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Old 21st February 2013, 02:29 PM   #12921
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funny Pa

confusing us , poor Greedy Boyz , all the time

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Old 21st February 2013, 02:33 PM   #12922
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One more question: What about these resistor values if I remove (as some have suggested) the current limiting section of the boards, but retain the thermistors?

I plan on using Speakon connectors both at the amp & my speakers to avoid shorting the outputs.
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Old 21st February 2013, 02:39 PM   #12923
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remove R19,R20,R21,R22 for dismantling current limiting , if you're sure in your well behaving

leave NTCs as is , they're here for cultivating biasing
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Old 21st February 2013, 02:42 PM   #12924
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In the F5 turbo manual, there's another F5 circuit with a couple new changes. The resistors on the input which are R1 & R2 on that schematic are 4.75K and 47.5K and they're configured differently. Also TH1 & TH2 don't go to the rails anymore. And P3 was added. Supposed to be subtle differences. Far as I know the latest circuit is the one in the F5 Turbo manual.

I would use the latest parts values and make the changes. But not absolutely neccessary.
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Old 21st February 2013, 02:52 PM   #12925
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The Turbo doesn't have the limiter. And trust me, I speak from experience, you can destroy one in 1/2 second without it.

Leave the limiter in the F5. It certainly doesn't hurt anything.
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Old 21st February 2013, 07:32 PM   #12926
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Hello fellas, today i bought 4 pcs. 20V 6A "toroid international" transformers from a surplus store, nearly for free. ($4 each)

Since a long time, i have been planning an F5 and i had nothing but a pair of big nice heatsinks in hand, that could be used for F5 with a little active cooling support. I thought that these trannies (480VA total) could be used for F5 too, and today i re-read the F5 datasheet and it looks like Pass recommends betveen 23-25 volts per rail.

The new transformers have 20V secondaries and it makes about 26,5-27,5 after the rectifier bridge with no load. I wonder would it be safe to use these trannies or should i use something at 25VDC (18VAC) sharp?

Last edited by fixxxxxer; 21st February 2013 at 07:39 PM.
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Old 21st February 2013, 07:57 PM   #12927
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You could build F5Cascode version, to better handel the additional voltage.
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Old 21st February 2013, 08:15 PM   #12928
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What PSU configuration are you using? If you're going with the standard Pass CRC, I'm guessing you might have enough losses to get closer to the 25VDC level between the rectifiers, caps, resistors, thermistors, and the drop that comes with load. You could also slightly increase the R in CRC if you're close but not quite there.
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Old 21st February 2013, 08:54 PM   #12929
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Quote:
Originally Posted by fixxxxxer View Post
20V 6A "toroid international" ($4 each)
From now on I'll call you XtraFixxxxxer.
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Old 21st February 2013, 10:04 PM   #12930
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Quote:
Originally Posted by fixxxxxer View Post
Hello fellas, today i bought 4 pcs. 20V 6A "toroid international" transformers from a surplus store, nearly for free. ($4 each)

Since a long time, i have been planning an F5 and i had nothing but a pair of big nice heatsinks in hand, that could be used for F5 with a little active cooling support. I thought that these trannies (480VA total) could be used for F5 too, and today i re-read the F5 datasheet and it looks like Pass recommends betveen 23-25 volts per rail.

The new transformers have 20V secondaries and it makes about 26,5-27,5 after the rectifier bridge with no load. I wonder would it be safe to use these trannies or should i use something at 25VDC (18VAC) sharp?
Based on my personal build
F5 standard with no mods can handle that easy I am using 24 V AC 1000VA trafo so they drop less than yours would
is all down to how big your big heath sinks are.
looking at your Signature keep in mind that is much colder here than where you hare and we use the F5 to help the central heating system
The J fet can handle up to 35 V dc I tried and chiken out at that

For peace of mind ad another RC stage
I did more for further riple reduction than else
Still cascoding can do no arm and is easy done

Last edited by Bksabath; 21st February 2013 at 10:08 PM.
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