.

We had another post recently about a cartridge loosing output, that I'm pretty sure was due to the small magnets on the end of the stylus cantilever becoming demagnetized. If this is your problem, then I wonder why we have had three possible issues of this unusual problem recently.

It leads me to suspect may be there are junk Far Eastern turntables coming into market. A turntable platter must not contain ferrous metal, nor in any way be possible for it to become magnetized under any circumstances. If it can become magnetized it eventually will. So it will have a North and South pole. As that spins under the the cartridge then over time it will progressively demagnetize the small magnets and reduce their flux density, and the output from the cartridge will fall.

I am really curious about what is going on here. If you have a loss of output problem then that would be the third report of that unusual problem recently.

 

[lovinthehd]

What exactly is your issue? What is your turntable and cartridge? What is your turntable connected to? When did the problem start, and over what period of time.

We had another post recently about a cartridge loosing output, that I'm pretty sure was due to the small magnets on the end of the stylus cantilever becoming demagnetized. If this is your problem, then I wonder why we have had three possible issues of this unusual problem recently.

It leads me to suspect may be there are junk Far Eastern turntables coming into market. A turntable platter must not contain ferrous metal, nor in any way be possible for it to become magnetized under any circumstances. If it can become magnetized it eventually will. So it will have a North and South pole. As that spins under the the cartridge then over time it will progressively demagnetize the small magnets and reduce their flux density, and the output from the cartridge will fall.

I am really curious about what is going on here. If you have a loss of output problem then that would be the third report of that unusual problem recently.

Senile alert. This is the same thread where you proposed the demagnetized cartridge yet a stylus from another cartridge worked fine....pretty sure at least for OP his cartridge isn't demagnetized since he was able to use another stylus successfully. Not sure what @DaisyBerry had that was similar or not....

 

[TLS Guy]

Senile alert. This is the same thread where you proposed the demagnetized cartridge yet a stylus from another cartridge worked fine....pretty sure at least for OP his cartridge isn't demagnetized since he was able to use another stylus successfully. Not sure what @DaisyBerry had that was similar or not....

No, I remember that, but this demagnetizations happens over a long period of time. As the turntable spins the North and South poles each pass under the cartridge 33 times per minute having a miniscule effect with each revolution until the demagnetization reaches a critical point. The other variable is to what degree of intensity the platter becomes magnetized. There are a lot of variables on how long this process would take to become manifest.

There really is no other plausible explanation of why a cartridge would loose output over time, other than demagnetization.

 

[lovinthehd]

No, I remember that, but this demagnetizations happens over a long period of time. As the turntable spins the North and South poles each pass under the cartridge 33 times per minute having a miniscule effect with each revolution until the demagnetization reaches a critical point. The other variable is to what degree of intensity the platter becomes magnetized. There are a lot of variables on how long this process would take to become manifest.

There really is no other plausible explanation of why a cartridge would loose output over time, other than demagnetization.

Then how do you explain another stylus working fine in the same cartridge?

 

[TLS Guy]

Then how do you explain another stylus working fine in the same cartridge?

As I explained to you before, in a moving magnet cartridge the magnets MOVE, the coils are fixed. So the tiny magnets are part of the stylus assembly and NOT the body. So the tiny magnets are attached to the stylus cantilever. So they are replaced when you change the stylus.

In a moving coil cartridge the coils move and the magnet is fixed, so the coils are attached to the stylus. That is why the stylus in NOT user replaceable, as the lead outs from the coils are attached to the connection pins on the back of the cartridge.

Then there is the variable reluctance, sometimes called moving iron, like my Decca ffss heads. Here the magnet and coils are fixed, and the iron moves within the magnetic field, and the signal is derived from the coils which are wound round the magnet. Again the stylus is not user replaceable.

 

[lovinthehd]

As I explained to you before, in a moving magnet cartridge the magnets MOVE, the coils are fixed. So the tiny magnets are part of the stylus assembly and NOT the body. So the tiny magnets are attached to the stylus cantilever. So they are replaced when you change the stylus.

In a moving coil cartridge the coils move and the magnet is fixed, so the coils are attached to the stylus. That is why the stylus in NOT user replaceable, as the lead outs from the coils are attached to the connection pins on the back of the cartridge.

