Are MC Cartridges commonly damaged in shipping?

[pderousse]

Hi,

Are MC cartridges prone to damage in shipping such that ground loops in otherwise fine systems become common, or is it me? I recently bought my first MC cartridge, Rega Ania Pro, to replace an Exact II. I mounted the Ania Pro, changed the JC3+ back pannel setting to MC 50-500 ohms, readjusted the arm and I got ground hum. I retraced my steps, re-mounded & adjusted again, but the hum remained. I had made no other adjustments to an otherwise fine sounding system [no I did not also take the opportunity to add a microwave oven, router or a garage door motor to the circuit]. When I switched to DAC at the preamp, there was no ground loop, so I figured it must be up-stream and not because the preamp had become some kind of nexus of uneven grounds. The head shell leads looked tight and unfrayed; I readjusted the RCAs into the JC3+, the ground lead going from the preamp (which never seemed to make a difference) and the XLRs from the JC3+ to the preamp. Everything looked fine, but the hum remained. So, I removed the Ania Pro, reinserted the Exact II and the ground loop was gone.

I returned the MC to the retailer on the assumption that it must be defective and am now awaiting a replacement; however, doubts remain, because I have a rather complex system, and I know how tricky ground loops can be to isolate. Everything becomes suspect, even cables (I once traced a loop to defective wire in a Monoprice XLR cable). So I'm wondering did I overlook something or are MC cartridges just that fragile.

 

[restorer-john]

Did you check the phono stage with shorted inputs (no cartridge) on the MC setting before sending the cart back?

There's 20dB more gain on a typical MC stage when switched from the normal (~40dB) gain of MM.

 

[pderousse]

Thanks for your reply. I'm not sure I understand. How might I have done that? It is the same phono stage I've been using with no difficulty before with MM and it is 1 year old (no guarantee). Are you thinking the MC portion could be defective? The increased gain is a nagging concern.

 

[DVDdoug]

I'm not sure I understand. How might I have done that? It is the same phono stage I've been using with no difficulty before with MM

MC cartridges have lower output. When you switch the preamp to MC it has higher gain and any hum is amplified more. The MC cartridge has lower impedance and lower inductance so the cartridge itself should pick-up less hum but it will be amplified more, and if the hum is coming from the preamp or the turntable or a from a ground loop related to the turntable, it will be worse with the higher gain.

Analog has it's problems... Especially the weak millivolt signals from phono cartridges (although the record itself is usually the weakest link), tape heads, microphones, and guitars.

 

[restorer-john]

An MC is a very low output, your ania pro was 350uV. (0.35mV)

The Rega Exact II MM cartridge is rated at 6.8-7.2mV.

When you flick the MC switch, you are adding a heap of gain so the MC cartridge will 'play' at a similar level. All gain has a cost in noise, and MC front ends will often make any hum WAY worse.

 

[pderousse]

An MC is a very low output, your ania pro was 350uV. (0.35mV)

The Rega Exact II MM cartridge is rated at 6.8-7.2mV.

When you flick the MC switch, you are adding a heap of gain so the MC cartridge will 'play' at a similar level. All gain has a cost in noise, and MC front ends will often make any hum WAY worse.

I guess that was part of the question. Is a ground loop amplified from the lowest of levels or is it just there or not there. I’m obviously a layman, but it seemed to me that adding gain increased noise floor, but is it also boosting ground hum? It appeared to me that hum was either there or not.

 

[somebodyelse]

Another thing to check - do your tonearm cables run close to any mains cables, or near any transformers? That's another way to pick up hum, the extra gain of the MC input accounting for the change in level. Moving the cable further from the source of interference will often cure it.

 

[anmpr1]

I've had mixed results with MC and hum. I've only used voltage amplification, and not current (transformer) step ups. As the last of the big spenders, I've used three 'outboard' designs, both more or less based upon Marshall Leach's Audio magazine project (dual 9 volt battery voltage step up) and found that box placement has a big influence. You have to find a 'best' location, which might not be practical.

I own nothing modern, but over the years found that, for example, the Acoustat TNP preamp was prone to hum in its MC stage, while the tube based 6DJ6 Counterpoint MC stage was unlistenable due to noise. On the other hand, an early and inexpensive PS Audio (when both Paul and Stan were talking) step up worked well--I remember it having a pretty substantial outboard power supply, and you could adjust loading if you cared to.

