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Cartridge Loading.....Part II

I read last night the below noted discussion with great interest.  It's a long post but worth the effort and I found it interesting.

It started me thinking about the amount of loading on my moving coil cartridges.  Years ago I purchased my first MC Cart, a very nice Benz Micro Glider, medium output of 0.5 mV as I recall.  At that time I inquired about loading here on Audiogon.  I was convinced, via discussion, by another member, that 300 Ohms was the magic number, so I thought.

Time moved onward and my second MC Cart is currently a Lyra Delos, again medium output 0.6mV.  Both carts had Boron cantilevers', 6 nines oxygen free copper coils and line contact diamond stylis.  When I set up the Delos I did not change or even consider 'loading' changes.  That was a grand mistake.....

Well, thanks to this specific thread I started to second guess myself . (you can do this when retired and more time is on your hands....)

My take from this recent thread is as follows.  Load at 100 Ohms or at 47K Ohms with a quality MC cartridge.  I opened up my Conrad Johnson EF1 Phono Stage this afternoon.  Found it set at 500 Ohms loading.  100 Ohms is not an available setting.  Damn...All these years I've been running the wrong loading, and on two carts, back to back...  I don't recall why I set the loading at 500 Ohms.  Faulty logic.

I reset the loading to 47K, buttoned things up and called the wife in for a listening session.  Sure as heck both of us noticed the highs were crisper and more 'apparent' than in the recent past.  Not a huge difference, but yes, a difference..  Hard lesson learned!

So, you smarter folks on this site might banter amongst yourselves, but in reality there are those of us, behind the curtains, reading and listening!  I just wish I hadn't wasted all those years listening to the incorrect load setting!

Ending with a sincere thank you very much!!

Lou

 

quincy
lewm
12,429 posts
 

Too late to edit my post, but I meant to say, "It connects the cartridge to the emitters of an array of discrete transistors."  Not "It connects the cartridge output to an the emitters of array of discrete transistors."

Sounds like driving a triode via its cathode, but I won't dare go there.

atmasphere's avatar
atmasphere
11,566 posts
 

I haven't kept track of which current driven phono stages on the market use op amps or discrete transistors or tubes in the input I/V stage, although I don't know of any that use a tube or how you could use a tube in that fashion. 

@lewm Transimpedance preamps have to use opamps since that is the only way to get a virtual ground. You can use discreet opamps as those do exist (a friend of mine designed his own) but you do need an opamp to pull it off.

Take a 30Ω cartridge and hook it up to an ideal voltage amp and then another one and hook it up to an ideal current amp.  Now take two AC microamp clamps and monitor the current output of each cartridge.  Will the currents be the same for each cartridge?

@intactaudio I doubt it but that depends on the actual impedance that the cartridge is driving in either case.

dover
2,173 posts
 

Take a 30Ω cartridge and hook it up to an ideal voltage amp and then another one and hook it up to an ideal current amp.  Now take two AC microamp clamps and monitor the current output of each cartridge.  Will the currents be the same for each cartridge?

@intactaudio I doubt it but that depends on the actual impedance that the cartridge is driving in either case.

@atmasphere @intactaudio 

I think it depends on the individual design.

I know from first hand knowledge that the BMC & ESE Nibiru react differently with different cartridges, but on the other hand I have a bespoke current sensing device built by a cartridge manufacturer that is superb across all my cartridges ranging from 3-40ohms internal impedance.

Also I recall the current sensing Goldmund PH2 sounding superb across a variety of cartridges, regardless of internal impedance of the MC.

intactaudio
293 posts
 

@dover  This needs to be distilled to the most basic level to get a solid foundation that everyone can build upon equally.  It is not about any particular design and more about cartridge loading as a whole.  My belief is that the nature of current amplification vs. voltage amplification (namely how they load a cartridge with low vs high impedance) has a dramatic effect on the mechanical behavior of the cartridge and may be partially responsible for the differences heard between the two types.

I am not suggesting that all current amps are the same but if we can separate them conceptually from their voltage amp brethren then a discussion about how each loads a cartridge can ensue.  

 

dave

atmasphere's avatar
atmasphere
11,566 posts
 

My belief is that the nature of current amplification vs. voltage amplification (namely how they load a cartridge with low vs high impedance) has a dramatic effect on the mechanical behavior of the cartridge and may be partially responsible for the differences heard between the two types.

 It also has a lot to do with distortion and RIAA EQ differences. Separating those out might be a bit difficult.

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