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Topic: New turntable, but I can hear some clipping... (Read 7794 times) previous topic - next topic
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New turntable, but I can hear some clipping...

I've just got my first ever turntable (a Pro-Ject Debut III), and I'm noticing some clipping distortion. I am using the supplied cartridge (an Ortofon OM 5E), and a NAD PP 2 preamplifier. I had a rummage through the papers, and I believe I have discovered the problem: The output voltage from the cartridge is 4mV, but the input sensitivity on the PP 2 is only 2.5mV.

I reckon the best course of action would be to replace the cartridge with one with a lower output voltage (I assume 2.5mV would be optimal). I have also considered trying to reduce the voltage with a potential divider made from resistors, but I'm not sure I dare.

Would replacing the cartridge be the thing to do? And if so, what cartridges would you recommend?
(Bear in mind this isn't a high end setup, so I wouldn't want to spend too much: Certainly not more than £50/$100)

Thanks in advance,
hinges.

New turntable, but I can hear some clipping...

Reply #1 –
That phono stage can handle that cartridge's output without any problem at all.  The listed input sensitivity of 2.5mV is what will produce the reference output signal of 200mV.  That's all that specification means; it's not indicative of a limit.  4mV is a very standard MM cartridge output.  Changing the cartridge will not help you at all.  I'd be more curious to hear about what you call "clipping."  Technically, if your system is clipping, the solution is to turn it down.  Clipping is an amp/speaker phenomenon, not a cartridge/phone stage one.

Now if you want a better cartridge sonically speaking, move to an Audio Technica 440MLa

New turntable, but I can hear some clipping...

Reply #2 –
I'm pretty sure it sounds like it's clipping, and I've tried it using 2 different amps. First time I heard it, my first instinct was to turn it down, but it doesn't seem to affect it.
On top of this, I've also used a variety of other sources inputting into the same amp I'm using now, and I've not noticed it on any of those (and they're producing similar or higher volumes at the same level of amplification).

Assuming it's not clipping, and it's not all in my head, any ideas of what else it could be that I'm hearing?

New turntable, but I can hear some clipping...

Reply #3 –
All phonograph records produce clicks and pops. Are you certain you recognize the difference?
All phonograph records are at least a little distorted relative to a CD produced from the same source. This does not include clipping distortion, although I've read that some recent LPs are being mastered with clipping, just like many CDs. Again, are you certain it is clipping and not some other problem you hear?

I don't know the general input level needed to induce clipping in most phono preamps, but I have one that claims to be able to output (for an appropriately high input) 40V peak to peak, without clipping. It would take a heck of a cartridge output to produce that when the nominal output is just a few millivolts.

New turntable, but I can hear some clipping...

Reply #4 –
Quote from: hinges on
I'm pretty sure it sounds like it's clipping, and I've tried it using 2 different amps. First time I heard it, my first instinct was to turn it down, but it doesn't seem to affect it.

Assuming it's not clipping, and it's not all in my head, any ideas of what else it could be that I'm hearing?

If what you're hearing is a sort of "roughness" on the loud bits, then it sounds very much like mistracking to me. A big problem here is that mistracking can cause permanent damage to the vinyl: the stylus loses contact with the groove wall and tends to "bounce around". As it does so, it can carve gouges into the groove wall. If you do have a mistracking problem, you need to stop playing your LPs until it's sorted out, otherwise you'll just end up damaging them.

The most likely causes of mistracking are one or more of the following:

1. Incorrect geometric alignment of the cartridge. Check it with this protractor: [attachment=2833:attachment]
2. Insufficient tracking force - you should set it at, or very near to, the recommended maximum, which for the OM5E is 2 grams.

3. Incorrect anti-skating. If the distortion is worse on the right channel, increase the anti-skating. If it's worse on the left channel, decrease the anti-skating.

How was this turntable set up? Who did it, and are you confident they knew what they were doing? You need to get the turntable looked at by someone who understands the process. If there is a specialist HiFi dealer nearby who still sells high end turntables, try asking them if they would take a look at it.

New turntable, but I can hear some clipping...

Reply #5 –
Did you set it up correctly?

If for instance the pressure of the cartidge touching the vinyl is too low, nasty distorsion will be the result.

Analog phono amp stages should have lots of headroom (over 20 dB) to not produce clipping
 

New turntable, but I can hear some clipping...

Reply #6 –
One other thing occurs to me.

If the LPs you're playing are old ones that have been played on other turntables, it is possible that your new turntable is fine and the distortion you're hearing is existing groove wall damage due to previous mistracking being faithfully played by the new turntable. A way to get a feel for this would be to buy some brand new vinyl LPs and see if you still get the distortion. If you don't (even on loud bits), then this could indicate that your existing LPs are already damaged. On the other hand, if you can play some of your existing LPs on another turntable that it known to be working well, and you don't hear the distortion, then this is a reasonably good indication that it's your turntable that has the problem.

If it is that your LPs are already damaged, then there's little that can be done. One thing you could try would be to get a different stylus profile, in the hope that it might trace the groove wall at a different height, and perhaps avoid the areas that have been previously damaged. The OM5E has an elliptical stylus, so perhaps you should try a spherical one, or (at much higher cost) a "super-elliptical" or "fine line" stylus. You'd need to change the cartridge, to do this, though.