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Old 12th February 2012, 05:15 PM   #481
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Default Fuse

Quote:
Originally Posted by pacificblue View Post
Yes.


Depends on the speaker impedance and how much capacitance your power supply has. Something like 12 W into 8 Ohm.


You will not be able to control that.


If the transformer is rated for 3 A, you can use a 3 A slow-blow fuse on the secondary side. You don't gain any safety by using a smaller fuse.


Use a split supply. You save on the virtual ground circuit and the output capacitor.


If you regulate it down to 13 V, you will only get 7-8 W into 8 Ohm, instead of 12 W. The regulators will produce a lot of extra heat, extra consumption, and they will increase the cost, size and complexity of the project.


No, you would skip the center tap, so your transformer will have 1x24 V instead of 2x12 V and the regulated voltage could be 26 V, too.


Split supply is better, but the difference is not that big. You basically add a big capacitor to the signal path, and that can or cannot have an influence on the sonic signature.
Why do you suggest a T3A fuse as opposed to the one mentioned in post #478 Blue? What about the primary fuse? Would you reccomend one of them?

Cheers Cobber.
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Old 13th February 2012, 05:38 PM   #482
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If you have a transformer rated for 2,8 A, use a 2,8 A fuse, if you find one. If you have a transformer rated for 3 A, use a 3 A fuse. Using a smaller fuse than nominal does not hurt, but it does not help either. On the contrary, although it appears strange, transformer secondaries are usually fused with the next higher fuse, e.g. a 3 A transformer would get a 3,15 A fuse, not a 2,5 A.

Why is that so, when we usually always take the next smaller fuse? Because the power rating of a transformer is a guaranteed performance promise. If you use a smaller fuse, the transformer cannot deliver that power, because the fuse will prevent it from doing that. Accordingly transformers are designed to work on the next higher available fuse size.

It is quite common to find a recommendation for the primary fuse on the transformer itself. Sometimes you also find it in the datasheet.
If the transformer manufacturer does not recommend a primary fuse, you will have to determine it by trial-&-error.
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Old 5th June 2012, 05:43 PM   #483
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Hello there....
Im currently building dual mono lm1875 ( two transformers with two rectifier, transformer is dual secondaries ) and 1 stereo pre amp ( 1 transformer CT )
And im using two outputs ( 4pc binding post and headphone out through one rotary switch ) and im using 4 inputs ( 4 pair rca through 1 rotary switch ) and im using 1 chassis for all of that
can i use stargrounding at post #66 as well ??? Thank you

Last edited by Overdream; 5th June 2012 at 05:46 PM.
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Old 5th June 2012, 05:45 PM   #484
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Quick guide on Grounding
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Old 5th June 2012, 05:52 PM   #485
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Thank you for replying, but that thread seems dont answering my question...
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Old 9th July 2012, 07:07 AM   #486
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would you mind to give me an advice for the grounding
please click on my problem
HUge dc offset

thank you
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Old 9th July 2012, 12:37 PM   #487
marce is offline marce  United Kingdom
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Read up on Henry Ott
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Old 9th July 2012, 12:44 PM   #488
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Read up on Henry Ott
Sorry, what is henry ott ???
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Old 9th July 2012, 02:51 PM   #489
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Sorry, what is henry ott ???
Henry Ott Consultants
Electromagnetic Compatibility Consulting and Training

home page
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Old 9th July 2012, 04:00 PM   #490
marce is offline marce  United Kingdom
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He is probably the best authority regarding grounding and its related issues. Star grounding is an oversimplificationof acomplex problem, with just basic analogue audio its bad enough, add digital (DAC's etc) into the equation and it gets worse.
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