Today I sometimes use a 25 year old Yamaha integrated amplifier in one of my systems, featuring MC capability that gives little to no hum with the Denon MC--the only MC I have on hand. Likewise, in my main system I've found that an inexpensive SS outboard Project Phonobox (with a MC switch) is not particularly hum prone.

Back in the day phono guru Mitch Cotter argued that the best way to deal with MC noise was to use a transformer that makes use of MC cartridge 'high energy' (in the form of current), but I have no first hand experience with those. Some in the field claimed they were just as prone to hum --in spite of their expense.

 

[pderousse]

Another thing to check - do your tonearm cables run close to any mains cables, or near any transformers? That's another way to pick up hum, the extra gain of the MC input accounting for the change in level. Moving the cable further from the source of interference will often cure it.

No, its a ‘safe’ straight route.

 

[pderousse]

I've had mixed results with MC and hum. I've only used voltage amplification, and not current (transformer) step ups. As the last of the big spenders, I've used three 'outboard' designs, both more or less based upon Marshall Leach's Audio magazine project (dual 9 volt battery voltage step up) and found that box placement has a big influence. You have to find a 'best' location, which might not be practical.

I own nothing modern, but over the years found that, for example, the Acoustat TNP preamp was prone to hum in its MC stage, while the tube based 6DJ6 Counterpoint MC stage was unlistenable due to noise. On the other hand, an early and inexpensive PS Audio (when both Paul and Stan were talking) step up worked well--I remember it having a pretty substantial outboard power supply, and you could adjust loading if you cared to.

Today I sometimes use a 25 year old Yamaha integrated amplifier in one of my systems, featuring MC capability that gives little to no hum with the Denon MC--the only MC I have on hand. Likewise, in my main system I've found that an inexpensive SS outboard Project Phonobox (with a MC switch) is not particularly hum prone.

Back in the day phono guru Mitch Cotter argued that the best way to deal with MC noise was to use a transformer that makes use of MC cartridge 'high energy' (in the form of current), but I have no first hand experience with those. Some in the field claimed they were just as prone to hum --in spite of their expense.

Thanks. Your post reminded me that I also tried bypassing the jc3+ and plugged into the MC of the McIntosh preamp. Same hum, which makes me suspect the cartridge.

 

[MaxwellsEq]

There may be a fault with the cartridge that is causing hum. See how you get on with the replacement.

As others have noted, the gain change needed for MC is massive compared to the gain needed for MM, so if you have an almost inaudible problem in your system it can be very very much louder when you switch to MC. MCs are really about as quiet a source as can be domestically accommodated and require a great deal of care over grounding, gain management, and cable cleanliness.

 

[pderousse]

Thanks, I understand that a MC signal needs to be amplified about 1000x, so naturally it is delicate; however, it is only the signal that is being amplified, right? If my preamp's phono stage produced the same noise with that cartridge as did my phonostage, and the old cartridge produces no noise in the system, I must look to the cartridge itself, not the amplifier(s). No other changes were made.

My experience (not necessairly the best guide) is that I either have the characteristic noise or I don't. Am I wrong to think that there is no such thing as a tiny ground loop that gets amplified? Or are previous posters, implying just that: that there could be a baby loop in the 0.35mV neighborhood getting amplified that I do not notice when I listen from the 6.8-7.2mV neighborhood?

Man, I loathe this problem ...

 

[MaxwellsEq]

If my preamp's phono stage produced the same noise with that cartridge as did my phonostage, and the old cartridge produces no noise in the system, I must look to the cartridge itself, not the amplifier(s). No other changes were made.

Certainly, if there is absolutely NO noise at all with MM, then there may be something faulty with the cartridge.

Some MM cartridges connect a ground pin to the body, but I don't know of any MC cartridges that do. This might be the case here which could make a difference.

 

[MaxwellsEq]

Am I wrong to think that there is no such thing as a tiny ground loop that gets amplified?

Grounding and ground loops are tricky, but if the current travelling through the loop is a constant, having a much higher gain can amplify the current more. So it's a mistake to assume ground loops are unaffected by gain.

