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Old 25th April 2012, 03:09 PM   #1921
Salas is offline Salas  Greece
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Quote:
Originally Posted by KatieandDad View Post
My B1 is inaudibly quiet with a standard toroidal transformer.

With a Salas Shunt Reg, that gets rid of almost all residual noise.

Is it realy necessary to go the added expense for inaudible gain.
No it isn't, line stage especially with zero gain is easy to make inaudible for hum.
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Old 25th April 2012, 04:35 PM   #1922
palmito is offline palmito  United States
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The rcore I bought with two other units and the seller did combined shipping. The total cost for the unit ended up being about $53, an equivalent toroid with shipping would've run at least $25. I can always use transformers for other projects, so to me the "extra expense" was not that much, since I needed to buy a new transformer anyway. I don't think I've read anywhere in this thread that you should be spending extra money on a rcore, that was my personal choice, just like it was to change caps and resistors. I believe that's why it's diy, so you put into your equipment what you believe makes a difference, if it makes no difference then you are the wiser not to do that again!
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Old 25th April 2012, 04:47 PM   #1923
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While encapsulated toroid are not too noisy and sounds very good I always prefer R-Cores for even lower noise, radiated field, better regulation and fuller sound.

My Selectronic 120VA R-Cores in the My_Ref loose only one volt under load Vs the 225VA Noratel toroid which looses more than 2V.

And the difference could be clearly heard: the 120VA R-Core sounds louder, fuller, more refined and absolutely silent.
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Old 25th April 2012, 04:50 PM   #1924
AndrewT is offline AndrewT  Scotland
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Originally Posted by ClaveFremen View Post
..........My Selectronic 120VA R-Cores in the My_Ref loose only one volt under load Vs the 225VA Noratel toroid which looses more than 2V..........
What are you measuring, AC, DC, ripple?
How are you measuring?
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Old 25th April 2012, 04:53 PM   #1925
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Originally Posted by AndrewT View Post
What are you measuring, AC, DC, ripple?
How are you measuring?
Simple... you measure with a voltmeter (multimeter) AC voltage on secondaries not connected to load and after you connect them to load.

If I remember correctly this voltage variation is called transformer regulation.
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Old 25th April 2012, 05:02 PM   #1926
AndrewT is offline AndrewT  Scotland
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Not transformer regulation.

That is defined as the [{measured output voltage on no load divided by the measured voltage when the secondary/ies are loaded with resistors to draw rated current for each winding (*)} - 1] * 100, when fed with the rated supply voltage.

If you measure the unloaded AC voltage while while connected to the rectifier and smoothing, you will get a reading very close to the unloaded condition.

The loaded AC voltage as you described cannot be the rated output voltage, it is feeding a capacitor input filter.
In addition, to get a fair comparison for the test you suggest both transformers should start with specification for equal regulation. I would suggest that the VA should also be equal to make the test comparison more valid.

(*) where the secondary total VA, is more than the maximum rated VA the current in each secondary should be reduced as specified by the manufacturer so that total draw during test does not exceed the rated maximum output VA.

eg, two secondaries each rated at 5Aac and 50Vac with a transformer that is rated as 350VA is permitted. Each secondary alone can supply 250VA while the total VA draw at any moment does not exceed the maximum transformer VA. i.e. one winding can supply 2Aac the other 5Aac and still operate within specification.
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Last edited by AndrewT; 25th April 2012 at 05:09 PM.
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Old 25th April 2012, 05:47 PM   #1927
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Quote:
Originally Posted by AndrewT View Post
Not transformer regulation.

That is defined as the [{measured output voltage on no load divided by the measured voltage when the secondary/ies are loaded with resistors to draw rated current for each winding (*)} - 1] * 100, when fed with the rated supply voltage.

If you measure the unloaded AC voltage while while connected to the rectifier and smoothing, you will get a reading very close to the unloaded condition.
Thanks Andrew for the clarification.

Probably you're right on how to make a more fair comparison, nevertheless the fact an inferior VA rated R-Core seems to perform better than an higher rated Toroid is a possible hint of R-Core superiority.
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Old 25th April 2012, 06:03 PM   #1928
atupi is offline atupi  Romania
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It's ok to have around 0.03-0.05vDC on output ?
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Old 25th April 2012, 07:38 PM   #1929
vgeorge is online now vgeorge  Greece
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30 το 50mV? If so it's too much.
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Old 25th April 2012, 07:42 PM   #1930
atupi is offline atupi  Romania
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Today i soldered only the buffer for testing and tomorrow i will continue with the shunt regulators and i have made some tests with two 9v batteries.
What can be the reason of this high dc on the output, unmatched fets, uneven rails voltage ?
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