Then there is the variable reluctance, sometimes called moving iron, like my Decca ffss heads. Here the magnet and coils are fixed, and the iron moves within the magnetic field, and the signal is derived from the coils which are wound round the magnet. Again the stylus is not user replaceable.

I don't remember that particular explanation but still don't see why the cartridge needs replacement, altho perhaps over time the particular tt could be an issue. Why isn't a stylus replacement the better alternative here?

 

[TLS Guy]

I don't remember that particular explanation but still don't see why the cartridge needs replacement, altho perhaps over time the particular tt could be an issue. Why isn't a stylus replacement the better alternative here?

It is the stylus that needs replacement and NOT the body.

 

[lovinthehd]

It is the stylus that needs replacement and NOT the body.

Sorry got distracted by your usual euro centric crapping on asian products

Plus you said this "There really is no other plausible explanation of why a cartridge would loose output over time, other than demagnetization. "

I had to go pull out my stylus and never suspected the magnets were there nor was interested enough in cartridge construction since the time I basically retired my tt from normal use....thanks for the lesson.

 

[highfigh]

As I explained to you before, in a moving magnet cartridge the magnets MOVE, the coils are fixed. So the tiny magnets are part of the stylus assembly and NOT the body. So the tiny magnets are attached to the stylus cantilever. So they are replaced when you change the stylus.

In a moving coil cartridge the coils move and the magnet is fixed, so the coils are attached to the stylus. That is why the stylus in NOT user replaceable, as the lead outs from the coils are attached to the connection pins on the back of the cartridge.

Then there is the variable reluctance, sometimes called moving iron, like my Decca ffss heads. Here the magnet and coils are fixed, and the iron moves within the magnetic field, and the signal is derived from the coils which are wound round the magnet. Again the stylus is not user replaceable.

The original post contained "After playing records for about 2 hours yesterday the sound on a record (Suffragette City - Bowie) suddenly dropped. That was two hours, not a long time.

Some MC cartridges had user-replaceable styli- I have two (Audio Technica AT30E and AT-31E).

 

[TLS Guy]

The original post contained "After playing records for about 2 hours yesterday the sound on a record (Suffragette City - Bowie) suddenly dropped. That was two hours, not a long time.

Some MC cartridges had user-replaceable styli- I have two (Audio Technica AT30E and AT-31E).

In those cartridges the stylus replacement is pretty much the whole cartridge, which it has to be, if you think about it.

I just wonder what that guys platter was made of. We don't know how long it had been in use. However for the output to drop, like that the only possible explanations is demagnetization of the magnets at the end of the cantilever. The chance of both coils failing at the same time is statistically so remote you can forget it.

A cartridge has very few components, so there are few suspects in failure.

 

[highfigh]

In those cartridges the stylus replacement is pretty much the whole cartridge, which it has to be, if you think about it.

I just wonder what that guys platter was made of. We don't know how long it had been in use. However for the output to drop, like that the only possible explanations is demagnetization of the magnets at the end of the cantilever. The chance of both coils failing at the same time is statistically so remote you can forget it.

A cartridge has very few components, so there are few suspects in failure.

I probably installed and inspected close to 1000 cartridges and styli in the ten years I worked at the stereo store- one problem that caused this very problem was caused by the stylus' suspension material failing- the plastic wouldn't necessarily scrape the LP, but it wouldn't cause the magnets or coils to move as they should- they looked normal after removal from the body, but they didn't do what they were supposed to. Between early 1978 (when I started working at that store) and about two years after CDs became available, we were buying some cartridge models by the case and IIRC, those boxes contained 300 pieces- we carried at least five brands, but only sold AudioTechnica in huge numbers at that time. We could use the scope to check for distortion by playing various test records if some wanted, so it wasn't a, "I hope this is right" situation.

But again, he said he was using it for about two hours- I think it was going to fail, regardless of whether he had stopped after fifteen minutes or 59- two hours was its limit by that point.

The end of the cantilever could have been damaged in some way from being removed/reinstalled- it happens more than anyone would want to admit. If the problem was solved by using a different stylus, we can't possibly know what happened without inspecting it.

If he can find someone who has a microscope, the cause might be visible.