• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Presenting the "Fartbottle" deluxe.

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G

G

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Joined 2002
#1
Hi all. I finally couldn't stand using a SS preamp with my tube amp anymore so I took out some parts I had been saving for a special project and made a few orders from Michael Percy and created the "Fartbottle" (that is what someone on this site called the 12au7) deluxe. It is basically an overbuilt Foreplay and I can say that all of the people that have praised the sound of the circuit are not wrong. It sounds very balanced and nuetral and natural. I thought I would share some pics. :

http://img.photobucket.com/albums/v224/GRaider/Image002.jpg

http://img.photobucket.com/albums/v224/GRaider/Image003.jpg

http://img.photobucket.com/albums/v224/GRaider/Image009.jpg

http://img.photobucket.com/albums/v224/GRaider/Image008.jpg

Cheers.

G
 
#10
bequerel said:
Gavin,
How did you do the grounding arrangement?
Do yo have one starground in each chassis and connect them to each other by an extra wire in the umbillical?

Very nice job by the way!
Click to expand...

Hi Bequerel.

I used two pieces of 3 conductor signal cable with a shield drain wire for the umbiblical. The black and the white of each piece was used for the negative conductor of the high voltage supply and the filtered DC filament supply respectively to give a very low resistance path back to the star ground point in the PSU chassis. The two Red wires were used for the B+ and the positive of the filament supply. The two drain wires were used as a chassis ground wire from the signal chassis to the star ground again providing a very low resistance path. I then grounded the PSU chassis and the signal chassis to earth at a star ground point. I floated the High voltage negative above earth using a 100 ohm resistor in parallel with a .22 uF cap between it and the star ground point. The preamp is as quiet as a church mouse. I also floated the filament supply about 50 volts above ground using a voltage divider. Thanks for the compliment.
 
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