A new upgrade for the Bottlehead Seduction Phono Pre-amp

In the interest of a little tweak for the Bottlehead Seduction Phono Pre-amp, a pair of Hammond 155J chokes were added to the power supply in place of the two 1K resistors. On paper, they are 1026 ohms +/- 15%. In practice, they measured about 900 ohms each, which should be close enough for this purpose. Chokes allows better filtering in the power supply (less hum in the output of the amp and less voltage drop) which should translate to better sound. There's a nice quick lesson on the purpose of chokes here. Since the stock Bottlehead design lifts the transformer with a pair of standoffs for noise reduction, I decided to use a pair of standoffs for the chokes to physically move them away from the tubes. As typical with Bottlehead kits, once you start dropping in some fancy parts, the real estate tends to go pretty quickly. The most accommodating place to mount them in my case was right next to the C4S constant current upgrade board.

Pair of Hammond 155J Chokes next to the C4S

 The upgrade required about a half hour of time to mount the chokes and solder them in place, along with about $30 plus shipping for the chokes themselves. I'm listening away to the new Radiohead The King of Limbs vinyl as I write this, the sound is warm and smooth, just as a record should sound.


Please read the full story here: http://www.diyaudioblog.com/2011/02/bottlehead-seduction-phono-pre-amp.html 

The Fine Print:

Please remember that building circuits and performing circuit modifications can be dangerous to you and/or your surroundings and should only be performed by a certified technician. The owner of this blog and all associated parties can not / will not be held responsible if you attempt a build or modification posted above and cause physical harm to yourself or your surroundings. Many electronics contain high voltages that can kill, and mods, if performed improperly, can be a fire hazard. Please keep this in mind.