A lucky find - Page 2

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Re: A lucky find
On Thursday, 18 May 2017 14:15:09 UTC+1, snipped-for-privacy@tubes.com  wrote:
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99.99% of hifi phono carts are MM 47k. You can try the 100k setting without harm, but that may not be true of the MC setting, which expects far lower input.


NT

Re: A lucky find

Yes, you got a lucky find!

I've bought a very nice receiver (a Proton) where the seller said it
didn't work at all, and the reason was that he hadn't read the manual
and seen that the receiver needs a jumper between "preamp out" and
"amp in" if you aren't using an external signal processor.  The
original jumpers had been lost at some point and the owner didn't do
his research...

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Ummm... search the Internet for its part number?

Or, measure its DC resistance with an ohmmeter.  If it reads a few
ohms, it's certainly a moving-coil amplifier.  If it reads hundreds,
it's probably a moving-magnet (there are some higher-impedance moving
coil cartridges but they're less common).

The numbers you see above are not those of the cartridges... they're
the parallel resistance of the phono stage itself, in that setting.
The frequency response of any phono cartridge will depend to some
extent on the load resistance.  The cartridge maker may specify the
recommended load.

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Cartridges that you can do that with, are almost all moving-magnet (or
moving-iron) cartridges.  The MM setting, and 47k ohms input
impedance, would very probably be the one to choose - that's the
industry-standard resistance.

MC cartridges typically have a significantly lower output
voltage... plugging them into an MM input will result in very low
audio levels.  One needs a bunch of additional voltage gain (provided
by the preamp in MC mode, by an external "head amp", or by a signal
transformer) to use a low-output MC cartridge.

Re: A lucky find
On Thu, 18 May 2017 14:25:42 -0700, snipped-for-privacy@coop.radagast.org (Dave
Platt) wrote:

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Sounds like you got a good deal too. I am very familiar with those
jumpers. My Altec Lansing commercial power amp has those.  

The guy that gave me this preamp did a similar thing. He thought that
the RCA jacks marked "Output" were for speakers. That threw me off too,
because he had said that, but in a matter of minutes I realized this is
not a power amp. Looking it up online confirmed that.

About the only things that I recall using RCA plugs on speakers were
some of those really old portable record players from the 50s and 60s.
The speakers would unplug using a RCA jack/plug and the speakers lifted
off the record player, using special hinges with pins that stuck out, so
the speakers could be moved.  


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