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 NEW  Matt presents bias and operation data for the 6V6 tube in SE operation - 6V6 Single-Ended (SE) Ultra Linear (UL) Bias Optimization.

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PostPosted: 27 Jul 2017, 15:47 
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Is this a good starting point to build the C3g Headphone amp(The PS in the schematic will not be use)?I will be using the same PS that Matt designed for the 12AU7/6SN7 Headphone amp,I'am thinking of adding another 159R Choke and a Capacitor in the PS will this be Ok?The reason i want to use Matt PS design incase the C3g will not be as good as the 6SN7 i can reuse the PS to build the 12AU7 version which i plan on building for work.

Thanks!
Alex


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PostPosted: 28 Jul 2017, 03:43 
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OH NOOOOO!!!!!!
I got a bunch of those too ....

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PostPosted: 28 Jul 2017, 15:03 
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I don't have that many(4 tubes)got these many years ago i completely forgot about them.


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PostPosted: 06 Aug 2017, 12:28 
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Suncalc wrote:
Alex;

Here is the PS schematic using the 5U4 rectifier and the transformer we discussed.
Attachment:
Schematic_PS_5U4GB.jpg

Ignore where it says 12A*7 by the 6.3v filament. You can go ahead and use the 6SN7. The same filters apply to both. The voltage numbers are based on the published Hammond DCR and Vo specs for the transformer.

If when you build it, the final B+ voltages are abve about 310V (with everything drawing appropriate current), then insert a series resistance in front of the main filter choke to tame the voltage. At 85mA you'll drop about 21v per 250Ω. This would be about a 1.8W. I would recommend that you order a 250Ω 5W wire-wound resistor just in case (5W due to derating). They're cheap and good to have around.

Let me know if you have any questions.


Hi MATT,
I'am building another one of this Power Supply you provided and i'am having a really high B+ (385VDC) i followed exactly what is in the schematic and even compared it to the one that i finished i just can't tell where did i made a mistake,I measured the Transformer's secondary output and they are all up to spec,Changed the 5U4 and still the same voltage read out.Thanks!

Alex


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PostPosted: 06 Aug 2017, 15:07 
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Alex Q wrote:
I'am building another one of this Power Supply you provided and i'am having a really high B+ (385VDC) i
What is the current draw at this voltage? That's close to a zero current number from a 275v secondary (275v * 1.414 = 388v). Remember that this PS design assumes about 85mA of load current.

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PostPosted: 07 Aug 2017, 11:56 
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Suncalc wrote:
Alex Q wrote:
I'am building another one of this Power Supply you provided and i'am having a really high B+ (385VDC) i
What is the current draw at this voltage? That's close to a zero current number from a 275v secondary (275v * 1.414 = 388v). Remember that this PS design assumes about 85mA of load current.


Sorry for the late reply!I tested it just the power supply circuit without the rest of the circuit(no load),I guess it's OK then,THANKS!

Alex


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PostPosted: 21 Aug 2017, 21:08 
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I made a temporary C3g to 6SN7 adapter just to listen how these C3g will sound like,Will it sound darn good the Bass is not as punchy like the 12AU7/6SN7 but the Mids and treble is really smooth specially the treble to my ears it sound more extended and smooth the sound of this tube is actually relaxing.


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PostPosted: 21 Aug 2017, 21:35 
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Alex Q wrote:
I made a temporary C3g to 6SN7 adapter just to listen how these C3g will sound like,Will it sound darn good the Bass is not as punchy like the 12AU7/6SN7 but the Mids and treble is really smooth specially the treble to my ears it sound more extended and smooth the sound of this tube is actually relaxing.


Great.

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PostPosted: 03 Sep 2017, 19:53 
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I would like to redo the 6AS7G/6SN7 Amp that i built from "Matt's circuit design" i would like to know if i can use this BELDEN 8423 GM shielded 20awg 3 conductors cable to rewire the entire amp hopefully this time i can cleanup my rat's nest wiring style.THANKS!

Alex


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PostPosted: 03 Sep 2017, 20:25 
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Alex Q wrote:
... hopefully this time i can cleanup my rat's nest wiring style.
Whereas I am always supportive of people cleaning up their wiring a little bit (but be careful not to take it too far) I am less sanguine about the widespread use of shielded wire. In exterior cabling where ground connections are set, it is very beneficial, but inside an amp it is very easy to set up noise inducing ground loops. I generally prefer simple wiring, well dressed within the chassis and maybe simple twisted pair for input signal runs.

Just my opinions on the matter.

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