How to distinguish its silver or copper version MU

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joelcwu

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How to distinguish its silver or copper version MU
« on: 21 Mar 2010, 12:36 am »
There's a MU for sell on Audiogon. Seller says it's the silver version.
How do we tell it's silver version without open it up.
Is there any marking or letter indicate it's silver.
thanks

Joel

John Chapman

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Re: How to distinguish its silver or copper version MU
« Reply #1 on: 22 Mar 2010, 04:35 pm »
Hello!

Most made here had a blue sticker on the bottom of each can with 'S' marked on it. Some were built as kits and would not be marked. It is possible with a meter to measure the resistance of the windings and tell that way - or as you mention to pop a lid and look at the leadout wires to tell the difference.

Feel free to put the seller in touch with me and I can sort out with him how to confirm.

Thansk!

John

kdl

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Re: How to distinguish its silver or copper version MU
« Reply #2 on: 22 Mar 2010, 05:01 pm »
Hi John,

Can you tell the reading on silver and copper?

Thanks,

Ken

John Chapman

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Re: How to distinguish its silver or copper version MU
« Reply #3 on: 22 Mar 2010, 06:58 pm »
Hello!

Remove the load resistor at the load posts

Measure ohms across the load posts.

Copper = 134 ohms

Silver = 182 ohms

Different meters will read a bit different so don't worry if your readings are a few ohms off these numbers. Also some meters do not want to read transformers at all - the inductance freaks them out. If you meter just blinks and can't get a steady reading then that would indicate the meter won't read it. Most are fine.

Thansk!

John

kdl

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Re: How to distinguish its silver or copper version MU
« Reply #4 on: 24 Mar 2010, 01:02 am »
Hi John,

Thanks. I assume the reading is when tx103 wired for 1:20? How about 1:10? much higher?

Ken

John Chapman

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Re: How to distinguish its silver or copper version MU
« Reply #5 on: 24 Mar 2010, 02:29 am »
Hello!

Good question! The primary impedance does indeed change when you switch gain levels but the reading at the load posts (as described above) is on the transformer secondary and so it is not affected by the gain wiring. That is why I used that reading.

Thansk!

John

gnnett

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Re: How to distinguish its silver or copper version MU
« Reply #6 on: 24 Mar 2010, 06:46 am »
So 174 ohm would be close enough for silver, or should I open them up to have a look? :?

John Chapman

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Re: How to distinguish its silver or copper version MU
« Reply #7 on: 24 Mar 2010, 02:06 pm »
Hello!

174 is plenty close for silver.

Thansk!

John

kdl

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Re: How to distinguish its silver or copper version MU
« Reply #8 on: 26 Mar 2010, 02:33 am »
Hi John,

Another question on possible difference between silver and copper which might have some impact on loads.

I know copper's 47Kohm imput load impedance is 475ohm on 1:10 and 120ohm on 1:20, how about silver? Same value or different?

Thanks,

Ken

John Chapman

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Re: How to distinguish its silver or copper version MU
« Reply #9 on: 26 Mar 2010, 04:38 am »
Hello!

The math of loads vs ratios is essentially the same but the tonal balance difference would lead me to expect that a different ideal load for copper and silver would be expected.

Thansk!

John

kdl

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Re: How to distinguish its silver or copper version MU
« Reply #10 on: 19 Apr 2010, 12:10 am »
Hi John,

Can you tell ball park how is the load shift between copper and silver on the tonal balance. For example, if I found 15Kohm load for 1:10 copper on Shelter 501 works pretty well balanced, switch to 1:10 silver, in order to maintain similar tonal balance, the load should be say 18Kohm or 13Kohm?

If the calculation is a bit off between copper and silver, can you tell what numbers to use for silver (load ohm at 1:10 and 1:20)

Thanks,

Ken

John Chapman

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Re: How to distinguish its silver or copper version MU
« Reply #11 on: 19 Apr 2010, 03:00 pm »
Hello!

I'd expect a lower load with silver to get things similar - but there is no calculation that will tell the story. For loading it is so dependent on cartridge and a number of other factors that you'll want to  swap loads and listen to get to the ideal loads. The MU was made to make it easy to swap load specifically so you could easily experiment and play.

Thansk!

John