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  3. 176314-2065

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
13,813 posts
 

To satisfy my curiosity and because life is short, I purchased a BMC MCCI Signature ULN. This unit has gain settings of 0, +7, +11, and +14db. My question to anyone is what is the meaning of these db values? At the 0db setting, the unit produces quite a bit of phono voltage gain at its output; I would guesstimate about 60db. Plus, db are units expressing the ratios of voltages, having nothing to do with current. Anyone?

Here’s what I think it might mean. The unit may have a certain baseline voltage gain at its output, but that is dependent upon its interaction with the current fed into it by the cartridge, which will vary depending upon the BMC’s own input impedance (I assume it's greater than zero) and the cartridge’s output voltage and internal impedance. Because of this interdependency with the cartridge, the voltage gain at the output cannot be specified by the manufacturer. (It will be different for every cartridge, and I have already verified that.) So the "0db" must be referenced to whatever is the signal voltage output based on its input current. The higher gain settings must invoke downstream gain stages that add to signal voltage output by the indicated db’s. Is that correct?

drbond
454 posts
 

@lewm 

Congrats on the new phono stage, but I would think the Steelhead might still be a step up from the BMC MCCI, but maybe I'm wrong. . .what's your impression between the two? 

lewm
13,813 posts
 

I have two complete systems in two different listening areas in my house. The Steelhead runs a system in my basement based on Beveridge 2SW speakers driven by Beveridge direct-drive amplifiers. The Beveridge outboard woofer system is long gone; I use a pair of Transmission Line cabinets employing KEF B139 woofers for frequencies below 80Hz. That system is single-ended all the way, as is the Steelhead. My upstairs system consists of Sound Lab 845PX speakers with modified crossovers driven by Atma-sphere amplifiers. The preamp is either an Atma MP1 or the 3160 Phonolinepreamp that was conceived and designed by Raul and his engineer friend. The entire system is all balanced from cartridge to speakers. The BMC was made for balanced operation, so I felt constrained to test it in the balanced system. To do that, I had to remove my CDP from its shelf and replace it with the BMC. The BMC goes into a balanced line level input on the 3160, right now. I can already tell the BMC is good, but what would make you think necessarily that the Steelhead would be better? Right now, I cannot make a direct comparison, at any rate.

dover
2,360 posts
 

@lewm 

how does the BMC compare to the 3160 phono stage ?

lewm
13,813 posts
 

Don’t have a formed opinion yet.

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