DIY Sony VFET pt 2 (N-Channel Build)

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#441
Mark Johnson said:
Just wait till you open the Detailed Parts List for the VFET front end card named Marauder. It provides error prone builders MANY more opportunities to order the wrong part, accidentally skip a line-item, mistype one character in a stock number, confuse nanofarads with microfarads, etc. A wonderful training exercise to (painfully) discover What Can Go Wrong.
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Haha! Love it!
 
#442
Rewind said:
..heat dissipation.
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This resistors are made and tested for work in harsh industrial conditions.

We see notes (2) and in Vishay Dale CMF50 data sheet with 70°C max ambient operating temperature
they power rating dissipation is 1/4 W = 0.25W
but with hot 125°C air they can handle only half = 1/8 W

Good news Vfet amplifier air temperature inside is much less 70°C max.

🙂 Kind regards
 

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#444
rgolan said:
I'm not sure if there is a real grounding issue or not. I had been trying to test with just a tablet as source, no preamp. After connecting a real preamp, the hum is completely gone.

I'm going to tie down the wiring, close it up and try in my primary system.

Thanks for the help, Zen Mod, astouffer and TungstenAudio.
Click to expand...

For what it’s worth I did not connect the dc connector to the case.
 
#445
Mark Johnson said:
Just wait till you open the Detailed Parts List for the VFET front end card named Marauder. It provides error prone builders MANY more opportunities to order the wrong part, accidentally skip a line-item, mistype one character in a stock number, confuse nanofarads with microfarads, etc. A wonderful training exercise to (painfully) discover What Can Go Wrong.
Click to expand...


😀 :rofl:
When, oh when, is it here?
 
#449
From article: "The Jfets are selected Toshiba 2SJ108 and 2SK370, the same chips as 2SJ74 and 2SK170 but in a smaller package, which provides for an input impedance to the amplifier of 330 Kohm and low distortion."

As in identical? Could Toshiba 2SJ74 + 2SK170 theoretically sound better?
 
#456
VFET 141 is up the running, it was a somewhat difficult build for me, primarily due a change of solder brands and gauge and tip size.
I blew C7 on the filter board, couldn’t fine the part number on the parts list, so replaced it with UES1H100MPM1TD. A Nichicon 10uf 50v 20% I had on hand. After an hour or two of use the left trim pot gave up as well, replaced that and everything has been fine. Left the top off for a few days so I could monitor the voltages and heat. Fingers crossed, the left channel was getting 36 volts for a bit…?
Very pleased with the sound which seems to be improving daily. Collecting parts for a T/A style dual mono power supply.
Thank you very much Nelson Pass, Jason and crew and all the forum members I’ve learned so much from.
 
#457
Thanks to Papa and the Diyaudio team for creating and organizing this project!

I'm enjoying listening to #185.

It was very easy to complete with all the parts, documentation and organization. I'm sure that took a lot of time and effort to achieve.
 

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#458
I have been listening to #138 for a few days and am thoroughly impressed. My speakers are quite inefficient, 83dB/W KEF Calindas and even with those at normal listening levels, the sound is mesmerizing. I can't wait to hear it with some more modern speakers. I'm currently using a B1-K preamp.

But that LED is blindingly bright. 🙂

Thank you, Nelson Pass, Mark Johnson, 6L6, Jason and Elena.
 
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