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I notice from the schematics that the EAR 834P does not load the moving coil inputs with a resistor. The inputs instead go directly into the moving coil transformers. Should I install a 100 ohm resistor to properly load the cartridge? I'm using the transformers on their own to step up the output of an Ortofon Rhomann MC cartridge into the phono stage of a Marantz 7 preamp. Ortofon recommend a loading resistor of 10-100 ohms.
Thanks in advance,
Steve
How do you manage that? Did you physically remove the transformers, or somehow rewired the unit so that you only use the transformers?The input Z of the MC stage of the 834P is around 470 Ohms, since the turns ratio is 10 and the input Z of the next stage is 47k. This is usually fine for most MCs (at least in the UK). If you are using the 834P in its entirely as a phono stage, you can change the 47k resistor to a 10k resistor to achieve a 100 ohm impedence.
If you rip out the transformers and install them into your Marantz, you would need to find out what the input Z of the MM stage of your Marantz is and make changes accordingly.
......right. Good one, Adrian.alan m. kafton
audio excellence az
Steve Hamilton wrote:I notice from the schematics that the EAR 834P does not load the moving coil inputs with a resistor. The inputs instead go directly into the moving coil transformers. Should I install a 100 ohm resistor to properly load the cartridge? I'm using the transformers on their own to step up the output of an Ortofon Rhomann MC cartridge into the phono stage of a Marantz 7 preamp. Ortofon recommend a loading resistor of 10-100 ohms.
The reason it's feeding straight into the transformers is because the cartridge load is determined by the load on the transformer's secondaries as this gets reflected back to the primaries. But you can't just slap a 100 ohm resistor across the secondaries. You need to know more about the transformers you're using.
Why not dump the 843P and just get the MC3 if you're going to be feeding a phono stage?
se
<> Perhaps I'm confused by your statement....the MC3 is a step-up transformer, and the 834P is the phono stage. And being designed by the same brilliant gent, Tim de P., they work exceedingly well together.
If you have specific questions regarding the cartridge loading, I strongly suggest you contact the EAR importer, Dan Meinwald, at 562-422-4747 or at "dmeinwald@loop.com" He's very knowledgeable and will be happy to help out. Don't experiment.
alan m. kafton
audio excellence az
alan m. kafton wrote:Perhaps I'm confused by your statement....the MC3 is a step-up transformer, and the 834P is the phono stage. And being designed by the same brilliant gent, Tim de P., they work exceedingly well together.
Yes, I'm aware of that. But the way I read the original post, he has an 834P but he's planning to use just the transformers in it to feed into the phono stage on his Marantz. To wit:
I'm using the transformers on their own to step up the output of an Ortofon Rhomann MC cartridge into the phono stage of a Marantz 7 preamp.
If he's insisting on using the phono stage in the Marantz over the 834P, then why not just dump the 834P and go with the MC3 to feed his Marantz phono stage?
se
That's correct, I'm using the MC transformers on their own. They were pulled from an EAR 834P which was being used for MM service. The phono stage of the Marantz 7 (12AX7 tubes) sounds quite good to my ears, but I'm into vintage stuff. I'm comparing the MC transformers with a tube MC stage I built from schematics found here:http://home.highway.ne.jp/teddy/e/tubes/pre1.htm
So far I prefer the tube MC stage over the MC transformers, but the transformer loading needs adjusting.
Thanks for the help - I'll keep y'all posted.
Steve
......I responded late last night, "to wit", and didn't read the post as carefully as you did. Perhaps, I had fewer "wits" than you. :--)alan m. kafton
audio excellence az
alan m. kafton wrote:......I responded late last night, "to wit", and didn't read the post as carefully as you did. Perhaps, I had fewer "wits" than you. :--)
Hehehe. Well if it's any consolation, I didn't pick up on it (that he was using just the transformers) until about the third read. :-)
se
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