Vinyl Asylum

Ah, so MC cartridge output is measured (for specs) open? Didn't know that, Thanks.

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bjh

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In Reply to: No, because... posted by anumber1 on October 3, 2006 at 17:12:14:

That implies that the typical "how much gain do I need?" question really ought to consider loading; at least for LOMC ... I assume for a MM the 47k load dwarft cartridges's impedance.
So for a 103 with 100 ohm loading (assume an active phono stage) the load "sees" about 70% of the voltage (I'm assuming the coil impedance of 40 ohm)?
Is that about right?
No Guru, No Method, No Teacher

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Try this article... - anumber1 19:28:18 10/03/06 (2)
The Vinyl Engine has a comprehensove article discussing cartridge loading and it's affect on gain.
It's a fry read but very informative..
--
Al G
Born To Tinker!
- Step ups at the Vinyl Engine (Open in New Window)
- Thanks. nt - bjh 22:22:39 10/03/06 (0)
  .
  No Guru, No Method, No Teacher
- Plus a bit more... - anumber1 19:48:53 10/03/06 (0)
  ...When you load a MC cartridge at or near to it's internal impedance it's output drops, I don't have the formula handy but it has been discussed on this forum recently (try a search perhaps).
  
  --
  Al G
  Born To Tinker!
DL-103R - JRags 17:55:46 10/03/06 (1)
My cartridge is a DL-103R. I see I mistakenly typed 103 in the text.
The DL-103R has an internal impedence of 14 not the 40 stated for the DL-103.
Also, the specifications that came with the cartridge note its voltage at 0.30 mv. (I am referring to a printout that came in the box specific to the serial number.) However, the setup brochure states the voltage at 0.25 mv.
Per Garth you want to load relative to the internal impedence with a passive device, like a SUT. So, using a 30k resistor I can present a load to the cartridge of 14-15. With an active device, you may want to start at 100 ohm. (See the Vinyl Engine rule of thumb, which I think would suggest 100 to 240.)

JRags
"Always Searching for Perfection"
- Re: the output voltage on the printout - Paul Tobin 07:49:39 10/04/06 (0)
  If your printout is similar to mine, then you may notice that the specified load is 47Kohms (my measurement indicated .28mV) - basically no voltage lost due to internal cartridge resistance. If you then crunch the numbers for a more typical 100ohm load (assuming the 14ohm internal resistance) the output will be reduced to about .25mV.
  
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