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Old 29th September 2002, 04:13 PM   #21
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Default Re: MC LOAD

Quote:
Originally posted by fdegrove

Yes,this has been done before, as indeed it seemed the more logical thing to do.
Should I read into that statement that there was also a sonic
improvement??

Quote:

Granted it is not a very elegant solution,and it kind of makes you wonder why the manufacturer doesn't build the R's in the coils in the first place?
The answer is in the previous post I made.
I'm not quite sure exactly what in your previous post you are
referring to, but I think it is obvious. Many MC amps already
have a very low input impedance, and it may be too low if
resistors are already built into the cartridge.

Quote:

Good thinking Christer!
But not new obviously. Thanks anyway.
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Old 29th September 2002, 04:41 PM   #22
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Default MC LOAD

Guy,

Sorry to have you confused as well.
I never intended this as a sonic tweak of any kind.
The load we're talking about is:

R+C+L:
where R is the load of the resistance the cartridge is going to see and C is the cable's + cartridge's own capacitance.
In reverse the cartridge's load is what your first stage is going to see as well.
I leave L out here since it can be neglected.(In a way that it not going to affect sound too much.)

What I referred to is that when you hook up some simple measuring gear such as a voltmeter you'd be able to actually find the real load the cartridge and the first stage is going to see.

I realise that what seemed simple at first is now turned into somewhat more complicated matter....

See you,
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Old 29th September 2002, 04:41 PM   #23
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Guy,

You won't need a voltmeter, but it is a good start if you know the
input impedance of your phono amp, so you can calculate the
resulting impedance (well resistance) of adding a resistor in
parallel with it. Otherwise, just try out some different values.
Although probably not very good for the sound, it can be
practical to first attach some short cables with alligator clips
so you can easily try different resistors and listen. Then, when
you know what you want, solder it in place and check that it
doesn't differ too much from what you heard with the alligator
clips in place.

Maybe I should try and move my resistors to the turntable too
some day. I have the additional ones in the phono contacts at
the amp end now. Should probably make some new tests also
and see if I still think it sounds best with only 10 Ohms.
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Old 29th September 2002, 04:52 PM   #24
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Default MC LOAD

Guy,

Christer is a dead serious fellow.
Me, I'm a bit less serious but take my stuff serious and ain't laughin' either.
In case you haven't noticed we posted more or less the same content just fractions of a second apart.
No laughin' here!

Cheers and heat up that solderin' stick and tell us some,
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Old 29th September 2002, 08:33 PM   #25
dice45 is offline dice45  Germany
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Default resistor at cartridge pins

Quote:
Originally posted by fdegrove .... Just kidding.
Frank,
if you have so much fun arising these questions, could you please be so kind as to take a swing at answering them? And no backing out please!
As they are there written they contribute to nothing but confusion.

Christer,
presumed the cable has low R (as it is usual, say below, maybe way below 1 Ohm), i do not see much difference between placing the input resistor directly on the cartridge pins and putting it at the input of the phono preamp.

The MC cartridge has a very low source impedance, low L and low R. These are in series. The phono cable's R also is in series The input cap is consisting of the cable capacitance and the real input cap in ||. The cartridge is looking on this cap as if it would be soldered across its pins, and it is looking on the input resistor as is if it would be soldered across its pins.
It does not matter where the resistor is.

Now if we claim the phono lead has 10R, then in for the case the input resistor being close to cartridge pins, the coil feeds a time constant of cable capacitance and input resisitor in || which are feeding the 10R of the cable as resisitive load. Or feeding the time constant of 10R in series and possible input cap.
You have different filters, depending on where the resistor is located. You are comparing apples and oranges. Different behaviour of phase for the high frequencies.

I belong to those nuts soldering the phono lead to the cartridge pins (i use a special made cooling clip for that in order not to desolder the coil wires -- i cannot but warn anyone trying this without a snugly fitting cooling clip). Makes a nice sonic step forward. But i would not dare to combine this with placing the input resistor at the cartridge pins as i use a phono lead having 10R.
Heat insertion for the thin wire is low. Heat insertion for the resistor legs is another matter, is much higher, i do not dare to do that. And i do not want to insert an additional RC in parallel at this place, due to changed phase response.
I am a conservative person, methinks phono EQ has to happen inside the preamp.
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Bernhard
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Old 29th September 2002, 09:31 PM   #26
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Bernhard,

You are right of course that the cable resistance should normally
be very much lower than the value of the resistor we add, even
when using only 10 Ohms, as in my case. I guess I was tricking
myself into making the problem more complex than it is, by
bringing in the discussion on electromechanical interactions
earlier. Even if the purpose of the resistor is to damp the
mechanical system electrically, it won't matter where it is, of
course, as long as the cable resistance is much lower. Yes, I
agree, the answer seems to be as straightforward and simple
as you say.
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Old 30th September 2002, 03:05 AM   #27
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Default Put the resistor at the load end!

Do I have to 'splain transmission line theory? I would rather not have to.

Jocko
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Old 30th September 2002, 10:40 AM   #28
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Default Re: Put the resistor at the load end!

Quote:
Originally posted by Jocko Homo
Do I have to 'splain transmission line theory? I would rather not have to.

Jocko
I admit I know very little about transmission lines. One of the
things I should read up on some day. However, since I know
so little about them, I am afraid to ignore them, which is
why I asked the question on where to put the resistor.

So, Jocko, do you think it would make a difference where to
put the resistor, even at the frequencies we are dealing with
here?
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Old 30th September 2002, 01:34 PM   #29
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Christer:

Maybe not at 1 kHz, but a twisted pair CAN start to act like one as low as 100 kHz. The main reason I would put it there has mainly to do with the fact, that no matter what you do, there will be low frequency RF energy there. It is VERY hard to shield that low RF stuff, but easy to filter.

Yeah, yeah.......I know........guys use unshielded stuff all the time. And they claim their stuff sounds great.

Doing things the right way from the beginning is always a good place to start.

Jocko
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Old 30th September 2002, 03:06 PM   #30
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You want this.....
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File Type: gif mcload1.gif (1.4 KB, 280 views)
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