 

[ban25]

Hi,

Are MC cartridges prone to damage in shipping such that ground loops in otherwise fine systems become common, or is it me? I recently bought my first MC cartridge, Rega Ania Pro, to replace an Exact II. I mounted the Ania Pro, changed the JC3+ back pannel setting to MC 50-500 ohms, readjusted the arm and I got ground hum. I retraced my steps, re-mounded & adjusted again, but the hum remained. I had made no other adjustments to an otherwise fine sounding system [no I did not also take the opportunity to add a microwave oven, router or a garage door motor to the circuit]. When I switched to DAC at the preamp, there was no ground loop, so I figured it must be up-stream and not because the preamp had become some kind of nexus of uneven grounds. The head shell leads looked tight and unfrayed; I readjusted the RCAs into the JC3+, the ground lead going from the preamp (which never seemed to make a difference) and the XLRs from the JC3+ to the preamp. Everything looked fine, but the hum remained. So, I removed the Ania Pro, reinserted the Exact II and the ground loop was gone.

I returned the MC to the retailer on the assumption that it must be defective and am now awaiting a replacement; however, doubts remain, because I have a rather complex system, and I know how tricky ground loops can be to isolate. Everything becomes suspect, even cables (I once traced a loop to defective wire in a Monoprice XLR cable). So I'm wondering did I overlook something or are MC cartridges just that fragile.

You say the ground lead from the turntable to the preamp makes no difference?

 

[DVDdoug]

It's probably not a ground loop. The coils in the cartridge aren't (normally) grounded until you connect the preamp. That's only one ground-point, so no loop. And a ground loop after the phono preamp wouldn't get worse with increased preamp gain.

The cartridge and wiring to the preamp can pick-up electromagnetic hum and some hum can get-into the preamp through its power supply.

You might think about going-back to MM. Moving coil isn't ALWAYS better and in your case it's worse.

P.S.
Back to the original question - It's highly-unlikely that any kind of shipping damage would make it more-prone to hum pick-up unless it was damaged to the point where it didn't function at all.

 

[sq225917]

If the canti isn't bent it's unlikely to be transit damage. More likely to be extra hum from the extra 20db of gain. Correct earthing will fix this.

I build bespoke phonostages, all discrete, dual mono, zero feedback design, all hand matched parts and very low noise. If requested I build them with a 3 way earth option. Tonearm earth to psu 0v, or to signal ground ( no chassis bond in phonostage) or to a fully floated chassis bond (which is actually back to psu 0v but via a back to back diode, cap, resistor, DDRC lift).

One of them is always silent at far beyond comfortable listening volume on the pre-amp. Have a play with earthing, if you can.

 

[pderousse]

You say the ground lead from the turntable to the preamp makes no difference?

The RP3 has no ground out from the TT. Ground is carried on the white. That is what some YouTubers state; however, the cartridge has red, blue, green and white connections…

 

[ban25]

The RP3 has no ground out from the TT. Ground is carried on the white. That is what some YouTubers state; however, the cartridge has red, blue, green and white connections…

Hmm...

Probably your best bet is just to go back to the MM cartridge that works well without ground hum. Your MM cartridge will be just as good as anything else you can buy and if you want to confirm, I would refer your to JP's excellent phono cartridge ABX test here on ASR:

Cartridge ABX

I tried a new cartridge today that struck me as being very similar to one I listened to a few weeks ago, so I did some comparisons, and indeed it did! I should've bought a lottery ticket instead. Here are four ABXs of the two cartridges, each with a different genre of music. I did a quick...

www.audiosciencereview.com

If you want to keep with MC, I would recommend finding the nearest wood chipper, tossing the Rega into it, and buying a quality direct-drive TT with a ground lug like a Technics.

 

[pderousse]

If the canti isn't bent it's unlikely to be transit damage. More likely to be extra hum from the extra 20db of gain. Correct earthing will fix this.

I build bespoke phonostages, all discrete, dual mono, zero feedback design, all hand matched parts and very low noise. If requested I build them with a 3 way earth option. Tonearm earth to psu 0v, or to signal ground ( no chassis bond in phonostage) or to a fully floated chassis bond (which is actually back to psu 0v but via a back to back diode, cap, resistor, DDRC lift).

One of them is always silent at far beyond comfortable listening volume on the pre-amp. Have a play with earthing, if you can.

Interesting, there are four leads to the cart and a four pin plug from the TT out to the external Neo PS, so the TT is grounded there presumably. When I get the replacement cart back, I have a couple more experiments I can try. I can’t believe that MC is somehow a flawed concept.