Setting up MU before phono cables?

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tbabb

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Setting up MU before phono cables?
« on: 24 Jul 2006, 02:39 am »
I was reading Authur Salvitore's recent audio notes and noted he suggested setting up the Bent MU right behind the turntable. I take this to mean running the wires coming from the tonarm or junction box directly into the MU.  I understand the concept but its hard to visualize how the wiring would work.  Anyone done this and have any photos  they can share.

Tim


>I would place the transformers behind the turntable, so the tiny signal is boosted immediately, before it enters the phono cable going to the preamplifier (or phono stage)

John Chapman

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Re: Setting up MU before phono cables?
« Reply #1 on: 29 Jul 2006, 05:41 pm »
Hello!

This is a good question. There are technical reasons why the standard MU keeps the cables AFTER the step-up short. Essentially despite the intuitive idea of stepping up the signal right after the cartridge it is better (again from a strictly techinical point of view) to keep the cable after the step-up short. This is because of the way any step-up translates the impedance driving the cable - essentially making that cable after the step-up 'look' much longer from the cartridges point of view.   The very low output impedance of a typical MC cartridge actually does a good job of driving the impedances of the cable before the step-up.

I have to quickly add though that phono front ends have a huge variety of variables so I would not be surprised if for some reason the alternate hook-up (longer cable  after the step-up) might for some reason work out better. The best answer is to keep both cables really short but this is not always (or even usually) possible........

For existing MU units an extension cable could be used to make the output cable long enough to reach the phono stage.  I think that is what Arthur was using when I last spoke to him. Then you just plunk the MU down at the table and use a really short cable from the arm to the input RCA on the MU step-up. For new MU units I can do custom output lead lengths (up to about 20" or so) and also I recently have added an option of RCA inputs and outputs so the users can use their own cables both on the input side and the output side. The RCA output option will be added to the web page soon.....


Thansk!

John