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Old 17th June 2013, 05:13 PM   #2081
WalterW is offline WalterW  Netherlands
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Quote:
Originally Posted by Rixsta View Post
Thanks, sorry If I sound a bit impatient at times im just eager, do appreciate the help!
yes if i connected +PGND and -PGND it would be good however what I find hard to get my head round is that my transformer only has 3 wires on secondary so i presume i cannot actually make that previous circuit and will have to use Single Graetz as only option
or
this circuit which with 2x24v would be too high voltage anyway, this is preferred to me by far but a shame as the output voltage would be too high
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Why would this give you 42Volts? The transformer used above is 2 x 25 Volt and gives an output of 35 volt ( without load ). So with load ( I calculate factor 1,305 always) and 2 x 24 Volt it will be around 31,5 Volt....
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Old 17th June 2013, 05:28 PM   #2082
6L6 is offline 6L6  United States
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The transformer used above is 25-0-25, not 0-25/0-25, and the bridges are rectifying across the entire 50 volts.
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Old 17th June 2013, 05:52 PM   #2083
WalterW is offline WalterW  Netherlands
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yes, but then voltage is divided by 2 by the two caps...
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Old 17th June 2013, 07:44 PM   #2084
Rixsta is offline Rixsta  United Kingdom
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Yes, it gave me the voltage I needed thanks 32v x 2 so I wired up this new point to point PSU with bridge rectifier and bang...

no the amp didn't blow up but I still had a ground loop! exiting! lol even when the right channel was almost total disconnected apart from the earth and RCA input.

So yeah same problem when both RCA are connected Hum, so here we go take 3 Time to mess with the grounding further! my insanity levels are being pushed perhaps that's a good thing ?

PS: its not as stressful if the project your making is for yourself! this ones for a friend and long overdue, £800 in parts, nice price that
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Old 18th June 2013, 01:46 AM   #2085
Rixsta is offline Rixsta  United Kingdom
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67 DEG heatsink
75 DEG washer on Mosfet
Bias 60mv or 0.06v across R1, target is 0.3v ! how the hell can i reach that lol

Any comments on this ? am i reading something wrong and have biased it way too high ?
That temperature is freaky at such low bias. by the time i make 0.3V across R1 this amp is going to be fried!

The heatsinks are massive!
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Old 18th June 2013, 02:18 AM   #2086
Rixsta is offline Rixsta  United Kingdom
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Because Ive rushed Ive not read things right, I wasn't even checking the right resistor all this time! pretty embarrassing. no wonder its hot anyway my bias is actually around 0.47v!

Heat issue explained!
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Last edited by Rixsta; 18th June 2013 at 02:22 AM.
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Old 18th June 2013, 06:11 AM   #2087
henryve is offline henryve  South Africa
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Poor trannies!
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Old 18th June 2013, 03:45 PM   #2088
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Quick question as were are talking PSU right now:

Is is worth going through the hassle and doing a "quasi"-dual mono ?

By "quasi" double mono I mean using one transformer with 4 secondaries and wiring 2 each per channel using 2 bridges per channel.

4 Bridges total.
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Old 18th June 2013, 03:48 PM   #2089
Variac is offline Variac  United States
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That's for 2 pieces I believe (a couple)

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That is some price for a single piece of bent plated steel.
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Old 18th June 2013, 04:05 PM   #2090
henryve is offline henryve  South Africa
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Quote:
Originally Posted by coolnose View Post
Quick question as were are talking PSU right now:

Is is worth going through the hassle and doing a "quasi"-dual mono ?

By "quasi" double mono I mean using one transformer with 4 secondaries and wiring 2 each per channel using 2 bridges per channel.

4 Bridges total.

You can, but that transformer will run hotter and not cost that much cheaper than 2 transformers with the same combined VA rating.
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