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. 

The Latest Updates - Bottlehead and MHDT

Like an artist may say that a painting is never done, or the guys at PIXAR saying a movie is never finished, some of us electronics nuts feel like a project is never done. There is always another tweak, another piece to be added, substituted or upgraded. In the interest of keeping all information on a particular project in one place, I regularly go back and edit existing posts to include updates.

The first update to cover is the MHDT Constantine NOS DAC. When I was placing an order for some nicer caps in the MHDT Paradisea, I opted to get a few for the older Constantine as well, replacing the four 0.10uF stock caps with Obbligatos. A little bit of drilling of the soldering eyelets was required for the thick leads. Luckily, the Constantine board is one sided and I didn't have to worry about the conductive shells of the Obbligatos touching any traces. I did opt to add Teflon sleeving to the leads so that they wouldn't short across the shell though.

A few more of those beautiful gold Obbligatos for the Constantine

You can find the rest of the story here:
http://www.diyaudioblog.com/2011/02/modifying-mhdt-constantine-nos-dac.html

The second update covers a few additional modifications for the Bottlehead Crack headphone amplifier.  I managed to squeeze in a Solen 220uF film cap in the final electrolytic power cap location, sitting on a pair of standoffs. I also took the time to bypass the other two power caps with a pair of low-cost Audiophiler 2.2uF film caps. A Triad C7X was selected with a rating of 270ohms to take the place of the final resistor in the power supply (also 270 ohms). Since pretty much all the real estate has been used up on the plate, two 2" aluminum standoffs were used to raise the choke above the capacitor near the RCA inputs. This required adding 1" spiked feet to the bottom of the wood base for adequate clearance, just like in the Bottlehead S.E.X. build.  

Large Solen power cap and Triad choke

You can find the rest of the story here:

http://www.diyaudioblog.com/2011/02/bottlehead-crack-otl-headphone.html

Finally, just a few days ago a MHDT Paradisea NOS DAC modification project was finished up. A variety of nice items were installed including Takman and Kiwame carbon film resistors along with Obbligato and Mundorf Silver Oil film capacitors. Next on the list for this mod is a Burr Brown op-amp to replace the stock Analog Devices one. 

Some creative mounting of the Mundorf Silve Oil Caps

You can see the whole story here:

http://www.diyaudioblog.com/2011/05/modifying-mhdt-paradisea-nos-dac.html  

Be sure to keep an eye out on other posts for new updates. I hope to be finishing up the Millett Jonokuchi headphone amplifier in the next few weeks, along with casing up a completed AMB Mini Cubed portable headphone amplifier. Of course it will be unique looking like my other projects ;)

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 modification posted below 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.