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Old 1st November 2013, 05:21 PM   #2291
Mallard is offline Mallard  Germany
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What are the source resistor values?
Did you finish your biasing meanwhile? What is the result?


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Buzz, I am using the diodes and the source resistor that was in your premium GB.
Based on that which is in your experience the maximun mV that I can reach during the bias?
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Old 2nd November 2013, 01:39 AM   #2292
emyeuoi is offline emyeuoi  Italy
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As per original schematic: 2 resistor 1 ohm in parallel.
I complete the biasing at 360 mV. Right channel is stable while the offset of the left is not so stable. Rechecked after 1 week and the offset value move from 0,2 to 17 mV. Re-biased at 0,0 mV and I will re-check time to time.
The result? Astonishing... I was expecting a good result but, togheter with the DCB1, the whole setup is fantastic. The only flaw... trafos are slightly humming
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Old 2nd November 2013, 11:51 AM   #2293
Mallard is offline Mallard  Germany
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Ok, thanks Emyeuoi. What kind of trafos do you use?


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Originally Posted by emyeuoi View Post
As per original schematic: 2 resistor 1 ohm in parallel.
I complete the biasing at 360 mV. Right channel is stable while the offset of the left is not so stable. Rechecked after 1 week and the offset value move from 0,2 to 17 mV. Re-biased at 0,0 mV and I will re-check time to time.
The result? Astonishing... I was expecting a good result but, togheter with the DCB1, the whole setup is fantastic. The only flaw... trafos are slightly humming
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Old 2nd November 2013, 03:34 PM   #2294
emyeuoi is offline emyeuoi  Italy
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Two Primerose toroidal 600VA 24V to get 32 Vdc rial. 2 separate PSU each one with the softstart.
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Old 2nd November 2013, 04:48 PM   #2295
Mallard is offline Mallard  Germany
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And what kind of caps?

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Two Primerose toroidal 600VA 24V to get 32 Vdc rial. 2 separate PSU each one with the softstart.
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Old 3rd November 2013, 01:34 AM   #2296
emyeuoi is offline emyeuoi  Italy
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The caps are nr. 8 22.000 50V for each PSU. Those caps was part of the F5T Premium kit GB organized by buzzforb that also included the parts for the PSU (the caps, the bledder and filter resistors and the diodes). The PCBs are from TeaBag... Thanks TeaBag

.... and Thanks Buzzforb

Last edited by emyeuoi; 3rd November 2013 at 01:38 AM.
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Old 11th November 2013, 04:43 AM   #2297
henryve is offline henryve  South Africa
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Quote:
Originally Posted by emyeuoi View Post
Two Primerose toroidal 600VA 24V to get 32 Vdc rial. 2 separate PSU each one with the softstart.
Those transformers are not supposed to hum. Do you have DC blockers on the primary side of the transformers? The hum could be caused by DC on the main supply line.
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Old 11th November 2013, 04:52 AM   #2298
emyeuoi is offline emyeuoi  Italy
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Those trasformers are not supposed to hum but they hum. I [just] replace the transformers 2 weeks ago and the hum disappear... is a mechanical hum
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Old 11th November 2013, 05:02 AM   #2299
henryve is offline henryve  South Africa
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Quote:
Originally Posted by emyeuoi View Post
Those trasformers are not supposed to hum but they hum. I [just] replace the transformers 2 weeks ago and the hum disappear... is a mechanical hum
Oi! Not good. Did you specify that the windings must be dipped to dampen mechanical vibration? It should be standard with these big VA transformers I believe.
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Old 11th November 2013, 05:10 AM   #2300
emyeuoi is offline emyeuoi  Italy
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Sorry but I can specify only that they are humming, I have not the skill to identify why they are humming
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